Account for right bearing in QFontMetrics::boundingRect(string)

QFontMetrics::boundingRect() that takes a string needs to account for
the right bearing of the last glyph, as it is documented to be the
rectangle that contains the pixels of the text. I've added a test for
this, and fixed tst_QFontMetrics::elidedText() to use boundingRect() to
find the actual width of the text drawn (width() will return the advance
of the text, which is larger than the actual width of the pixels.)

I've also fixed a small typo in the "len" -> "ilen".

Reviewed-by: Simon Hausmann

2 files changed, 20 insertions, 3 deletions

diff --git a/src/gui/text/qtextengine.cpp b/src/gui/text/qtextengine.cpp
index c9b6c38..88837ca 100644
--- a/src/gui/text/qtextengine.cpp
+++ b/src/gui/text/qtextengine.cpp
@@ -1594,11 +1594,13 @@ glyph_metrics_t QTextEngine::boundingBox(int from,  int len) const
 
     for (int i = 0; i < layoutData->items.size(); i++) {
         const QScriptItem *si = layoutData->items.constData() + i;
+        QFontEngine *fe = fontEngine(*si);
+
         int pos = si->position;
         int ilen = length(i);
         if (pos > from + len)
             break;
-        if (pos + len > from) {
+        if (pos + ilen > from) {
             if (!si->num_glyphs)
                 shape(i);
 
@@ -1631,7 +1633,6 @@ glyph_metrics_t QTextEngine::boundingBox(int from,  int len) const
                     charEnd++;
                 glyphEnd = (charEnd == ilen) ? si->num_glyphs : logClusters[charEnd];
                 if (glyphStart <= glyphEnd ) {
-                    QFontEngine *fe = fontEngine(*si);
                     glyph_metrics_t m = fe->boundingBox(glyphs.mid(glyphStart, glyphEnd - glyphStart));
                     gm.x = qMin(gm.x, m.x + gm.xoff);
                     gm.y = qMin(gm.y, m.y + gm.yoff);
@@ -1641,6 +1642,10 @@ glyph_metrics_t QTextEngine::boundingBox(int from,  int len) const
                     gm.yoff += m.yoff;
                 }
             }
+
+            glyph_t glyph = glyphs.glyphs[logClusters[pos + ilen - 1]];
+            glyph_metrics_t gi = fe->boundingBox(glyph);
+            gm.width -= qRound(gi.xoff - gi.x - gi.width);
         }
     }
     return gm;
diff --git a/tests/auto/qfontmetrics/tst_qfontmetrics.cpp b/tests/auto/qfontmetrics/tst_qfontmetrics.cpp
index ee6d442..665107a 100644
--- a/tests/auto/qfontmetrics/tst_qfontmetrics.cpp
+++ b/tests/auto/qfontmetrics/tst_qfontmetrics.cpp
@@ -72,6 +72,7 @@ private slots:
     void veryNarrowElidedText();
     void averageCharWidth();
     void elidedMultiLength();
+    void bearingIncludedInBoundingRect();
 };
 
 tst_QFontMetrics::tst_QFontMetrics()
@@ -214,7 +215,7 @@ void tst_QFontMetrics::elidedMultiLength()
     QCOMPARE(fm.elidedText(text1,Qt::ElideRight, 8000), text1_long);
     QCOMPARE(fm.elidedText(text1,Qt::ElideRight, width_long + 1), text1_long);
     QCOMPARE(fm.elidedText(text1,Qt::ElideRight, width_long - 1), text1_short);
-    int width_short = fm.width(text1_short);
+    int width_short = fm.boundingRect(text1_short).width();
     QCOMPARE(fm.elidedText(text1,Qt::ElideRight, width_short + 1), text1_short);
     QCOMPARE(fm.elidedText(text1,Qt::ElideRight, width_short - 1), text1_small);
 
@@ -226,5 +227,16 @@ void tst_QFontMetrics::elidedMultiLength()
 
 }
 
+void tst_QFontMetrics::bearingIncludedInBoundingRect()
+{
+    QFont font;
+    font.setItalic(true);
+    QRect brectItalic = QFontMetrics(font).boundingRect("ITALIC");
+    font.setItalic(false);
+    QRect brectNormal = QFontMetrics(font).boundingRect("ITALIC");
+
+    QVERIFY(brectItalic.width() > brectNormal.width());
+}
+
 QTEST_MAIN(tst_QFontMetrics)
 #include "tst_qfontmetrics.moc"