First attempt to implement screenshooter

backend/drm/drm.c

@@ -634,6 +634,15 @@ static bool wlr_drm_connector_move_cursor(struct wlr_output *output,
 	return drm->iface->crtc_move_cursor(drm, conn->crtc, x, y);
 }
 
+static void wlr_drm_connector_read_pixels(struct wlr_output *_output,
+		void *out_data) {
+	struct wlr_drm_output *output = (struct wlr_drm_output *)_output;
+	struct wlr_drm_crtc *crtc = output->crtc;
+	struct wlr_drm_plane *plane = crtc->primary;
+	glReadPixels(0, 0, plane->width, plane->height, GL_BGRA_EXT, GL_UNSIGNED_BYTE,
+		out_data);
+}
+
 static void wlr_drm_connector_destroy(struct wlr_output *output) {
 	struct wlr_drm_connector *conn = (struct wlr_drm_connector *)output;
 	wlr_drm_connector_cleanup(conn);
@@ -652,6 +661,7 @@ static struct wlr_output_impl output_impl = {
 	.swap_buffers = wlr_drm_connector_swap_buffers,
 	.set_gamma = wlr_drm_connector_set_gamma,
 	.get_gamma_size = wlr_drm_connector_get_gamma_size,
+	.read_pixels = wlr_drm_connector_read_pixels,
 };
 
 static int retry_pageflip(void *data) {

examples/meson.build

@@ -22,3 +22,9 @@ executable(
 	dependencies: wlroots,
 	link_with: lib_shared,
 )
+
+executable(
+	'screenshot',
+	'screenshot.c',
+	dependencies: [wayland_client, wlr_protos, dependency('cairo')],
+)

examples/screenshot.c

@@ -0,0 +1,292 @@
+/*
+ * 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 <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <wayland-client.h>
+#include <limits.h>
+#include <sys/param.h>
+#include <cairo.h>
+#include <screenshooter-client-protocol.h>
+#include "../backend/wayland/os-compatibility.c"
+
+static struct wl_shm *shm;
+static struct orbital_screenshooter *screenshooter;
+static struct wl_list output_list;
+int min_x, min_y, max_x, max_y;
+int buffer_copy_done;
+
+struct screenshooter_output {
+	struct wl_output *output;
+	struct wl_buffer *buffer;
+	int width, height, offset_x, offset_y;
+	void *data;
+	struct wl_list link;
+};
+
+static void
+display_handle_geometry(void *data,
+			struct wl_output *wl_output,
+			int x,
+			int y,
+			int physical_width,
+			int physical_height,
+			int subpixel,
+			const char *make,
+			const char *model,
+			int transform)
+{
+	struct screenshooter_output *output;
+
+	output = wl_output_get_user_data(wl_output);
+
+	if (wl_output == output->output) {
+		output->offset_x = x;
+		output->offset_y = y;
+	}
+}
+
+static void
+display_handle_mode(void *data,
+		    struct wl_output *wl_output,
+		    uint32_t flags,
+		    int width,
+		    int height,
+		    int refresh)
+{
+	struct screenshooter_output *output;
+
+	output = wl_output_get_user_data(wl_output);
+
+	if (wl_output == output->output && (flags & WL_OUTPUT_MODE_CURRENT)) {
+		output->width = width;
+		output->height = height;
+	}
+}
+
+static const struct wl_output_listener output_listener = {
+	display_handle_geometry,
+	display_handle_mode
+};
+
+static void
+screenshot_done(void *data, struct orbital_screenshot *screenshot)
+{
+	buffer_copy_done = 1;
+}
+
+static const struct orbital_screenshot_listener screenshot_listener = {
+	screenshot_done
+};
+
+static void
+handle_global(void *data, struct wl_registry *registry,
+	      uint32_t name, const char *interface, uint32_t version)
+{
+	static struct screenshooter_output *output;
+
+	if (strcmp(interface, "wl_output") == 0) {
+		output = calloc(1, sizeof *output);
+		output->output = wl_registry_bind(registry, name,
+						  &wl_output_interface, 1);
+		wl_list_insert(&output_list, &output->link);
+		wl_output_add_listener(output->output, &output_listener, output);
+	} else if (strcmp(interface, "wl_shm") == 0) {
+		shm = wl_registry_bind(registry, name, &wl_shm_interface, 1);
+	} else if (strcmp(interface, "orbital_screenshooter") == 0) {
+		screenshooter = wl_registry_bind(registry, name,
+						 &orbital_screenshooter_interface,
+						 1);
+	}
+}
+
+static void
+handle_global_remove(void *data, struct wl_registry *registry, uint32_t name)
+{
+	/* XXX: unimplemented */
+}
+
+static const struct wl_registry_listener registry_listener = {
+	handle_global,
+	handle_global_remove
+};
+
+static struct wl_buffer *
+create_shm_buffer(int width, int height, void **data_out)
+{
+	struct wl_shm_pool *pool;
+	struct wl_buffer *buffer;
+	int fd, size, stride;
+	void *data;
+
+	stride = width * 4;
+	size = stride * height;
+
+	fd = os_create_anonymous_file(size);
+	if (fd < 0) {
+		fprintf(stderr, "creating a buffer file for %d B failed: %m\n",
+			size);
+		return NULL;
+	}
+
+	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;
+	}
+
+	pool = wl_shm_create_pool(shm, fd, size);
+	close(fd);
+	buffer = wl_shm_pool_create_buffer(pool, 0, width, height, stride,
+					   WL_SHM_FORMAT_XRGB8888);
+	wl_shm_pool_destroy(pool);
+
+	*data_out = data;
+
+	return buffer;
+}
+
+static void
+write_png(int width, int height)
+{
+	int output_stride, buffer_stride, i;
+	cairo_surface_t *surface;
+	void *data, *d, *s;
+	struct screenshooter_output *output, *next;
+
+	buffer_stride = width * 4;
+
+	data = calloc(1, buffer_stride * height);
+	if (!data)
+		return;
+
+	wl_list_for_each_safe(output, next, &output_list, link) {
+		output_stride = output->width * 4;
+		s = output->data;
+		d = data + (output->offset_y - min_y) * buffer_stride +
+			   (output->offset_x - min_x) * 4;
+
+		for (i = 0; i < output->height; i++) {
+			memcpy(d, s, output_stride);
+			d += buffer_stride;
+			s += output_stride;
+		}
+
+		free(output);
+	}
+
+	surface = cairo_image_surface_create_for_data(data,
+						      CAIRO_FORMAT_ARGB32,
+						      width, height, buffer_stride);
+	cairo_surface_write_to_png(surface, "wayland-screenshot.png");
+	cairo_surface_destroy(surface);
+	free(data);
+}
+
+static int
+set_buffer_size(int *width, int *height)
+{
+	struct screenshooter_output *output;
+	min_x = min_y = INT_MAX;
+	max_x = max_y = INT_MIN;
+	int position = 0;
+
+	wl_list_for_each_reverse(output, &output_list, link) {
+		output->offset_x = position;
+		position += output->width;
+	}
+
+	wl_list_for_each(output, &output_list, link) {
+		min_x = MIN(min_x, output->offset_x);
+		min_y = MIN(min_y, output->offset_y);
+		max_x = MAX(max_x, output->offset_x + output->width);
+		max_y = MAX(max_y, output->offset_y + output->height);
+	}
+
+	if (max_x <= min_x || max_y <= min_y)
+		return -1;
+
+	*width = max_x - min_x;
+	*height = max_y - min_y;
+
+	return 0;
+}
+
+int main(int argc, char *argv[])
+{
+	struct wl_display *display;
+	struct wl_registry *registry;
+	struct screenshooter_output *output;
+	int width, height;
+
+	display = wl_display_connect(NULL);
+	if (display == NULL) {
+		fprintf(stderr, "failed to create display: %m\n");
+		return -1;
+	}
+
+	wl_list_init(&output_list);
+	registry = wl_display_get_registry(display);
+	wl_registry_add_listener(registry, &registry_listener, NULL);
+	wl_display_dispatch(display);
+	wl_display_roundtrip(display);
+
+	if (screenshooter == NULL) {
+		fprintf(stderr, "display doesn't support screenshooter\n");
+		return -1;
+	}
+
+	if (set_buffer_size(&width, &height)) {
+		fprintf(stderr, "cannot set buffer size\n");
+		return -1;
+	}
+
+	wl_list_for_each(output, &output_list, link) {
+		if (output->width == 0 || output->height == 0) {
+			continue;
+		}
+
+		output->buffer = create_shm_buffer(output->width, output->height, &output->data);
+		if (output->buffer == NULL) {
+			return -1;
+		}
+		struct orbital_screenshot *screenshot = orbital_screenshooter_shoot(
+			screenshooter, output->output, output->buffer);
+		orbital_screenshot_add_listener(screenshot, &screenshot_listener, screenshot);
+		buffer_copy_done = 0;
+		while (!buffer_copy_done)
+			wl_display_roundtrip(display);
+	}
+
+	write_png(width, height);
+
+	return 0;
+}

include/wlr/interfaces/wlr_output.h

@@ -19,6 +19,7 @@ struct wlr_output_impl {
 	void (*set_gamma)(struct wlr_output *output,
 			uint16_t size, uint16_t *r, uint16_t *g, uint16_t *b);
 	uint16_t (*get_gamma_size)(struct wlr_output *output);
+	void (*read_pixels)(struct wlr_output *_output, void *out_data);
 };
 
 void wlr_output_init(struct wlr_output *output, const struct wlr_output_impl *impl);

include/wlr/types/wlr_output.h

@@ -70,5 +70,6 @@ void wlr_output_swap_buffers(struct wlr_output *output);
 void wlr_output_set_gamma(struct wlr_output *output,
 	uint16_t size, uint16_t *r, uint16_t *g, uint16_t *b);
 uint16_t wlr_output_get_gamma_size(struct wlr_output *output);
+void wlr_output_read_pixels(struct wlr_output *output, void *out_data);
 
 #endif

protocol/meson.build

@@ -28,6 +28,8 @@ protocols = [
 
 client_protocols = [
 	[wl_protocol_dir, 'unstable/xdg-shell/xdg-shell-unstable-v6.xml'],
+	'gamma-control.xml',
+	'screenshooter.xml',
 ]
 
 wl_protos_src = []

types/wlr_output.c

@@ -247,3 +247,9 @@ uint16_t wlr_output_get_gamma_size(struct wlr_output *output) {
 	}
 	return output->impl->get_gamma_size(output);
 }
+
+void wlr_output_read_pixels(struct wlr_output *output, void *out_data) {
+	if (output->impl->read_pixels) {
+		output->impl->read_pixels(output, out_data);
+	}
+}

types/wlr_screenshooter.c

@@ -6,9 +6,44 @@
 #include <wlr/util/log.h>
 #include "screenshooter-protocol.h"
 
+struct screenshot_state {
+	struct wl_shm_buffer *shm_buffer;
+	struct wlr_output *output;
+	struct wlr_screenshot *screenshot;
+	struct wl_listener frame_listener;
+};
+
+static void output_frame_notify(struct wl_listener *listener, void *_data) {
+	struct screenshot_state *state = wl_container_of(listener, state, frame_listener);
+
+	void *data = wl_shm_buffer_get_data(state->shm_buffer);
+	wl_shm_buffer_begin_access(state->shm_buffer);
+	wlr_output_read_pixels(state->output, data);
+	wl_shm_buffer_end_access(state->shm_buffer);
+
+	wl_list_remove(&listener->link);
+	orbital_screenshot_send_done(state->screenshot->resource);
+
+	// TODO: free(state)
+}
+
 static void screenshooter_shoot(struct wl_client *client,
 		struct wl_resource *_screenshooter, uint32_t id,
 		struct wl_resource *_output, struct wl_resource *_buffer) {
+	struct wlr_output *output = wl_resource_get_user_data(_output);
+	if (!wl_shm_buffer_get(_buffer)) {
+		wlr_log(L_ERROR, "Invalid buffer: not a shared memory buffer");
+		return;
+	}
+	struct wl_shm_buffer *shm_buffer = wl_shm_buffer_get(_buffer);
+	int32_t width = wl_shm_buffer_get_width(shm_buffer);
+	int32_t height = wl_shm_buffer_get_height(shm_buffer);
+	// TODO: int32_t stride = wl_shm_buffer_get_stride(shm_buffer);
+	if (width < output->width || height < output->height) {
+		wlr_log(L_ERROR, "Invalid buffer: too small");
+		return;
+	}
+
 	struct wlr_screenshot *screenshot;
 	if (!(screenshot = calloc(1, sizeof(struct wlr_screenshot)))) {
 		return;
@@ -18,7 +53,13 @@ static void screenshooter_shoot(struct wl_client *client,
 		&orbital_screenshot_interface, wl_resource_get_version(_screenshooter), id);
 	wlr_log(L_DEBUG, "new screenshot %p (res %p)", screenshot, screenshot->resource);
 	wl_resource_set_implementation(screenshot->resource, NULL, screenshot, NULL);
-	// TODO: orbital_screenshot_send_done(screenshot->resource);
+
+	struct screenshot_state *state = calloc(1, sizeof(struct screenshot_state));
+	state->shm_buffer = shm_buffer;
+	state->output = output;
+	state->screenshot = screenshot;
+	state->frame_listener.notify = output_frame_notify;
+	wl_signal_add(&output->events.frame, &state->frame_listener);
 }
 
 static struct orbital_screenshooter_interface screenshooter_impl = {