render/pixel_format: introduce pixel format info table

include/render/pixel_format.h

@@ -0,0 +1,23 @@
+#ifndef RENDER_PIXEL_FORMAT_H
+#define RENDER_PIXEL_FORMAT_H
+
+#include <wayland-server-protocol.h>
+
+struct wlr_pixel_format_info {
+	uint32_t drm_format;
+
+	/* 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;
+
+	/* True if the format has an alpha channel */
+	bool has_alpha;
+};
+
+const struct wlr_pixel_format_info *drm_get_pixel_format_info(uint32_t fmt);
+
+#endif

render/meson.build

@@ -5,6 +5,7 @@ wlr_files += files(
 	'drm_format_set.c',
 	'gbm_allocator.c',
 	'shm_format.c',
+	'pixel_format.c',
 	'swapchain.c',
 	'wlr_renderer.c',
 	'wlr_texture.c',

render/pixel_format.c

@@ -0,0 +1,30 @@
+#include <drm_fourcc.h>
+#include "render/pixel_format.h"
+
+static const struct wlr_pixel_format_info pixel_format_info[] = {
+	{
+		.drm_format = DRM_FORMAT_XRGB8888,
+		.opaque_substitute = DRM_FORMAT_INVALID,
+		.bpp = 32,
+		.has_alpha = false,
+	},
+	{
+		.drm_format = DRM_FORMAT_ARGB8888,
+		.opaque_substitute = DRM_FORMAT_XRGB8888,
+		.bpp = 32,
+		.has_alpha = true,
+	}
+};
+
+static const size_t pixel_format_info_size =
+	sizeof(pixel_format_info) / sizeof(pixel_format_info[0]);
+
+const struct wlr_pixel_format_info *drm_get_pixel_format_info(uint32_t fmt) {
+	for (size_t i = 0; i < pixel_format_info_size; ++i) {
+		if (pixel_format_info[i].drm_format == fmt) {
+			return &pixel_format_info[i];
+		}
+	}
+
+	return NULL;
+}