render: introduce wlr_texture_from_buffer

This adds a a function to create a wlr_texture from a wlr_buffer.

The main motivation for this is to allow the renderer to create a
single wlr_texture per wlr_buffer. This can avoid needless imports
by re-using existing textures.

include/render/wlr_texture.h

@@ -0,0 +1,15 @@
+#ifndef RENDER_WLR_TEXTURE_H
+#define RENDER_WLR_TEXTURE_H
+
+#include <wlr/render/wlr_texture.h>
+
+/**
+ * Create a new texture from a buffer.
+ *
+ * Should not be called in a rendering block like renderer_begin()/end() or
+ * between attaching a renderer to an output and committing it.
+ */
+struct wlr_texture *wlr_texture_from_buffer(struct wlr_renderer *renderer,
+	struct wlr_buffer *buffer);
+
+#endif

include/wlr/render/interface.h

@@ -57,6 +57,8 @@ struct wlr_renderer_impl {
 		struct wl_display *wl_display);
 	int (*get_drm_fd)(struct wlr_renderer *renderer);
 	uint32_t (*get_render_buffer_caps)(void);
+	struct wlr_texture *(*texture_from_buffer)(struct wlr_renderer *renderer,
+		struct wlr_buffer *buffer);
 };
 
 void wlr_renderer_init(struct wlr_renderer *renderer,

render/wlr_texture.c

@@ -3,6 +3,7 @@
 #include <stdlib.h>
 #include <wlr/render/interface.h>
 #include <wlr/render/wlr_texture.h>
+#include "render/wlr_texture.h"
 
 void wlr_texture_init(struct wlr_texture *texture,
 		const struct wlr_texture_impl *impl, uint32_t width, uint32_t height) {
@@ -46,6 +47,15 @@ struct wlr_texture *wlr_texture_from_dmabuf(struct wlr_renderer *renderer,
 	return renderer->impl->texture_from_dmabuf(renderer, attribs);
 }
 
+struct wlr_texture *wlr_texture_from_buffer(struct wlr_renderer *renderer,
+		struct wlr_buffer *buffer) {
+	assert(!renderer->rendering);
+	if (!renderer->impl->texture_from_buffer) {
+		return NULL;
+	}
+	return renderer->impl->texture_from_buffer(renderer, buffer);
+}
+
 bool wlr_texture_is_opaque(struct wlr_texture *texture) {
 	if (!texture->impl->is_opaque) {
 		return false;