Fix glyph advance on Mac/Carbon

Device metrics was turned on for Mac/Carbon to work around a bug
in WebKit that required the font engine to report only integer values.
This in turn caused positioning of glyphs to be slightly off compared
to native applications. The bug has been fixed in WebKit, so now we
can turn off the device metrics flag. Since we are now reporting
fractional values as well, we need to round the numbers when the
ForceIntegerMetrics style strategy flag is set.

Task-number: qtbug-5529
Reviewed-by: Trond

1 files changed, 43 insertions, 10 deletions

diff --git a/src/gui/text/qfontengine_mac.mm b/src/gui/text/qfontengine_mac.mm
index fd662e3..3f84544 100644
--- a/src/gui/text/qfontengine_mac.mm
+++ b/src/gui/text/qfontengine_mac.mm
@@ -53,6 +53,7 @@
 #include <qvarlengtharray.h>
 #include <qdebug.h>
 #include <qendian.h>
+#include <qmath.h>
 
 #include <ApplicationServices/ApplicationServices.h>
 #include <AppKit/AppKit.h>
@@ -816,6 +817,7 @@ struct QGlyphLayoutInfo
     int *mappedFonts;
     QTextEngine::ShaperFlags flags;
     QFontEngineMacMulti::ShaperItem *shaperItem;
+    unsigned int styleStrategy;
 };
 
 static OSStatus atsuPostLayoutCallback(ATSULayoutOperationSelector selector, ATSULineRef lineRef, URefCon refCon,
@@ -885,6 +887,11 @@ static OSStatus atsuPostLayoutCallback(ATSULayoutOperationSelector selector, ATS
         QFixed yAdvance = FixedToQFixed(baselineDeltas[glyphIdx]);
         QFixed xAdvance = FixedToQFixed(layoutData[glyphIdx + 1].realPos - layoutData[glyphIdx].realPos);
 
+        if (nfo->styleStrategy & QFont::ForceIntegerMetrics) {
+            yAdvance = yAdvance.ceil();
+            xAdvance = xAdvance.ceil();
+        }
+
         if (glyphId != 0xffff || i == 0) {
             if (i < nfo->glyphs->numGlyphs)
             {
@@ -1061,6 +1068,7 @@ bool QFontEngineMacMulti::stringToCMapInternal(const QChar *str, int len, QGlyph
     nfo.callbackCalled = false;
     nfo.flags = flags;
     nfo.shaperItem = shaperItem;
+    nfo.styleStrategy = fontDef.styleStrategy;
 
     int prevNumGlyphs = *nglyphs;
 
@@ -1090,8 +1098,6 @@ bool QFontEngineMacMulti::stringToCMapInternal(const QChar *str, int len, QGlyph
                                        | kATSLineDisableAllJustification
                                        ;
 
-	layopts |= kATSLineUseDeviceMetrics;
-
         if (fontDef.styleStrategy & QFont::NoAntialias)
             layopts |= kATSLineNoAntiAliasing;
 
@@ -1395,14 +1401,22 @@ void QFontEngineMac::recalcAdvances(QGlyphLayout *glyphs, QTextEngine::ShaperFla
     for (int i = 0; i < glyphs->numGlyphs; ++i) {
         glyphs->advances_x[i] = QFixed::fromReal(metrics[i].deviceAdvance.x);
         glyphs->advances_y[i] = QFixed::fromReal(metrics[i].deviceAdvance.y);
+
+        if (fontDef.styleStrategy & QFont::ForceIntegerMetrics) {
+            glyphs->advances_x[i] = glyphs->advances_x[i].ceil();
+            glyphs->advances_y[i] = glyphs->advances_y[i].ceil();
+        }
     }
 }
 
 glyph_metrics_t QFontEngineMac::boundingBox(const QGlyphLayout &glyphs)
 {
     QFixed w;
-    for (int i = 0; i < glyphs.numGlyphs; ++i)
-        w += glyphs.effectiveAdvance(i);
+    for (int i = 0; i < glyphs.numGlyphs; ++i) {
+        w += (fontDef.styleStrategy & QFont::ForceIntegerMetrics)
+             ? glyphs.effectiveAdvance(i).ceil()
+             : glyphs.effectiveAdvance(i);
+    }
     return glyph_metrics_t(0, -(ascent()), w, ascent()+descent(), w, 0);
 }
 
@@ -1427,39 +1441,58 @@ glyph_metrics_t QFontEngineMac::boundingBox(glyph_t glyph)
     gm.xoff = QFixed::fromReal(metrics.deviceAdvance.x);
     gm.yoff = QFixed::fromReal(metrics.deviceAdvance.y);
 
+    if (fontDef.styleStrategy & QFont::ForceIntegerMetrics) {
+        gm.x = gm.x.floor();
+        gm.y = gm.y.floor();
+        gm.xoff = gm.xoff.ceil();
+        gm.yoff = gm.yoff.ceil();
+    }
+
     return gm;
 }
 
 QFixed QFontEngineMac::ascent() const
 {
-    return m_ascent;
+    return (fontDef.styleStrategy & QFont::ForceIntegerMetrics)
+            ? m_ascent.ceil()
+            : m_ascent;
 }
 
 QFixed QFontEngineMac::descent() const
 {
     // subtract a pixel to even out the historical +1 in QFontMetrics::height().
     // Fix in Qt 5.
-    return m_descent - 1;
+    return (fontDef.styleStrategy & QFont::ForceIntegerMetrics)
+            ? m_descent.ceil() - 1
+            : m_descent;
 }
 
 QFixed QFontEngineMac::leading() const
 {
-    return m_leading;
+    return (fontDef.styleStrategy & QFont::ForceIntegerMetrics)
+            ? m_leading.ceil()
+            : m_leading;
 }
 
 qreal QFontEngineMac::maxCharWidth() const
 {
-    return m_maxCharWidth;
+    return (fontDef.styleStrategy & QFont::ForceIntegerMetrics)
+            ? qCeil(m_maxCharWidth)
+            : m_maxCharWidth;
 }
 
 QFixed QFontEngineMac::xHeight() const
 {
-    return m_xHeight;
+    return (fontDef.styleStrategy & QFont::ForceIntegerMetrics)
+            ? m_xHeight.ceil()
+            : m_xHeight;
 }
 
 QFixed QFontEngineMac::averageCharWidth() const
 {
-    return m_averageCharWidth;
+    return (fontDef.styleStrategy & QFont::ForceIntegerMetrics)
+            ? m_averageCharWidth.ceil()
+            : m_averageCharWidth;
 }
 
 static void addGlyphsToPathHelper(ATSUStyle style, glyph_t *glyphs, QFixedPoint *positions, int numGlyphs, QPainterPath *path)