From 0405e0cfc7974cd9369747077fb388144e8bc4de Mon Sep 17 00:00:00 2001
From: Seungha Yang <seungha@centricular.com>
Date: Sat, 5 Nov 2022 21:35:08 +0900
Subject: [PATCH] d3d11videosink: Always clear back buffer on resize

Swapchain may not need to be resized if the size of backbuffer
is equal to the previous size. Then previously rendered frame will be stay
on the screen. Do clear back buffer whenever resize() is called

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/3341>
---
 subprojects/gst-plugins-bad/sys/d3d11/gstd3d11window.cpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/subprojects/gst-plugins-bad/sys/d3d11/gstd3d11window.cpp b/subprojects/gst-plugins-bad/sys/d3d11/gstd3d11window.cpp
index 1e4894da14..b4de7a6c34 100644
--- a/subprojects/gst-plugins-bad/sys/d3d11/gstd3d11window.cpp
+++ b/subprojects/gst-plugins-bad/sys/d3d11/gstd3d11window.cpp
@@ -299,8 +299,10 @@ gst_d3d11_window_on_resize_default (GstD3D11Window * self, guint width,
   GstMemory *mem;
   GstD3D11Memory *dmem;
   ID3D11RenderTargetView *rtv;
+  ID3D11DeviceContext *context;
   gsize size;
   GstD3D11DeviceLockGuard lk (device);
+  const FLOAT clear_color[] = { 0.0, 0.0, 0.0, 1.0 };
 
   gst_clear_buffer (&self->backbuffer);
   if (!self->swap_chain)
@@ -348,6 +350,9 @@ gst_d3d11_window_on_resize_default (GstD3D11Window * self, guint width,
     return;
   }
 
+  context = gst_d3d11_device_get_device_context_handle (self->device);
+  context->ClearRenderTargetView (rtv, clear_color);
+
   self->backbuffer = gst_buffer_new ();
   gst_buffer_append_memory (self->backbuffer, mem);