[kwinglutils] Improve cleanup handling

* add static cleanup handlers to GLTexturePrivate and GLRenderTarget
* revert the runtime resolved features (e.g. RenderTargets are not
  supported once we run the cleanup code)
* clear the extension lists
* reset the version variables

REVIEW: 117484

libkwineffects/kwingltexture.cpp

@@ -175,6 +175,14 @@ void GLTexturePrivate::initStatic()
 #endif
 }
 
+void GLTexturePrivate::cleanup()
+{
+    sNPOTTextureSupported = false;
+    sFramebufferObjectSupported = false;
+    sSaturationSupported = false;
+    sTextureFormat = GL_RGBA; // custom dummy, GL_BGRA is not present on GLES
+}
+
 bool GLTexture::isNull() const
 {
     Q_D(const GLTexture);

libkwineffects/kwingltexture_p.h

@@ -77,6 +77,8 @@ public:
     static uint s_fbo;
     static uint s_textureObjectCounter;
 private:
+    friend void KWin::cleanupGL();
+    static void cleanup();
     Q_DISABLE_COPY(GLTexturePrivate)
 };
 

libkwineffects/kwinglutils.cpp

@@ -136,8 +136,19 @@ void initGL(OpenGLPlatformInterface platformInterface)
 void cleanupGL()
 {
     ShaderManager::cleanup();
+    GLTexturePrivate::cleanup();
+    GLRenderTarget::cleanup();
     GLVertexBuffer::cleanup();
     GLPlatform::cleanup();
+
+    glExtensions.clear();
+    glxExtensions.clear();
+    eglExtension.clear();
+
+    glVersion = 0;
+    glXVersion = 0;
+    eglVersion = 0;
+    glTextureUnitsCount = 0;
 }
 
 bool hasGLVersion(int major, int minor, int release)
@@ -924,6 +935,13 @@ void GLRenderTarget::initStatic()
 #endif
 }
 
+void GLRenderTarget::cleanup()
+{
+    Q_ASSERT(s_renderTargets.isEmpty());
+    sSupported = false;
+    s_blitSupported = false;
+}
+
 bool GLRenderTarget::isRenderTargetBound()
 {
     return !s_renderTargets.isEmpty();
@@ -1873,6 +1891,10 @@ void GLVertexBuffer::cleanup()
     delete GLVertexBufferPrivate::s_indexBuffer;
     GLVertexBufferPrivate::s_indexBuffer = nullptr;
 #endif
+    GLVertexBufferPrivate::hasMapBufferRange = false;
+    GLVertexBufferPrivate::supportsIndexedQuads = false;
+    delete GLVertexBufferPrivate::streamingBuffer;
+    GLVertexBufferPrivate::streamingBuffer = nullptr;
 }
 
 GLVertexBuffer *GLVertexBuffer::streamingBuffer()

libkwineffects/kwinglutils.h

@@ -511,6 +511,8 @@ protected:
 
 
 private:
+    friend void KWin::cleanupGL();
+    static void cleanup();
     static bool sSupported;
     static bool s_blitSupported;
     static QStack<GLRenderTarget*> s_renderTargets;