output: remove wlr_output_impl.transform

The backend doesn't need to handle transform changes, since everything is done
in software. In fact, all of the implementations were all identical and just
set the transform.

We could add support for hardware transforms, but:

- This would require a different field (something like hardware_transform)
- Not all combinations are possible because there often are hardware
  limitations
- The Wayland protocol isn't ready for this (in particular xdg-output, see [1])

This belongs to a different patch series anyway.

[1]: https://patchwork.freedesktop.org/series/52324/

backend/drm/drm.c

@@ -678,11 +678,6 @@ bool wlr_drm_connector_add_mode(struct wlr_output *output,
 	return true;
 }
 
-static void drm_connector_transform(struct wlr_output *output,
-		enum wl_output_transform transform) {
-	output->transform = transform;
-}
-
 static bool drm_connector_set_cursor(struct wlr_output *output,
 		struct wlr_texture *texture, int32_t scale,
 		enum wl_output_transform transform,
@@ -963,7 +958,6 @@ static void drm_connector_destroy(struct wlr_output *output) {
 static const struct wlr_output_impl output_impl = {
 	.enable = enable_drm_connector,
 	.set_mode = drm_connector_set_mode,
-	.transform = drm_connector_transform,
 	.set_cursor = drm_connector_set_cursor,
 	.move_cursor = drm_connector_move_cursor,
 	.destroy = drm_connector_destroy,

backend/headless/output.c

@@ -49,13 +49,6 @@ static bool output_set_custom_mode(struct wlr_output *wlr_output, int32_t width,
 	return true;
 }
 
-static void output_transform(struct wlr_output *wlr_output,
-		enum wl_output_transform transform) {
-	struct wlr_headless_output *output =
-		headless_output_from_output(wlr_output);
-	output->wlr_output.transform = transform;
-}
-
 static bool output_attach_render(struct wlr_output *wlr_output,
 		int *buffer_age) {
 	struct wlr_headless_output *output =
@@ -84,7 +77,6 @@ static void output_destroy(struct wlr_output *wlr_output) {
 
 static const struct wlr_output_impl output_impl = {
 	.set_custom_mode = output_set_custom_mode,
-	.transform = output_transform,
 	.destroy = output_destroy,
 	.attach_render = output_attach_render,
 	.commit = output_commit,

backend/noop/output.c

@@ -12,11 +12,6 @@ static struct wlr_noop_output *noop_output_from_output(
 	return (struct wlr_noop_output *)wlr_output;
 }
 
-static void output_transform(struct wlr_output *wlr_output,
-		enum wl_output_transform transform) {
-	// empty
-}
-
 static bool output_set_custom_mode(struct wlr_output *wlr_output,
 		int32_t width, int32_t height, int32_t refresh) {
 	wlr_output_update_custom_mode(wlr_output, width, height, refresh);
@@ -42,7 +37,6 @@ static void output_destroy(struct wlr_output *wlr_output) {
 }
 
 static const struct wlr_output_impl output_impl = {
-	.transform = output_transform,
 	.set_custom_mode = output_set_custom_mode,
 	.destroy = output_destroy,
 	.attach_render = output_attach_render,

backend/rdp/output.c

@@ -62,13 +62,6 @@ static bool output_set_custom_mode(struct wlr_output *wlr_output, int32_t width,
 	return true;
 }
 
-static void output_transform(struct wlr_output *wlr_output,
-		enum wl_output_transform transform) {
-	struct wlr_rdp_output *output =
-		rdp_output_from_output(wlr_output);
-	output->wlr_output.transform = transform;
-}
-
 static bool output_attach_render(struct wlr_output *wlr_output,
 		int *buffer_age) {
 	struct wlr_rdp_output *output =
@@ -242,7 +235,6 @@ static void output_destroy(struct wlr_output *wlr_output) {
 
 static const struct wlr_output_impl output_impl = {
 	.set_custom_mode = output_set_custom_mode,
-	.transform = output_transform,
 	.destroy = output_destroy,
 	.attach_render = output_attach_render,
 	.commit = output_commit,

backend/wayland/output.c

@@ -86,12 +86,6 @@ static bool output_commit(struct wlr_output *wlr_output) {
 	return true;
 }
 
-static void output_transform(struct wlr_output *wlr_output,
-		enum wl_output_transform transform) {
-	struct wlr_wl_output *output = get_wl_output_from_output(wlr_output);
-	output->wlr_output.transform = transform;
-}
-
 static bool output_set_cursor(struct wlr_output *wlr_output,
 		struct wlr_texture *texture, int32_t scale,
 		enum wl_output_transform transform,
@@ -226,7 +220,6 @@ static bool output_schedule_frame(struct wlr_output *wlr_output) {
 
 static const struct wlr_output_impl output_impl = {
 	.set_custom_mode = output_set_custom_mode,
-	.transform = output_transform,
 	.destroy = output_destroy,
 	.attach_render = output_attach_render,
 	.commit = output_commit,

backend/x11/output.c

@@ -75,12 +75,6 @@ static bool output_set_custom_mode(struct wlr_output *wlr_output,
 	return true;
 }
 
-static void output_transform(struct wlr_output *wlr_output,
-		enum wl_output_transform transform) {
-	struct wlr_x11_output *output = get_x11_output_from_output(wlr_output);
-	output->wlr_output.transform = transform;
-}
-
 static void output_destroy(struct wlr_output *wlr_output) {
 	struct wlr_x11_output *output = get_x11_output_from_output(wlr_output);
 	struct wlr_x11_backend *x11 = output->x11;
@@ -122,7 +116,6 @@ static bool output_commit(struct wlr_output *wlr_output) {
 
 static const struct wlr_output_impl output_impl = {
 	.set_custom_mode = output_set_custom_mode,
-	.transform = output_transform,
 	.destroy = output_destroy,
 	.attach_render = output_attach_render,
 	.commit = output_commit,

include/wlr/interfaces/wlr_output.h

@@ -19,8 +19,6 @@ struct wlr_output_impl {
 	bool (*set_mode)(struct wlr_output *output, struct wlr_output_mode *mode);
 	bool (*set_custom_mode)(struct wlr_output *output, int32_t width,
 		int32_t height, int32_t refresh);
-	void (*transform)(struct wlr_output *output,
-		enum wl_output_transform transform);
 	bool (*set_cursor)(struct wlr_output *output, struct wlr_texture *texture,
 		int32_t scale, enum wl_output_transform transform,
 		int32_t hotspot_x, int32_t hotspot_y, bool update_texture);

types/wlr_output.c

@@ -217,7 +217,11 @@ void wlr_output_update_custom_mode(struct wlr_output *output, int32_t width,
 
 void wlr_output_set_transform(struct wlr_output *output,
 		enum wl_output_transform transform) {
-	output->impl->transform(output, transform);
+	if (output->transform == transform) {
+		return;
+	}
+
+	output->transform = transform;
 	output_update_matrix(output);
 
 	struct wl_resource *resource;
@@ -291,7 +295,7 @@ static void handle_display_destroy(struct wl_listener *listener, void *data) {
 
 void wlr_output_init(struct wlr_output *output, struct wlr_backend *backend,
 		const struct wlr_output_impl *impl, struct wl_display *display) {
-	assert(impl->attach_render && impl->commit && impl->transform);
+	assert(impl->attach_render && impl->commit);
 	if (impl->set_cursor || impl->move_cursor) {
 		assert(impl->set_cursor && impl->move_cursor);
 	}