types/wlr_buffer: introduce wlr_buffer_cap

include/types/wlr_buffer.h

@@ -3,6 +3,18 @@
 
 #include <wlr/types/wlr_buffer.h>
 
+/**
+ * Buffer capabilities.
+ *
+ * These bits indicate the features supported by a wlr_buffer. There is one bit
+ * per function in wlr_buffer_impl.
+ */
+enum wlr_buffer_cap {
+	WLR_BUFFER_CAP_DATA_PTR = 1 << 0,
+	WLR_BUFFER_CAP_DMABUF = 1 << 1,
+	WLR_BUFFER_CAP_SHM = 1 << 2,
+};
+
 /**
  * Access a pointer to the allocated data from the underlying implementation,
  * its format and its stride.