weston_buffer: Add pixel format and modifier info

Promote these to weston_buffer rather than burying them in the renderers
and backends.

Signed-off-by: Daniel Stone <daniels@collabora.com>

include/libweston/libweston.h

@@ -1193,6 +1193,9 @@ struct weston_buffer {
 	uint32_t busy_count;
 	int y_inverted;
 	void *backend_private;
+
+	const struct pixel_format_info *pixel_format;
+	uint64_t format_modifier;
 };
 
 struct weston_buffer_reference {

libweston/compositor.c

@@ -52,6 +52,7 @@
 #include <time.h>
 #include <errno.h>
 #include <inttypes.h>
+#include <drm_fourcc.h>
 
 #include "timeline.h"
 
@@ -2415,11 +2416,25 @@ weston_buffer_from_resource(struct weston_compositor *ec,
 		buffer->width = wl_shm_buffer_get_width(shm);
 		buffer->height = wl_shm_buffer_get_height(shm);
 		buffer->y_inverted = true;
+		/* wl_shm might create a buffer with an unknown format, so check
+		 * and reject */
+		buffer->pixel_format =
+			pixel_format_get_info_shm(wl_shm_buffer_get_format(shm));
+		buffer->format_modifier = DRM_FORMAT_MOD_LINEAR;
+
+		if (!buffer->pixel_format)
+			goto fail;
 	} else if ((dmabuf = linux_dmabuf_buffer_get(buffer->resource))) {
 		buffer->type = WESTON_BUFFER_DMABUF;
 		buffer->dmabuf = dmabuf;
 		buffer->width = dmabuf->attributes.width;
 		buffer->height = dmabuf->attributes.height;
+		buffer->pixel_format =
+			pixel_format_get_info(dmabuf->attributes.format);
+		/* dmabuf import should assure we don't create a buffer with an
+		 * unknown format */
+		assert(buffer->pixel_format);
+		buffer->format_modifier = dmabuf->attributes.modifier[0];
 		buffer->y_inverted =
 			!(dmabuf->attributes.flags & ZWP_LINUX_BUFFER_PARAMS_V1_FLAGS_Y_INVERT);
 	} else {
@@ -2431,6 +2446,10 @@ weston_buffer_from_resource(struct weston_compositor *ec,
 		buffer->type = WESTON_BUFFER_RENDERER_OPAQUE;
 	}
 
+	/* Don't accept any formats we can't reason about: the importer should
+	 * make sure this never happens */
+	assert(buffer->pixel_format);
+
 	return buffer;
 
 fail:

libweston/renderer-gl/gl-renderer.c

@@ -2158,6 +2158,8 @@ gl_renderer_fill_buffer_info(struct weston_compositor *ec,
 			     struct weston_buffer *buffer)
 {
 	struct gl_renderer *gr = get_renderer(ec);
+	EGLint format;
+	uint32_t fourcc;
 	bool ret = true;
 
 	buffer->legacy_buffer = (struct wl_buffer *)buffer->resource;
@@ -2165,6 +2167,37 @@ gl_renderer_fill_buffer_info(struct weston_compositor *ec,
 			        EGL_WIDTH, &buffer->width);
 	ret &= gr->query_buffer(gr->egl_display, buffer->legacy_buffer,
 				EGL_HEIGHT, &buffer->height);
+	ret &= gr->query_buffer(gr->egl_display, buffer->legacy_buffer,
+				EGL_TEXTURE_FORMAT, &format);
+	if (!ret)
+		return false;
+
+	/* The legacy EGL buffer interface only describes the channels we can
+	 * sample from; not their depths or order. Take a stab at something
+	 * which might be representative. Pessimise extremely hard for
+	 * TEXTURE_EXTERNAL_OES. */
+	switch (format) {
+	case EGL_TEXTURE_RGB:
+		fourcc = DRM_FORMAT_XRGB8888;
+		break;
+	case EGL_TEXTURE_EXTERNAL_WL:
+	case EGL_TEXTURE_RGBA:
+		fourcc = DRM_FORMAT_ARGB8888;
+		break;
+	case EGL_TEXTURE_Y_XUXV_WL:
+		fourcc = DRM_FORMAT_YUYV;
+		break;
+	case EGL_TEXTURE_Y_UV_WL:
+		fourcc = DRM_FORMAT_NV12;
+		break;
+	case EGL_TEXTURE_Y_U_V_WL:
+		fourcc = DRM_FORMAT_YUV420;
+		break;
+	}
+
+	buffer->pixel_format = pixel_format_get_info(fourcc);
+	assert(buffer->pixel_format);
+	buffer->format_modifier = DRM_FORMAT_MOD_INVALID;
 
 	/* Assume scanout co-ordinate space i.e. (0,0) is top-left
 	 * if the query fails */
@@ -2172,7 +2205,7 @@ gl_renderer_fill_buffer_info(struct weston_compositor *ec,
 	gr->query_buffer(gr->egl_display, buffer->legacy_buffer,
 			 EGL_WAYLAND_Y_INVERTED_WL, &buffer->y_inverted);
 
-	return ret;
+	return true;
 }
 
 static void