screencopy-v1: add basic implementation

examples/meson.build

@@ -56,3 +56,9 @@ if libavutil.found() and libavcodec.found() and libavformat.found()
 				libavformat, wlroots, threads ]
 	)
 endif
+
+executable(
+	'screencopy',
+	'screencopy.c',
+	dependencies: [wayland_client, wlr_protos, wlroots]
+)

examples/screencopy.c

@@ -0,0 +1,232 @@
+/*
+ * Copyright © 2008 Kristian Høgsberg
+ *
+ * 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.
+ */
+
+#define _XOPEN_SOURCE 700
+#define _POSIX_C_SOURCE 199309L
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/param.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <wayland-client-protocol.h>
+#include "wlr-screencopy-unstable-v1-client-protocol.h"
+
+static struct wl_shm *shm = NULL;
+static struct zwlr_screencopy_manager_v1 *screencopy_manager = NULL;
+static struct wl_output *output = NULL;
+
+static struct {
+	struct wl_buffer *wl_buffer;
+	void *data;
+	int width, height, stride;
+} buffer;
+bool buffer_copy_done = false;
+
+static int backingfile(off_t size) {
+	char template[] = "/tmp/wlroots-shared-XXXXXX";
+	int fd = mkstemp(template);
+	if (fd < 0) {
+		return -1;
+	}
+
+	int ret;
+	while ((ret = ftruncate(fd, size)) == EINTR) {
+		// No-op
+	}
+	if (ret < 0) {
+		close(fd);
+		return -1;
+	}
+
+	unlink(template);
+	return fd;
+}
+
+static struct wl_buffer *create_shm_buffer(int width, int height,
+		int *stride_out, void **data_out) {
+	int stride = width * 4;
+	int size = stride * height;
+
+	int fd = backingfile(size);
+	if (fd < 0) {
+		fprintf(stderr, "creating a buffer file for %d B failed: %m\n", size);
+		return NULL;
+	}
+
+	void *data = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+	if (data == MAP_FAILED) {
+		fprintf(stderr, "mmap failed: %m\n");
+		close(fd);
+		return NULL;
+	}
+
+	struct wl_shm_pool *pool = wl_shm_create_pool(shm, fd, size);
+	close(fd);
+	struct wl_buffer *buffer = wl_shm_pool_create_buffer(pool, 0, width, height,
+		stride, WL_SHM_FORMAT_XRGB8888);
+	wl_shm_pool_destroy(pool);
+
+	*data_out = data;
+	*stride_out = stride;
+	return buffer;
+}
+
+static void frame_handle_buffer(void *data,
+		struct zwlr_screencopy_frame_v1 *frame, uint32_t width, uint32_t height,
+		uint32_t flags, uint32_t format, uint32_t stride) {
+	buffer.width = width;
+	buffer.height = height;
+	buffer.wl_buffer =
+		create_shm_buffer(width, height, &buffer.stride, &buffer.data);
+	if (buffer.wl_buffer == NULL) {
+		fprintf(stderr, "failed to create buffer\n");
+		exit(EXIT_FAILURE);
+	}
+
+	zwlr_screencopy_frame_v1_copy(frame, buffer.wl_buffer);
+}
+
+static void frame_handle_ready(void *data,
+		struct zwlr_screencopy_frame_v1 *frame) {
+	buffer_copy_done = true;
+}
+
+static void frame_handle_failed(void *data,
+		struct zwlr_screencopy_frame_v1 *frame) {
+	fprintf(stderr, "failed to copy frame\n");
+	exit(EXIT_FAILURE);
+}
+
+static const struct zwlr_screencopy_frame_v1_listener frame_listener = {
+	.buffer = frame_handle_buffer,
+	.ready = frame_handle_ready,
+	.failed = frame_handle_failed,
+};
+
+static void handle_global(void *data, struct wl_registry *registry,
+		uint32_t name, const char *interface, uint32_t version) {
+	if (strcmp(interface, wl_output_interface.name) == 0 && output == NULL) {
+		output = wl_registry_bind(registry, name, &wl_output_interface, 1);
+	} else if (strcmp(interface, wl_shm_interface.name) == 0) {
+		shm = wl_registry_bind(registry, name, &wl_shm_interface, 1);
+	} else if (strcmp(interface, zwlr_screencopy_manager_v1_interface.name)
+			== 0) {
+		screencopy_manager = wl_registry_bind(registry, name,
+			&zwlr_screencopy_manager_v1_interface, 1);
+	}
+}
+
+static void handle_global_remove(void *data, struct wl_registry *registry,
+		uint32_t name) {
+	// Who cares?
+}
+
+static const struct wl_registry_listener registry_listener = {
+	.global = handle_global,
+	.global_remove = handle_global_remove,
+};
+
+static void write_image(const char *filename, int width, int height, int stride,
+		void *data) {
+	char size[10 + 1 + 10 + 2 + 1]; // int32_t are max 10 digits
+	sprintf(size, "%dx%d+0", width, height);
+
+	int fd[2];
+	if (pipe(fd) != 0) {
+		fprintf(stderr, "cannot create pipe: %s\n", strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	pid_t child = fork();
+	if (child < 0) {
+		fprintf(stderr, "fork() failed\n");
+		exit(EXIT_FAILURE);
+	} else if (child != 0) {
+		close(fd[0]);
+		if (write(fd[1], data, stride * height) < 0) {
+			fprintf(stderr, "write() failed: %s\n", strerror(errno));
+			exit(EXIT_FAILURE);
+		}
+		close(fd[1]);
+		waitpid(child, NULL, 0);
+	} else {
+		close(fd[1]);
+		if (dup2(fd[0], 0) != 0) {
+			fprintf(stderr, "cannot dup the pipe\n");
+			exit(EXIT_FAILURE);
+		}
+		close(fd[0]);
+		// We requested WL_SHM_FORMAT_XRGB8888 in little endian, so that's BGRA
+		// in big endian.
+		execlp("convert", "convert", "-depth", "8", "-size", size, "bgra:-",
+			"-alpha", "opaque", filename, NULL);
+		fprintf(stderr, "cannot execute convert\n");
+		exit(EXIT_FAILURE);
+	}
+}
+
+int main(int argc, char *argv[]) {
+	struct wl_display * display = wl_display_connect(NULL);
+	if (display == NULL) {
+		fprintf(stderr, "failed to create display: %m\n");
+		return EXIT_FAILURE;
+	}
+
+	struct wl_registry *registry = wl_display_get_registry(display);
+	wl_registry_add_listener(registry, &registry_listener, NULL);
+	wl_display_dispatch(display);
+	wl_display_roundtrip(display);
+
+	if (shm == NULL) {
+		fprintf(stderr, "compositor is missing wl_shm\n");
+		return EXIT_FAILURE;
+	}
+	if (screencopy_manager == NULL) {
+		fprintf(stderr, "compositor doesn't support wlr-screencopy-unstable-v1\n");
+		return EXIT_FAILURE;
+	}
+	if (output == NULL) {
+		fprintf(stderr, "no output available\n");
+		return EXIT_FAILURE;
+	}
+
+	struct zwlr_screencopy_frame_v1 *frame =
+		zwlr_screencopy_manager_v1_capture_output(screencopy_manager, output);
+	zwlr_screencopy_frame_v1_add_listener(frame, &frame_listener, NULL);
+
+	while (!buffer_copy_done) {
+		wl_display_roundtrip(display);
+	}
+
+	write_image("wayland-screenshot.png", buffer.width, buffer.height,
+		buffer.stride, buffer.data);
+	wl_buffer_destroy(buffer.wl_buffer);
+
+	return EXIT_SUCCESS;
+}