[gnome-boxes/wip/dont-crash-gl] spice-display: Take client-side screenshots when GL is ON

[Felipe Borges <felipeborges src gnome org>]

commit 26939ec91d2b68bd264ab0721935bb84fc1a74dd
Author: Felipe Borges <felipeborges gnome org>
Date:   Fri May 24 15:36:33 2019 +0200

    spice-display: Take client-side screenshots when GL is ON
    
    Boxes crashes when taking screenshots (calling spice_display_get_pixbuf ()
    when GL (virgl) is enabled. This is a known Mesa issue, reported
    at https://bugs.freedesktop.org/106811
    
    This solution is a workaround and could be reverted once the mesa
    issue above is fixed. It is not ideal because it is dependend on the
    widget size-allocation, i.e. a screenshot taken when Boxes isn't
    fullscreen would result in an image with the same dimensions as the
    Boxes display.
    
    Fixes #311

 src/spice-display.vala | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
---
diff --git a/src/spice-display.vala b/src/spice-display.vala
index f5d6e7bd..5eff2043 100644
--- a/src/spice-display.vala
+++ b/src/spice-display.vala
@@ -193,9 +193,28 @@ public override void set_enable_audio (bool enable) {
         if (!display.ready)
             return null;
 
+        /* FIXME: This is a temporary workaround for a mesa issue that causes
+         * Boxes to crash when calling spice_display_get_pixbuf ();
+         * See https://bugs.freedesktop.org/106811 */
+        if ((machine as LibvirtMachine).acceleration_3d) {
+            return draw_pixbuf_client_side (display);
+        }
+
         return display.get_pixbuf ();
     }
 
+    private Gdk.Pixbuf draw_pixbuf_client_side (Spice.Display display) {
+        Gtk.Allocation alloc;
+        var widget = display as Gtk.Widget;
+        widget.get_allocation (out alloc);
+
+        var surface = new Cairo.ImageSurface (ARGB32, alloc.width, alloc.height);
+        var context = new Cairo.Context (surface);
+        widget.draw (context);
+
+        return Gdk.pixbuf_get_from_surface (surface, 0, 0, alloc.width, alloc.height);
+    }
+
     public override void collect_logs (StringBuilder builder) {
         builder.append_printf ("URL: %s\n", uri);
         if (gtk_session != null) {