Speed up QPixmap::width(), height(), isNull() and depth().

This change moves the w, h, d variables to QPixmapData and introduces
is_null to keep track of nullness. This is possible only because
QPixmapData is internal API; otherwise we'd have to be smarter.

The optimization makes the QPixmap::width() function take 7 instructions,
down from 34 before. For the calculator demo in the declarative ui branch
this reduces a block of 750000 instructions (out of 30000000) to around
100000-150000 instructions.

Tested on Windows, Linux, Mac. Raster, X11 and OpenGL paint engines. Have
not tested the DirectFB engine.

Reviewed-by: Trond

1 files changed, 9 insertions, 1 deletions

diff --git a/src/gui/image/qpixmap_x11.cpp b/src/gui/image/qpixmap_x11.cpp
index b7fe92aa38..86cf515da7 100644
--- a/src/gui/image/qpixmap_x11.cpp
+++ b/src/gui/image/qpixmap_x11.cpp
@@ -312,7 +312,7 @@ static int qt_pixmap_serial = 0;
 int Q_GUI_EXPORT qt_x11_preferred_pixmap_depth = 0;
 
 QX11PixmapData::QX11PixmapData(PixelType type)
-    : QPixmapData(type, X11Class), hd(0), w(0), h(0), d(0),
+    : QPixmapData(type, X11Class), hd(0),
       uninit(true), read_only(false), x11_mask(0), picture(0), mask_picture(0), hd2(0),
       share_mode(QPixmap::ImplicitlyShared), pengine(0)
 {
@@ -324,6 +324,7 @@ void QX11PixmapData::resize(int width, int height)
 
     w = width;
     h = height;
+    is_null = (w <= 0 || h <= 0);
 
     if (defaultScreen >= 0 && defaultScreen != xinfo.screen()) {
         QX11InfoData* xd = xinfo.getX11Data(true);
@@ -347,6 +348,7 @@ void QX11PixmapData::resize(int width, int height)
     if (make_null || d == 0) {
         w = 0;
         h = 0;
+        is_null = true;
         hd = 0;
         picture = 0;
         d = 0;
@@ -375,6 +377,7 @@ void QX11PixmapData::fromImage(const QImage &img,
     w = img.width();
     h = img.height();
     d = img.depth();
+    is_null = (w <= 0 || h <= 0);
 
     if (defaultScreen >= 0 && defaultScreen != xinfo.screen()) {
         QX11InfoData* xd = xinfo.getX11Data(true);
@@ -395,6 +398,7 @@ void QX11PixmapData::fromImage(const QImage &img,
 
     if (uint(w) >= 32768 || uint(h) >= 32768) {
         w = h = 0;
+        is_null = true;
         return;
     }
 
@@ -1109,6 +1113,7 @@ void QX11PixmapData::bitmapFromImage(const QImage &image)
     w = img.width();
     h = img.height();
     d = 1;
+    is_null = (w <= 0 || h <= 0);
     int bpl = (w + 7) / 8;
     int ibpl = img.bytesPerLine();
     if (bpl != ibpl) {
@@ -1876,6 +1881,7 @@ QPixmap QX11PixmapData::transformed(const QTransform &transform,
         x11Data->d = d;
         x11Data->w = w;
         x11Data->h = h;
+        x11Data->is_null = (w <= 0 || h <= 0);
         x11Data->hd = (Qt::HANDLE)XCreatePixmap(X11->display,
                                                 RootWindow(X11->display, xinfo.screen()),
                                                 w, h, d);
@@ -2132,6 +2138,7 @@ void QX11PixmapData::copy(const QPixmapData *data, const QRect &rect)
     d = x11Data->d;
     w = rect.width();
     h = rect.height();
+    is_null = (w <= 0 || h <= 0);
     hd = (Qt::HANDLE)XCreatePixmap(X11->display,
                                    RootWindow(X11->display, x11Data->xinfo.screen()),
                                    w, h, d);
@@ -2250,6 +2257,7 @@ QPixmap QPixmap::fromX11Pixmap(Qt::HANDLE pixmap, QPixmap::ShareMode mode)
     data->uninit = false;
     data->w = width;
     data->h = height;
+    data->is_null = (width <= 0 || height <= 0);
     data->d = depth;
     data->hd = pixmap;