output: atomic mode, enabled, scale and transform

This commit makes more output properties (mode, enabled, scale and transform)
atomic. This means that they are double-buffered and only applied on commit.

Compositors now need to call wlr_output_commit after setting any of those
properties.

Internally, backends still apply properties sequentially. The behaviour should
be exactly the same as before. Future commits will update some backends to take
advantage of the atomic interface. Some backends are non-atomic by design, e.g.
the X11 backend or the legacy DRM backend.

Updates: https://github.com/swaywm/wlroots/issues/1640

1 files changed, 30 insertions, 4 deletions

diff --git a/backend/rdp/output.c b/backend/rdp/output.c
index 45eba3aa..68d2ed17 100644
--- a/backend/rdp/output.c
+++ b/backend/rdp/output.c
@@ -166,9 +166,9 @@ static bool nsc_swap_buffers(
 	return true;
 }
 
-static bool output_commit(struct wlr_output *wlr_output) {
-	struct wlr_rdp_output *output =
-		rdp_output_from_output(wlr_output);
+static bool output_commit_buffer(struct wlr_rdp_output *output) {
+	struct wlr_output *wlr_output = &output->wlr_output;
+
 	bool ret = false;
 
 	pixman_region32_t output_region;
@@ -220,6 +220,33 @@ out:
 	return ret;
 }
 
+static bool output_commit(struct wlr_output *wlr_output) {
+	struct wlr_rdp_output *output = rdp_output_from_output(wlr_output);
+
+	if (wlr_output->pending.committed & WLR_OUTPUT_STATE_ENABLED) {
+		wlr_log(WLR_DEBUG, "Cannot disable an RDP output");
+		return false;
+	}
+
+	if (wlr_output->pending.committed & WLR_OUTPUT_STATE_MODE) {
+		assert(wlr_output->pending.mode_type == WLR_OUTPUT_STATE_MODE_CUSTOM);
+		if (!output_set_custom_mode(wlr_output,
+				wlr_output->pending.custom_mode.width,
+				wlr_output->pending.custom_mode.height,
+				wlr_output->pending.custom_mode.refresh)) {
+			return false;
+		}
+	}
+
+	if (wlr_output->pending.committed & WLR_OUTPUT_STATE_BUFFER) {
+		if (!output_commit_buffer(output)) {
+			return false;
+		}
+	}
+
+	return true;
+}
+
 static void output_destroy(struct wlr_output *wlr_output) {
 	struct wlr_rdp_output *output =
 		rdp_output_from_output(wlr_output);
@@ -234,7 +261,6 @@ static void output_destroy(struct wlr_output *wlr_output) {
 }
 
 static const struct wlr_output_impl output_impl = {
-	.set_custom_mode = output_set_custom_mode,
 	.destroy = output_destroy,
 	.attach_render = output_attach_render,
 	.commit = output_commit,