7 files changed, 36 insertions, 3 deletions
diff --git a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
index edee29584c..d016e79641 100644
--- a/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
+++ b/src/quick/scenegraph/coreapi/qsgbatchrenderer.cpp
@@ -2914,6 +2914,11 @@ void Renderer::renderRenderNode(Batch *batch)
         glBindFramebuffer(GL_FRAMEBUFFER, prevFbo);
 }
 
+void Renderer::releaseCachedResources()
+{
+    m_shaderManager->invalidated();
+}
+
 class VisualizeShader : public QOpenGLShaderProgram
 {
 public:
diff --git a/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h b/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h
index 2c0f8667e8..b0a14d23b9 100644
--- a/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h
+++ b/src/quick/scenegraph/coreapi/qsgbatchrenderer_p.h
@@ -629,6 +629,7 @@ public:
 protected:
     void nodeChanged(QSGNode *node, QSGNode::DirtyState state) Q_DECL_OVERRIDE;
     void render() Q_DECL_OVERRIDE;
+    void releaseCachedResources() Q_DECL_OVERRIDE;
 
 private:
     enum ClipTypeBit
diff --git a/src/quick/scenegraph/coreapi/qsgrenderer_p.h b/src/quick/scenegraph/coreapi/qsgrenderer_p.h
index 4589685765..d96d893ca5 100644
--- a/src/quick/scenegraph/coreapi/qsgrenderer_p.h
+++ b/src/quick/scenegraph/coreapi/qsgrenderer_p.h
@@ -92,7 +92,8 @@ public:
     QSGNodeUpdater *nodeUpdater() const;
     void setNodeUpdater(QSGNodeUpdater *updater);
     inline QSGMaterialShader::RenderState state(QSGMaterialShader::RenderState::DirtyStates dirty) const;
-    virtual void setCustomRenderMode(const QByteArray &) { };
+    virtual void setCustomRenderMode(const QByteArray &) { }
+    virtual void releaseCachedResources() { }
 
     void clearChangedFlag() { m_changed_emitted = false; }
 
diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index bc65dc1bc3..2c73339b7a 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -56,6 +56,7 @@
 #include <QtQuick/QQuickWindow>
 #include <QtQuick/private/qquickwindow_p.h>
 #include <QtQuick/private/qsgcontext_p.h>
+#include <QtQuick/private/qsgrenderer_p.h>
 #include <private/qquickprofiler_p.h>
 
 #if QT_CONFIG(opengl)
@@ -152,7 +153,7 @@ public:
     void update(QQuickWindow *window) { maybeUpdate(window); } // identical for this implementation.
     void handleUpdateRequest(QQuickWindow *);
 
-    void releaseResources(QQuickWindow *) { }
+    void releaseResources(QQuickWindow *) Q_DECL_OVERRIDE;
 
     QAnimationDriver *animationDriver() const { return 0; }
 
@@ -505,6 +506,14 @@ QSGContext *QSGGuiThreadRenderLoop::sceneGraphContext() const
     return sg;
 }
 
+void QSGGuiThreadRenderLoop::releaseResources(QQuickWindow *w)
+{
+    // No full invalidation of the rendercontext, just clear some caches.
+    QQuickWindowPrivate *d = QQuickWindowPrivate::get(w);
+    if (d->renderer)
+        d->renderer->releaseCachedResources();
+}
+
 void QSGGuiThreadRenderLoop::handleUpdateRequest(QQuickWindow *window)
 {
     renderWindow(window);
diff --git a/src/quick/scenegraph/qsgthreadedrenderloop.cpp b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
index d28a73da20..e0f78a9873 100644
--- a/src/quick/scenegraph/qsgthreadedrenderloop.cpp
+++ b/src/quick/scenegraph/qsgthreadedrenderloop.cpp
@@ -406,6 +406,13 @@ bool QSGRenderThread::event(QEvent *e)
                 stopEventProcessing = true;
         } else {
             qCDebug(QSG_LOG_RENDERLOOP) << QSG_RT_PAD << "- not releasing because window is still active";
+            if (window) {
+                QQuickWindowPrivate *d = QQuickWindowPrivate::get(window);
+                if (d->renderer) {
+                    qCDebug(QSG_LOG_RENDERLOOP) << QSG_RT_PAD << "- requesting renderer to release cached resources";
+                    d->renderer->releaseCachedResources();
+                }
+            }
         }
         waitCondition.wakeOne();
         wm->m_lockedForSync = false;
diff --git a/src/quick/scenegraph/qsgwindowsrenderloop.cpp b/src/quick/scenegraph/qsgwindowsrenderloop.cpp
index e10e52d95e..e33f31f2ac 100644
--- a/src/quick/scenegraph/qsgwindowsrenderloop.cpp
+++ b/src/quick/scenegraph/qsgwindowsrenderloop.cpp
@@ -48,6 +48,7 @@
 
 #include <QtQuick/private/qsgcontext_p.h>
 #include <QtQuick/private/qquickwindow_p.h>
+#include <QtQuick/private/qsgrenderer_p.h>
 #include <QtQuick/private/qsgdefaultrendercontext_p.h>
 
 #include <QtQuick/QQuickWindow>
@@ -503,6 +504,15 @@ void QSGWindowsRenderLoop::renderWindow(QQuickWindow *window)
                               QQuickProfiler::SceneGraphRenderLoopSwap);
 }
 
+void QSGWindowsRenderLoop::releaseResources(QQuickWindow *w)
+{
+    // No full invalidation of the rendercontext, just clear some caches.
+    RLDEBUG("releaseResources");
+    QQuickWindowPrivate *d = QQuickWindowPrivate::get(w);
+    if (d->renderer)
+        d->renderer->releaseCachedResources();
+}
+
 QT_END_NAMESPACE
 
 #include "moc_qsgwindowsrenderloop_p.cpp"
diff --git a/src/quick/scenegraph/qsgwindowsrenderloop_p.h b/src/quick/scenegraph/qsgwindowsrenderloop_p.h
index 1940a66af2..a1188fed8a 100644
--- a/src/quick/scenegraph/qsgwindowsrenderloop_p.h
+++ b/src/quick/scenegraph/qsgwindowsrenderloop_p.h
@@ -86,7 +86,7 @@ public:
     QSGContext *sceneGraphContext() const override { return m_sg; }
     QSGRenderContext *createRenderContext(QSGContext *) const override;
 
-    void releaseResources(QQuickWindow *) override { }
+    void releaseResources(QQuickWindow *) override;
 
     void render();
     void renderWindow(QQuickWindow *window);