Rework how Qt handles GL extensions.

Qt used to store the GL extensions a particular implementation supported
in a global cache, which was initialized once and never updated.
This could cause problems because different types of context might
support different kinds of extensions (e.g. the difference between
sw and hw contexts). With this patch, the GL extensions are cached
and updated within each QGLContext. It also makes the extension
initialization lazy, which saves application initialization costs for
embedded platforms.
The patch introduces a internal cross platform QGLTemporaryContext
class that is used to create a light-weight GL context without going
via QGLWidget and friends (QWS and WinCE still have QGLWidget fallbacks
for now).

Reviewed-by: Kim
Reviewed-by: Samuel

1 files changed, 62 insertions, 48 deletions

diff --git a/src/opengl/qgl_mac.mm b/src/opengl/qgl_mac.mm
index 6ed07e5..c01575b 100644
--- a/src/opengl/qgl_mac.mm
+++ b/src/opengl/qgl_mac.mm
@@ -116,6 +116,68 @@ extern void qt_mac_dispose_rgn(RgnHandle); //qregion_mac.cpp
 extern QRegion qt_mac_convert_mac_region(RgnHandle); //qregion_mac.cpp
 extern void qt_mac_to_pascal_string(QString s, Str255 str, TextEncoding encoding=0, int len=-1);  //qglobal.cpp
 
+/*
+    QGLTemporaryContext implementation
+*/
+
+class QGLTemporaryContextPrivate
+{
+public:
+#ifndef QT_MAC_USE_COCOA
+    AGLContext ctx;
+#else
+    NSOpenGLContext *ctx;
+#endif
+};
+
+QGLTemporaryContext::QGLTemporaryContext(bool, QWidget *)
+    : d(new QGLTemporaryContextPrivate)
+{
+    d->ctx = 0;
+#ifndef QT_MAC_USE_COCOA
+    GLint attribs[] = {AGL_RGBA, AGL_NONE};
+    AGLPixelFormat fmt = aglChoosePixelFormat(0, 0, attribs);
+    if (!fmt) {
+        qDebug("QGLTemporaryContext: Couldn't find any RGB visuals");
+        return;
+    }
+    d->ctx = aglCreateContext(fmt, 0);
+    if (!d->ctx)
+        qDebug("QGLTemporaryContext: Unable to create context");
+    else
+        aglSetCurrentContext(d->ctx);
+    aglDestroyPixelFormat(fmt);
+#else
+    QMacCocoaAutoReleasePool pool;
+    NSOpenGLPixelFormatAttribute attribs[] = { 0 };
+    NSOpenGLPixelFormat *fmt = [[NSOpenGLPixelFormat alloc] initWithAttributes:attribs];
+    if (!fmt) {
+        qWarning("QGLTemporaryContext: Cannot find any visuals");
+        return;
+    }
+
+    d->ctx = [[NSOpenGLContext alloc] initWithFormat:fmt shareContext:0];
+    if (!d->ctx)
+        qWarning("QGLTemporaryContext: Cannot create context");
+    else
+        [d->ctx makeCurrentContext];
+    [fmt release];
+#endif
+}
+
+QGLTemporaryContext::~QGLTemporaryContext()
+{
+    if (d->ctx) {
+#ifndef QT_MAC_USE_COCOA
+        aglSetCurrentContext(0);
+        aglDestroyContext(d->ctx);
+#else
+        [NSOpenGLContext clearCurrentContext];
+        [d->ctx release];
+#endif
+    }
+}
+
 bool QGLFormat::hasOpenGL()
 {
     return true;
@@ -918,54 +980,6 @@ void QGLWidgetPrivate::updatePaintDevice()
     q->update();
 }
 
-
-void QGLExtensions::init()
-{
-    static bool init_done = false;
-
-    if (init_done)
-        return;
-    init_done = true;
-
-#ifndef QT_MAC_USE_COCOA
-    GLint attribs[] = { AGL_RGBA, AGL_NONE };
-    AGLPixelFormat fmt = aglChoosePixelFormat(0, 0, attribs);
-    if (!fmt) {
-        qDebug("QGLExtensions: Couldn't find any RGB visuals");
-        return;
-    }
-    AGLContext ctx = aglCreateContext(fmt, 0);
-    if (!ctx) {
-        qDebug("QGLExtensions: Unable to create context");
-    } else {
-        aglSetCurrentContext(ctx);
-        init_extensions();
-        aglSetCurrentContext(0);
-        aglDestroyContext(ctx);
-    }
-    aglDestroyPixelFormat(fmt);
-#else
-    QMacCocoaAutoReleasePool pool;
-    NSOpenGLPixelFormatAttribute attribs[] = { 0 };
-    NSOpenGLPixelFormat *fmt = [[NSOpenGLPixelFormat alloc] initWithAttributes:attribs];
-    if (!fmt) {
-        qWarning("QGLExtensions: Cannot find any visuals");
-        return;
-    }
-
-    NSOpenGLContext *ctx = [[NSOpenGLContext alloc] initWithFormat:fmt shareContext:0];
-    if (!ctx) {
-        qWarning("QGLExtensions: Cannot create context");
-    } else {
-        [ctx makeCurrentContext];
-        init_extensions();
-        [NSOpenGLContext clearCurrentContext];
-        [ctx release];
-    }
-    [fmt release];
-#endif
-}
-
 #endif
 
 QT_END_NAMESPACE