Decorationless EGL apps are broken in toytoolkit

[Pekka Paalanen]

Hi,

as I was working on the screensaver stuff, I found out that EGL
applications that do not want decorations are broken. This is easy to
reproduce, just apply the following hunk:

diff --git a/clients/gears.c b/clients/gears.c
index bc85f54..4a1d660 100644
--- a/clients/gears.c
+++ b/clients/gears.c
@@ -319,6 +319,7 @@ gears_create(struct display *display)
        gears->window = window_create(display, width, height);
        window_set_transparent(gears->window, 0);
        window_set_title(gears->window, "Wayland Gears");
+       window_set_decoration(gears->window, 0);
 
        gears->display = display_get_egl_display(gears->d);
        if (gears->display == NULL)

After that, the gears demo should be decorationless, but instead it
triggers this error:

libEGL debug: EGL user error 0x300d (EGL_BAD_SURFACE) in eglSwapBuffers

That's fun, because nowhere in the Wayland demos toytoolkit code we
call eglSwapBuffers ourselves. The finger points at Cairo-egl.

I made a hack that makes it work:

diff --git a/clients/window.c b/clients/window.c
index 20500b4..8e11892 100644
--- a/clients/window.c
+++ b/clients/window.c
@@ -930,6 +930,20 @@ window_create_surface(struct window *window)
 }
 
 static void
+window_draw_none(struct window *window)
+{
+       cairo_t *cr;
+
+       window_create_surface(window);
+
+       /* XXX FIXME: what an ugly hack!
+        * But without this, decorationless EGL apps do not work. */
+       cr = cairo_create(window->cairo_surface);
+       cairo_paint(cr);
+       cairo_destroy(cr);
+}
+
+static void
 window_draw_menu(struct window *window)
 {
        cairo_t *cr;
@@ -1098,7 +1112,7 @@ window_draw(struct window *window)
        if (window->parent)
                window_draw_menu(window);
        else if (!window->decoration)
-               window_create_surface(window);
+               window_draw_none(window);
        else
                window_draw_decorations(window);
 }

I'm using this hack to continue my work, as I have no idea what is
wrong.

I am still using the cairo commit 9bdfae6e218185dd9, and have not yet
tried the current HEAD. There is also this in
window_draw_decorations():

	/* FIXME: this breakes gears, fix cairo? */
#if 0 
	cairo_device_flush (window->display->device);
#endif

Maybe it is related?

Do you have any idea what is going on, or if it is fixed already?


Thanks,
pq