PlatformSurfaceFilter/Renderer: render only when surface is exposed

Change-Id: Idec2f0ee5f3ace590421698293742932e8843aae
Reviewed-by: Andy Nichols <andy.nichols@theqtcompany.com>

1 files changed, 11 insertions, 2 deletions

diff --git a/src/render/backend/renderer.cpp b/src/render/backend/renderer.cpp
index 5ad77b19d..73d0b453e 100644
--- a/src/render/backend/renderer.cpp
+++ b/src/render/backend/renderer.cpp
@@ -143,6 +143,7 @@ Renderer::Renderer(QRenderAspect::RenderType type)
     , m_vsyncFrameAdvanceService(new VSyncFrameAdvanceService())
     , m_debugLogger(Q_NULLPTR)
     , m_pickEventFilter(new PickEventFilter())
+    , m_exposed(0)
 {
     // Set renderer as running - it will wait in the context of the
     // RenderThread for RenderViews to be submitted
@@ -332,7 +333,6 @@ void Renderer::initialize(QOpenGLContext *context)
     if (enableDebugLogging)
         sf.setOption(QSurfaceFormat::DebugContext);
 
-
     QOpenGLContext* ctx = context ? context : new QOpenGLContext;
     if (!context) {
         qCDebug(Backend) << "Creating OpenGL context with format" << sf;
@@ -395,6 +395,12 @@ void Renderer::shutdown()
     }
 }
 
+void Renderer::setSurfaceExposed(bool exposed)
+{
+    qCDebug(Backend) << "Window exposed: " << exposed;
+    m_exposed.fetchAndStoreOrdered(exposed);
+}
+
 void Renderer::setFrameGraphRoot(const Qt3DCore::QNodeId &frameGraphRootUuid)
 {
     m_frameGraphRootUuid = frameGraphRootUuid;
@@ -526,7 +532,10 @@ void Renderer::render()
     // One framegraph description
 
     while (m_running.load() > 0) {
-        doRender();
+        if (m_exposed.load() > 0)
+            doRender();
+        else
+            QThread::msleep(250);
     }
 }