Have the basic render loop notify when the renderpass desc. disappears

Unlike the threaded one, this runs into the well-known issue of
referencing the QRhiRenderPassDescriptor from data structures that are
tied to the rendercontext.

In the 'basic' loop there is one rendercontext that is reused for all
windows. With threaded there would be one rendercontext per window,
because there each window gets its own render thread, and so the problem
cannot arise.

Fix up the basic loop accordingly.

Change-Id: Iea6713c6167ead7df96ac5f01d7b92d2ec57ce71
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/quick/scenegraph/qsgrenderloop.cpp b/src/quick/scenegraph/qsgrenderloop.cpp
index a9f7a3a963..aa956fda9e 100644
--- a/src/quick/scenegraph/qsgrenderloop.cpp
+++ b/src/quick/scenegraph/qsgrenderloop.cpp
@@ -464,6 +464,15 @@ void QSGGuiThreadRenderLoop::handleDeviceLoss()
 void QSGGuiThreadRenderLoop::releaseSwapchain(QQuickWindow *window)
 {
     QQuickWindowPrivate *wd = QQuickWindowPrivate::get(window);
+
+    // Unlike the threaded render loop, this one reuses the same rendercontext
+    // for all QQuickWindows for the entire lifetime of the render loop.
+    // Therefore the renderer, if there is one, needs to be notified about the
+    // destruction of certain resources because they may be referenced from
+    // per-rendercontext data structures.
+    if (wd->renderer)
+        wd->renderer->invalidatePipelineCacheDependency(wd->rpDescForSwapchain);
+
     delete wd->rpDescForSwapchain;
     wd->rpDescForSwapchain = nullptr;
     delete wd->swapchain;