Made extension resolving work with Core profile.

The Core profile was introduced in OpenGL 3.2 and if chosen removes
all deprecated functionality from the OpenGL API.

In the Core profile glGetString(GL_EXTENSIONS) is unsupported, so
instead we need to use glGetStringi(GL_EXTENSIONS, index) together with
glGetIntegerv(GL_NUM_EXTENSIONS). Also optimized the QGLExtensionMatcher
to not have to recompute the split positions all the time.

Preliminary support to prevent non-core-functions to be called in the GL
2 engine has also been added.

Reviewed-by: Kim

1 files changed, 58 insertions, 1 deletions

diff --git a/src/opengl/qgl.cpp b/src/opengl/qgl.cpp
index 684116c8b0..b3b459ddca 100644
--- a/src/opengl/qgl.cpp
+++ b/src/opengl/qgl.cpp
@@ -5359,12 +5359,69 @@ QGLWidget::QGLWidget(QGLContext *context, QWidget *parent,
 
 #endif // QT3_SUPPORT
 
+typedef GLubyte * (*qt_glGetStringi)(GLenum, GLuint);
+
+#ifndef GL_NUM_EXTENSIONS
+#define GL_NUM_EXTENSIONS 0x821D
+#endif
+
+QGLExtensionMatcher::QGLExtensionMatcher(const char *str)
+{
+    init(str);
+}
+
+QGLExtensionMatcher::QGLExtensionMatcher()
+{
+    const char *extensionStr = reinterpret_cast<const char *>(glGetString(GL_EXTENSIONS));
+
+    if (extensionStr) {
+        init(extensionStr);
+    } else {
+        // clear error state
+        while (glGetError()) {}
+
+        const QGLContext *ctx = QGLContext::currentContext();
+        if (ctx) {
+            qt_glGetStringi glGetStringi = (qt_glGetStringi)ctx->getProcAddress(QLatin1String("glGetStringi"));
+
+            GLint numExtensions;
+            glGetIntegerv(GL_NUM_EXTENSIONS, &numExtensions);
+
+            for (int i = 0; i < numExtensions; ++i) {
+                const char *str = reinterpret_cast<const char *>(glGetStringi(GL_EXTENSIONS, i));
+
+                m_offsets << m_extensions.size();
+
+                while (*str != 0)
+                    m_extensions.append(*str++);
+                m_extensions.append(' ');
+            }
+        }
+    }
+}
+
+void QGLExtensionMatcher::init(const char *str)
+{
+    m_extensions = str;
+
+    // make sure extension string ends with a space
+    if (!m_extensions.endsWith(' '))
+        m_extensions.append(' ');
+
+    int index = 0;
+    int next = 0;
+    while ((next = m_extensions.indexOf(' ', index)) >= 0) {
+        m_offsets << index;
+        index = next + 1;
+    }
+}
+
 /*
     Returns the GL extensions for the current context.
 */
 QGLExtensions::Extensions QGLExtensions::currentContextExtensions()
 {
-    QGLExtensionMatcher extensions(reinterpret_cast<const char *>(glGetString(GL_EXTENSIONS)));
+    QGLExtensionMatcher extensions;
     Extensions glExtensions;
 
     if (extensions.match("GL_ARB_texture_rectangle"))