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, 5 insertions, 7 deletions

diff --git a/src/opengl/qglframebufferobject.cpp b/src/opengl/qglframebufferobject.cpp
index ed21923..ce80796 100644
--- a/src/opengl/qglframebufferobject.cpp
+++ b/src/opengl/qglframebufferobject.cpp
@@ -396,7 +396,7 @@ void QGLFramebufferObjectPrivate::init(QGLFramebufferObject *q, const QSize &sz,
     QGLContext *ctx = const_cast<QGLContext *>(QGLContext::currentContext());
     fbo_guard.setContext(ctx);
 
-    bool ext_detected = (QGLExtensions::glExtensions & QGLExtensions::FramebufferObject);
+    bool ext_detected = (QGLExtensions::glExtensions() & QGLExtensions::FramebufferObject);
     if (!ext_detected || (ext_detected && !qt_resolve_framebufferobject_extensions(ctx)))
         return;
 
@@ -466,7 +466,7 @@ void QGLFramebufferObjectPrivate::init(QGLFramebufferObject *q, const QSize &sz,
     }
 
     if (attachment == QGLFramebufferObject::CombinedDepthStencil
-        && (QGLExtensions::glExtensions & QGLExtensions::PackedDepthStencil)) {
+        && (QGLExtensions::glExtensions() & QGLExtensions::PackedDepthStencil)) {
         // depth and stencil buffer needs another extension
         glGenRenderbuffers(1, &depth_stencil_buffer);
         Q_ASSERT(!glIsRenderbuffer(depth_stencil_buffer));
@@ -1028,8 +1028,7 @@ QPaintEngine *QGLFramebufferObject::paintEngine() const
 */
 bool QGLFramebufferObject::hasOpenGLFramebufferObjects()
 {
-    QGLExtensions::init();
-    return (QGLExtensions::glExtensions & QGLExtensions::FramebufferObject);
+    return (QGLExtensions::glExtensions() & QGLExtensions::FramebufferObject);
 }
 
 /*!
@@ -1188,8 +1187,7 @@ bool QGLFramebufferObject::isBound() const
 */
 bool QGLFramebufferObject::hasOpenGLFramebufferBlit()
 {
-    QGLExtensions::init();
-    return (QGLExtensions::glExtensions & QGLExtensions::FramebufferBlit);
+    return (QGLExtensions::glExtensions() & QGLExtensions::FramebufferBlit);
 }
 
 /*!
@@ -1229,7 +1227,7 @@ void QGLFramebufferObject::blitFramebuffer(QGLFramebufferObject *target, const Q
                                            GLbitfield buffers,
                                            GLenum filter)
 {
-    if (!(QGLExtensions::glExtensions & QGLExtensions::FramebufferBlit))
+    if (!(QGLExtensions::glExtensions() & QGLExtensions::FramebufferBlit))
         return;
 
     const QGLContext *ctx = QGLContext::currentContext();