overlay: Double buffer the x11 window

For pleasant remote transport.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/overlay/overlay.c b/overlay/overlay.c
index ce3b645..c6234bf 100644 (file)
--- a/overlay/overlay.c
+++ b/overlay/overlay.c
@@ -55,8 +55,6 @@ static void overlay_show(cairo_surface_t *surface)
 {
        struct overlay *overlay;
 
-       cairo_surface_flush(surface);
-
        overlay = cairo_surface_get_user_data(surface, &overlay_key);
        if (overlay == NULL)
                return;

diff --git a/overlay/x11/x11-window.c b/overlay/x11/x11-window.c
index 7f7d6d7..89d5c73 100644 (file)
--- a/overlay/x11/x11-window.c
+++ b/overlay/x11/x11-window.c
@@ -36,6 +36,7 @@
 
 struct x11_window {
        struct overlay base;
+       cairo_surface_t *front;
        Display *dpy;
        Window win;
        int width, height;
@@ -55,6 +56,15 @@ static int noop(Display *dpy, XErrorEvent *event)
 static void x11_window_show(struct overlay *overlay)
 {
        struct x11_window *priv = to_x11_window(overlay);
+       cairo_t *cr;
+
+       cr = cairo_create(priv->front);
+       cairo_set_operator(cr, CAIRO_OPERATOR_SOURCE);
+       cairo_set_source_surface(cr, priv->base.surface, 0, 0);
+       cairo_paint(cr);
+       cairo_destroy(cr);
+
+       cairo_surface_flush(priv->front);
 
        if (!priv->visible) {
                XMapWindow(priv->dpy, priv->win);
@@ -104,11 +114,24 @@ static void x11_window_hide(struct overlay *overlay)
 static void x11_window_destroy(void *data)
 {
        struct x11_window *priv = data;
+       cairo_surface_destroy(priv->front);
        XDestroyWindow(priv->dpy, priv->win);
        XCloseDisplay(priv->dpy);
        free(priv);
 }
 
+static int prefer_image(struct config *config)
+{
+       const char *v = config_get_value(config, "x11", "prefer-image");
+
+       if (v == NULL)
+               return 0;
+       if (*v == '\0')
+               return 1;
+
+       return atoi(v);
+}
+
 cairo_surface_t *
 x11_window_create(struct config *config, int *width, int *height)
 {
@@ -148,24 +171,33 @@ x11_window_create(struct config *config, int *width, int *height)
        if (priv == NULL)
                goto err_surface;
 
-       priv->base.surface = surface;
+       if (prefer_image(config))
+               priv->base.surface = cairo_image_surface_create(CAIRO_FORMAT_RGB24, w, h);
+       else
+               priv->base.surface = cairo_surface_create_similar(surface, CAIRO_CONTENT_COLOR, w, h);
+       if (cairo_surface_status(priv->base.surface))
+               goto err_priv;
+
        priv->base.show = x11_window_show;
        priv->base.position = x11_window_position;
        priv->base.hide = x11_window_hide;
 
        priv->dpy = dpy;
        priv->win = win;
+       priv->front = surface;
        priv->visible = false;
 
        priv->width = w;
        priv->height = h;
 
-       cairo_surface_set_user_data(surface, &overlay_key, priv, x11_window_destroy);
+       cairo_surface_set_user_data(priv->base.surface, &overlay_key, priv, x11_window_destroy);
 
        *width = w;
        *height = h;
-       return surface;
+       return priv->base.surface;
 
+err_priv:
+       free(priv);
 err_surface:
        cairo_surface_destroy(surface);
 err_win: