Symbian: allow apps to disable GL multisampling

On Symbian, QML apps had no way to disable GL multisampling if the
hardware supported it. This caused some apps to run out of graphics
memory and fail.

This change adds a way for apps to indicate that they don't want
multisampling, by setting an environment variable. For example:
  qputenv("QT_SYMBIAN_DISABLE_GL_MULTISAMPLE", "1");

This non-public API style was used as the use case is platform and
application specific, and not appropriate for public API.

Task-number: ou1cimx1#947771
Reviewed-by: Gareth Stockwell

1 files changed, 4 insertions, 1 deletions

diff --git a/src/opengl/qgl_symbian.cpp b/src/opengl/qgl_symbian.cpp
index 94c63fc..0148304 100644
--- a/src/opengl/qgl_symbian.cpp
+++ b/src/opengl/qgl_symbian.cpp
@@ -181,7 +181,10 @@ bool QGLContext::chooseContext(const QGLContext* shareContext) // almost same as
         d->ownsEglContext = true;
         d->eglContext->setApi(QEgl::OpenGL);
 
-        if (!QSymbianGraphicsSystemEx::hasBCM2727()) {
+        // Allow apps to override ability to use multisampling by setting an environment variable. Eg:
+        //   qputenv("QT_SYMBIAN_DISABLE_GL_MULTISAMPLE", "1");
+        // Added to allow camera app to start with limited memory.
+        if (!QSymbianGraphicsSystemEx::hasBCM2727() && !qgetenv("QT_SYMBIAN_DISABLE_GL_MULTISAMPLE").toInt()) {
             // Most likely we have hw support for multisampling
             // so let's enable it.
             d->glFormat.setSampleBuffers(1);