Correct last right bearing in boundingBox(glyphs)

Commit 07880542ecc479807c23c5646d263135240822ff introduced regression to
QFontMetrics::boundingRect and QTextEngine::boundingBox on FT, XLFD and
QPF font engine. Because on these platforms, rightBearing of the last
glyphs is already removed from the width returned in glyph_metrics_t.
Subtracting that rightBearing twice will cause the resulting boundingBox
smaller than expected.

This patch fix this by removing last right bearing accounting code from
generic QTextEngine::boundingBox, instead, we put it into font engines
that need them: QFontEngineWin, QCoreTextFontEngine, QFontEngineMac,
QFontEngineS60 and QFontEngineQWS. So that the resulting width should be
correct on all platforms without introducing any performance penalties.

Task-number: QTBUG-6854, QTBUG-12950
Reviewed-by: Eskil

1 files changed, 9 insertions, 8 deletions

diff --git a/src/gui/text/qfontengine_mac.mm b/src/gui/text/qfontengine_mac.mm
index 91b6082..bdf3848 100644
--- a/src/gui/text/qfontengine_mac.mm
+++ b/src/gui/text/qfontengine_mac.mm
@@ -455,12 +455,13 @@ bool QCoreTextFontEngine::stringToCMap(const QChar *, int, QGlyphLayout *, int *
 glyph_metrics_t QCoreTextFontEngine::boundingBox(const QGlyphLayout &glyphs)
 {
     QFixed w;
+    bool round = fontDef.styleStrategy & QFont::ForceIntegerMetrics;
+
     for (int i = 0; i < glyphs.numGlyphs; ++i) {
-        w += (fontDef.styleStrategy & QFont::ForceIntegerMetrics)
-             ? glyphs.effectiveAdvance(i).round()
-             : glyphs.effectiveAdvance(i);
+        w += round ? glyphs.effectiveAdvance(i).round()
+                   : glyphs.effectiveAdvance(i);
     }
-    return glyph_metrics_t(0, -(ascent()), w, ascent()+descent(), w, 0);
+    return glyph_metrics_t(0, -(ascent()), w - lastRightBearing(glyphs, round), ascent()+descent(), w, 0);
 }
 glyph_metrics_t QCoreTextFontEngine::boundingBox(glyph_t glyph)
 {
@@ -1480,12 +1481,12 @@ void QFontEngineMac::recalcAdvances(QGlyphLayout *glyphs, QTextEngine::ShaperFla
 glyph_metrics_t QFontEngineMac::boundingBox(const QGlyphLayout &glyphs)
 {
     QFixed w;
+    bool round = fontDef.styleStrategy & QFont::ForceIntegerMetrics;
     for (int i = 0; i < glyphs.numGlyphs; ++i) {
-        w += (fontDef.styleStrategy & QFont::ForceIntegerMetrics)
-             ? glyphs.effectiveAdvance(i).round()
-             : glyphs.effectiveAdvance(i);
+        w += round ? glyphs.effectiveAdvance(i).round()
+                   : glyphs.effectiveAdvance(i);
     }
-    return glyph_metrics_t(0, -(ascent()), w, ascent()+descent(), w, 0);
+    return glyph_metrics_t(0, -(ascent()), w - lastRightBearing(glyphs, round), ascent()+descent(), w, 0);
 }
 
 glyph_metrics_t QFontEngineMac::boundingBox(glyph_t glyph)