gbm: lock and release buffer in swap buffers

Otherwise mesa prints "libEGL debug: EGL user error 0x300d
(EGL_BAD_SURFACE) in dri2_swap_buffers" when environment
variable EGL_LOG_LEVEL=debug.

Fixes #17: https://github.com/waffle-gl/waffle/pull/17
Reviewed-by: Chad Versace <chad.versace@linux.intel.com>

3 files changed, 21 insertions, 1 deletions

diff --git a/src/waffle/gbm/wgbm_platform.c b/src/waffle/gbm/wgbm_platform.c
index 5624660..d556145 100644
--- a/src/waffle/gbm/wgbm_platform.c
+++ b/src/waffle/gbm/wgbm_platform.c
@@ -156,7 +156,7 @@ static const struct wcore_platform_vtbl wgbm_platform_vtbl = {
         .create = wgbm_window_create,
         .destroy = wgbm_window_destroy,
         .show = wgbm_window_show,
-        .swap_buffers = wegl_window_swap_buffers,
+        .swap_buffers = wgbm_window_swap_buffers,
         .get_native = wgbm_window_get_native,
     },
 };
diff --git a/src/waffle/gbm/wgbm_window.c b/src/waffle/gbm/wgbm_window.c
index 85378da..bce32a4 100644
--- a/src/waffle/gbm/wgbm_window.c
+++ b/src/waffle/gbm/wgbm_window.c
@@ -100,6 +100,23 @@ wgbm_window_show(struct wcore_window *wc_self)
     return true;
 }
 
+
+bool
+wgbm_window_swap_buffers(struct wcore_window *wc_self)
+{
+    if (!wegl_window_swap_buffers(wc_self))
+        return false;
+
+    struct wgbm_window *self = wgbm_window(wc_self);
+    struct gbm_bo *bo = gbm_surface_lock_front_buffer(self->gbm_surface);
+    if (!bo)
+        return false;
+
+    gbm_surface_release_buffer(self->gbm_surface, bo);
+    return true;
+}
+
+
 union waffle_native_window*
 wgbm_window_get_native(struct wcore_window *wc_self)
 {
diff --git a/src/waffle/gbm/wgbm_window.h b/src/waffle/gbm/wgbm_window.h
index 7cd752b..0a895db 100644
--- a/src/waffle/gbm/wgbm_window.h
+++ b/src/waffle/gbm/wgbm_window.h
@@ -60,5 +60,8 @@ wgbm_window_destroy(struct wcore_window *wc_self);
 bool
 wgbm_window_show(struct wcore_window *wc_self);
 
+bool
+wgbm_window_swap_buffers(struct wcore_window *wc_self);
+
 union waffle_native_window*
 wgbm_window_get_native(struct wcore_window *wc_self);