render/gles2: remove assumptions about supported formats

We were assuming GL_BGRA_EXT was always supported.

We now check that it's supported for rendering. We fail if it isn't because
this format is specified as "always supported" by the Wayland protocol.

We also check if it's supported for reading pixels. A new preferred_read_format
function returns the preferred format that can be used to read pixels. This is
used by the screencopy protocol.

1 files changed, 16 insertions, 4 deletions

diff --git a/render/gles2/pixel_format.c b/render/gles2/pixel_format.c
index 6f42e72e..a4b4c101 100644
--- a/render/gles2/pixel_format.c
+++ b/render/gles2/pixel_format.c
@@ -3,9 +3,9 @@
 #include "render/gles2.h"
 
 /*
-* The wayland formats are little endian while the GL formats are big endian,
-* so WL_SHM_FORMAT_ARGB8888 is actually compatible with GL_BGRA_EXT.
-*/
+ * The wayland formats are little endian while the GL formats are big endian,
+ * so WL_SHM_FORMAT_ARGB8888 is actually compatible with GL_BGRA_EXT.
+ */
 static const struct wlr_gles2_pixel_format formats[] = {
 	{
 		.wl_format = WL_SHM_FORMAT_ARGB8888,
@@ -60,7 +60,19 @@ const struct wlr_gles2_pixel_format *get_gles2_format_from_wl(
 	return NULL;
 }
 
-const enum wl_shm_format *get_gles2_formats(size_t *len) {
+const struct wlr_gles2_pixel_format *get_gles2_format_from_gl(
+		GLint gl_format, GLint gl_type, bool alpha) {
+	for (size_t i = 0; i < sizeof(formats) / sizeof(*formats); ++i) {
+		if (formats[i].gl_format == gl_format &&
+				formats[i].gl_type == gl_type &&
+				formats[i].has_alpha == alpha) {
+			return &formats[i];
+		}
+	}
+	return NULL;
+}
+
+const enum wl_shm_format *get_gles2_wl_formats(size_t *len) {
 	*len = sizeof(wl_formats) / sizeof(wl_formats[0]);
 	return wl_formats;
 }