ui/gtk: set scanout-mode right before scheduling draw

Setting scanout mode is better to be done very last minute
right because the mode can be reset anytime after it is set in
dpy_gl_scanout_texture by any asynchronouse dpy_refresh call,
which eventually cancels drawing of the guest scanout texture.

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-ID: <20230706183355.29361-1-dongwon.kim@intel.com>

ui/gtk-egl.c

@@ -242,7 +242,6 @@ void gd_egl_scanout_texture(DisplayChangeListener *dcl,
     eglMakeCurrent(qemu_egl_display, vc->gfx.esurface,
                    vc->gfx.esurface, vc->gfx.ectx);
 
-    gtk_egl_set_scanout_mode(vc, true);
     egl_fb_setup_for_tex(&vc->gfx.guest_fb, backing_width, backing_height,
                          backing_id, false);
 }
@@ -353,6 +352,7 @@ void gd_egl_flush(DisplayChangeListener *dcl,
     if (vc->gfx.guest_fb.dmabuf && !vc->gfx.guest_fb.dmabuf->draw_submitted) {
         graphic_hw_gl_block(vc->gfx.dcl.con, true);
         vc->gfx.guest_fb.dmabuf->draw_submitted = true;
+        gtk_egl_set_scanout_mode(vc, true);
         gtk_widget_queue_draw_area(area, x, y, w, h);
         return;
     }

ui/gtk-gl-area.c

@@ -264,7 +264,6 @@ void gd_gl_area_scanout_texture(DisplayChangeListener *dcl,
         return;
     }
 
-    gtk_gl_area_set_scanout_mode(vc, true);
     egl_fb_setup_for_tex(&vc->gfx.guest_fb, backing_width, backing_height,
                          backing_id, false);
 }
@@ -284,6 +283,7 @@ void gd_gl_area_scanout_flush(DisplayChangeListener *dcl,
     if (vc->gfx.guest_fb.dmabuf && !vc->gfx.guest_fb.dmabuf->draw_submitted) {
         graphic_hw_gl_block(vc->gfx.dcl.con, true);
         vc->gfx.guest_fb.dmabuf->draw_submitted = true;
+        gtk_gl_area_set_scanout_mode(vc, true);
     }
     gtk_gl_area_queue_render(GTK_GL_AREA(vc->gfx.drawing_area));
 }