TextImager.cpp

/*
 * Copyright(c) Sophist Solutions, Inc. 1990-2025.  All rights reserved
 */
#include "Stroika/Frameworks/StroikaPreComp.h"
 
#include "Stroika/Frameworks/Led/GDI.h"
 
#include "TextImager.h"
 
using namespace Stroika::Foundation;
 
using namespace Stroika::Foundation;
using namespace Stroika::Frameworks;
using namespace Stroika::Frameworks::Led;
 
#if qStroika_Frameworks_Led_SupportGDI
 
/*
 ********************************************************************************
 *********************** TextImager::FontCacheInfoUpdater ***********************
 ********************************************************************************
 */
#if qStroika_Foundation_Common_Platform_Windows
namespace {
    inline bool LogFontsEqual_ (LOGFONT lhs, LOGFONT rhs)
    {
        size_t bytesToCompare = offsetof (LOGFONT, lfFaceName) + (::_tcslen (lhs.lfFaceName) + 1) * sizeof (Characters::SDKChar);
        Require (bytesToCompare <= sizeof (LOGFONT)); // else we were passed bogus LogFont (and we should validate them before here!)
        return ::memcmp (&lhs, &rhs, bytesToCompare) == 0;
    }
    inline bool LogFontsEqual_ (const FontSpecification& lhs, const FontSpecification& rhs)
    {
        if (lhs.GetStyle_SubOrSuperScript () == rhs.GetStyle_SubOrSuperScript ()) {
            LOGFONT lhslf;
            lhs.GetOSRep (&lhslf);
            LOGFONT rhslf;
            rhs.GetOSRep (&rhslf);
            return LogFontsEqual_ (lhslf, rhslf);
        }
        else {
            return false;
        }
    }
}
#endif
TextImager::FontCacheInfoUpdater::FontCacheInfoUpdater (const TextImager* imager, Tablet* tablet, const FontSpecification& fontSpec)
    : fImager{imager}
#if qStroika_Foundation_Common_Platform_Windows
    , fTablet{tablet}
    , fRestoreObject{nullptr}
    , fRestoreAttribObject{nullptr}
#endif
{
#if qStroika_Foundation_Common_Platform_Windows
    /*
     *  For Windows:
     *
     *      Just set the font using the font-spec. Cache font, so we don't keep creating. But select it
     *  in to tablet each time. And on DTOR, restore old font into tablet.
     */
    bool changed = false;
    if (imager->fCachedFont == nullptr or !LogFontsEqual_ (fontSpec, imager->fCachedFontSpec)) {
        changed = true;
        delete imager->fCachedFont;
        imager->fCachedFont = nullptr;
        imager->fCachedFont = new FontObject ();
        LOGFONT lf;
        fontSpec.GetOSRep (&lf);
        if (fontSpec.GetStyle_SubOrSuperScript () != FontSpecification::eNoSubOrSuperscript) {
            // See SPR#1523- was 'lf.lfHeight /= 2'
            // Careful to sync this with TextImager::DrawSegment_ () 'drawTop' adjustment
            lf.lfHeight = lf.lfHeight * 2 / 3;
            if (lf.lfHeight == 0) {
                lf.lfHeight = 1;
            }
        }
        Verify (imager->fCachedFont->CreateFontIndirect (&lf));
        imager->fCachedFontSpec = fontSpec;
    }
    AssertNotNull (imager->fCachedFont);
 
    // See CDC::SelectObject for the logic..., but we do better than thiers and restore
    // right object to right DC!!!! - LGP 950525
    if (tablet->m_hDC != tablet->m_hAttribDC) {
        fRestoreObject = ::SelectObject (tablet->m_hDC, imager->fCachedFont->m_hObject);
        // At one point i had Asserts() here that fRestoreObject != nullptr - but at least for PrintDC's, apparently
        // fRestoreObject can be nullptr, and apparently it isn't a problem...
    }
    if (tablet->m_hAttribDC != nullptr) {
        fRestoreAttribObject = ::SelectObject (tablet->m_hAttribDC, imager->fCachedFont->m_hObject);
        // At one point i had Asserts() here that fRestoreAttribObject != nullptr - but at least for PrintDC's, apparently
        // fRestoreAttribObject can be nullptr, and apparently it isn't a problem...
    }
    if (changed) {
        imager->fCachedFontInfo = tablet->GetFontMetrics ();
    }
#elif qStroika_FeatureSupported_XWindows
    tablet->SetFont (fontSpec);
    imager->fCachedFontInfo = tablet->GetFontMetrics ();
#endif
}
 
/*
 ********************************************************************************
 ************************************** TextImager ******************************
 ********************************************************************************
 */
TextImager::TextImager ()
    : fTextStore{nullptr}
    , fDefaultFont{GetStaticDefaultFont ()}
    , fForceAllRowsShowing{true}
    , fImageUsingOffscreenBitmaps{qUseOffscreenBitmapsToReduceFlicker}
    , fHScrollPos{0}
    , fSuppressGoalColumnRecompute{false}
    , fSelectionGoalColumn{TWIPS{0}}
    , fUseEOLBOLRowHilightStyle{true}
    , fSelectionShown{false}
    , fWindowRect{Led_Rect{0, 0, 0, 0}}
    , fHiliteMarker{nullptr}
    , fWeAllocedHiliteMarker{false} //,  fDefaultColorIndex{},
    , fCachedFontSpec{}
    , fCachedFontInfo{}
    ,
#if qStroika_Foundation_Common_Platform_Windows
    fCachedFont{nullptr}
#else
    fCachedFontValid{false}
#endif
{
    for (Color** i = &fDefaultColorIndex[0]; i < &fDefaultColorIndex[eMaxDefaultColorIndex]; ++i) {
        *i = nullptr;
    }
}
 
TextImager::~TextImager ()
{
    Require (fTextStore == nullptr);
    Require (fHiliteMarker == nullptr);
    for (Color** i = &fDefaultColorIndex[0]; i < &fDefaultColorIndex[eMaxDefaultColorIndex]; ++i) {
        delete *i;
        *i = nullptr;
    }
#if qStroika_Foundation_Common_Platform_Windows
    delete fCachedFont;
#endif
}
 
TextStore* TextImager::PeekAtTextStore () const
{
    return fTextStore; // Can return nullptr if no markers owned
}
 
/*
@METHOD:        TextImager::SpecifyTextStore
@DESCRIPTION:   <p>Associate this TextImager with the given @'TextStore'.</p>
        <p>Note that this will - as a side-effect - call
    @'TextStore::AddMarkerOwner'. So be sure that this @'TextImager' has not yet been added as a @'MarkerOwner' for
    any other (or this given) TextStore.</p>
*/
void TextImager::SpecifyTextStore (TextStore* useTextStore)
{
    if (fTextStore != useTextStore) {
        if (fTextStore != nullptr) {
            HookLosingTextStore ();
        }
        fTextStore = useTextStore;
        if (fTextStore != nullptr) {
            HookGainedNewTextStore ();
        }
    }
}
 
void TextImager::HookLosingTextStore ()
{
    HookLosingTextStore_ ();
}
 
void TextImager::HookLosingTextStore_ ()
{
    // BE MORE CAREFUL HERE - NO NEED TO DELETE HILIGHT MARKER - JUST REMOVE AND RE_ADD!!!
    AssertNotNull (fTextStore);
    if (fHiliteMarker != nullptr) {
        Assert (fWeAllocedHiliteMarker); // otherwise setter better have unset!!!
        GetTextStore ().RemoveMarker (fHiliteMarker);
        delete fHiliteMarker;
        fHiliteMarker = nullptr;
        fTextStore->RemoveMarkerOwner (this);
    }
}
 
void TextImager::HookGainedNewTextStore ()
{
    HookGainedNewTextStore_ ();
}
 
void TextImager::HookGainedNewTextStore_ ()
{
    AssertNotNull (fTextStore);
    if (fHiliteMarker == nullptr) {
        fTextStore->AddMarkerOwner (this);
        SetHilightMarker (nullptr); // forces creation of default one...
    }
}
 
/*
@METHOD:        TextImager::PurgeUnneededMemory
@DESCRIPTION:   <p>Call when you want to have the text engine save a little bit of memory. Frees up data
            that isn't required. This doesn't NEED to be called, but can be called by memory-restricted applications.
            The default implementation calls @'TextImager::InvalidateAllCaches'.
            </p>
*/
void TextImager::PurgeUnneededMemory ()
{
    InvalidateAllCaches ();
}
 
/*
@METHOD:        TextImager::InvalidateAllCaches
@DESCRIPTION:   <p>This is called - for example - when you change the wrap width for the entire document, or font information
            for the entire document, or maybe something about the @'Tablet*' metrics you are imaging to.
            TextImager::InvalidateAllCaches is called automatically from @'MultiRowTextImager::TabletChangedMetrics ()'
            </p>
*/
void TextImager::InvalidateAllCaches ()
{
// Classes which cache font-based information must OVERRIDE and invalidate it...
#if qStroika_Foundation_Common_Platform_Windows
    delete fCachedFont;
    fCachedFont = nullptr;
#else
    fCachedFontValid = false;
#endif
}
 
/*
@METHOD:        TextImager::SetDefaultFont
@DESCRIPTION:   <p>Sets the default font associated with the given imager. This is NOT necessarily the one you will
            see displayed, as the font displayed maybe overriden by more specific font information from
            @'StyledTextImager::StyleMarker' or @'StandardStyledTextImager'.
            </p>
                <p>Note that the semantics of SetDefaultFontChanged in 3.1a4. If you want to set the font
            of a specific range of styled text (e.g. in a word-processor class) - then you may want to
            use @'StandardStyledTextInteractor::InteractiveSetFont'.
            </p>
*/
void TextImager::SetDefaultFont (const IncrementalFontSpecification& defaultFont)
{
    SetDefaultFont_ (defaultFont);
}
 
void TextImager::SetDefaultFont_ (const IncrementalFontSpecification& defaultFont)
{
    if (PeekAtTextStore () != nullptr) {
        TextStore::SimpleUpdater u (GetTextStore (), 0, GetTextStore ().GetEnd (), false); // update buffer so cached measurement values refreshed
        fDefaultFont.MergeIn (defaultFont);
        if (defaultFont.GetTextColor_Valid ()) {
            SetDefaultTextColor (eDefaultTextColor, defaultFont.GetTextColor ());
        }
    }
    else {
        fDefaultFont.MergeIn (defaultFont);
        if (defaultFont.GetTextColor_Valid ()) {
            SetDefaultTextColor (eDefaultTextColor, defaultFont.GetTextColor ());
        }
    }
}
 
/*
@METHOD:        TextImager::GetDefaultSelectionFont
@DESCRIPTION:   <p>Some applications - such as updating the font of the IME - need to know the
            current selections font. For some @'TextImager's this is easy - its just the font used
            for the entire widget (or default implementation). But for others - say an imager with
            multiple runs of fonts - it can be ambiguous. There is no strictly <em>right</em> answer
            for what to return if there are overlapping runs of font information. Just return the best
            fit possible.
                </p>
                <p>The default implementation just returns @'TextImager::GetDefaultFont', but
            should be subclassed by @'StandardStyledTextImager::GetDefaultSelectionFont' to reflect just
            the selection's current font.
            </p>
*/
FontSpecification TextImager::GetDefaultSelectionFont () const
{
    return GetDefaultFont ();
}
 
void TextImager::SetSelectionShown (bool shown)
{
    fSelectionShown = shown;
}
 
/*
@METHOD:        TextImager::GetTabStopList
@DESCRIPTION:   <p>Return the tabstop list (@'TabStopList') active at a particular position in the text. Typically this will
    apply to an entire region (often a paragraph/partitionmarker). And we only need specify
    one point in that range.</p>
        <p>Override this to provide a different tabstop list. The default is a @'TextImager::SimpleTabStopList' of width
    roughly 1/3 of an inch.</p>
*/
const TabStopList& TextImager::GetTabStopList (size_t /*containingPos*/) const
{
    // 1/3 inch tabstops by default (roughly 4 chars wide on Mac in Courier 10-point)
    static SimpleTabStopList sDefaultTabStopList = SimpleTabStopList (TWIPS (1440 / 3));
    return sDefaultTabStopList;
}
 
/*
@METHOD:        TextImager::SetWindowRect
@DESCRIPTION:   <p>See also @'TextImager::GetWindowRect'.
*/
void TextImager::SetWindowRect (const Led_Rect& windowRect)
{
    SetWindowRect_ (windowRect);
}
 
/*
@METHOD:        TextImager::ScrollSoShowingHHelper
@DESCRIPTION:   <p>You probably should NOT call this directly. This is a helper to share code in implementing
    @'TextImager::ScrollSoShowing' in subclasses.</p>
*/
void TextImager::ScrollSoShowingHHelper (size_t markerPos, size_t andTryToShowMarkerPos)
{
    CoordinateType maxHScrollPos = ComputeMaxHScrollPos ();
    CoordinateType hsp           = GetHScrollPos ();
 
    /*
     *  Speed tweek - avoid alot of computations which are unneeded if this is true.
     */
    if (maxHScrollPos == 0) {
        if (hsp != 0) {
            SetHScrollPos (0);
        }
        return;
    }
 
    Led_Rect windowRect = GetWindowRect ();
 
    {
        // Try to see if we can accomodate the 'andTryToShowMarkerPos'.
        Led_Rect       andTryRRR             = GetCharWindowLocation (andTryToShowMarkerPos);
        CoordinateType whereAtInGlobalCoords = windowRect.left - andTryRRR.left;
        if (andTryRRR.left < windowRect.left) {
            Assert (hsp >= whereAtInGlobalCoords);
            hsp -= whereAtInGlobalCoords;
        }
        else if (andTryRRR.right > windowRect.right) {
            CoordinateType howFarOffRight = andTryRRR.right - windowRect.right;
            hsp += howFarOffRight; // now the char should be just barely showing.
            hsp = min (hsp, maxHScrollPos);
        }
    }
    Assert (hsp >= 0);
    Assert (hsp <= maxHScrollPos);
 
    {
        // Make sure the 'markerPos' is shown. Do this second - in case there is a conflict between 'markerPos' and 'andTryToShowMarkerPos'
        Led_Rect rrr = GetCharWindowLocation (markerPos);
 
        {
            CoordinateType adjustRRRBy = GetHScrollPos () - hsp;
            rrr += Led_Point (0, adjustRRRBy);
        }
 
        CoordinateType whereAtInGlobalCoords = windowRect.GetLeft () - rrr.GetLeft ();
        if (rrr.GetLeft () < windowRect.GetLeft ()) {
            Assert (hsp >= whereAtInGlobalCoords);
            hsp -= whereAtInGlobalCoords;
        }
        else if (rrr.GetRight () > windowRect.GetRight ()) {
            CoordinateType howFarOffRight = rrr.GetRight () - windowRect.GetRight ();
            hsp += howFarOffRight; // now the char should be just barely showing.
            hsp = min (hsp, maxHScrollPos);
        }
    }
 
    Assert (hsp >= 0);
    Assert (hsp <= maxHScrollPos);
    SetHScrollPos (hsp);
}
 
void TextImager::SetHScrollPos (CoordinateType hScrollPos)
{
    if (hScrollPos != GetHScrollPos ()) {
        SetHScrollPos_ (hScrollPos);
        InvalidateScrollBarParameters ();
    }
}
 
/*
@METHOD:        TextImager::ComputeMaxHScrollPos
@DESCRIPTION:   <p>This routine is used for horizontal scrolling (though not from within this class).
            It is mainly called by @'TextInteractor' or @'Led_Win32' etc methods to handle display/positioning
            of the scrollbar. Subclasses can OVERRIDE this to implement whatever horizontal scrolling
            they might want to.
            </p>
                <p>A plausible OVERRIDE
            of this routine might return (roughly - taking care of min'ing out to zero)
            <code>CalculateLongestRowInWindowPixelWidth () - GetWindowRect ().GetWidth ()</code>
            or perhaps even better:
            <code>CalculateLongestRowInDocumentPixelWidth () - GetWindowRect ().GetWidth ()</code>
            </p>
                <p>Some subclasses - such as @'WordProcessor' - already contain their own implementation
            (@'WordProcessor::ComputeMaxHScrollPos').
            </p>
*/
DistanceType TextImager::ComputeMaxHScrollPos () const
{
    return 0;
}
 
/*
@METHOD:        TextImager::CalculateLongestRowInWindowPixelWidth
@DESCRIPTION:   <p>This is a utility methods, very handy for implementing horizontal scrolling.
    It can (and should be) overriden in certain subclasses for efficiency. But the default implementation will work.</p>
*/
DistanceType TextImager::CalculateLongestRowInWindowPixelWidth () const
{
    size_t startOfWindow = GetMarkerPositionOfStartOfWindow ();
    size_t endOfWindow   = GetMarkerPositionOfEndOfWindow ();
 
    DistanceType longestRowWidth = 0;
    for (size_t curOffset = startOfWindow; curOffset < endOfWindow;) {
        DistanceType thisRowWidth = CalcSegmentSize (curOffset, GetEndOfRowContainingPosition (curOffset));
        longestRowWidth           = max (longestRowWidth, thisRowWidth);
        {
            size_t newOffset = GetStartOfNextRowFromRowContainingPosition (curOffset);
            if (newOffset <= curOffset) {
                break; // can happen at end of doc...
            }
            curOffset = newOffset;
        }
    }
    return longestRowWidth;
}
 
/*
@METHOD:        TextImager::TabletChangedMetrics
@DESCRIPTION:   <p>Call this method when something external, Led cannot detect, has happened to the tablet which would
    invalidate any information the @'TextImager' has cached. This is called automaticly, internal to Led, by anything
    Led knows about which would change the metrics.</p>
*/
void TextImager::TabletChangedMetrics ()
{
    InvalidateAllCaches ();
}
 
void TextImager::SetSelection (size_t start, size_t end)
{
    Assert (start >= 0);
    Assert (end <= GetEnd ()); // char 1 between positions 1..2
    if (start != GetSelectionStart () or end != GetSelectionEnd ()) {
        SetSelection_ (start, end);
    }
}
 
size_t TextImager::GetSelectionStart () const
{
    RequireNotNull (PeekAtTextStore ()); // Must specify TextStore before calling this, or any routine that calls it.
    return (fHiliteMarker->GetStart ());
}
 
size_t TextImager::GetSelectionEnd () const
{
    RequireNotNull (PeekAtTextStore ()); // Must specify TextStore before calling this, or any routine that calls it.
    return (fHiliteMarker->GetEnd ());
}
 
void TextImager::GetSelection (size_t* start, size_t* end) const
{
    RequireNotNull (PeekAtTextStore ()); // Must specify TextStore before calling this, or any routine that calls it.
    AssertNotNull (start);
    AssertNotNull (end);
    fHiliteMarker->GetRange (start, end);
}
 
void TextImager::SetSelection_ (size_t start, size_t end)
{
    Require (start >= 0);
    Require (end <= GetEnd ());
    Require (start <= end);
    GetTextStore ().SetMarkerRange (fHiliteMarker, start, end);
}
 
void TextImager::SetHilightMarker (HilightMarker* newHilightMarker)
{
    size_t start = 0;
    size_t end   = 0;
    if (fHiliteMarker != nullptr) {
        fHiliteMarker->GetRange (&start, &end);
        GetTextStore ().RemoveMarker (fHiliteMarker);
        if (fWeAllocedHiliteMarker) {
            delete fHiliteMarker;
        }
    }
    fHiliteMarker          = newHilightMarker;
    fWeAllocedHiliteMarker = bool (fHiliteMarker == nullptr);
    if (fHiliteMarker == nullptr) {
        fHiliteMarker = new HilightMarker ();
    }
    AssertNotNull (fHiliteMarker);
    GetTextStore ().AddMarker (fHiliteMarker, start, end - start, this);
}
 
/*
@METHOD:        TextImager::RecomputeSelectionGoalColumn
@DESCRIPTION:   <p></p>
*/
void TextImager::RecomputeSelectionGoalColumn ()
{
    if (not fSuppressGoalColumnRecompute) {
        // We now maintain a goal-column-target using pixel offsets within the row, rather than
        // character offsets, cuz thats what LEC/Alan Pollack prefers, and I think most
        // Texteditors seem todo likewise - LedSPR#0315
        DistanceType lhs = 0;
        DistanceType rhs = 0;
        GetRowRelativeCharLoc (GetSelectionStart (), &lhs, &rhs);
        SetSelectionGoalColumn (Tablet_Acquirer (this)->CvtToTWIPSH (lhs + (rhs - lhs) / 2));
    }
}
 
/*
@METHOD:        TextImager::ComputeRelativePosition
@DESCRIPTION:   <p></p>
*/
size_t TextImager::ComputeRelativePosition (size_t fromPos, CursorMovementDirection direction, CursorMovementUnit movementUnit)
{
    /*
     *  Handle all the different cases of movement directions (back, forward etc) and units (by char, word etc).
     *  Take the given starting point, and produce no side effects - returning the new resulting position.
     */
    switch (direction) {
        case eCursorBack: {
            switch (movementUnit) {
                case eCursorByChar: {
                    return (FindPreviousCharacter (fromPos));
                } break;
 
                case eCursorByWord: {
                    return (GetTextStore ().FindFirstWordStartStrictlyBeforePosition (fromPos));
                } break;
 
                case eCursorByRow: {
                    size_t startOfStartRow = GetStartOfRowContainingPosition (fromPos);
                    size_t startOfPrevRow  = GetStartOfPrevRowFromRowContainingPosition (fromPos);
                    if (startOfStartRow == startOfPrevRow) {
                        // no change
                        return (fromPos);
                    }
                    else {
                        return GetRowRelativeCharAtLoc (Tablet_Acquirer (this)->CvtFromTWIPSH (GetSelectionGoalColumn ()), startOfPrevRow);
                    }
                } break;
 
                case eCursorByLine: {
                    size_t fromLine = GetTextStore ().GetLineContainingPosition (fromPos);
                    size_t newLine  = (fromLine > 0) ? fromLine - 1 : 0;
                    if (newLine == fromLine) {
                        // no change
                        return (fromPos);
                    }
                    else {
                        // try to maintain the same horizontal position across lines
                        size_t positionInLine = fromPos - GetTextStore ().GetStartOfLine (fromLine); // ZERO RELATIVE
                        Assert (positionInLine <= GetTextStore ().GetLineLength (fromLine));
                        positionInLine = min (positionInLine, GetTextStore ().GetLineLength (newLine)); // don't go past end of new line...
                        return GetTextStore ().GetStartOfLine (newLine) + positionInLine;
                    }
                } break;
 
                case eCursorByWindow: {
                    Assert (false); // nyi
                } break;
 
                case eCursorByBuffer: {
                    Assert (false); // makes no sense - use toStart...
                } break;
 
                default:
                    Assert (false);
            }
        } break;
 
        case eCursorForward: {
            switch (movementUnit) {
                case eCursorByChar: {
                    return (FindNextCharacter (fromPos));
                } break;
 
                case eCursorByWord: {
                    TextStore& ts = GetTextStore ();
                    return (ts.FindFirstWordStartAfterPosition (ts.FindNextCharacter (fromPos)));
                } break;
 
                case eCursorByRow: {
                    size_t startOfStartRow = GetStartOfRowContainingPosition (fromPos);
                    size_t startOfNextRow  = GetStartOfNextRowFromRowContainingPosition (fromPos);
                    if (startOfStartRow == startOfNextRow) {
                        // no change
                        return (fromPos);
                    }
                    else {
                        return GetRowRelativeCharAtLoc (Tablet_Acquirer (this)->CvtFromTWIPSH (GetSelectionGoalColumn ()), startOfNextRow);
                    }
                } break;
 
                case eCursorByLine: {
                    size_t fromLine = GetTextStore ().GetLineContainingPosition (fromPos);
                    size_t newLine  = (fromLine == GetTextStore ().GetLineCount () - 1) ? fromLine : (fromLine + 1);
                    Assert (newLine <= GetTextStore ().GetLineCount () - 1);
                    if (newLine == fromLine) {
                        // no change
                        return (fromPos);
                    }
                    else {
                        // try to maintain the same horizontal position across rows
                        size_t positionInLine = fromPos - GetTextStore ().GetStartOfLine (fromLine); // ZERO RELATIVE
                        Assert (positionInLine <= GetTextStore ().GetLineLength (fromLine));
                        positionInLine = min (positionInLine, GetTextStore ().GetLineLength (newLine)); // don't go past end of new line...
                        return (GetTextStore ().GetStartOfLine (newLine) + positionInLine);
                    }
                } break;
 
                case eCursorByWindow: {
                    Assert (false); // nyi
                } break;
 
                case eCursorByBuffer: {
                    Assert (false); // makes no sense - use eCursorToEnd...
                } break;
 
                default:
                    Assert (false);
            }
        } break;
 
        case eCursorToStart: {
            switch (movementUnit) {
                case eCursorByChar: {
                    Assert (false); // to start of character - does this make sense???
                } break;
 
                case eCursorByWord: {
                    return (GetTextStore ().FindFirstWordStartStrictlyBeforePosition (FindNextCharacter (fromPos)));
                } break;
 
                case eCursorByRow: {
                    size_t fromRow = GetRowContainingPosition (fromPos);
                    return (GetStartOfRow (fromRow));
                } break;
 
                case eCursorByLine: {
                    size_t result = GetTextStore ().GetStartOfLineContainingPosition (fromPos);
                    if (fromPos == result) {
                        result = GetTextStore ().GetStartOfLineContainingPosition (GetTextStore ().FindPreviousCharacter (result));
                    }
                    return result;
                } break;
 
                case eCursorByWindow: {
                    return (GetMarkerPositionOfStartOfWindow ());
                } break;
 
                case eCursorByBuffer: {
                    return (0);
                } break;
 
                default:
                    Assert (false);
            }
        } break;
 
        case eCursorToEnd: {
            switch (movementUnit) {
                case eCursorByChar: {
                    Assert (false); // to start of character - does this make sense???
                } break;
 
                case eCursorByWord: {
                    return (GetTextStore ().FindFirstWordEndAfterPosition (fromPos));
                } break;
 
                case eCursorByRow: {
                    size_t fromRow = GetRowContainingPosition (fromPos);
                    return (GetEndOfRow (fromRow));
                } break;
 
                case eCursorByLine: {
                    size_t result = GetTextStore ().GetEndOfLineContainingPosition (fromPos);
                    if (fromPos == result) {
                        result = GetTextStore ().GetEndOfLineContainingPosition (GetTextStore ().FindNextCharacter (result));
                    }
                    return result;
                } break;
 
                case eCursorByWindow: {
                    return (GetMarkerPositionOfEndOfWindow ());
                } break;
 
                case eCursorByBuffer: {
                    return (GetTextStore ().GetEnd ());
                } break;
 
                default:
                    Assert (false);
            }
        } break;
 
        default:
            Assert (false);
    }
    Assert (false); // not reached...
    return (fromPos);
}
 
/*
@METHOD:        TextImager::GetTextWindowBoundingRect
@DESCRIPTION:   <p>GetTextWindowBoundingRect () return a @'Led_Rect' which bounds
    the characters defined by the given marker positions. The will fit nicely around the
    characters if they all fit in one row (and one directional run), but may have sluff around the left/right sides
    if the range crosses row boundaries or directional runs (since the shape wouldn't be a rectangle, but a region -
    try GetSelectionWindowRegion () for that).</p>
        <p>This function operates on CharacterCells.</p>
        <p>This function operates in Window coordinates (ie window relative, calling @'TextImager::GetCharWindowLocation').</p>
        <p>Return value is pinned to be within the WindowRect.</p>
        <p>See also @'TextImager::GetIntraRowTextWindowBoundingRect'</p>
*/
Led_Rect TextImager::GetTextWindowBoundingRect (size_t fromMarkerPos, size_t toMarkerPos) const
{
    Require (fromMarkerPos <= toMarkerPos);
 
    Led_Rect windowRect = GetWindowRect ();
    Led_Rect r1         = GetCharWindowLocation (fromMarkerPos);
    Led_Rect r2         = r1;
    if (fromMarkerPos != toMarkerPos) {
        r2 = GetCharWindowLocation (FindPreviousCharacter (toMarkerPos));
    }
 
    size_t realEndOfRowOfFromMarkerPos = GetRealEndOfRowContainingPosition (fromMarkerPos);
 
    Led_Rect boundingRect;
    boundingRect.top    = r1.GetTop ();
    boundingRect.bottom = r2.GetBottom (); // too aggressive??? for case of end of row it is...
 
    if (realEndOfRowOfFromMarkerPos >= toMarkerPos) {
        /*
         *  One ROW case
         *
         *      This is pretty complicated. We must worry about multiple overlapping runs, and about the
         *  extensions from the start/end of the text to the window borders (depending on the
         *  segmentHilightedAtStart/segmentHilightedAtEnd flags).
         *
         *      I'm not terribly confident this code is all right, but it really doesn't need to be perfect (though
         *  it SHOULD be). Its just important that it returns a rectangle BIG ENOUGH to wrap ALL the releveant text.
         *  Being a little TOO big is only inelegant, and not tragic.
         *
         *      See SPR#1237 for some details (and a test case).
         */
 
        // A bit of a sloppy hack to make sure any drawing to the right or left of the text (up to the margin)
        // gets erased as well.
        size_t startOfRow              = GetStartOfRowContainingPosition (fromMarkerPos);
        size_t endOfRow                = GetEndOfRowContainingPosition (fromMarkerPos);
        bool   segmentHilightedAtStart = (fromMarkerPos == startOfRow);
        bool   segmentHilightedAtEnd   = endOfRow < toMarkerPos;
 
        boundingRect.left  = min (r1.GetLeft (), r2.GetLeft ());
        boundingRect.right = max (r1.GetRight (), r2.GetRight ());
 
        /*
         *
         *  Trouble is we could have something like:
         *      1 2 7 8 3 4 5 6 9
         *  and if I select from 6 to 9, I'll get just the right side of the row, and miss the
         *  characters from 7-8.
         *  Really I want all the way from the LHS of 7 to the RHS of 9 in this case.
         */
        TextLayoutBlock_Copy text = GetTextLayoutBlock (startOfRow, endOfRow);
 
        using ScriptRunElt        = TextLayoutBlock::ScriptRunElt;
        vector<ScriptRunElt> runs = text.GetScriptRuns ();
        if (runs.size () > 1) {
            // Only needed if there are nested runs...
            for (auto i = runs.begin (); i != runs.end (); ++i) {
                const ScriptRunElt& se = *i;
                if (TextStore::Overlap (startOfRow + se.fRealStart, startOfRow + se.fRealEnd, fromMarkerPos, toMarkerPos)) {
                    /*
                    *   OK - there is SOME overlap between this run and the [fromMarkerPos, toMarkerPos] range.
                    *
                    *   Now see if the run endpoints are in the from/to range, and if so, then extend the
                    *   bounding rectangle to accomodate them.
                    */
                    if (fromMarkerPos <= startOfRow + se.fRealStart and startOfRow + se.fRealStart <= toMarkerPos) {
                        Led_Rect t1        = GetCharWindowLocation (startOfRow + se.fRealStart);
                        boundingRect.left  = min (boundingRect.left, t1.GetLeft ());
                        boundingRect.right = max (boundingRect.right, t1.GetRight ());
                    }
 
                    if (fromMarkerPos <= startOfRow + se.fRealEnd and startOfRow + se.fRealEnd <= toMarkerPos) {
                        Led_Rect t2        = GetCharWindowLocation (FindPreviousCharacter (startOfRow + se.fRealEnd));
                        boundingRect.left  = min (boundingRect.left, t2.GetLeft ());
                        boundingRect.right = max (boundingRect.right, t2.GetRight ());
                    }
                }
            }
        }
 
        if (segmentHilightedAtStart) {
            boundingRect.left = windowRect.left;
        }
        if (segmentHilightedAtEnd) {
            boundingRect.right = windowRect.right;
        }
    }
    else {
        /*
         *  Two or more ROWS case
         */
        boundingRect.left  = windowRect.left;
        boundingRect.right = windowRect.right;
    }
 
    // pin the results to be within the boundingRect (left and right)
    boundingRect.left  = max (boundingRect.left, windowRect.left);
    boundingRect.right = min (boundingRect.right, windowRect.right);
 
    Ensure (boundingRect.right >= boundingRect.left);
    return (boundingRect);
}
 
/*
@METHOD:        TextImager::GetIntraRowTextWindowBoundingRect
@ACCESS:        public
@DESCRIPTION:   <p>GetIntraRowTextWindowBoundingRect () return a Rect which bounds
            the characters defined by the given marker positions. The marker positions are required to fall
            within a single row.
                <p>This function operates on CharacterCells.</p>
                <p>This function operates in Window coordinates (ie the same coordinates as the WindowRect,
            is specified in - calling @'TextImager::GetCharWindowLocation').</p>
                <p>See also @'TextImager::GetTextBoundingRect',
            @'TextImager::GetTextWindowBoundingRect' and @'TextImager::GetIntraRowTextWindowBoundingRect'</p>
                <p>You CAN call this function with any range of 'fromMarkerPos' to 'toMarkerPos' within a row, but it only REALLY
            makes sense if you call it within a directional segment.</p>
*/
Led_Rect TextImager::GetIntraRowTextWindowBoundingRect (size_t fromMarkerPos, size_t toMarkerPos) const
{
    Require (fromMarkerPos <= toMarkerPos); // and they must be within the same row!!! Assert later...
 
    Led_Rect windowRect = GetWindowRect ();
 
    /*
     *  Note that we could use one side of one character and the same side of the other (e.g. for LTR text
     *  the left side of the first and second charaters). The trouble with this is that the character at 'toMarkerPos'
     *  can sometimes be on another line - not RIGHT after the one we are interested in. Furthermore - now that
     *  we support BIDI text - it could be left or right or almost anywhere if it was the start of another run.
     *
     *  So - instead - we measure (taking the LTR case) from the LEFT side of the 'fromMarkerPos' character
     *  to the RIGHT side of the character PRECEDING the 'toMarkerPos' character (with the special case of when the two
     *  markerPos positions are the same.
     */
    Led_Rect r1 = GetCharWindowLocation (fromMarkerPos);
    Led_Rect r2 = r1;
    if (fromMarkerPos != toMarkerPos) {
        r2 = GetCharWindowLocation (FindPreviousCharacter (toMarkerPos));
    }
 
    Led_Rect boundingRect = r1;
 
    if (GetTextDirection (fromMarkerPos) == eLeftToRight) {
        boundingRect.left  = r1.GetLeft ();
        boundingRect.right = (fromMarkerPos == toMarkerPos) ? boundingRect.left : r2.GetRight ();
    }
    else {
        boundingRect.right = r1.GetRight ();
        boundingRect.left  = (fromMarkerPos == toMarkerPos) ? boundingRect.right : r2.GetLeft ();
    }
    Ensure (boundingRect.right >= boundingRect.left); // If this is triggered, its probably cuz your from/to crossed
    // a directional segment boundary?
    return (boundingRect);
}
 
/*
@METHOD:        TextImager::GetRowHilightRects
@ACCESS:        public
@DESCRIPTION:   <p>Compute the subregion of the row demarcated by 'rowStart' and 'rowEnd' which interesects with the given
            'hilightStart' and 'hilightEnd'. If the hilights extend past the row (either start or end) this is OK- and the
            hilight rectangle list is adjusted accordingly to display that extended hilgiht
            (if @'TextImager::GetUseSelectEOLBOLRowHilightStyle' is set).</p>
                <p>This routine is called by @'TextImager::GetSelectionWindowRegion' and @'TextImager::DrawRowHilight' to figure out what areas
            of the screen to hilight.</p>
*/
vector<Led_Rect> TextImager::GetRowHilightRects (const TextLayoutBlock& text, size_t rowStart, size_t rowEnd, size_t hilightStart, size_t hilightEnd) const
{
    Require (rowEnd == GetEndOfRowContainingPosition (rowStart)); // passed in for performance reasons - so not computed multiple times
 
    vector<Led_Rect> result;
 
    size_t realEndOfRow     = GetRealEndOfRowContainingPosition (rowStart);
    bool   segmentHilighted = max (rowStart, hilightStart) < min (realEndOfRow, hilightEnd);
    if (segmentHilighted) {
        bool segmentHilightedAtStart = false;
        bool segmentHilightedAtEnd   = false;
        if (GetUseSelectEOLBOLRowHilightStyle ()) {
            segmentHilightedAtStart = (hilightStart < rowStart) or (hilightStart == 0);
            segmentHilightedAtEnd   = rowEnd < hilightEnd;
            if (segmentHilightedAtEnd and rowEnd >= GetEnd ()) {
                segmentHilightedAtEnd = false; // last row always contains no NL - so no invert off to the right...
            }
        }
 
        hilightStart = max (hilightStart, rowStart);
 
        using ScriptRunElt        = TextLayoutBlock::ScriptRunElt;
        vector<ScriptRunElt> runs = text.GetScriptRuns ();
        //NB: it doesn't matter what order we iterate over the blocks and draw their hilight
        for (auto i = runs.begin (); i != runs.end (); ++i) {
            const ScriptRunElt& se        = *i;
            size_t              hRunStart = max (se.fRealStart + rowStart, hilightStart);
            size_t              hRunEnd   = min (se.fRealEnd + rowStart, hilightEnd);
            if (hRunStart < hRunEnd) {
                Led_Rect hilightRect = GetIntraRowTextWindowBoundingRect (hRunStart, hRunEnd);
                Assert (hilightRect.GetWidth () >= 0);
                Assert (hilightRect.GetHeight () >= 0);
                if (not hilightRect.IsEmpty ()) { // don't add empty rectangles
                    result.push_back (hilightRect);
                }
            }
        }
 
        // Add extra rects before or after all the text to the start/end of the row, as needed
        if (segmentHilightedAtStart) {
            size_t realOffsetOfVirtualRowStart = rowStart;
            if (text.GetTextLength () != 0) {
                realOffsetOfVirtualRowStart += text.MapVirtualOffsetToReal (0);
            }
            // Make sure the 'segmentHilightAtStart is drawn even if the selection only comes up to just before first char in row
            Led_Rect hilightRect = GetCharWindowLocation (realOffsetOfVirtualRowStart);
            hilightRect.right    = hilightRect.left;
            hilightRect.left     = min (GetWindowRect ().GetLeft (), hilightRect.left);
            Assert (hilightRect.GetWidth () >= 0);
            Assert (hilightRect.GetHeight () >= 0);
            if (not hilightRect.IsEmpty ()) { // don't add empty rectangles
                result.push_back (hilightRect);
            }
        }
        if (segmentHilightedAtEnd) {
            size_t realOffsetOfVirtualRowEnd = rowStart;
            if (text.GetTextLength () != 0) {
                realOffsetOfVirtualRowEnd += text.MapVirtualOffsetToReal (text.GetTextLength () - 1);
            }
            // Make sure the 'segmentHilightAtStart is drawn even if the selection only comes up to just before first char in row
            Led_Rect hilightRect = GetCharWindowLocation (realOffsetOfVirtualRowEnd);
            hilightRect.left     = hilightRect.GetRight ();
            hilightRect.right    = max (hilightRect.right, GetWindowRect ().GetRight ());
            Assert (hilightRect.GetWidth () >= 0);
            Assert (hilightRect.GetHeight () >= 0);
            if (not hilightRect.IsEmpty ()) { // don't add empty rectangles
                result.push_back (hilightRect);
            }
        }
    }
 
    if constexpr (qStroika_Foundation_Debug_AssertionsChecked) {
        // Make sure rectangles don't overlap with one another (can share an edge) -- SPR#1226
        for (auto orit = result.begin (); orit != result.end (); ++orit) {
            Ensure ((*orit).GetWidth () > 0);
            Ensure ((*orit).GetHeight () > 0);
            for (auto irit = orit + 1; irit != result.end (); ++irit) {
                Led_Rect hr = *irit;
                Ensure (hr.GetWidth () > 0);
                Ensure (hr.GetHeight () > 0);
                Ensure (not Intersect (hr, *orit));
            }
        }
    }
 
    return result;
}
 
/*
@METHOD:        TextImager::GetTextLayoutBlock
@ACCESS:        public
@DESCRIPTION:   <p>REQUIRE that rowStart and rowEnd are valid rowstart/end values</p>
*/
TextLayoutBlock_Copy TextImager::GetTextLayoutBlock (size_t rowStart, size_t rowEnd) const
{
    size_t                         rowLen = rowEnd - rowStart;
    Memory::StackBuffer<Led_tChar> rowBuf{Memory::eUninitialized, rowLen};
    CopyOut (rowStart, rowLen, rowBuf.data ());
    TextLayoutBlock_Basic text{rowBuf.data (), rowBuf.data () + rowLen};
    return TextLayoutBlock_Copy (text);
}
 
/*
@METHOD:        TextImager::GetSelectionWindowRects
@ACCESS:        public
@DESCRIPTION:   <p>Compute the window-relative region (list of rectangles) bounding the
            given segment of text. This is useful for displaying some sort of text hilight,
            in addition (or apart from) the standard hilighting of text.</p>
                <p>This function uses @'TextImager::GetRowHilightRects' to figure out what areas of the
            screen to hilight. This routine also tries to take into account interline space by
            extending the hilight from succeeding rows back to the bottom of the preceeding row.</p>
                <p>See also @'TextImager::GetSelectionWindowRegion'</p>
*/
vector<Led_Rect> TextImager::GetSelectionWindowRects (size_t from, size_t to) const
{
    Require (from <= to);
 
    vector<Led_Rect> result;
 
    from = max (from, GetMarkerPositionOfStartOfWindow ());
    to   = min (to, FindNextCharacter (GetMarkerPositionOfEndOfWindow ()));
 
    if (from >= to) {
        return result;
    }
    Assert (from < to);
 
    size_t topRow    = GetRowContainingPosition (from);
    size_t bottomRow = GetRowContainingPosition (to);
    Assert (topRow <= bottomRow);
 
    // If to is at the start of a row (remember - we wanted the to select char UP-TO that
    // MARKER POS) then we've gone one row too far
    if (GetStartOfRow (bottomRow) == to) {
        // then use end of previous row
        Assert (topRow < bottomRow);
        --bottomRow;
    }
 
    CoordinateType lastRowBottom = 0; // Keep track of last row's bottom for interline-space support
    for (size_t curRow = topRow;;) {
        size_t firstCharInRow = from;
        if (topRow != curRow) {
            firstCharInRow = GetStartOfRow (curRow);
        }
 
        size_t startOfRow = GetStartOfRowContainingPosition (firstCharInRow);
        size_t endOfRow   = GetEndOfRowContainingPosition (startOfRow);
#if 1
        TextLayoutBlock_Copy text = GetTextLayoutBlock (startOfRow, endOfRow);
#else
        size_t                         rowLen = endOfRow - startOfRow;
        Memory::StackBuffer<Led_tChar> rowBuf{Memory::eUninitialized, rowLen};
        CopyOut (startOfRow, rowLen, rowBuf);
        TextLayoutBlock_Basic text{rowBuf, rowBuf + rowLen};
#endif
 
        vector<Led_Rect> hilightRects = GetRowHilightRects (text, startOfRow, endOfRow, GetSelectionStart (), GetSelectionEnd ());
        CoordinateType   newMinTop    = lastRowBottom;
        CoordinateType   newMaxBottom = lastRowBottom;
        for (auto i = hilightRects.begin (); i != hilightRects.end (); ++i) {
            Led_Rect hilightRect = *i;
            Require (hilightRect.GetWidth () >= 0);
            Assert (hilightRect.GetHeight () > 0);
            if (not hilightRect.IsEmpty ()) {
                result.push_back (hilightRect);
            }
            newMinTop    = min (newMinTop, hilightRect.top);
            newMaxBottom = max (newMaxBottom, hilightRect.bottom);
        }
 
        /*
         *  Now that we've kept that lastRowBottom and this emitted rows minTop and maxBottom, we can
         *  see if there is any gap between the lastRowBottom and the newMinTop. If yes, then fill
         *  that gap.
         */
        if (lastRowBottom < newMinTop) {
            // Compute this hScrollAdjustedWR inside loop since it should happen extremely rarely, and doing it
            // outside would mean it gets called more (cuz we can only do the test inside).
            Led_Rect hScrollAdjustedWR = GetWindowRect () - Led_Point (0, GetHScrollPos ());
            result.push_back (Led_Rect (lastRowBottom, hScrollAdjustedWR.GetLeft (), newMinTop - lastRowBottom, hScrollAdjustedWR.GetWidth ()));
        }
        lastRowBottom = newMaxBottom;
 
        if (curRow == bottomRow) {
            break;
        }
        ++curRow;
    }
 
    if constexpr (qStroika_Foundation_Debug_AssertionsChecked) {
        // Make sure rectangles don't overlap with one another (can share an edge) -- SPR#1226
        for (auto orit = result.begin (); orit != result.end (); ++orit) {
            Ensure ((*orit).GetWidth () > 0);
            Ensure ((*orit).GetHeight () > 0);
            for (auto irit = orit + 1; irit != result.end (); ++irit) {
                Led_Rect hr = *irit;
                Ensure (hr.GetWidth () > 0);
                Ensure (hr.GetHeight () > 0);
                Ensure (not Intersect (hr, *orit));
            }
        }
    }
    return result;
}
 
/*
@METHOD:        TextImager::GetSelectionWindowRegion
@ACCESS:        public
@DESCRIPTION:   <p>Figure the region bounding the given segment of text. Useful for displaying
            some sort of text hilight, in addition (or apart from) the standard hilighting
            of text. Note we use a VAR parameter for the region rather than returing it
            cuz MFC's CRgn class doesn't support being copied.</p>
                <p>This routine is a simple wrapper on @'TextImager::GetSelectionWindowRects'</p>
*/
void TextImager::GetSelectionWindowRegion (Region* r, size_t from, size_t to) const
{
    RequireNotNull (r);
    vector<Led_Rect> selRects = GetSelectionWindowRects (from, to);
    for (auto i = selRects.begin (); i != selRects.end (); ++i) {
        AddRectangleToRegion (*i, r);
    }
}
 
/*
@METHOD:        TextImager::EraseBackground
@DESCRIPTION:   <p>EraseBackground () is called internally by TextImagers to get arbitrary subsets of the current
    window being drawn to erased. This erasure must only apply to the argument 'subsetToDraw'. Clipping is
    not used to gaurantee this. Failure to follow that rule can produce undesirably results where other bits of
    surrounding text get erased.</p>
        <p>The erasebackground call is made virtual so that you can use this as a hook to provide some sort
    of multi-media, picture or whatever as your background. Note that the is called during the draw
    process as a side-effect. So to have a changing background, you would need to both force periodic
    updates, and OVERRIDE this routine.</p>
        <p>NB: the argument 'subsetToDraw' can occasionally be outside of the WindowRect. If so - then DO draw where this
    function says to draw. This is because you maybe asked to erase window margins/borders outside the Led 'WindowRect' using
    the same color/algorithm as that used inside the Led WindowRect.</p>
        <p>By default - this simply calls @'Tablet::EraseBackground_SolidHelper' with @'Led_GetTextBackgroundColor' ().</p>
        <p>Note - typically when you OVERRIDE this - you will want to OVERRIDE @'TextImager::HilightARectangle' to change
    its implementation to specify a new background color (so inverting works properly). Perhaps see SPR#0708 for details.</p>
*/
void TextImager::EraseBackground (Tablet* tablet, const Led_Rect& subsetToDraw, bool printing)
{
    RequireNotNull (tablet);
    // Don't erase when printing - at least by default. Tends to screw up most print drivers.
    if (not printing) {
        tablet->EraseBackground_SolidHelper (subsetToDraw, GetEffectiveDefaultTextColor (TextImager::eDefaultBackgroundColor));
    }
}
 
/*
@METHOD:        TextImager::HilightArea
@DESCRIPTION:   <p>Hilight the given rectangle of the screen, after its been drawn. This is typically done via
    some sort of pixel or color invesion. The default implemtation uses @'Tablet::HilightArea_SolidHelper'.</p>
        <p>Override this mostly if you want different hilighting behavior, or if you want your hilighting behavior
    to remain in sync with other changes to the EraseBackground behavior.</p>
*/
void TextImager::HilightArea (Tablet* tablet, Led_Rect hiliteArea)
{
    RequireNotNull (tablet);
    tablet->HilightArea_SolidHelper (hiliteArea, GetEffectiveDefaultTextColor (eDefaultSelectedTextBackgroundColor),
                                     GetEffectiveDefaultTextColor (eDefaultSelectedTextColor),
                                     GetEffectiveDefaultTextColor (eDefaultBackgroundColor), GetEffectiveDefaultTextColor (eDefaultTextColor));
}
 
/*
@METHOD:        TextImager::HilightArea
@DESCRIPTION:   <p>Hilight the given region of the screen, after its been drawn. This is typically done via
    some sort of pixel or color invesion. The default implemtation uses @'Tablet::HilightArea_SolidHelper'.</p>
        <p>Override this mostly if you want different hilighting behavior, or if you want your hilighting behavior
    to remain in sync with other changes to the EraseBackground behavior.</p>
*/
void TextImager::HilightArea (Tablet* tablet, const Region& hiliteArea)
{
    RequireNotNull (tablet);
    tablet->HilightArea_SolidHelper (hiliteArea, GetEffectiveDefaultTextColor (eDefaultSelectedTextBackgroundColor),
                                     GetEffectiveDefaultTextColor (eDefaultSelectedTextColor),
                                     GetEffectiveDefaultTextColor (eDefaultBackgroundColor), GetEffectiveDefaultTextColor (eDefaultTextColor));
}
 
/*
@METHOD:        TextImager::DrawRow
@DESCRIPTION:   <p>Draw the given row of text. Erase the background (by calling @'TextImager::EraseBackground'), and
            then draw the segments of the row by calling @'TextImager::DrawRowSegments'. Then draw any hilighting.
            This routine CAN cause flicker. Flicker is eliminated at a higher level (caller) by using offscreen bitmaps (see @'MultiRowTextImager::Draw'
            or @'TextImager::GetImageUsingOffscreenBitmaps').</p>
                <p>NB: This bit about flicker changed in Led 2.2. Earlier Led versions tried to elminate flicker at all levels
            and avoid offscreen bitmaps. But problems with kerning made this difficult.</p>
                <p>Note, only the invalidRect subset of currentRowRect need be drawn, though the rest CAN be.</p>
                <p>Renamed to @'TextImager::DrawRowSegments' from MutliRowTextImager::DrawRowSegments for Led 3.1a3 release.</p>
*/
void TextImager::DrawRow (Tablet* tablet, const Led_Rect& currentRowRect, const Led_Rect& invalidRowRect, const TextLayoutBlock& text,
                          size_t rowStart, size_t rowEnd, bool printing)
{
    RequireNotNull (tablet);
    Require (rowEnd == GetEndOfRowContainingPosition (rowStart)); // passed in for performance reasons - so not computed multiple times
 
    /*
     *  Could CONSIDER doing something like:
     *
     *      Tablet::ClipNarrowAndRestore   clipFurtherTo (tablet, currentRowRect);
     *
     *  here, but it might have too much of a performance cost. Perhaps I should test this. See SPR#?????
     */
 
    EraseBackground (tablet, currentRowRect, printing);
 
    DrawRowSegments (tablet, currentRowRect, invalidRowRect, text, rowStart, rowEnd);
 
    /*
     *  Only draw hilighting if we aren't printing, because this doesn't show up well on printers.
     */
    if (not printing) {
        DrawRowHilight (tablet, currentRowRect, invalidRowRect, text, rowStart, rowEnd);
    }
}
 
/*
@METHOD:        TextImager::DrawRowSegments
@DESCRIPTION:   <p>Called by @'TextImager::DrawRow' to draw (in or mode - don't worry about erasing) all the segments
            which make up the row of text. Here, we take care of any sort of justification, or indending (in subclasses which OVERRIDE
            this method). Its rowRect its called with represents the entire row. Subclasses can call DrawSegment () with adjusted row-rects
            taking into account indents, etc.</p>
                <p>Note, only the invalidRect subset of currentRowRect need be drawn, though the rest CAN be.</p>
                <p>Renamed to @'TextImager::DrawRowSegments' from MutliRowTextImager::DrawRowSegments for Led 3.1a3 release.</p>
*/
void TextImager::DrawRowSegments (Tablet* tablet, const Led_Rect& currentRowRect, const Led_Rect& invalidRowRect,
                                  const TextLayoutBlock& text, size_t rowStart, size_t rowEnd)
{
    RequireNotNull (tablet);
 
#if qStroika_Foundation_Debug_AssertionsChecked && 0
    // try to get this code enabled again - even here!!! LGP 2002-12-02
    {
        size_t startOfRow   = GetStartOfRow (row);
        size_t endOfRow     = GetEndOfRow (row);
        size_t realEndOfRow = GetRealEndOfRow (row);
        Assert (startOfRow == start);
        Assert (endOfRow <= end);
        Assert (end <= realEndOfRow);
    }
#endif
 
    /*
     *  We always want to draw all the characters in the row - including the character
     *  that terminates the row. Typically - this is a space in a word-wrap so it
     *  cannot be seen. Or a NEWLINE char. In the case of a NEWLINE char - these
     *  don't really display properly - so we skip drawing those.
     *
     *  An earlier attempt at this said - DONT BOTHER drawing the wrap character. The problem
     *  with this is that in SOME languages (e.g. Japanese) the character used as a wrap-char
     *  may be a real useful (Japanese) character!
     */
    size_t         segEnd   = rowEnd;
    CoordinateType baseLine = currentRowRect.top + MeasureSegmentBaseLine (rowStart, segEnd);
 
    /*
     *  Its OK for the baseline to be outside of the currentRowRect. But the text display of this
     *  seems to mimic MSWord better if you pin the baseLine inside the rowRect.
     */
    baseLine = min (baseLine, currentRowRect.bottom);
 
    DrawSegment (tablet, rowStart, segEnd, text, currentRowRect, invalidRowRect, baseLine, nullptr);
}
 
/*
@METHOD:        TextImager::DrawRowHilight
@DESCRIPTION:   <p>Called by @'TextImager::DrawRow' to draw any necessary hilighting for the current selection
            for the given row.</p>
                <p>Note, only the invalidRect subset of currentRowRect need be drawn, though the rest CAN be.</p>
                <p>Renamed/Moved to @'TextImager::DrawRowHilight' from MutliRowTextImager::DrawRowHilight for Led 3.1a3 release.</p>
*/
void TextImager::DrawRowHilight (Tablet* tablet, [[maybe_unused]] const Led_Rect& currentRowRect, const Led_Rect& /*invalidRowRect*/,
                                 const TextLayoutBlock& text, size_t rowStart, size_t rowEnd)
{
    Require (rowEnd == GetEndOfRowContainingPosition (rowStart)); // passed in for performance reasons - so not computed multiple times
 
    if (GetSelectionShown ()) {
        vector<Led_Rect> hilightRects = GetRowHilightRects (text, rowStart, rowEnd, GetSelectionStart (), GetSelectionEnd ());
        for (auto i = hilightRects.begin (); i != hilightRects.end (); ++i) {
            Led_Rect hilightRect = *i;
            if constexpr (qStroika_Foundation_Debug_AssertionsChecked) {
                // Funky test - see SPR# 0470 for details...
                if (Intersect (hilightRect, currentRowRect) or hilightRect.IsEmpty ()) {
                    Led_Rect x = hilightRect;
                    Led_Rect y = currentRowRect;
                    x.left     = y.left;
                    x.right    = y.right;
                    Assert (Intersect (x, y) or x.IsEmpty ());
                }
            }
            HilightArea (tablet, hilightRect);
        }
    }
}
 
/*
@METHOD:        TextImager::DrawInterLineSpace
@DESCRIPTION:   <p>Typically called by @'MultiRowTextImager::DrawPartitionElement' or @'SimpleTextImager::DrawPartitionElement' to draw space between paragraphs (lines).
            Typically this is nothing. But this hook can be used to draw various sorts of annotations on
            paragraphs (as in LECs LVEJ side-by-side mode).</p>
                <p>Renamed to @'TextImager::DrawInterLineSpace' from MutliRowTextImager::DrawInterLineSpace for Led 3.1a3 release.</p>
*/
void TextImager::DrawInterLineSpace (DistanceType interlineSpace, Tablet* tablet, CoordinateType vPosOfTopOfInterlineSpace,
                                     bool segmentHilighted, bool printing)
{
    // This code not been checked/tested since I rewrote the erasing code etc.. Maybe wrong - probably wrong? No matter, anybody
    // ever using interline space would probably OVERRIDE this anyhow..
    // LGP 960516
    AssertNotNull (tablet);
    if (interlineSpace != 0) {
        Led_Rect fillRect = GetWindowRect ();
        fillRect.top      = vPosOfTopOfInterlineSpace;
        fillRect.bottom   = vPosOfTopOfInterlineSpace + interlineSpace;
        EraseBackground (tablet, fillRect, printing);
        if (segmentHilighted) {
            HilightArea (tablet, fillRect);
        }
    }
}
 
/*
@METHOD:        TextImager::ContainsMappedDisplayCharacters
@DESCRIPTION:   <p>Override this to specify if any of the given characters should be hidden, removed,
    or mapped to some other display character.
    You can change the behavior of this
    function at runtime (depending on user settings). But when its changed - you should invalidate all cached information,
    since cached font metrics will we invalid (often with @'MultiRowTextImager::InvalidateAllCaches ()').</p>
        <p>Note - this function doesn't REPLACE the given character from the text. Instead -
    it merely causes the @'TextImager::ReplaceMappedDisplayCharacters', @'TextImager::RemoveMappedDisplayCharacters',
    and @'TextImager::RemoveMappedDisplayCharacters' () methods to get called.</p>
        <p>Note also that this function takes an array of characters as a performance optimization (so it doesn't need to
    be called too many times, and to avoid copying buffers when nothing need be done). It could have been more logically
    (though less efficiently) implemented as bool IsMappedDisplayCharacter (Led_tChar).</p>
        <p>If you OVERRIDE this - you may find it handy to call @'TextImager::ContainsMappedDisplayCharacters_HelperForChar'
    to do most of the work.</p>
*/
bool TextImager::ContainsMappedDisplayCharacters (const Led_tChar* /*text*/, size_t /*nTChars*/) const
{
    return false;
}
 
/*
@METHOD:        TextImager::ReplaceMappedDisplayCharacters
@DESCRIPTION:   <p>Override this to specify any characters which should be mapped to different values at the last minute for
    display purposes only. This can be used to give a (simple to implement) funny display for particular special characters.
    For example, this technique can be used to make a NEWLINE character display as a special end-of-paragraph marker.</p>
        <p>If you OVERRIDE this - you may find it handy to call @'TextImager::ReplaceMappedDisplayCharacters_HelperForChar'
    to do most of the work.</p>
        <p>See also @'TextImager::ContainsMappedDisplayCharacters'.</p>
*/
void TextImager::ReplaceMappedDisplayCharacters (const Led_tChar* srcText, Led_tChar* copyText, size_t nTChars) const
{
    // Default to none replaced- just plain copy...
    (void)::memcpy (copyText, srcText, nTChars * sizeof (Led_tChar));
}
 
/*
@METHOD:        TextImager::RemoveMappedDisplayCharacters
@DESCRIPTION:   <p>Override this to specify any characters which should be removed at the last minute for
    display purposes only. This can be used to give a (simple to implement) way to hide some special characters.
    For example, this technique can be used to implement SHIFT-RETURN soft line breaks (as is done in
    @'WordWrappedTextImager::RemoveMappedDisplayCharacters').</p>
        <p>If you OVERRIDE this - you may find it handy to call @'TextImager::RemoveMappedDisplayCharacters_HelperForChar'
    to do most of the work.</p>
        <p>See also @'TextImager::ContainsMappedDisplayCharacters'.</p>
*/
size_t TextImager::RemoveMappedDisplayCharacters (Led_tChar* /*copyText*/, size_t nTChars) const
{
    // Default to none removed
    return nTChars;
}
 
/*
@METHOD:        TextImager::PatchWidthRemoveMappedDisplayCharacters
@DESCRIPTION:   <p>Override this to specify any characters which should be removed at the last minute for
    display purposes only. This particular function patches the distanceResults to zero out the removed characters.
    This can be used to give a (simple to implement) way to hide some special characters.</p>
        <p>For example, this technique can be used to implement SHIFT-RETURN soft line breaks (as is done in
    @'WordWrappedTextImager::RemoveMappedDisplayCharacters').</p>
        <p>If you OVERRIDE this - you may find it handy to call @'TextImager::PatchWidthRemoveMappedDisplayCharacters_HelperForChar'
    to do most of the work.</p>
        <p>See also @'TextImager::ContainsMappedDisplayCharacters'.</p>
*/
void TextImager::PatchWidthRemoveMappedDisplayCharacters (const Led_tChar* /*srcText*/, DistanceType* /*distanceResults*/, size_t /*nTChars*/) const
{
}
 
/*
@METHOD:        TextImager::ContainsMappedDisplayCharacters_HelperForChar
@DESCRIPTION:   <p>Simple implementation of See also @'TextImager::ContainsMappedDisplayCharacters' which is frequently applicable.
    Just specify the special character you are looking for.</p>
*/
bool TextImager::ContainsMappedDisplayCharacters_HelperForChar (const Led_tChar* text, size_t nTChars, Led_tChar charToMap)
{
    // 'charToMap' characters can appear anywhere in a segment of text (cuz this gets called to compute widths for an entire paragraph at a time).
    const Led_tChar* end = &text[nTChars];
    for (const Led_tChar* cur = text; cur < end; cur = Led_NextChar (cur)) {
        if (*cur == charToMap) {
            return true;
        }
    }
    return false;
}
 
/*
@METHOD:        TextImager::ReplaceMappedDisplayCharacters_HelperForChar
@DESCRIPTION:   <p>Simple implementation of See also @'TextImager::ReplaceMappedDisplayCharacters_HelperForChar' which is frequently applicable.
    Just specify the special character you are looking for, and the one you are mapping to.</p>
        <p>See also @'TextImager::ContainsMappedDisplayCharacters'.</p>
*/
void TextImager::ReplaceMappedDisplayCharacters_HelperForChar (Led_tChar* copyText, size_t nTChars, Led_tChar charToMap, Led_tChar charToMapTo)
{
    // 'charToMap' characters can appear anywhere in a segment of text (cuz this gets called to compute widths for an entire paragraph at a time).
    Led_tChar* end = &copyText[nTChars];
    for (Led_tChar* cur = copyText; cur < end; cur = Led_NextChar (cur)) {
        if (*cur == charToMap) {
            *cur = charToMapTo;
        }
    }
}
 
/*
@METHOD:        TextImager::RemoveMappedDisplayCharacters_HelperForChar
@DESCRIPTION:   <p>Simple implementation of See also @'TextImager::RemoveMappedDisplayCharacters' which is frequently applicable.
    Just specify the special character you are looking to remove.</p>
        <p>See also @'TextImager::ContainsMappedDisplayCharacters'.</p>
*/
size_t TextImager::RemoveMappedDisplayCharacters_HelperForChar (Led_tChar* copyText, size_t nTChars, Led_tChar charToRemove)
{
    // Trim out any kSoftLineBreakChar characters
    Led_tChar* outPtr = copyText;
    Led_tChar* end    = copyText + nTChars;
    for (const Led_tChar* cur = copyText; cur < end; cur = Led_NextChar (cur)) {
        if (*cur != charToRemove) {
            *outPtr = *cur;
            outPtr  = Led_NextChar (outPtr);
        }
    }
    size_t newLen = outPtr - copyText;
    Assert (newLen <= nTChars);
    return newLen;
}
 
/*
@METHOD:        TextImager::PatchWidthRemoveMappedDisplayCharacters_HelperForChar
@DESCRIPTION:   <p>Simple implementation of See also @'TextImager::PatchWidthRemoveMappedDisplayCharacters' which is frequently applicable.
    Just specify the special character you are looking to remove.</p>
        <p>See also @'TextImager::ContainsMappedDisplayCharacters'.</p>
*/
void TextImager::PatchWidthRemoveMappedDisplayCharacters_HelperForChar (const Led_tChar* srcText, DistanceType* distanceResults,
                                                                        size_t nTChars, Led_tChar charToRemove)
{
    // Each of these kSoftLineBreakChar will be mapped to ZERO-WIDTH. So walk text (and distanceResults) and when
    // I see a softlinebreak - zero its size, and subtrace from start point total amount of zero-ed softlinebreaks.
    DistanceType     cumSubtract = 0;
    const Led_tChar* end         = srcText + nTChars;
    for (const Led_tChar* cur = srcText; cur < end; cur = Led_NextChar (cur)) {
        size_t i = cur - srcText;
        Assert (i < nTChars);
        if (*cur == charToRemove) {
            DistanceType thisSoftBreakWidth = i == 0 ? distanceResults[0] : (distanceResults[i] - distanceResults[i - 1]);
            cumSubtract                     = thisSoftBreakWidth;
        }
        distanceResults[i] -= cumSubtract;
    }
}
 
/*
@METHOD:        TextImager::DrawSegment
@DESCRIPTION:   <p>DrawSegment () is responsible for rendering the text within a segment (subset of a row).
            Note that because of bidirectional display, the 'from' and 'to' are LOGICAL offsets (what are
            used to lookup in @'TextStore'), but they may NOT be the same as the display-order offsets. That is to
            say - a character between offset 10-11 could be either to the right or left of one at offset 13-14.
            </p>
                <p>Note we REQUIRE that useBaseLine be contained within drawInto invalidRect specified the subset of the drawInto
            rect which really must be filled in. This can be ignored, or used for logical clipping.</p>
                <p>See also @'TextImager::DrawSegment_'. The variable 'pixelsDrawn' is OPTIONAL parameter
            (ie filled in if non-nullptr)</p>
                <p>See also @'TextImager::DrawSegment_'.</p>
*/
void TextImager::DrawSegment (Tablet* tablet, size_t from, size_t to, const TextLayoutBlock& text, const Led_Rect& drawInto,
                              const Led_Rect& /*invalidRect*/, CoordinateType useBaseLine, DistanceType* pixelsDrawn)
{
    DrawSegment_ (tablet, GetDefaultFont (), from, to, text, drawInto, useBaseLine, pixelsDrawn);
}
 
/*
@DESCRIPTION:   <p>Helper function to access tablet text drawing. This function takes care of setting the background/foreground colors,
            and setting up a font object to be used in the Tablet::TabbedTextOut calls (maybe can go away if we do better integrating
            font code into Tablet. LedGDI and out of TextImager).
                <p>The 'from' marker position must be legit, since it is used to grab the tabstop list.
            The 'end' marker position is OK to fake (passing in other text), as it is just used to determine the string length. Note
            text in 'text' argument need not match the REAL text in the TextStore buffer.
        <p>See also @'TextImager::MeasureSegmentWidth_'.</p>
*/
void TextImager::DrawSegment_ (Tablet* tablet, const FontSpecification& fontSpec, size_t from, size_t to, const TextLayoutBlock& text,
                               const Led_Rect& drawInto, CoordinateType useBaseLine, DistanceType* pixelsDrawn) const
{
    RequireNotNull (tablet);
    Assert (from <= to);
 
    /*
     *  In the presence of multiple markers, you might VERY plaisbly OVERRIDE this method and
     *  change how the layout of text is done within a segment.
     *
     *  I've thought long and hard about how to automatically combine the drawing effects
     *  of different markers which overlap, and have come up with noting reasonable. So its
     *  up to YOU by overriding this method todo what you want.
     */
    [[maybe_unused]] size_t length = to - from;
 
    /*
     *  Setup the colors to be drawn.
     */
    Color foreColor = fontSpec.GetTextColor ();
    Color backColor = GetEffectiveDefaultTextColor (eDefaultBackgroundColor);
    tablet->SetBackColor (backColor);
    tablet->SetForeColor (foreColor);
 
    FontCacheInfoUpdater fontCacheUpdater{this, tablet, fontSpec};
 
    DistanceType ascent = fCachedFontInfo.GetAscent ();
    Assert (useBaseLine >= drawInto.top);
 
    //Assert (useBaseLine <= drawInto.bottom);      Now allowed... LGP 2000-06-12 - see SPR#0760 - and using EXACT-height of a small height, and use a large font
    CoordinateType drawCharTop = useBaseLine - ascent; // our PortableGDI_TabbedTextOut() assumes draw in topLeft
    //Require (drawCharTop >= drawInto.top);        // Same deal as for useBaseLine - LGP 2000-06-12
 
    if (fontSpec.GetStyle_SubOrSuperScript () == FontSpecification::eSuperscript) {
        // See SPR#1523- was 'drawCharTop -= fCachedFontInfo.GetAscent ()'
        // Careful to sync this with FontCacheInfoUpdater::CTOR () height adjustment
        // get back to (roughly - round down) original ascent. If we did TIMES 2/3 now
        // mutliply by reciprocal to get back (again - rounding down so we don't go
        // up too high).
        drawCharTop = useBaseLine - ascent * 3 / 2;
    }
    else if (fontSpec.GetStyle_SubOrSuperScript () == FontSpecification::eSubscript) {
        drawCharTop += fCachedFontInfo.GetDescent ();
    }
 
    using ScriptRunElt        = TextLayoutBlock::ScriptRunElt;
    vector<ScriptRunElt> runs = text.GetScriptRuns ();
    Assert (not runs.empty () or (length == 0));
    if (runs.size () > 1) {
        // sort by virtual start
        sort (runs.begin (), runs.end (), TextLayoutBlock::LessThanVirtualStart ());
    }
 
    const Led_tChar* fullVirtualText = text.PeekAtVirtualText ();
    Led_Point        outputAt        = Led_Point (drawCharTop, drawInto.left);
    if (pixelsDrawn != nullptr) {
        *pixelsDrawn = 0;
    }
    for (auto i = runs.begin (); i != runs.end (); ++i) {
        const ScriptRunElt& se        = *i;
        size_t              runLength = se.fVirtualEnd - se.fVirtualStart;
 
        /*
         *  Fill in the useVirtualText buffer with the text to draw.
         */
        Memory::StackBuffer<Led_tChar> useVirtualText{Memory::eUninitialized, runLength};
        (void)::memcpy (static_cast<Led_tChar*> (useVirtualText), &fullVirtualText[se.fVirtualStart], runLength * sizeof (Led_tChar));
 
        /*
         *  Process 'mapped display characters'
         */
        Led_tChar*                     drawText    = useVirtualText.data ();
        size_t                         drawTextLen = runLength;
        Memory::StackBuffer<Led_tChar> mappedDisplayBuf{1};
        if (ContainsMappedDisplayCharacters (drawText, drawTextLen)) {
            mappedDisplayBuf.GrowToSize (drawTextLen);
            ReplaceMappedDisplayCharacters (drawText, mappedDisplayBuf.data (), drawTextLen);
            size_t newLength = RemoveMappedDisplayCharacters (mappedDisplayBuf.data (), drawTextLen);
            Assert (newLength <= drawTextLen);
            drawText    = mappedDisplayBuf.data ();
            drawTextLen = newLength;
        }
 
        /*
         *  Actually draw the text.
         */
        DistanceType amountDrawn = 0;
        tablet->TabbedTextOut (fCachedFontInfo, drawText, drawTextLen, se.fDirection, outputAt, GetWindowRect ().left,
                               GetTabStopList (from), &amountDrawn, GetHScrollPos ());
        outputAt.h += amountDrawn;
        if (pixelsDrawn != nullptr) {
            *pixelsDrawn += amountDrawn;
        }
    }
}
 
void TextImager::MeasureSegmentWidth (size_t from, size_t to, const Led_tChar* text, DistanceType* distanceResults) const
{
    MeasureSegmentWidth_ (GetDefaultFont (), from, to, text, distanceResults);
}
 
/*
@METHOD:        TextImager::MeasureSegmentWidth_
@DESCRIPTION:   <p>Helper function to access tablet text measurement.</p>
                <p>The 'from' and 'to' marker positions are ignored, except to compute the width. There is no
            requirement that the 'text' argument refer to the same text as that stored in the TextStore object.
        <p>See also @'TextImager::DrawSegment_'.</p>
*/
void TextImager::MeasureSegmentWidth_ (const FontSpecification& fontSpec, size_t from, size_t to, const Led_tChar* text, DistanceType* distanceResults) const
{
    Require (to > from);
 
    Tablet_Acquirer tablet (this);
 
    size_t length = to - from;
    Assert (length > 0);
 
    FontCacheInfoUpdater fontCacheUpdater{this, tablet, fontSpec};
 
    if (ContainsMappedDisplayCharacters (text, length)) {
        Memory::StackBuffer<Led_tChar> buf2{Memory::eUninitialized, length};
        ReplaceMappedDisplayCharacters (text, buf2.data (), length);
        tablet->MeasureText (fCachedFontInfo, buf2.data (), length, distanceResults);
        PatchWidthRemoveMappedDisplayCharacters (buf2.data (), distanceResults, length);
    }
    else {
        tablet->MeasureText (fCachedFontInfo, text, length, distanceResults);
    }
}
 
DistanceType TextImager::MeasureSegmentHeight (size_t from, size_t to) const
{
    return (MeasureSegmentHeight_ (GetDefaultFont (), from, to));
}
 
DistanceType TextImager::MeasureSegmentHeight_ (const FontSpecification& fontSpec, size_t /*from*/, size_t /*to*/) const
{
    Tablet_Acquirer tablet (this);
    AssertNotNull (static_cast<Tablet*> (tablet));
    FontCacheInfoUpdater fontCacheUpdater{this, tablet, fontSpec};
    return (fCachedFontInfo.GetLineHeight ());
}
 
DistanceType TextImager::MeasureSegmentBaseLine (size_t from, size_t to) const
{
    return (MeasureSegmentBaseLine_ (GetDefaultFont (), from, to));
}
 
DistanceType TextImager::MeasureSegmentBaseLine_ (const FontSpecification& fontSpec, size_t /*from*/, size_t /*to*/) const
{
    Tablet_Acquirer tablet (this);
    AssertNotNull (static_cast<Tablet*> (tablet));
    FontCacheInfoUpdater fontCacheUpdater{this, tablet, fontSpec};
    return fCachedFontInfo.GetAscent ();
}
 
FontMetrics TextImager::GetFontMetricsAt ([[maybe_unused]] size_t charAfterPos) const
{
    Tablet_Acquirer tablet (this);
    AssertNotNull (static_cast<Tablet*> (tablet));
 
    FontSpecification fontSpec = GetDefaultFont ();
 
    FontCacheInfoUpdater fontCacheUpdater{this, tablet, fontSpec};
    return fCachedFontInfo;
}
 
#endif