Speed optimization for QStaticText

Don't use QVector to store the text items, but put them in a regular
array for quick access.

drawStaticText() is now about 2.7 times the speed of drawText().

6 files changed, 40 insertions, 23 deletions

diff --git a/src/gui/painting/qpainter.cpp b/src/gui/painting/qpainter.cpp
index 6bb8acd..50d27ac 100644
--- a/src/gui/painting/qpainter.cpp
+++ b/src/gui/painting/qpainter.cpp
@@ -5724,14 +5724,18 @@ void QPainter::drawText(const QPointF &p, const QString &str)
 */
 void QPainter::drawStaticText(const QPointF &position, const QStaticText &staticText)
 {
+    Q_D(QPainter);
+    if (!d->engine || staticText.isEmpty() || pen().style() == Qt::NoPen)
+        return;
+
     const QStaticTextPrivate *staticText_d = QStaticTextPrivate::get(&staticText);
 
     QFixed x = QFixed::fromReal(position.x());
-    for (int i=0; i<staticText_d->items.size();++i) {
-        QTextItemInt *gf = staticText_d->items.at(i);
-        if (gf->num_chars != 0)
-            drawTextItem(QPointF(x.toReal(), position.y()), *gf);
-        x += gf->width;
+    for (int i=0; i<staticText_d->itemCount; ++i) {
+        const QTextItemInt &gf = staticText_d->items[i];
+        if (gf.num_chars != 0)
+            drawTextItem(QPointF(x.toReal(), position.y()), gf);
+        x += gf.width;
     }
 }
 
diff --git a/src/gui/text/qstatictext.cpp b/src/gui/text/qstatictext.cpp
index e9fd9c5..d97c0c9 100644
--- a/src/gui/text/qstatictext.cpp
+++ b/src/gui/text/qstatictext.cpp
@@ -227,7 +227,13 @@ QString QStaticText::toString() const
     return text();
 }
 
-QStaticTextPrivate::QStaticTextPrivate() : glyphLayoutMemory(0), logClusterMemory(0)
+bool QStaticText::isEmpty() const
+{
+    return d_ptr->text.isEmpty();
+}
+
+QStaticTextPrivate::QStaticTextPrivate()
+        : glyphLayoutMemory(0), logClusterMemory(0), items(0), itemCount(0)
 {
     ref = 1;    
 }
@@ -244,7 +250,7 @@ QStaticTextPrivate::~QStaticTextPrivate()
 {
     delete[] glyphLayoutMemory;
     delete[] logClusterMemory;
-    qDeleteAll(items);
+    delete[] items;
 }
 
 QStaticTextPrivate *QStaticTextPrivate::get(const QStaticText *q)
@@ -256,7 +262,7 @@ void QStaticTextPrivate::init()
 {
     delete[] glyphLayoutMemory;
     delete[] logClusterMemory;
-    qDeleteAll(items);
+    delete[] items;
 
     QStackTextEngine engine(text, font);
     engine.itemize();
@@ -276,6 +282,8 @@ void QStaticTextPrivate::init()
     int numGlyphs = engine.layoutData->used;
     glyphLayoutMemory = new char[QGlyphLayout::spaceNeededForGlyphLayout(numGlyphs)];
     logClusterMemory = new unsigned short[numGlyphs];
+    items = new QTextItemInt[nItems];
+    itemCount = nItems;
 
     char *currentGlyphLayout = glyphLayoutMemory;
     unsigned short *currentLogCluster = logClusterMemory;
@@ -285,29 +293,24 @@ void QStaticTextPrivate::init()
 
         QFont f = engine.font(si);
         if (si.analysis.flags >= QScriptAnalysis::TabOrObject) {
-            QTextItemInt *gf = new QTextItemInt(si, &f);
-            gf->width = si.width;
-            items.append(gf);
+            items[i].width = si.width;
             continue;
         }        
 
-        QTextItemInt *gf = new QTextItemInt(si, &f);
+        items[i].init(si, &f);
+
         QGlyphLayout l = engine.shapedGlyphs(&si);
-        gf->glyphs = l.clone(currentGlyphLayout);
+        items[i].glyphs = l.clone(currentGlyphLayout);
         currentGlyphLayout += QGlyphLayout::spaceNeededForGlyphLayout(l.numGlyphs);
 
-        gf->chars = text.unicode() + si.position;
-        gf->num_chars = engine.length(item);
-        gf->width = si.width;
+        items[i].chars = text.unicode() + si.position;
+        items[i].num_chars = engine.length(item);
+        items[i].width = si.width;
 
         memmove(currentLogCluster, engine.logClusters(&si), sizeof(unsigned short) * l.numGlyphs);
-        gf->logClusters = currentLogCluster;
-        currentLogCluster += l.numGlyphs;
-
-        items.append(gf);
+        items[i].logClusters = currentLogCluster;
+        currentLogCluster += l.numGlyphs;        
     }
-
-    items.squeeze();
 }
 
 QT_END_NAMESPACE
diff --git a/src/gui/text/qstatictext.h b/src/gui/text/qstatictext.h
index bcafaa9..7247bf7 100644
--- a/src/gui/text/qstatictext.h
+++ b/src/gui/text/qstatictext.h
@@ -73,6 +73,8 @@ public:
 
     QString toString() const;
 
+    bool isEmpty() const;
+
 private:
     void detach();
 
diff --git a/src/gui/text/qstatictext_p.h b/src/gui/text/qstatictext_p.h
index aaaf300..a0d16d4 100644
--- a/src/gui/text/qstatictext_p.h
+++ b/src/gui/text/qstatictext_p.h
@@ -68,7 +68,8 @@ public:
     void init();
 
     QAtomicInt ref;
-    QVector<QTextItemInt *> items;
+    QTextItemInt *items;
+    int itemCount;
     QString text;
     QFont font;
     char *glyphLayoutMemory;
diff --git a/src/gui/text/qtextengine.cpp b/src/gui/text/qtextengine.cpp
index da3a3c0..5343085 100644
--- a/src/gui/text/qtextengine.cpp
+++ b/src/gui/text/qtextengine.cpp
@@ -2637,6 +2637,11 @@ QTextItemInt::QTextItemInt(const QScriptItem &si, QFont *font, const QTextCharFo
     : justified(false), underlineStyle(QTextCharFormat::NoUnderline), charFormat(format),
       num_chars(0), chars(0), logClusters(0), f(0), fontEngine(0)
 {
+    init(si, font, format);
+}
+
+void QTextItemInt::init(const QScriptItem &si, QFont *font, const QTextCharFormat &format)
+{
     // explicitly initialize flags so that initFontAttributes can be called
     // multiple times on the same TextItem
     flags = 0;
diff --git a/src/gui/text/qtextengine_p.h b/src/gui/text/qtextengine_p.h
index 2edbd98..0491d87 100644
--- a/src/gui/text/qtextengine_p.h
+++ b/src/gui/text/qtextengine_p.h
@@ -312,7 +312,9 @@ public:
         : justified(false), underlineStyle(QTextCharFormat::NoUnderline), num_chars(0), chars(0),
           logClusters(0), f(0), fontEngine(0)
     {}
+
     QTextItemInt(const QScriptItem &si, QFont *font, const QTextCharFormat &format = QTextCharFormat());
+    void init(const QScriptItem &si, QFont *font, const QTextCharFormat &format = QTextCharFormat());
 
     /// copy the structure items, adjusting the glyphs arrays to the right subarrays.
     /// the width of the returned QTextItemInt is not adjusted, for speed reasons