Minor OpenVG optimization when setting the EGL surface attribute.

Calling eglGetError() is expensive so we should avoid doing it unless
we know there actually is an error. The function returns EGL_FALSE upon
error so we can test for that instead of using eglGetError().

Reviewed-by: Jani Hautakangas

1 files changed, 2 insertions, 3 deletions

diff --git a/src/openvg/qwindowsurface_vgegl.cpp b/src/openvg/qwindowsurface_vgegl.cpp
index e3f52f4e..37e5f40 100644
--- a/src/openvg/qwindowsurface_vgegl.cpp
+++ b/src/openvg/qwindowsurface_vgegl.cpp
@@ -709,10 +709,9 @@ QEglContext *QVGEGLWindowSurfaceDirect::ensureContext(QWidget *widget)
 #if !defined(QVG_NO_PRESERVED_SWAP)
     // Try to force the surface back buffer to preserve its contents.
     if (needToSwap) {
-        eglGetError();  // Clear error state first.
-        eglSurfaceAttrib(QEgl::display(), windowSurface,
+        bool succeeded = eglSurfaceAttrib(QEgl::display(), windowSurface,
                 EGL_SWAP_BEHAVIOR, EGL_BUFFER_PRESERVED);
-        if (eglGetError() != EGL_SUCCESS) {
+        if (!succeeded && eglGetError() != EGL_SUCCESS) {
             qWarning("QVG: could not enable preserved swap");
         }
     }