wlr_texture: Introduce wlr_texture_preferred_read_format

include/wlr/render/interface.h

@@ -54,6 +54,7 @@ struct wlr_texture_impl {
 		struct wlr_buffer *buffer, const pixman_region32_t *damage);
 	bool (*read_pixels)(struct wlr_texture *texture,
 		const struct wlr_texture_read_pixels_options *options);
+	uint32_t (*preferred_read_format)(struct wlr_texture *texture);
 	void (*destroy)(struct wlr_texture *texture);
 };
 

include/wlr/render/wlr_texture.h

@@ -42,6 +42,8 @@ struct wlr_texture_read_pixels_options {
 bool wlr_texture_read_pixels(struct wlr_texture *texture,
 	const struct wlr_texture_read_pixels_options *options);
 
+uint32_t wlr_texture_preferred_read_format(struct wlr_texture *texture);
+
 /**
  * Create a new texture from raw pixel data. `stride` is in bytes. The returned
  * texture is mutable.

render/wlr_texture.c

@@ -1,4 +1,5 @@
 #include <assert.h>
+#include <drm_fourcc.h>
 #include <stdbool.h>
 #include <stdlib.h>
 #include <string.h>
@@ -61,6 +62,14 @@ bool wlr_texture_read_pixels(struct wlr_texture *texture,
 	return texture->impl->read_pixels(texture, options);
 }
 
+uint32_t wlr_texture_preferred_read_format(struct wlr_texture *texture) {
+	if (!texture->impl->preferred_read_format) {
+		return DRM_FORMAT_INVALID;
+	}
+
+	return texture->impl->preferred_read_format(texture);
+}
+
 struct wlr_texture *wlr_texture_from_pixels(struct wlr_renderer *renderer,
 		uint32_t fmt, uint32_t stride, uint32_t width, uint32_t height,
 		const void *data) {