1 files changed, 49 insertions, 11 deletions
diff --git a/include/render/pixel_format.h b/include/render/pixel_format.h
index d045b6a..6ca11f3 100644
--- a/include/render/pixel_format.h
+++ b/include/render/pixel_format.h
@@ -1,26 +1,64 @@
-#ifndef RENDER_PIXEL_FORMAT_H
-#define RENDER_PIXEL_FORMAT_H
+#ifndef FX_RENDER_PIXEL_FORMAT_H
+#define FX_RENDER_PIXEL_FORMAT_H
 
 #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>).
+ *
+ * Simple formats have a block size of 1×1 pixels and bytes_per_block contains
+ * the number of bytes per pixel (including padding).
+ *
+ * Tiled formats (e.g. sub-sampled YCbCr) are described with a block size
+ * greater than 1×1 pixels. A block is a rectangle of pixels which are stored
+ * next to each other in a byte-aligned memory region.
+ */
 struct wlr_pixel_format_info {
-  uint32_t drm_format;
+	uint32_t drm_format;
 
-  /* Equivalent of the format if it has an alpha channel,
-   * DRM_FORMAT_INVALID (0) if NA
-   */
-  uint32_t opaque_substitute;
+	/* Equivalent of the format if it has an alpha channel,
+	 * DRM_FORMAT_INVALID (0) if NA
+	 */
+	uint32_t opaque_substitute;
 
-  /* Bits per pixels */
-  uint32_t bpp;
+	/* Bytes per block (including padding) */
+	uint32_t bytes_per_block;
+	/* Size of a block in pixels (zero for 1×1) */
+	uint32_t block_width, block_height;
 
-  /* True if the format has an alpha channel */
-  bool has_alpha;
+	/* True if the format has an alpha channel */
+	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);
+/**
+ * Get the number of pixels per block for a pixel format.
+ */
+uint32_t pixel_format_info_pixels_per_block(const struct wlr_pixel_format_info *info);
+/**
+ * Get the minimum stride for a given pixel format and width.
+ */
+int32_t pixel_format_info_min_stride(const struct wlr_pixel_format_info *info, int32_t width);
+/**
+ * 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