Optimize QStaticText for space

By caching the results of getGlyphPositions() we can make a code path
in the critical paint engines which is optimal both in space and speed.
The engines where speed is of less importance (pdf engine etc.) which
may need more information, we choose the slower code path of drawText()
which lays out the text again. We should have optimal paths in raster,
vg and GL2 paint engines. The others are less important. Memory
consumption of static text is now 14 bytes per glyph, 8 bytes per item
and a static overhead of 40 bytes per QStaticText object.

10 files changed, 137 insertions, 110 deletions

diff --git a/src/gui/painting/qpaintengine_raster.cpp b/src/gui/painting/qpaintengine_raster.cpp
index 3f2322e..387d646 100644
--- a/src/gui/painting/qpaintengine_raster.cpp
+++ b/src/gui/painting/qpaintengine_raster.cpp
@@ -67,6 +67,7 @@
 //   #include <private/qpolygonclipper_p.h>
 //   #include <private/qrasterizer_p.h>
 #include <private/qimage_p.h>
+#include <private/qstatictext_p.h>
 
 #include "qpaintengine_raster_p.h"
 //   #include "qbezier_p.h"
@@ -3006,27 +3007,23 @@ void QRasterPaintEngine::alphaPenBlt(const void* src, int bpl, int depth, int rx
         blend(current, spans, &s->penData);
 }
 
-void QRasterPaintEngine::drawCachedGlyphs(const QPointF &p, const QTextItemInt &ti)
+void QRasterPaintEngine::drawCachedGlyphs(const QVarLengthArray<glyph_t> &glyphs,
+                                          const QVarLengthArray<QFixedPoint> &positions,
+                                          QFontEngine *fontEngine,
+                                          const QTransform &matrix)
 {
     Q_D(QRasterPaintEngine);
-    QRasterPaintEngineState *s = state();
-
-    QVarLengthArray<QFixedPoint> positions;
-    QVarLengthArray<glyph_t> glyphs;
-    QTransform matrix = s->matrix;
-    matrix.translate(p.x(), p.y());
-    ti.fontEngine->getGlyphPositions(ti.glyphs, matrix, ti.flags, glyphs, positions);
 
-    QFontEngineGlyphCache::Type glyphType = ti.fontEngine->glyphFormat >= 0 ? QFontEngineGlyphCache::Type(ti.fontEngine->glyphFormat) : d->glyphCacheType;
+    QFontEngineGlyphCache::Type glyphType = fontEngine->glyphFormat >= 0 ? QFontEngineGlyphCache::Type(fontEngine->glyphFormat) : d->glyphCacheType;
 
     QImageTextureGlyphCache *cache =
-        (QImageTextureGlyphCache *) ti.fontEngine->glyphCache(0, glyphType, s->matrix);
+        static_cast<QImageTextureGlyphCache *>(fontEngine->glyphCache(0, glyphType, matrix));
     if (!cache) {
-        cache = new QImageTextureGlyphCache(glyphType, s->matrix);
-        ti.fontEngine->setGlyphCache(0, cache);
+        cache = new QImageTextureGlyphCache(glyphType, matrix);
+        fontEngine->setGlyphCache(0, cache);
     }
 
-    cache->populate(ti, glyphs, positions);
+    cache->populate(fontEngine, glyphs, positions);
 
     const QImage &image = cache->image();
     int bpl = image.bytesPerLine();
@@ -3216,6 +3213,26 @@ QRasterPaintEnginePrivate::getPenFunc(const QRectF &rect,
     return isUnclipped(rect, penWidth) ? data->unclipped_blend : data->blend;
 }
 
+void QRasterPaintEngine::drawStaticTextItem(const QPointF &p, QStaticTextItem *textItem)
+{
+    ensurePen();
+    ensureState();
+
+    QTransform matrix;
+    matrix.translate(p.x(), p.y());
+
+    // Translate to actual position
+    QVarLengthArray<QFixedPoint> glyphPositions = textItem->glyphPositions;
+
+    QFixed fx = QFixed::fromReal(p.x());
+    QFixed fy = QFixed::fromReal(p.y());
+    for (int i=0; i<glyphPositions.size(); ++i) {
+        glyphPositions[i].x += fx;
+        glyphPositions[i].y += fy;
+    }
+    drawCachedGlyphs(textItem->glyphs, glyphPositions, textItem->fontEngine, matrix);
+}
+
 /*!
     \reimp
 */
@@ -3264,7 +3281,15 @@ void QRasterPaintEngine::drawTextItem(const QPointF &p, const QTextItem &textIte
         drawCached = false;
 #endif
     if (drawCached) {
-        drawCachedGlyphs(p, ti);
+        QRasterPaintEngineState *s = state();
+
+        QVarLengthArray<QFixedPoint> positions;
+        QVarLengthArray<glyph_t> glyphs;
+        QTransform matrix = s->matrix;
+        matrix.translate(p.x(), p.y());
+        ti.fontEngine->getGlyphPositions(ti.glyphs, matrix, ti.flags, glyphs, positions);
+
+        drawCachedGlyphs(glyphs, positions, ti.fontEngine, matrix);
         return;
     }
 
diff --git a/src/gui/painting/qpaintengine_raster_p.h b/src/gui/painting/qpaintengine_raster_p.h
index b937f66..0250c3d 100644
--- a/src/gui/painting/qpaintengine_raster_p.h
+++ b/src/gui/painting/qpaintengine_raster_p.h
@@ -257,7 +257,12 @@ private:
     void fillRect(const QRectF &rect, QSpanData *data);
     void drawBitmap(const QPointF &pos, const QImage &image, QSpanData *fill);
 
-    void drawCachedGlyphs(const QPointF &p, const QTextItemInt &ti);
+    void drawCachedGlyphs(const QVarLengthArray<glyph_t> &glyphs,
+                          const QVarLengthArray<QFixedPoint> &positions,
+                          QFontEngine *fontEngine,
+                          const QTransform &matrix);
+
+    void drawStaticTextItem(const QPointF &p, QStaticTextItem *textItem);
 
 #if defined(Q_OS_SYMBIAN) && defined(QT_NO_FREETYPE)
     void drawGlyphsS60(const QPointF &p, const QTextItemInt &ti);
diff --git a/src/gui/painting/qpaintengineex.cpp b/src/gui/painting/qpaintengineex.cpp
index 058f226..15085f9 100644
--- a/src/gui/painting/qpaintengineex.cpp
+++ b/src/gui/painting/qpaintengineex.cpp
@@ -44,6 +44,7 @@
 #include "qstroker_p.h"
 #include "qbezier_p.h"
 #include <private/qpainterpath_p.h>
+#include <private/qstatictext_p.h>
 
 #include <qvarlengtharray.h>
 #include <qdebug.h>
@@ -589,6 +590,11 @@ void QPaintEngineEx::stroke(const QVectorPath &path, const QPen &pen)
     }
 }
 
+void QPaintEngineEx::drawStaticTextItem(const QPointF &position, QStaticTextItem *item)
+{
+    // ### fall back (we need to recalculate the text item and call drawTextItem())
+}
+
 void QPaintEngineEx::draw(const QVectorPath &path)
 {
     const QBrush &brush = state()->brush;
diff --git a/src/gui/painting/qpaintengineex_p.h b/src/gui/painting/qpaintengineex_p.h
index fccd1dc..4096907 100644
--- a/src/gui/painting/qpaintengineex_p.h
+++ b/src/gui/painting/qpaintengineex_p.h
@@ -70,6 +70,7 @@ QT_MODULE(Gui)
 
 class QPainterState;
 class QPaintEngineExPrivate;
+class QStaticTextItem;
 struct StrokeHandler;
 
 struct QIntRect {
@@ -200,6 +201,8 @@ public:
 
     virtual void updateState(const QPaintEngineState &state);
 
+    virtual void drawStaticTextItem(const QPointF &position, QStaticTextItem *item);
+
     virtual void setState(QPainterState *s);
     inline QPainterState *state() { return static_cast<QPainterState *>(QPaintEngine::state); }
     inline const QPainterState *state() const { return static_cast<const QPainterState *>(QPaintEngine::state); }
diff --git a/src/gui/painting/qpainter.cpp b/src/gui/painting/qpainter.cpp
index 83f66e2..1d7f57d 100644
--- a/src/gui/painting/qpainter.cpp
+++ b/src/gui/painting/qpainter.cpp
@@ -5719,8 +5719,10 @@ void QPainter::drawText(const QPointF &p, const QString &str)
 /*!
     Draws the given \a staticText beginning at the given \a position. 
 
-    This function can be used to optimize drawing text if the text and its layout is updated 
+    This function can be used to optimize drawing text if the text and its layout is updated     
     seldomly.
+
+    \sa QStaticText
 */
 void QPainter::drawStaticText(const QPointF &position, const QStaticText &staticText)
 {
@@ -5728,9 +5730,19 @@ void QPainter::drawStaticText(const QPointF &position, const QStaticText &static
     if (!d->engine || staticText.isEmpty() || pen().style() == Qt::NoPen)
         return;
 
-    const QStaticTextPrivate *staticText_d = QStaticTextPrivate::get(&staticText);        
-    bool restoreWhenFinished = false;
+    const QStaticTextPrivate *staticText_d = QStaticTextPrivate::get(&staticText);
 
+    // If we don't have an extended paint engine, or if the painter is transformed,
+    // we go through standard code path
+    if (d->extended == 0 || !d->state->matrix.isIdentity()) {
+        if (staticText_d->size.isValid())
+            drawText(QRectF(position, staticText_d->size), staticText_d->text);
+        else
+            drawText(position, staticText_d->text);
+        return;
+    }
+
+    bool restoreWhenFinished = false;
     if (staticText_d->size.isValid()) {
         setClipRect(QRectF(position, staticText_d->size));
 
@@ -5746,8 +5758,8 @@ void QPainter::drawStaticText(const QPointF &position, const QStaticText &static
     }
 
     for (int i=0; i<staticText_d->itemCount; ++i) {
-        const QTextItemInt &gf = staticText_d->items[i];
-        d->engine->drawTextItem(staticText_d->itemPositions[i] + position, gf);
+        QStaticTextItem *item = staticText_d->items + i;
+        d->extended->drawStaticTextItem(position, item);
     }
 
     if (restoreWhenFinished)
diff --git a/src/gui/painting/qtextureglyphcache.cpp b/src/gui/painting/qtextureglyphcache.cpp
index 7b7f325..46da88e 100644
--- a/src/gui/painting/qtextureglyphcache.cpp
+++ b/src/gui/painting/qtextureglyphcache.cpp
@@ -55,7 +55,7 @@ QT_BEGIN_NAMESPACE
 
 // #define CACHE_DEBUG
 
-void QTextureGlyphCache::populate(const QTextItemInt &ti,
+void QTextureGlyphCache::populate(QFontEngine *fontEngine,
                                   const QVarLengthArray<glyph_t> &glyphs,
                                   const QVarLengthArray<QFixedPoint> &)
 {
@@ -64,7 +64,7 @@ void QTextureGlyphCache::populate(const QTextItemInt &ti,
     qDebug() << " -> current transformation: " << m_transform;
 #endif
 
-    m_current_textitem = &ti;
+    m_current_fontengine = fontEngine;
     const int margin = glyphMargin();
 
     QHash<glyph_t, Coord> listItemCoordinates;
@@ -77,7 +77,7 @@ void QTextureGlyphCache::populate(const QTextItemInt &ti,
             continue;
         if (listItemCoordinates.contains(glyph))
             continue;
-        glyph_metrics_t metrics = ti.fontEngine->boundingBox(glyph, m_transform);
+        glyph_metrics_t metrics = fontEngine->boundingBox(glyph, m_transform);
 
 #ifdef CACHE_DEBUG
         printf("'%c' (%4x): w=%.2f, h=%.2f, xoff=%.2f, yoff=%.2f, x=%.2f, y=%.2f, ti.ascent=%.2f, ti.descent=%.2f\n",
@@ -182,7 +182,7 @@ QImage QTextureGlyphCache::textureMapForGlyph(glyph_t g) const
             break;
         };
 
-        QFontEngineFT *ft = static_cast<QFontEngineFT*> (m_current_textitem->fontEngine);
+        QFontEngineFT *ft = static_cast<QFontEngineFT*> (m_current_fontengine);
         QFontEngineFT::QGlyphSet *gset = ft->loadTransformedGlyphSet(m_transform);
 
         if (gset && ft->loadGlyphs(gset, &g, 1, format)) {
@@ -194,9 +194,9 @@ QImage QTextureGlyphCache::textureMapForGlyph(glyph_t g) const
     } else
 #endif
     if (m_type == QFontEngineGlyphCache::Raster_RGBMask)
-        return m_current_textitem->fontEngine->alphaRGBMapForGlyph(g, glyphMargin(), m_transform);
+        return m_current_fontengine->alphaRGBMapForGlyph(g, glyphMargin(), m_transform);
     else
-        return m_current_textitem->fontEngine->alphaMapForGlyph(g, m_transform);
+        return m_current_fontengine->alphaMapForGlyph(g, m_transform);
 
     return QImage();
 }
@@ -321,13 +321,13 @@ void QImageTextureGlyphCache::fillTexture(const Coord &c, glyph_t g)
 #ifdef CACHE_DEBUG
 //     QPainter p(&m_image);
 //     p.drawLine(
-    QPoint base(c.x + glyphMargin(), c.y + glyphMargin() + c.baseLineY-1);
+    /*QPoint base(c.x + glyphMargin(), c.y + glyphMargin() + c.baseLineY-1);
     if (m_image.rect().contains(base))
         m_image.setPixel(base, 255);
     m_image.save(QString::fromLatin1("cache-%1-%2-%3.png")
                  .arg(m_current_textitem->font().family())
                  .arg(m_current_textitem->font().pointSize())
-                 .arg(m_transform.type()));
+                 .arg(m_transform.type()));*/
 #endif
 }
 
diff --git a/src/gui/painting/qtextureglyphcache_p.h b/src/gui/painting/qtextureglyphcache_p.h
index d347e61..2f7fc96 100644
--- a/src/gui/painting/qtextureglyphcache_p.h
+++ b/src/gui/painting/qtextureglyphcache_p.h
@@ -76,7 +76,8 @@ class Q_GUI_EXPORT QTextureGlyphCache : public QFontEngineGlyphCache
 {
 public:
     QTextureGlyphCache(QFontEngineGlyphCache::Type type, const QTransform &matrix)
-        : QFontEngineGlyphCache(matrix, type), m_w(0), m_h(0), m_cx(0), m_cy(0) { }
+        : QFontEngineGlyphCache(matrix, type), m_w(0), m_h(0), m_cx(0), m_cy(0), 
+          m_current_fontengine(0) { }
 
     virtual ~QTextureGlyphCache() { }
 
@@ -90,7 +91,7 @@ public:
         int baseLineY;
     };
 
-    void populate(const QTextItemInt &ti,
+    void populate(QFontEngine *fontEngine,
                   const QVarLengthArray<glyph_t> &glyphs,
                   const QVarLengthArray<QFixedPoint> &positions);
 
@@ -113,7 +114,7 @@ public:
     QImage textureMapForGlyph(glyph_t g) const;
 
 protected:
-    const QTextItemInt *m_current_textitem;
+    QFontEngine *m_current_fontengine;
 
     int m_w; // image width
     int m_h; // image height
diff --git a/src/gui/text/qstatictext.cpp b/src/gui/text/qstatictext.cpp
index 70e1c47..c43eeb0 100644
--- a/src/gui/text/qstatictext.cpp
+++ b/src/gui/text/qstatictext.cpp
@@ -262,7 +262,7 @@ bool QStaticText::isEmpty() const
 }
 
 QStaticTextPrivate::QStaticTextPrivate()
-        : glyphLayoutMemory(0), logClusterMemory(0), items(0), itemPositions(0), itemCount(0)
+        : items(0), itemCount(0)
 {
     ref = 1;    
 }
@@ -278,10 +278,7 @@ QStaticTextPrivate::QStaticTextPrivate(const QStaticTextPrivate &other)
 
 QStaticTextPrivate::~QStaticTextPrivate()
 {
-    delete[] glyphLayoutMemory;
-    delete[] logClusterMemory;    
-    delete[] items;
-    delete[] itemPositions;
+    delete[] items;    
 }
 
 QStaticTextPrivate *QStaticTextPrivate::get(const QStaticText *q)
@@ -298,43 +295,37 @@ namespace {
     class DrawTextItemRecorder: public QPaintEngine
     {
     public:
-        DrawTextItemRecorder(int expectedItemCount, int expectedGlyphCount,
-                             QTextItemInt *items,
-                             QPointF *positions,
-                             char *glyphLayoutMemory,
-                             unsigned short *logClusterMemory)
+        DrawTextItemRecorder(int expectedItemCount, QStaticTextItem *items)
                 : m_items(items),
-                  m_positions(positions),
-                  m_glyphLayoutMemory(glyphLayoutMemory),
-                  m_logClusterMemory(logClusterMemory),
-                  m_glyphLayoutMemoryOffset(0),
-                  m_logClusterMemoryOffset(0),
                   m_expectedItemCount(expectedItemCount),
-                  m_expectedGlyphCount(expectedGlyphCount),
-                  m_glyphCount(0),
                   m_itemCount(0)
         {
         }
 
         virtual void drawTextItem(const QPointF &p, const QTextItem &textItem)
         {
-            const QTextItemInt &ti = static_cast<const QTextItemInt &>(textItem);
-
+            const QTextItemInt &ti = static_cast<const QTextItemInt &>(textItem);          
+            
+            Q_ASSERT(m_expectedItemCount < 0 || m_itemCount < m_expectedItemCount);
             m_itemCount++;
-            m_glyphCount += ti.glyphs.numGlyphs;
 
-            Q_ASSERT(m_expectedItemCount < 0 || m_itemCount <= m_expectedItemCount);
-            Q_ASSERT(m_expectedGlyphCount < 0 || m_glyphCount <= m_expectedGlyphCount);
-
-            if (m_items == 0 || m_glyphLayoutMemory == 0 || m_logClusterMemory == 0 || m_positions == 0)
+            if (m_items == 0)
                 return;
 
-            m_items[m_itemCount - 1] = ti.clone(m_glyphLayoutMemory + m_glyphLayoutMemoryOffset,
-                                                m_logClusterMemory + m_logClusterMemoryOffset);
-            m_positions[m_itemCount - 1] = p;
+            QStaticTextItem *currentItem = (m_items + (m_itemCount - 1));
+            currentItem->fontEngine = ti.fontEngine;
+            currentItem->chars = ti.chars;
+            currentItem->numChars = ti.num_chars;
+            ti.fontEngine->getGlyphPositions(ti.glyphs, QTransform(), ti.flags, currentItem->glyphs,
+                                             currentItem->glyphPositions);
+
+            QFixed fx = QFixed::fromReal(p.x());
+            QFixed fy = QFixed::fromReal(p.y());
 
-            m_glyphLayoutMemoryOffset += QGlyphLayout::spaceNeededForGlyphLayout(ti.glyphs.numGlyphs);
-            m_logClusterMemoryOffset += ti.glyphs.numGlyphs;
+            for (int i=0; i<currentItem->glyphPositions.size(); ++i) {
+                currentItem->glyphPositions[i].x += fx;
+                currentItem->glyphPositions[i].y += fy;
+            }
         }                
 
 
@@ -347,40 +338,23 @@ namespace {
             return User;
         }
 
-        int glyphCount() const
-        {
-            return m_glyphCount;
-        }
-
         int itemCount() const
         {
             return m_itemCount;
         }
 
     private:
-        QTextItemInt *m_items;
-        char *m_glyphLayoutMemory;
-        unsigned short *m_logClusterMemory;
-        QPointF *m_positions;
-
-        int m_glyphLayoutMemoryOffset;
-        int m_logClusterMemoryOffset;
-        int m_expectedGlyphCount;
-        int m_expectedItemCount;
-        int m_glyphCount;
+        QStaticTextItem *m_items;
         int m_itemCount;
+        int m_expectedItemCount;
     };
 
     class DrawTextItemDevice: public QPaintDevice
     {
     public:
-        DrawTextItemDevice(int expectedItemCount = -1, int expectedGlyphCount = -1,
-                           QTextItemInt *items = 0, QPointF *positions = 0,
-                           char *glyphLayoutMemory = 0, unsigned short *logClusterMemory = 0)
+        DrawTextItemDevice(int expectedItemCount = -1,  QStaticTextItem *items = 0)
         {
-            m_paintEngine = new DrawTextItemRecorder(expectedItemCount, expectedGlyphCount,
-                                                     items, positions,glyphLayoutMemory,
-                                                     logClusterMemory);
+            m_paintEngine = new DrawTextItemRecorder(expectedItemCount, items);
         }
 
         ~DrawTextItemDevice()
@@ -424,11 +398,6 @@ namespace {
             return m_paintEngine;
         }
 
-        int glyphCount() const
-        {
-            return m_paintEngine->glyphCount();
-        }
-
         int itemCount() const
         {
             return m_paintEngine->itemCount();
@@ -438,17 +407,13 @@ namespace {
 
     private:
         DrawTextItemRecorder *m_paintEngine;
-        QRectF brect;
     };
 
 }
 
 void QStaticTextPrivate::init()
 {
-    delete[] glyphLayoutMemory;
-    delete[] logClusterMemory;
     delete[] items;
-    delete[] itemPositions;
 
     // Draw once to count number of items and glyphs, so that we can use as little memory
     // as possible to store the data
@@ -464,16 +429,10 @@ void QStaticTextPrivate::init()
     }
 
     itemCount = counterDevice.itemCount();
-    items = new QTextItemInt[itemCount];
-    itemPositions = new QPointF[itemCount];
-
-    int glyphCount = counterDevice.glyphCount();
-    glyphLayoutMemory = new char[QGlyphLayout::spaceNeededForGlyphLayout(glyphCount)];
-    logClusterMemory = new unsigned short[glyphCount];
+    items = new QStaticTextItem[itemCount];
 
     // Draw again to actually record the items and glyphs
-    DrawTextItemDevice recorderDevice(itemCount, glyphCount, items, itemPositions,
-                                      glyphLayoutMemory, logClusterMemory);
+    DrawTextItemDevice recorderDevice(itemCount, items);
     {
         QPainter painter(&recorderDevice);
         painter.setFont(font);
diff --git a/src/gui/text/qstatictext_p.h b/src/gui/text/qstatictext_p.h
index f5fd8d3..2a8d23a 100644
--- a/src/gui/text/qstatictext_p.h
+++ b/src/gui/text/qstatictext_p.h
@@ -54,8 +54,26 @@
 //
 
 #include <private/qtextengine_p.h>
+#include <private/qfontengine_p.h>
 
-QT_BEGIN_NAMESPACE              
+QT_BEGIN_NAMESPACE
+
+class QStaticTextItem
+{
+public:    
+    QStaticTextItem() : chars(0), numChars(0), fontEngine(0) {}
+
+    QVarLengthArray<QFixedPoint> glyphPositions; // 8 bytes per glyph
+    QVarLengthArray<glyph_t> glyphs;             // 4 bytes per glyph
+    const QChar *chars;                          // 2 bytes per glyph
+                                                 // =================
+                                                 // 14 bytes per glyph
+
+    int numChars;                                // 4 bytes per item
+    QFontEngine *fontEngine;                     // 4 bytes per item
+                                                 // ================
+                                                 // 8 bytes per item
+};
 
 class QStaticText;
 class QStaticTextPrivate
@@ -67,19 +85,17 @@ public:
 
     void init();
 
-    QAtomicInt ref;
+    QAtomicInt ref;          // 4 bytes per text
 
-    QString text;
-    QFont font;
-    QSizeF size;
+    QString text;            // 4 bytes per text
+    QFont font;              // 8 bytes per text
+    QSizeF size;             // 16 bytes per text
 
-    QTextItemInt *items;
-    QPointF *itemPositions;
-    int itemCount;
+    QStaticTextItem *items;  // 4 bytes per text
+    int itemCount;           // 4 bytes per text
+                             // ================
+                             // 40 bytes per text
 
-    char *glyphLayoutMemory;
-    unsigned short *logClusterMemory;
-    
     static QStaticTextPrivate *get(const QStaticText *q);
 };
 
diff --git a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
index caa679b..02a5246 100644
--- a/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
+++ b/src/opengl/gl2paintengineex/qpaintengineex_opengl2.cpp
@@ -1272,7 +1272,7 @@ void QGL2PaintEngineExPrivate::drawCachedGlyphs(const QPointF &p, QFontEngineGly
     }
 
     cache->setPaintEnginePrivate(this);
-    cache->populate(ti, glyphs, positions);
+    cache->populate(ti.fontEngine, glyphs, positions);
 
     if (cache->width() == 0 || cache->height() == 0)
         return;