Make QStaticText layout lazy

To avoid the unnecessary overhead of doing the text layout every time
a part of the QStaticText object is changed, we mark it as invalid
instead and do the layout when we have to. This means an overhead on
the first paint event for most users. The overhead can be avoided by
using the QStaticText::prepare() function and will probably not be
noticable anyway, since it's a one-time thing.

Task-number: QTBUG-9030
Reviewed-by: Gunnar

1 files changed, 6 insertions, 0 deletions

diff --git a/src/gui/text/qstatictext_p.h b/src/gui/text/qstatictext_p.h
index 3bbc61f..f017ed1 100644
--- a/src/gui/text/qstatictext_p.h
+++ b/src/gui/text/qstatictext_p.h
@@ -118,6 +118,11 @@ public:
     void init();
     void paintText(const QPointF &pos, QPainter *p);
 
+    void invalidate()
+    {
+        needsRelayout = true;
+    }
+
     QAtomicInt ref;                      // 4 bytes per text
 
     QString text;                        // 4 bytes per text
@@ -132,6 +137,7 @@ public:
     glyph_t *glyphPool;                  // 4 bytes per text
     QFixedPoint *positionPool;           // 4 bytes per text
 
+    unsigned char needsRelayout : 1;
     unsigned char useBackendOptimizations : 1; // 1 byte per text
     unsigned char textFormat              : 2;
                                          // ================