Change Symbian to use destroyed swap behaviour in GL

Destroyed swap behaviour is a little bit faster than
preserved swap with heavily animated UIs like QML.

Task-number: QTBUG-18270
Reviewed-by: Samuel Rødal

1 files changed, 14 insertions, 7 deletions

diff --git a/src/opengl/qgl_symbian.cpp b/src/opengl/qgl_symbian.cpp
index 78624a2..7caaabd 100644
--- a/src/opengl/qgl_symbian.cpp
+++ b/src/opengl/qgl_symbian.cpp
@@ -228,13 +228,20 @@ bool QGLContext::chooseContext(const QGLContext* shareContext) // almost same as
 
         d->eglSurface = QEgl::createSurface(device(), d->eglContext->config());
 
-#if !defined(QGL_NO_PRESERVED_SWAP)
-        eglGetError();  // Clear error state first.
-        eglSurfaceAttrib(QEgl::display(), d->eglSurface,
-                EGL_SWAP_BEHAVIOR, EGL_BUFFER_PRESERVED);
-        if (eglGetError() != EGL_SUCCESS) {
-            qWarning("QGLContext: could not enable preserved swap");
-        }
+    eglGetError();  // Clear error state first.
+
+#ifdef QGL_NO_PRESERVED_SWAP
+    eglSurfaceAttrib(QEgl::display(), d->eglSurface,
+            EGL_SWAP_BEHAVIOR, EGL_BUFFER_DESTROYED);
+
+    if (eglGetError() != EGL_SUCCESS)
+        qWarning("QGLContext: could not enable destroyed swap behaviour");
+#else
+    eglSurfaceAttrib(QEgl::display(), d->eglSurface,
+            EGL_SWAP_BEHAVIOR, EGL_BUFFER_PRESERVED);
+
+    if (eglGetError() != EGL_SUCCESS)
+        qWarning("QGLContext: could not enable preserved swap behaviour");
 #endif
 
         setWindowCreated(true);