Redesign wlr_texture

- Textures are now immutable (apart from those created from raw
  pixels), no more invalid textures
- Move all wl_drm stuff in wlr_renderer
- Most of wlr_texture fields are now private
- Remove some duplicated DMA-BUF code in the DRM backend
- Add more assertions
- Stride is now always given as bytes rather than pixels
- Drop wl_shm functions

Fun fact: this patch has been written 10,000 meters up in the air.

render/wlr_renderer.c

@@ -1,3 +1,4 @@
+#include <assert.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <wlr/render/interface.h>
@@ -6,6 +7,15 @@
 
 void wlr_renderer_init(struct wlr_renderer *renderer,
 		const struct wlr_renderer_impl *impl) {
+	assert(impl->begin);
+	assert(impl->clear);
+	assert(impl->scissor);
+	assert(impl->render_texture_with_matrix);
+	assert(impl->render_quad);
+	assert(impl->render_ellipse);
+	assert(impl->formats);
+	assert(impl->format_supported);
+	assert(impl->texture_from_pixels);
 	renderer->impl = impl;
 }
 
@@ -22,7 +32,9 @@ void wlr_renderer_begin(struct wlr_renderer *r, int width, int height) {
 }
 
 void wlr_renderer_end(struct wlr_renderer *r) {
-	r->impl->end(r);
+	if (r->impl->end) {
+		r->impl->end(r);
+	}
 }
 
 void wlr_renderer_clear(struct wlr_renderer *r, const float color[static 4]) {
@@ -33,16 +45,15 @@ void wlr_renderer_scissor(struct wlr_renderer *r, struct wlr_box *box) {
 	r->impl->scissor(r, box);
 }
 
-struct wlr_texture *wlr_render_texture_create(struct wlr_renderer *r) {
-	return r->impl->texture_create(r);
-}
-
 bool wlr_render_texture(struct wlr_renderer *r, struct wlr_texture *texture,
 		const float projection[static 9], int x, int y, float alpha) {
+	int width, height;
+	wlr_texture_get_size(texture, &width, &height);
+
 	float mat[9];
 	wlr_matrix_identity(mat);
 	wlr_matrix_translate(mat, x, y);
-	wlr_matrix_scale(mat, texture->width, texture->height);
+	wlr_matrix_scale(mat, width, height);
 	wlr_matrix_multiply(mat, projection, mat);
 
 	return wlr_render_texture_with_matrix(r, texture, mat, alpha);
@@ -69,15 +80,29 @@ const enum wl_shm_format *wlr_renderer_get_formats(
 	return r->impl->formats(r, len);
 }
 
-bool wlr_renderer_buffer_is_drm(struct wlr_renderer *r,
-		struct wl_resource *buffer) {
-	return r->impl->buffer_is_drm(r, buffer);
+bool wlr_renderer_resource_is_wl_drm_buffer(struct wlr_renderer *r,
+		struct wl_resource *resource) {
+	if (!r->impl->resource_is_wl_drm_buffer) {
+		return false;
+	}
+	return r->impl->resource_is_wl_drm_buffer(r, resource);
+}
+
+void wlr_renderer_wl_drm_buffer_get_size(struct wlr_renderer *r,
+		struct wl_resource *buffer, int *width, int *height) {
+	if (!r->impl->wl_drm_buffer_get_size) {
+		return;
+	}
+	return r->impl->wl_drm_buffer_get_size(r, buffer, width, height);
 }
 
 bool wlr_renderer_read_pixels(struct wlr_renderer *r, enum wl_shm_format fmt,
 		uint32_t stride, uint32_t width, uint32_t height,
 		uint32_t src_x, uint32_t src_y, uint32_t dst_x, uint32_t dst_y,
 		void *data) {
+	if (!r->impl->read_pixels) {
+		return false;
+	}
 	return r->impl->read_pixels(r, fmt, stride, width, height, src_x, src_y,
 		dst_x, dst_y, data);
 }