tests: add writeback sreenshooter test

This adds a test to ensure that the DRM-backend writeback screenshooter
is working properly.

Signed-off-by: Leandro Ribeiro <leandro.ribeiro@collabora.com>

tests/drm-writeback-screenshot-test.c

@@ -0,0 +1,150 @@
+/*
+ * Copyright © 2023 Collabora, Ltd.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial
+ * portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include "config.h"
+
+#include "weston-test-client-helper.h"
+#include "weston-test-fixture-compositor.h"
+#include "weston-output-capture-client-protocol.h"
+
+static enum test_result_code
+fixture_setup(struct weston_test_harness *harness)
+{
+	struct compositor_setup setup;
+
+	compositor_setup_defaults(&setup);
+	setup.backend = WESTON_BACKEND_DRM;
+	setup.renderer = WESTON_RENDERER_PIXMAN;
+	setup.shell = SHELL_TEST_DESKTOP;
+
+	weston_ini_setup(&setup,
+			 cfgln("[shell]"),
+			 cfgln("startup-animation=%s", "none"));
+
+	return weston_test_harness_execute_as_client(harness, &setup);
+}
+DECLARE_FIXTURE_SETUP(fixture_setup);
+
+static void
+draw_stuff(pixman_image_t *image)
+{
+	int w, h;
+	int stride; /* bytes */
+	int x, y;
+	uint32_t r, g, b;
+	uint32_t *pixels;
+	uint32_t *pixel;
+	pixman_format_code_t fmt;
+
+	fmt = pixman_image_get_format(image);
+	w = pixman_image_get_width(image);
+	h = pixman_image_get_height(image);
+	stride = pixman_image_get_stride(image);
+	pixels = pixman_image_get_data(image);
+
+	assert(PIXMAN_FORMAT_BPP(fmt) == 32);
+
+	for (x = 0; x < w; x++)
+		for (y = 0; y < h; y++) {
+			b = x;
+			g = x + y;
+			r = y;
+			pixel = pixels + (y * stride / 4) + x;
+			*pixel = (255U << 24) | (r << 16) | (g << 8) | b;
+		}
+}
+
+TEST(drm_writeback_screenshot) {
+
+	struct client *client;
+	struct buffer *buffer;
+	struct buffer *screenshot = NULL;
+	pixman_image_t *reference = NULL;
+	pixman_image_t *diffimg = NULL;
+	struct wl_surface *surface;
+	struct rectangle clip;
+	const char *fname;
+	bool match;
+	int frame;
+
+	/* create client */
+	testlog("Creating client for test\n");
+	client = create_client_and_test_surface(100, 100, 100, 100);
+	assert(client);
+	surface = client->surface->wl_surface;
+
+	/* move pointer away from image so it does not interfere with the
+	 * comparison of the writeback screenshot with the reference image */
+	weston_test_move_pointer(client->test->weston_test, 0, 1, 0, 0, 0);
+
+	buffer = create_shm_buffer_a8r8g8b8(client, 100, 100);
+	draw_stuff(buffer->image);
+
+	wl_surface_attach(surface, buffer->proxy, 0, 0);
+	wl_surface_damage(surface, 0, 0, 100, 100);
+	frame_callback_set(surface, &frame);
+	wl_surface_commit(surface);
+	frame_callback_wait(client, &frame);
+
+	/* take screenshot */
+	testlog("Taking a screenshot\n");
+	screenshot = client_capture_output(client, client->output,
+                                           WESTON_CAPTURE_V1_SOURCE_WRITEBACK);
+	assert(screenshot);
+
+	/* take another screenshot; this is important to ensure the
+	 * writeback state machine is working correctly */
+	testlog("Taking another screenshot\n");
+	screenshot = client_capture_output(client, client->output,
+                                           WESTON_CAPTURE_V1_SOURCE_WRITEBACK);
+	assert(screenshot);
+
+	/* load reference image */
+	fname = screenshot_reference_filename("drm-writeback-screenshot", 0);
+	testlog("Loading good reference image %s\n", fname);
+	reference = load_image_from_png(fname);
+	assert(reference);
+
+	/* check if they match - only the colored square matters, so the
+	 * clip is used to ignore the background */
+	clip.x = 100;
+	clip.y = 100;
+	clip.width = 100;
+	clip.height = 100;
+	match = check_images_match(screenshot->image, reference, &clip, NULL);
+	testlog("Screenshot %s reference image\n", match? "equal to" : "different from");
+	if (!match) {
+		diffimg = visualize_image_difference(screenshot->image, reference, &clip, NULL);
+		fname = screenshot_output_filename("drm-writeback-screenshot-error", 0);
+		write_image_as_png(diffimg, fname);
+		pixman_image_unref(diffimg);
+	}
+
+	pixman_image_unref(reference);
+	buffer_destroy(screenshot);
+	client_destroy(client);
+
+	assert(match);
+}

tests/meson.build

@@ -156,6 +156,7 @@ tests = [
 		'dep_objs': dep_libdrm_headers,
 	},
 	{	'name': 'drm-smoke', 'run_exclusive': true },
+	{	'name': 'drm-writeback-screenshot', 'run_exclusive': true },
 	{	'name': 'event', },
 	{	'name': 'internal-screenshot', },
 	{