Implement Texture-From-Pixmap using EGLImage extensions on X11/EGL

There's lots of EGLImage extensions, split between EGL and client
rendering APIs like OpenGL ES & OpenVG. To implement texture-from-
pixmap using EGLImage, both EGL extensions and OpenGL ES extensions
are needed. This patch resolves the EGL extension function pointers
after the display is initialized in QEgl::display(). These are then
exported from QtGui so they can be used in QtOpenGL. The OpenGL ES
extension function pointers are resolved using the usual
qglextensions.cpp mechanism.

Using EGLImage seems to remove a fixed ~10 millisecond overhead per
pixmap bind when compared to using EGLSurface. Exact results per bind
for 100 QPixmaps are:

   8x8   Pixmap: 12   -> 1.71 msecs (EGLSurface -> EGLImage)
  64x64  Pixmap: 11.6 -> 1.83 msecs (EGLSurface -> EGLImage)
 128x128 Pixmap: 12.8 -> 2.74 msecs (EGLSurface -> EGLImage)
 256x256 Pixmap: 16   -> 6.20 msecs (EGLSurface -> EGLImage)

Reviewed-By: Trond

1 files changed, 11 insertions, 0 deletions

diff --git a/src/opengl/qglextensions.cpp b/src/opengl/qglextensions.cpp
index 02d5501..ef3c4cd 100644
--- a/src/opengl/qglextensions.cpp
+++ b/src/opengl/qglextensions.cpp
@@ -222,6 +222,17 @@ bool qt_resolve_buffer_extensions(QGLContext *ctx)
 #endif
 }
 
+#ifndef QT_NO_EGL
+bool qt_resolve_eglimage_gl_extensions(QGLContext *ctx)
+{
+    if (glEGLImageTargetTexture2DOES || glEGLImageTargetRenderbufferStorageOES)
+        return true;
+    glEGLImageTargetTexture2DOES = (_glEGLImageTargetTexture2DOES) ctx->getProcAddress(QLatin1String("glEGLImageTargetTexture2DOES"));
+    glEGLImageTargetRenderbufferStorageOES = (_glEGLImageTargetRenderbufferStorageOES) ctx->getProcAddress(QLatin1String("glEGLImageTargetRenderbufferStorageOES"));
+    return glEGLImageTargetTexture2DOES && glEGLImageTargetRenderbufferStorageOES;
+}
+#endif
+
 bool qt_resolve_glsl_extensions(QGLContext *ctx)
 {
     // Geometry shaders are optional...