render/pixel-format: add docs

include/render/pixel_format.h

@@ -3,6 +3,11 @@
 
 #include <wayland-server-protocol.h>
 
+/**
+ * Information about a pixel format.
+ *
+ * A pixel format is identified via its DRM four character code (see <drm_fourcc.h>).
+ */
 struct wlr_pixel_format_info {
 	uint32_t drm_format;
 
@@ -18,11 +23,25 @@ struct wlr_pixel_format_info {
 	bool has_alpha;
 };
 
+/**
+ * Get pixel format information from a DRM FourCC.
+ *
+ * NULL is returned if the pixel format is unknown.
+ */
 const struct wlr_pixel_format_info *drm_get_pixel_format_info(uint32_t fmt);
+/**
+ * Check whether a stride is large enough for a given pixel format and width.
+ */
 bool pixel_format_info_check_stride(const struct wlr_pixel_format_info *info,
 	int32_t stride, int32_t width);
 
+/**
+ * Convert an enum wl_shm_format to a DRM FourCC.
+ */
 uint32_t convert_wl_shm_format_to_drm(enum wl_shm_format fmt);
+/**
+ * Convert a DRM FourCC to an enum wl_shm_format.
+ */
 enum wl_shm_format convert_drm_format_to_wl_shm(uint32_t fmt);
 
 #endif