buffer: introduce wlr_readonly_data_buffer

include/types/wlr_buffer.h

@@ -25,6 +25,34 @@ struct wlr_shm_client_buffer {
 struct wlr_shm_client_buffer *shm_client_buffer_create(
 	struct wl_resource *resource);
 
+/**
+ * A read-only buffer that holds a data pointer.
+ *
+ * This is suitable for passing raw pixel data to a function that accepts a
+ * wlr_buffer.
+ */
+struct wlr_readonly_data_buffer {
+	struct wlr_buffer base;
+
+	const void *data;
+	uint32_t format;
+	size_t stride;
+
+	void *saved_data;
+};
+
+/**
+ * Wraps a read-only data pointer into a wlr_buffer. The data pointer may be
+ * accessed until readonly_data_buffer_drop() is called.
+ */
+struct wlr_readonly_data_buffer *readonly_data_buffer_create(uint32_t format,
+		size_t stride, uint32_t width, uint32_t height, const void *data);
+/**
+ * Drops ownership of the buffer (see wlr_buffer_drop() for more details) and
+ * perform a copy of the data pointer if a consumer still has the buffer locked.
+ */
+bool readonly_data_buffer_drop(struct wlr_readonly_data_buffer *buffer);
+
 /**
  * Buffer capabilities.
  *