Optimize drawStaticText() with rectangle destination

In order to be feature consistent with drawText(), we have to clip the
text whenever the text expands beyond its borders. This is a
performance hit, but luckily we can detect the cases where it's
necessary before-hand.

3 files changed, 14 insertions, 6 deletions

diff --git a/src/gui/painting/qpainter.cpp b/src/gui/painting/qpainter.cpp
index 524f243..114492d 100644
--- a/src/gui/painting/qpainter.cpp
+++ b/src/gui/painting/qpainter.cpp
@@ -5773,7 +5773,7 @@ void QPainter::drawStaticText(const QPointF &position, const QStaticText &static
     }
 
     bool restoreWhenFinished = false;
-    if (staticText_d->size.isValid()) {
+    if (staticText_d->needsClipRect) {
         save();
         setClipRect(QRectF(position, staticText_d->size));
 
diff --git a/src/gui/text/qstatictext.cpp b/src/gui/text/qstatictext.cpp
index 9a0ddca..85d3c81 100644
--- a/src/gui/text/qstatictext.cpp
+++ b/src/gui/text/qstatictext.cpp
@@ -263,7 +263,7 @@ bool QStaticText::isEmpty() const
 }
 
 QStaticTextPrivate::QStaticTextPrivate()
-        : items(0), itemCount(0), glyphPool(0), positionPool(0)
+        : items(0), itemCount(0), glyphPool(0), positionPool(0), needsClipRect(false)
 {
     ref = 1;    
 }
@@ -482,10 +482,17 @@ void QStaticTextPrivate::init()
         painter.setFont(font);
         painter.setTransform(matrix);
 
-        if (size.isValid())
-            painter.drawText(QRectF(QPointF(0, 0), size), text);
-        else
+        if (size.isValid()) {
+            QRectF boundingRect;
+            painter.drawText(QRectF(QPointF(0, 0), size), 0, text, &boundingRect);
+
+            needsClipRect = boundingRect.width() > size.width()
+                            || boundingRect.height() > size.height();
+
+        } else {
             painter.drawText(0, 0, text);
+            needsClipRect = false;
+        }
     }
 
 }
diff --git a/src/gui/text/qstatictext_p.h b/src/gui/text/qstatictext_p.h
index 4756773..0677920 100644
--- a/src/gui/text/qstatictext_p.h
+++ b/src/gui/text/qstatictext_p.h
@@ -62,7 +62,6 @@ class Q_GUI_EXPORT QStaticTextItem
 public:    
     QStaticTextItem() : chars(0), numChars(0), fontEngine(0) {}
 
-    // ### Use constant length arrays here to minimize memory consumption
     QFixedPoint *glyphPositions;                 // 8 bytes per glyph
     glyph_t *glyphs;                             // 4 bytes per glyph
     const QChar *chars;                          // 2 bytes per glyph
@@ -98,6 +97,8 @@ public:
     int itemCount;             // 4 bytes per text
     glyph_t *glyphPool;        // 4 bytes per text
     QFixedPoint *positionPool; // 4 bytes per text
+
+    char needsClipRect : 1;    // 1 byte per text
                                // ================
                                // 144 bytes per text