gtk: add opengl support, using egl

This adds opengl rendering support to the gtk ui, using egl.
It's off by default for now, use 'qemu -display gtk,gl=on'
to play with this.

Note that gtk got native opengl support with release 3.16.
There most likely will be a separate implementation for 3.16+,
using the native gtk opengl support.  This patch covers older
versions (and for the time being 3.16 too, hopefully without
rendering quirks).

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 10 insertions, 1 deletions

diff --git a/vl.c b/vl.c
index 15bccc49a2..26b1e7e28c 100644
--- a/vl.c
+++ b/vl.c
@@ -2047,6 +2047,15 @@ static DisplayType select_display(const char *p)
                 } else {
                     goto invalid_gtk_args;
                 }
+            } else if (strstart(opts, ",gl=", &nextopt)) {
+                opts = nextopt;
+                if (strstart(opts, "on", &nextopt)) {
+                    request_opengl = 1;
+                } else if (strstart(opts, "off", &nextopt)) {
+                    request_opengl = 0;
+                } else {
+                    goto invalid_gtk_args;
+                }
             } else {
             invalid_gtk_args:
                 fprintf(stderr, "Invalid GTK option string: %s\n", p);
@@ -4012,7 +4021,7 @@ int main(int argc, char **argv, char **envp)
 
 #if defined(CONFIG_GTK)
     if (display_type == DT_GTK) {
-        early_gtk_display_init();
+        early_gtk_display_init(request_opengl);
     }
 #endif
 #if defined(CONFIG_SDL)