ui/gtk-egl: Check EGLSurface before doing scanout

The first time gd_egl_scanout_texture() is called, there's a possibility
that the GTK drawing area might not be realized yet, in which case its
associated GdkWindow is NULL. This means gd_egl_init() was also skipped
and the EGLContext and EGLSurface stored in the VirtualGfxConsole are
not valid yet.

Continuing with the scanout in this conditions would result in hitting
an assert in libepoxy: "Couldn't find current GLX or EGL context".

A possible workaround is to just ignore the scanout request, giving the
the GTK drawing area some time to finish its realization. At that point,
the gd_egl_init() will succeed and the EGLContext and EGLSurface stored
in the VirtualGfxConsole will be valid.

Signed-off-by: Antonio Caggiano <quic_acaggian@quicinc.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20231016123215.2699269-1-quic_acaggian@quicinc.com>

diff --git a/ui/gtk-egl.c b/ui/gtk-egl.c
index a1060fd80f2746cb7aaf1915cf510310c201e029..3e8d1c1d02da811958d7bcdd36c19c2756095309 100644 (file)
--- a/ui/gtk-egl.c
+++ b/ui/gtk-egl.c
@@ -243,12 +243,19 @@ void gd_egl_scanout_texture(DisplayChangeListener *dcl,
     vc->gfx.h = h;
     vc->gfx.y0_top = backing_y_0_top;
 
-    eglMakeCurrent(qemu_egl_display, vc->gfx.esurface,
-                   vc->gfx.esurface, vc->gfx.ectx);
+    if (!vc->gfx.esurface) {
+        gd_egl_init(vc);
+        if (!vc->gfx.esurface) {
+            return;
+        }
+
+        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);
+        gtk_egl_set_scanout_mode(vc, true);
+        egl_fb_setup_for_tex(&vc->gfx.guest_fb, backing_width, backing_height,
+                             backing_id, false);
+    }
 }
 
 void gd_egl_scanout_dmabuf(DisplayChangeListener *dcl,