New class: QGlyphs

Introduce an API to access glyph indexes in a font directly.

A bug was discovered during this work, where different hinting flags
in loadGlyph() and loadGlyphMetrics() would make the metrics in
the two functions different, thus causing drawCachedGlyphs()
(which uses loadGlyphMetrics() indirectly) to use different metrics
than the standard drawTextItem() code path (which uses loadGlyph()).
The bug was visible in the tst_QGlyphs::drawExistingGlyphs() test.

Reviewed-by: Simon Hausmann

1 files changed, 40 insertions, 12 deletions

diff --git a/src/gui/painting/qpainter.cpp b/src/gui/painting/qpainter.cpp
index dd3584a..cb56ac8 100644
--- a/src/gui/painting/qpainter.cpp
+++ b/src/gui/painting/qpainter.cpp
@@ -61,6 +61,8 @@
 #include "qstyle.h"
 #include "qthread.h"
 #include "qvarlengtharray.h"
+#include "qstatictext.h"
+#include "qglyphs.h"
 
 #include <private/qfontengine_p.h>
 #include <private/qpaintengine_p.h>
@@ -70,8 +72,8 @@
 #include <private/qwidget_p.h>
 #include <private/qpaintengine_raster_p.h>
 #include <private/qmath_p.h>
-#include <qstatictext.h>
 #include <private/qstatictext_p.h>
+#include <private/qglyphs_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -5704,16 +5706,47 @@ void QPainter::drawImage(const QRectF &targetRect, const QImage &image, const QR
     d->engine->drawImage(QRectF(x, y, w, h), image, QRectF(sx, sy, sw, sh), flags);
 }
 
+/*!
+    Draws the glyphs represented by \a glyphs at \a position. The \a position gives the
+    edge of the baseline for the string of glyphs. The glyphs will be retrieved from the font
+    selected on \a glyphs and at offsets given by the positions in \a glyphs.
+
+    \since 4.8
+
+    \sa QGlyphs::setFont(), QGlyphs::setPositions(), QGlyphs::setGlyphIndexes()
+*/
+void QPainter::drawGlyphs(const QPointF &position, const QGlyphs &glyphs)
+{
+    Q_D(QPainter);
+
+    QFont oldFont = d->state->font;
+    d->state->font = glyphs.font();
+
+    QVector<quint32> glyphIndexes = glyphs.glyphIndexes();
+    QVector<QPointF> glyphPositions = glyphs.positions();
+
+    int count = qMin(glyphIndexes.size(), glyphPositions.size());
+    QVarLengthArray<QFixedPoint, 128> fixedPointPositions(count);
+    for (int i=0; i<count; ++i)
+        fixedPointPositions[i] = QFixedPoint::fromPointF(position + glyphPositions.at(i));    
+
+    d->drawGlyphs(glyphIndexes.data(), fixedPointPositions.data(), count);
+
+    d->state->font = oldFont;
+}
 
 void qt_draw_glyphs(QPainter *painter, const quint32 *glyphArray, const QPointF *positionArray,
                     int glyphCount)
-{
+{    
+    QVarLengthArray<QFixedPoint, 128> positions(glyphCount);
+    for (int i=0; i<glyphCount; ++i)
+        positions[i] = QFixedPoint::fromPointF(positionArray[i]);
+
     QPainterPrivate *painter_d = QPainterPrivate::get(painter);
-    painter_d->drawGlyphs(glyphArray, positionArray, glyphCount);
+    painter_d->drawGlyphs(const_cast<quint32 *>(glyphArray), positions.data(), glyphCount);
 }
 
-void QPainterPrivate::drawGlyphs(const quint32 *glyphArray, const QPointF *positionArray,
-                                 int glyphCount)
+void QPainterPrivate::drawGlyphs(quint32 *glyphArray, QFixedPoint *positions, int glyphCount)
 {
     updateState(state);
 
@@ -5729,11 +5762,6 @@ void QPainterPrivate::drawGlyphs(const quint32 *glyphArray, const QPointF *posit
         fontEngine = static_cast<QFontEngineMulti *>(fontEngine)->engine(engineIdx);
     }
 
-    QVarLengthArray<QFixedPoint, 128> positions;
-    for (int i=0; i<glyphCount; ++i) {
-        QFixedPoint fp = QFixedPoint::fromPointF(positionArray[i]);
-        positions.append(fp);
-    }
 
     if (extended != 0) {
         QStaticTextItem staticTextItem;
@@ -5742,7 +5770,7 @@ void QPainterPrivate::drawGlyphs(const quint32 *glyphArray, const QPointF *posit
         staticTextItem.fontEngine = fontEngine;
         staticTextItem.numGlyphs = glyphCount;
         staticTextItem.glyphs = reinterpret_cast<glyph_t *>(const_cast<glyph_t *>(glyphArray));
-        staticTextItem.glyphPositions = positions.data();
+        staticTextItem.glyphPositions = positions;
 
         extended->drawStaticTextItem(&staticTextItem);
     } else {
@@ -5759,7 +5787,7 @@ void QPainterPrivate::drawGlyphs(const quint32 *glyphArray, const QPointF *posit
 
         textItem.glyphs.numGlyphs = glyphCount;
         textItem.glyphs.glyphs = reinterpret_cast<HB_Glyph *>(const_cast<quint32 *>(glyphArray));
-        textItem.glyphs.offsets = positions.data();
+        textItem.glyphs.offsets = positions;
         textItem.glyphs.advances_x = advances.data();
         textItem.glyphs.advances_y = advances.data();
         textItem.glyphs.justifications = glyphJustifications.data();