[vlc-devel] [PATCH] vout/opengl: Store and restore last viewport

[Marvin Scholz]

Between the call to vout_display_opengl_Viewport and the call to
vout_display_opengl_Display the viewport can be changed by the OS
causing the picture to render incorrectly.

To prevent that, store the last set viewport and restore it in the
display function.

Fix #21357
Fix #22209
---
 modules/video_output/opengl/vout_helper.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/modules/video_output/opengl/vout_helper.c b/modules/video_output/opengl/vout_helper.c
index b37b653257..2a8ec9cc12 100644
--- a/modules/video_output/opengl/vout_helper.c
+++ b/modules/video_output/opengl/vout_helper.c
@@ -166,6 +166,13 @@ struct vout_display_opengl_t {
     float f_fovy; /* to avoid recalculating them when needed.      */
     float f_z;    /* Position of the camera on the shpere radius vector */
     float f_sar;
+
+    struct {
+        GLint i_x;
+        GLint i_y;
+        GLint i_width;
+        GLint i_height;
+    } last_viewport;
 };
 
 static const vlc_fourcc_t gl_subpicture_chromas[] = {
@@ -1021,6 +1028,10 @@ void vout_display_opengl_SetWindowAspectRatio(vout_display_opengl_t *vgl,
 void vout_display_opengl_Viewport(vout_display_opengl_t *vgl, int x, int y,
                                   unsigned width, unsigned height)
 {
+    vgl->last_viewport.i_x = x;
+    vgl->last_viewport.i_y = y;
+    vgl->last_viewport.i_width = width;
+    vgl->last_viewport.i_height = height;
     vgl->vt.Viewport(x, y, width, height);
 }
 
@@ -1564,6 +1575,12 @@ int vout_display_opengl_Display(vout_display_opengl_t *vgl,
 {
     GL_ASSERT_NOERROR();
 
+    // Restore Viewport
+    vgl->vt.Viewport(vgl->last_viewport.i_x,
+                     vgl->last_viewport.i_y,
+                     vgl->last_viewport.i_width,
+                     vgl->last_viewport.i_height);
+
     /* Why drawing here and not in Render()? Because this way, the
        OpenGL providers can call vout_display_opengl_Display to force redraw.
        Currently, the OS X provider uses it to get a smooth window resizing */
-- 
2.19.1