24 files changed, 721 insertions, 100 deletions
diff --git a/backend/drm/renderer.c b/backend/drm/renderer.c
index c5840436..0d338490 100644
--- a/backend/drm/renderer.c
+++ b/backend/drm/renderer.c
@@ -14,6 +14,7 @@
 #include <wlr/render/gles2.h>
 #include <wlr/render.h>
 #include "backend/drm/drm.h"
+#include "render/glapi.h"
 
 bool wlr_drm_renderer_init(struct wlr_drm_backend *drm,
 		struct wlr_drm_renderer *renderer) {
@@ -191,7 +192,7 @@ static struct wlr_texture *get_tex_for_bo(struct wlr_drm_renderer *renderer, str
 		EGL_NONE,
 	};
 
-	tex->img = renderer->egl.eglCreateImageKHR(renderer->egl.display, EGL_NO_CONTEXT,
+	tex->img = eglCreateImageKHR(renderer->egl.display, EGL_NO_CONTEXT,
 		EGL_LINUX_DMA_BUF_EXT, NULL, attribs);
 	if (!tex->img) {
 		wlr_log(L_ERROR, "Failed to create EGL image: %s", egl_error());
diff --git a/backend/meson.build b/backend/meson.build
index c5c73288..cf62a56f 100644
--- a/backend/meson.build
+++ b/backend/meson.build
@@ -38,5 +38,5 @@ lib_wlr_backend = static_library(
 	'wlr_backend',
 	backend_files,
 	include_directories: wlr_inc,
-	dependencies: [wayland_server, egl, gbm, libinput, systemd, elogind, wlr_protos],
+	dependencies: [wayland_server, egl, gbm, libinput, systemd, elogind, wlr_render, wlr_protos],
 )
diff --git a/backend/x11/backend.c b/backend/x11/backend.c
index 2134536c..1eb5a952 100644
--- a/backend/x11/backend.c
+++ b/backend/x11/backend.c
@@ -62,16 +62,31 @@ static bool handle_x11_event(struct wlr_x11_backend *x11, xcb_generic_event_t *e
 	case XCB_BUTTON_PRESS:
 	case XCB_BUTTON_RELEASE: {
 		xcb_button_press_event_t *ev = (xcb_button_press_event_t *)event;
-		struct wlr_event_pointer_button button = {
-			.device = &x11->pointer_dev,
-			.time_sec = ev->time / 1000,
-			.time_usec = ev->time * 1000,
-			.button = xcb_button_to_wl(ev->detail),
-			.state = event->response_type == XCB_BUTTON_PRESS ?
-				WLR_BUTTON_PRESSED : WLR_BUTTON_RELEASED,
-		};
 
-		wl_signal_emit(&x11->pointer.events.button, &button);
+		if (ev->detail == XCB_BUTTON_INDEX_4 ||
+				ev->detail == XCB_BUTTON_INDEX_5) {
+			double delta = (ev->detail == XCB_BUTTON_INDEX_4 ? -15 : 15);
+			struct wlr_event_pointer_axis axis = {
+				.device = &x11->pointer_dev,
+				.time_sec = ev->time / 1000,
+				.time_usec = ev->time * 1000,
+				.source = WLR_AXIS_SOURCE_WHEEL,
+				.orientation = WLR_AXIS_ORIENTATION_VERTICAL,
+				.delta = delta,
+			};
+			wl_signal_emit(&x11->pointer.events.axis, &axis);
+		} else {
+			struct wlr_event_pointer_button button = {
+				.device = &x11->pointer_dev,
+				.time_sec = ev->time / 1000,
+				.time_usec = ev->time * 1000,
+				.button = xcb_button_to_wl(ev->detail),
+				.state = event->response_type == XCB_BUTTON_PRESS ?
+					WLR_BUTTON_PRESSED : WLR_BUTTON_RELEASED,
+			};
+
+			wl_signal_emit(&x11->pointer.events.button, &button);
+		}
 		x11->time = ev->time;
 		break;
 	}
@@ -260,6 +275,7 @@ static bool wlr_x11_backend_start(struct wlr_backend *backend) {
 
 	xcb_map_window(x11->xcb_conn, output->win);
 	xcb_flush(x11->xcb_conn);
+	wlr_output_create_global(&output->wlr_output, x11->wl_display);
 
 	wl_signal_emit(&x11->backend.events.output_add, output);
 	wl_signal_emit(&x11->backend.events.input_add, &x11->keyboard_dev);
diff --git a/examples/meson.build b/examples/meson.build
index 6ec40843..a29a3310 100644
--- a/examples/meson.build
+++ b/examples/meson.build
@@ -22,3 +22,9 @@ executable(
 	dependencies: wlroots,
 	link_with: lib_shared,
 )
+
+executable(
+	'screenshot',
+	'screenshot.c',
+	dependencies: [wayland_client, wlr_protos],
+)
diff --git a/examples/screenshot.c b/examples/screenshot.c
new file mode 100644
index 00000000..95af49ca
--- /dev/null
+++ b/examples/screenshot.c
@@ -0,0 +1,288 @@
+/*
+ * 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 <sys/wait.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <wayland-client.h>
+#include <limits.h>
+#include <sys/param.h>
+#include <screenshooter-client-protocol.h>
+#include "../backend/wayland/os-compatibility.c"
+
+static struct wl_shm *shm = NULL;
+static struct orbital_screenshooter *screenshooter = NULL;
+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 output_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 = wl_output_get_user_data(wl_output);
+
+	if (wl_output == output->output) {
+		output->offset_x = x;
+		output->offset_y = y;
+	}
+}
+
+static void output_handle_mode(void *data, struct wl_output *wl_output,
+		uint32_t flags, int width, int height, int refresh) {
+	struct screenshooter_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 void output_handle_done(void *data, struct wl_output *wl_output) {
+
+}
+
+static const struct wl_output_listener output_listener = {
+	.geometry = output_handle_geometry,
+	.mode = output_handle_mode,
+	.done = output_handle_done,
+};
+
+static void screenshot_done(void *data, struct orbital_screenshot *screenshot) {
+	buffer_copy_done = 1;
+}
+
+static const struct orbital_screenshot_listener screenshot_listener = {
+	.done = 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) {
+	// Unimplemented
+}
+
+static const struct wl_registry_listener registry_listener = {
+	.global = handle_global,
+	.global_remove = handle_global_remove,
+};
+
+static struct wl_buffer *create_shm_buffer(int width, int height,
+		void **data_out) {
+	int stride = width * 4;
+	int size = stride * height;
+
+	int fd = os_create_anonymous_file(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;
+
+	return buffer;
+}
+
+static void argb_to_rgba(uint32_t *data, size_t height, size_t stride) {
+	size_t n = height*stride/4;
+	for (size_t i = 0; i < n; ++i) {
+		uint32_t v = data[i];
+		uint32_t rgb = v & 0x00ffffff;
+		uint32_t a = (v & 0xff000000) >> 24;
+		data[i] = (rgb << 8) | a;
+	}
+}
+
+static void write_image(const char *filename, int width, int height) {
+	int buffer_stride = width * 4;
+
+	void *data = calloc(1, buffer_stride * height);
+	if (!data) {
+		return;
+	}
+
+	struct screenshooter_output *output, *next;
+	wl_list_for_each_safe(output, next, &output_list, link) {
+		int output_stride = output->width * 4;
+		void *s = output->data;
+		void *d = data + (output->offset_y - min_y) * buffer_stride +
+			(output->offset_x - min_x) * 4;
+
+		for (int i = 0; i < output->height; i++) {
+			memcpy(d, s, output_stride);
+			d += buffer_stride;
+			s += output_stride;
+		}
+
+		free(output);
+	}
+
+	argb_to_rgba(data, height, buffer_stride);
+
+	char size[10 + 1 + 10 + 2 + 1]; // int32_t are max 10 digits
+	sprintf(size, "%dx%d+0", width, height);
+
+	int fd[2];
+	pipe(fd);
+
+	pid_t child = fork();
+	if (child < 0) {
+		fprintf(stderr, "fork() failed\n");
+		exit(EXIT_FAILURE);
+	} else if (child != 0) {
+		close(fd[0]);
+		write(fd[1], data, buffer_stride * height);
+		close(fd[1]);
+		free(data);
+		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]);
+		execlp("convert", "convert", "-depth", "8", "-size", size, "rgba:-",
+			"-alpha", "opaque", filename, NULL);
+		fprintf(stderr, "cannot execute convert\n");
+		exit(EXIT_FAILURE);
+	}
+}
+
+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 = wl_display_connect(NULL);
+	if (display == NULL) {
+		fprintf(stderr, "failed to create display: %m\n");
+		return -1;
+	}
+
+	wl_list_init(&output_list);
+	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 (screenshooter == NULL) {
+		fprintf(stderr, "display doesn't support screenshooter\n");
+		return -1;
+	}
+
+	int width, height;
+	if (set_buffer_size(&width, &height)) {
+		fprintf(stderr, "cannot set buffer size\n");
+		return -1;
+	}
+
+	struct screenshooter_output *output;
+	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_image("wayland-screenshot.png", width, height);
+	return EXIT_SUCCESS;
+}
diff --git a/glgen.sh b/glgen.sh
new file mode 100755
index 00000000..d9de6f9f
--- /dev/null
+++ b/glgen.sh
@@ -0,0 +1,91 @@
+#!/bin/sh
+
+# Generates a simple GL/EGL extension function loader.
+#
+# The input is a .txt file, with each function to load on its own line.
+# If a line starts with a -, it is optional, and will not cause the loader
+# to fail if it can't load the function. You'll need to check if that function
+# is NULL before using it.
+
+if [ $# -ne 2 ]; then
+	exit 1
+fi
+
+SPEC=$1
+OUT=$2
+
+BASE=$(basename "$SPEC" .txt)
+INCLUDE_GUARD=$(printf %s "$SPEC" | tr -c [:alnum:] _ | tr [:lower:] [:upper:])
+
+DECL=""
+DEFN=""
+LOADER=""
+
+DECL_FMT='extern %s %s;'
+DEFN_FMT='%s %s;'
+LOADER_FMT='%s = (%s)eglGetProcAddress("%s");'
+CHECK_FMT='if (!%s) {
+	wlr_log(L_ERROR, "Unable to load %s");
+	return false;
+}'
+
+while read -r COMMAND; do
+	[ ${COMMAND::1} = "-" ]
+	OPTIONAL=$?
+
+	COMMAND=${COMMAND#-}
+	if [ ${COMMAND: -2} = "WL" ]; then
+		FUNC_PTR_FMT='PFN%s'
+	else
+		FUNC_PTR_FMT='PFN%sPROC'
+	fi
+
+	FUNC_PTR=$(printf "$FUNC_PTR_FMT" "$COMMAND" | tr [:lower:] [:upper:])
+
+	DECL="$DECL$(printf "\n$DECL_FMT" "$FUNC_PTR" "$COMMAND")"
+	DEFN="$DEFN$(printf "\n$DEFN_FMT" "$FUNC_PTR" "$COMMAND")"
+	LOADER="$LOADER$(printf "\n$LOADER_FMT" "$COMMAND" "$FUNC_PTR" "$COMMAND")"
+
+	if [ $OPTIONAL -ne 0 ]; then
+		LOADER="$LOADER$(printf "\n$CHECK_FMT" "$COMMAND" "$COMMAND")"
+	fi
+done < $SPEC
+
+if [ ${OUT: -2} = '.h' ]; then
+	cat > $OUT << EOF
+	#ifndef $INCLUDE_GUARD
+	#define $INCLUDE_GUARD
+
+	#include <stdbool.h>
+
+	#include <EGL/egl.h>
+	#include <EGL/eglext.h>
+	#include <EGL/eglmesaext.h>
+	#include <GLES2/gl2.h>
+	#include <GLES2/gl2ext.h>
+
+	bool load_$BASE(void);
+	$DECL
+
+	#endif
+EOF
+elif [ ${OUT: -2} = '.c' ]; then
+	cat > $OUT << EOF
+	#include <wlr/util/log.h>
+	#include "$BASE.h"
+	$DEFN
+
+	bool load_$BASE(void) {
+		static bool done = false;
+		if (done) {
+			return true;
+		}
+	$LOADER
+
+		done = true;
+		return true;
+	}
+EOF
+else
+	exit 1
+fi
diff --git a/include/rootston/desktop.h b/include/rootston/desktop.h
index 0d641848..68fc5b94 100644
--- a/include/rootston/desktop.h
+++ b/include/rootston/desktop.h
@@ -8,6 +8,7 @@
 #include <wlr/types/wlr_wl_shell.h>
 #include <wlr/types/wlr_xdg_shell_v6.h>
 #include <wlr/types/wlr_gamma_control.h>
+#include <wlr/types/wlr_screenshooter.h>
 #include <wlr/util/list.h>
 #include "rootston/view.h"
 #include "rootston/config.h"
@@ -36,6 +37,7 @@ struct roots_desktop {
 	struct wlr_xdg_shell_v6 *xdg_shell_v6;
 	struct wlr_xwayland *xwayland;
 	struct wlr_gamma_control_manager *gamma_control_manager;
+	struct wlr_screenshooter *screenshooter;
 
 	struct wl_listener output_add;
 	struct wl_listener output_remove;
diff --git a/include/wlr/egl.h b/include/wlr/egl.h
index 25329175..9ab4d9ce 100644
--- a/include/wlr/egl.h
+++ b/include/wlr/egl.h
@@ -10,15 +10,6 @@ struct wlr_egl {
 	EGLConfig config;
 	EGLContext context;
 
-	PFNEGLGETPLATFORMDISPLAYEXTPROC get_platform_display;
-	PFNEGLCREATEPLATFORMWINDOWSURFACEEXTPROC create_platform_window_surface;
-
-	PFNEGLCREATEIMAGEKHRPROC eglCreateImageKHR;
-	PFNEGLDESTROYIMAGEKHRPROC eglDestroyImageKHR;
-	PFNEGLQUERYWAYLANDBUFFERWL eglQueryWaylandBufferWL;
-	PFNEGLBINDWAYLANDDISPLAYWL eglBindWaylandDisplayWL;
-	PFNEGLUNBINDWAYLANDDISPLAYWL eglUnbindWaylandDisplayWL;
-
 	const char *egl_exts;
 	const char *gl_exts;
 
diff --git a/include/wlr/render.h b/include/wlr/render.h
index 2fbfb476..5027064d 100644
--- a/include/wlr/render.h
+++ b/include/wlr/render.h
@@ -30,27 +30,32 @@ struct wlr_texture *wlr_render_texture_create(struct wlr_renderer *r);
  * This will render the texture at <123, 321>.
  */
 bool wlr_render_with_matrix(struct wlr_renderer *r,
-		struct wlr_texture *texture, const float (*matrix)[16]);
+	struct wlr_texture *texture, const float (*matrix)[16]);
 /**
  * Renders a solid quad in the specified color.
  */
 void wlr_render_colored_quad(struct wlr_renderer *r,
-		const float (*color)[4], const float (*matrix)[16]);
+	const float (*color)[4], const float (*matrix)[16]);
 /**
  * Renders a solid ellipse in the specified color.
  */
 void wlr_render_colored_ellipse(struct wlr_renderer *r,
-		const float (*color)[4], const float (*matrix)[16]);
+	const float (*color)[4], const float (*matrix)[16]);
 /**
  * Returns a list of pixel formats supported by this renderer.
  */
 const enum wl_shm_format *wlr_renderer_get_formats(
-		struct wlr_renderer *r, size_t *len);
+	struct wlr_renderer *r, size_t *len);
 /**
  * Returns true if this wl_buffer is a DRM buffer.
  */
 bool wlr_renderer_buffer_is_drm(struct wlr_renderer *renderer,
-		struct wl_resource *buffer);
+	struct wl_resource *buffer);
+/**
+ * Reads pixels and stores them in out_data as ARGB8888.
+ */
+void wlr_renderer_read_pixels(struct wlr_renderer *r, int x, int y,
+	int width, int height, void *out_data);
 /**
  * Destroys this wlr_renderer. Textures must be destroyed separately.
  */
diff --git a/include/wlr/render/interface.h b/include/wlr/render/interface.h
index cbe33822..bbc5acb4 100644
--- a/include/wlr/render/interface.h
+++ b/include/wlr/render/interface.h
@@ -28,6 +28,8 @@ struct wlr_renderer_impl {
 		struct wlr_renderer *renderer, size_t *len);
 	bool (*buffer_is_drm)(struct wlr_renderer *renderer,
 		struct wl_resource *buffer);
+	void (*read_pixels)(struct wlr_renderer *renderer, int x, int y, int width,
+		int height, void *out_data);
 	void (*destroy)(struct wlr_renderer *renderer);
 };
 
diff --git a/include/wlr/types/wlr_output.h b/include/wlr/types/wlr_output.h
index 1fa6ad9e..52d377e3 100644
--- a/include/wlr/types/wlr_output.h
+++ b/include/wlr/types/wlr_output.h
@@ -37,6 +37,7 @@ struct wlr_output {
 
 	struct {
 		struct wl_signal frame;
+		struct wl_signal swap_buffers;
 		struct wl_signal resolution;
 		struct wl_signal destroy;
 	} events;
diff --git a/include/wlr/types/wlr_screenshooter.h b/include/wlr/types/wlr_screenshooter.h
new file mode 100644
index 00000000..4bda3d3c
--- /dev/null
+++ b/include/wlr/types/wlr_screenshooter.h
@@ -0,0 +1,26 @@
+#ifndef _WLR_SCREENSHOOTER_H
+#define _WLR_SCREENSHOOTER_H
+#include <wayland-server.h>
+
+struct wlr_screenshooter {
+	struct wl_global *wl_global;
+	struct wlr_renderer *renderer;
+
+	void *data;
+};
+
+struct wlr_screenshot {
+	struct wl_resource *resource;
+	struct wl_resource *output_resource;
+
+	struct wlr_output *output;
+	struct wlr_screenshooter *screenshooter;
+
+	void* data;
+};
+
+struct wlr_screenshooter *wlr_screenshooter_create(struct wl_display *display,
+	struct wlr_renderer *renderer);
+void wlr_screenshooter_destroy(struct wlr_screenshooter *screenshooter);
+
+#endif
diff --git a/meson.build b/meson.build
index 57c26b0f..179550d6 100644
--- a/meson.build
+++ b/meson.build
@@ -14,6 +14,10 @@ add_project_arguments(
 	'-DWLR_SRC_DIR="@0@"'.format(meson.source_root()),
 	language: 'c',
 )
+add_project_arguments(
+	'-I@0@'.format(meson.build_root()),
+	language: 'c',
+)
 add_project_link_arguments(
 	'-Wl,-rpath,@0@'.format(meson.build_root()),
 	language: 'c',
@@ -69,8 +73,8 @@ if elogind.found() and get_option('enable_elogind')
 endif
 
 subdir('protocol')
-subdir('backend')
 subdir('render')
+subdir('backend')
 subdir('types')
 subdir('util')
 subdir('xcursor')
diff --git a/protocol/meson.build b/protocol/meson.build
index 6dc88d76..79871fea 100644
--- a/protocol/meson.build
+++ b/protocol/meson.build
@@ -22,11 +22,14 @@ wayland_scanner_client = generator(
 
 protocols = [
 	[wl_protocol_dir, 'unstable/xdg-shell/xdg-shell-unstable-v6.xml'],
-	'gamma-control.xml'
+	'gamma-control.xml',
+	'screenshooter.xml',
 ]
 
 client_protocols = [
-	[wl_protocol_dir, 'unstable/xdg-shell/xdg-shell-unstable-v6.xml']
+	[wl_protocol_dir, 'unstable/xdg-shell/xdg-shell-unstable-v6.xml'],
+	'gamma-control.xml',
+	'screenshooter.xml',
 ]
 
 wl_protos_src = []
diff --git a/protocol/screenshooter.xml b/protocol/screenshooter.xml
new file mode 100644
index 00000000..fc48eac9
--- /dev/null
+++ b/protocol/screenshooter.xml
@@ -0,0 +1,16 @@
+<protocol name="orbital_screenshooter">
+
+    <interface name="orbital_screenshooter" version="1">
+        <request name="shoot">
+            <arg name="id" type="new_id" interface="orbital_screenshot"/>
+            <arg name="output" type="object" interface="wl_output"/>
+            <arg name="buffer" type="object" interface="wl_buffer"/>
+        </request>
+    </interface>
+
+    <interface name="orbital_screenshot" version="1">
+        <event name="done">
+        </event>
+    </interface>
+
+</protocol>
diff --git a/render/egl.c b/render/egl.c
index 82dea50c..9815b923 100644
--- a/render/egl.c
+++ b/render/egl.c
@@ -4,6 +4,7 @@
 #include <stdlib.h>
 #include <wlr/util/log.h>
 #include <wlr/egl.h>
+#include "render/glapi.h"
 
 // Extension documentation
 // https://www.khronos.org/registry/EGL/extensions/KHR/EGL_KHR_image_base.txt.
@@ -46,27 +47,6 @@ const char *egl_error(void) {
 	}
 }
 
-static bool egl_exts(struct wlr_egl *egl) {
-	egl->get_platform_display = (PFNEGLGETPLATFORMDISPLAYEXTPROC)
-		eglGetProcAddress("eglGetPlatformDisplayEXT");
-
-	if (!egl->get_platform_display) {
-		wlr_log(L_ERROR, "Failed to load EGL extension 'eglGetPlatformDisplayEXT'");
-		return false;
-	}
-
-	egl->create_platform_window_surface = (PFNEGLCREATEPLATFORMWINDOWSURFACEEXTPROC)
-		eglGetProcAddress("eglCreatePlatformWindowSurfaceEXT");
-
-	if (!egl->create_platform_window_surface) {
-		wlr_log(L_ERROR,
-			"Failed to load EGL extension 'eglCreatePlatformWindowSurfaceEXT'");
-		return false;
-	}
-
-	return true;
-}
-
 static bool egl_get_config(EGLDisplay disp, EGLConfig *out, EGLint visual_id) {
 	EGLint count = 0, matched = 0, ret;
 
@@ -103,7 +83,7 @@ static bool egl_get_config(EGLDisplay disp, EGLConfig *out, EGLint visual_id) {
 
 bool wlr_egl_init(struct wlr_egl *egl, EGLenum platform, EGLint visual_id,
 		void *remote_display) {
-	if (!egl_exts(egl)) {
+	if (!load_glapi()) {
 		return false;
 	}
 
@@ -112,7 +92,7 @@ bool wlr_egl_init(struct wlr_egl *egl, EGLenum platform, EGLint visual_id,
 		goto error;
 	}
 
-	egl->display = egl->get_platform_display(platform, remote_display, NULL);
+	egl->display = eglGetPlatformDisplayEXT(platform, remote_display, NULL);
 	if (egl->display == EGL_NO_DISPLAY) {
 		wlr_log(L_ERROR, "Failed to create EGL display: %s", egl_error());
 		goto error;
@@ -142,22 +122,11 @@ bool wlr_egl_init(struct wlr_egl *egl, EGLenum platform, EGLint visual_id,
 	eglMakeCurrent(egl->display, EGL_NO_SURFACE, EGL_NO_SURFACE, egl->context);
 	egl->egl_exts = eglQueryString(egl->display, EGL_EXTENSIONS);
 	if (strstr(egl->egl_exts, "EGL_WL_bind_wayland_display") == NULL ||
-		strstr(egl->egl_exts, "EGL_KHR_image_base") == NULL) {
+			strstr(egl->egl_exts, "EGL_KHR_image_base") == NULL) {
 		wlr_log(L_ERROR, "Required egl extensions not supported");
 		goto error;
 	}
 
-	egl->eglCreateImageKHR = (PFNEGLCREATEIMAGEKHRPROC)
-		eglGetProcAddress("eglCreateImageKHR");
-	egl->eglDestroyImageKHR = (PFNEGLDESTROYIMAGEKHRPROC)
-		eglGetProcAddress("eglDestroyImageKHR");
-	egl->eglQueryWaylandBufferWL = (PFNEGLQUERYWAYLANDBUFFERWL)
-		(void*) eglGetProcAddress("eglQueryWaylandBufferWL");
-	egl->eglBindWaylandDisplayWL = (PFNEGLBINDWAYLANDDISPLAYWL)
-		(void*) eglGetProcAddress("eglBindWaylandDisplayWL");
-	egl->eglUnbindWaylandDisplayWL = (PFNEGLUNBINDWAYLANDDISPLAYWL)
-		(void*) eglGetProcAddress("eglUnbindWaylandDisplayWL");
-
 	egl->gl_exts = (const char*) glGetString(GL_EXTENSIONS);
 	wlr_log(L_INFO, "Using EGL %d.%d", (int)major, (int)minor);
 	wlr_log(L_INFO, "Supported EGL extensions: %s", egl->egl_exts);
@@ -174,8 +143,8 @@ error:
 
 void wlr_egl_free(struct wlr_egl *egl) {
 	eglMakeCurrent(EGL_NO_DISPLAY, EGL_NO_SURFACE, EGL_NO_SURFACE, EGL_NO_CONTEXT);
-	if (egl->wl_display && egl->eglUnbindWaylandDisplayWL) {
-		egl->eglUnbindWaylandDisplayWL(egl->display, egl->wl_display);
+	if (egl->wl_display && eglUnbindWaylandDisplayWL) {
+		eglUnbindWaylandDisplayWL(egl->display, egl->wl_display);
 	}
 
 	eglDestroyContext(egl->display, egl->context);
@@ -184,11 +153,11 @@ void wlr_egl_free(struct wlr_egl *egl) {
 }
 
 bool wlr_egl_bind_display(struct wlr_egl *egl, struct wl_display *local_display) {
-	if (!egl->eglBindWaylandDisplayWL) {
+	if (!eglBindWaylandDisplayWL) {
 		return false;
 	}
 
-	if (egl->eglBindWaylandDisplayWL(egl->display, local_display)) {
+	if (eglBindWaylandDisplayWL(egl->display, local_display)) {
 		egl->wl_display = local_display;
 		return true;
 	}
@@ -198,33 +167,33 @@ bool wlr_egl_bind_display(struct wlr_egl *egl, struct wl_display *local_display)
 
 bool wlr_egl_query_buffer(struct wlr_egl *egl, struct wl_resource *buf,
 		int attrib, int *value) {
-	if (!egl->eglQueryWaylandBufferWL) {
+	if (!eglQueryWaylandBufferWL) {
 		return false;
 	}
-	return egl->eglQueryWaylandBufferWL(egl->display, buf, attrib, value);
+	return eglQueryWaylandBufferWL(egl->display, buf, attrib, value);
 }
 
 EGLImage wlr_egl_create_image(struct wlr_egl *egl, EGLenum target,
 		EGLClientBuffer buffer, const EGLint *attribs) {
-	if (!egl->eglCreateImageKHR) {
+	if (!eglCreateImageKHR) {
 		return false;
 	}
 
-	return egl->eglCreateImageKHR(egl->display, egl->context, target,
+	return eglCreateImageKHR(egl->display, egl->context, target,
 		buffer, attribs);
 }
 
 bool wlr_egl_destroy_image(struct wlr_egl *egl, EGLImage image) {
-	if (!egl->eglDestroyImageKHR) {
+	if (!eglDestroyImageKHR) {
 		return false;
 	}
 
-	egl->eglDestroyImageKHR(egl->display, image);
+	eglDestroyImageKHR(egl->display, image);
 	return true;
 }
 
 EGLSurface wlr_egl_create_surface(struct wlr_egl *egl, void *window) {
-	EGLSurface surf = egl->create_platform_window_surface(egl->display, egl->config,
+	EGLSurface surf = eglCreatePlatformWindowSurfaceEXT(egl->display, egl->config,
 		window, NULL);
 	if (surf == EGL_NO_SURFACE) {
 		wlr_log(L_ERROR, "Failed to create EGL surface: %s", egl_error());
diff --git a/render/glapi.txt b/render/glapi.txt
new file mode 100644
index 00000000..81791204
--- /dev/null
+++ b/render/glapi.txt
@@ -0,0 +1,8 @@
+eglGetPlatformDisplayEXT
+eglCreatePlatformWindowSurfaceEXT
+-eglCreateImageKHR
+-eglDestroyImageKHR
+-eglQueryWaylandBufferWL
+-eglBindWaylandDisplayWL
+-eglUnbindWaylandDisplayWL
+-glEGLImageTargetTexture2DOES
diff --git a/render/gles2/renderer.c b/render/gles2/renderer.c
index d6c22ebe..94c50b9a 100644
--- a/render/gles2/renderer.c
+++ b/render/gles2/renderer.c
@@ -12,8 +12,8 @@
 #include <wlr/render/matrix.h>
 #include <wlr/util/log.h>
 #include "render/gles2.h"
+#include "render/glapi.h"
 
-PFNGLEGLIMAGETARGETTEXTURE2DOESPROC glEGLImageTargetTexture2DOES = NULL;
 struct shaders shaders;
 
 static bool compile_shader(GLuint type, const GLchar *src, GLuint *shader) {
@@ -101,25 +101,7 @@ error:
 	wlr_log(L_ERROR, "Failed to set up default shaders!");
 }
 
-static void init_image_ext() {
-	if (glEGLImageTargetTexture2DOES) {
-		return;
-	}
-
-	const char *exts = (const char*) glGetString(GL_EXTENSIONS);
-	if (strstr(exts, "GL_OES_EGL_image_external")) {
- 		glEGLImageTargetTexture2DOES = (PFNGLEGLIMAGETARGETTEXTURE2DOESPROC)
-			eglGetProcAddress("glEGLImageTargetTexture2DOES");
-	}
-
-	if (!glEGLImageTargetTexture2DOES) {
-		wlr_log(L_INFO, "Failed to load glEGLImageTargetTexture2DOES "
-			"Will not be able to attach drm buffers");
-	}
-}
-
 static void init_globals() {
-	init_image_ext();
 	init_default_shaders();
 }
 
@@ -226,7 +208,23 @@ static bool wlr_gles2_buffer_is_drm(struct wlr_renderer *_renderer,
 		(struct wlr_gles2_renderer *)_renderer;
 	EGLint format;
 	return wlr_egl_query_buffer(renderer->egl, buffer,
-			EGL_TEXTURE_FORMAT, &format);
+		EGL_TEXTURE_FORMAT, &format);
+}
+
+static void rgba_to_argb(uint32_t *data, size_t height, size_t stride) {
+	size_t n = height*stride/4;
+	for (size_t i = 0; i < n; ++i) {
+		uint32_t v = data[i];
+		uint32_t rgb = (v & 0xffffff00) >> 8;
+		uint32_t a = v & 0x000000ff;
+		data[i] = rgb | (a << 24);
+	}
+}
+
+static void wlr_gles2_read_pixels(struct wlr_renderer *renderer, int x, int y,
+		int width, int height, void *out_data) {
+	glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, out_data);
+	rgba_to_argb(out_data, height, width*4);
 }
 
 static struct wlr_renderer_impl wlr_renderer_impl = {
@@ -238,6 +236,7 @@ static struct wlr_renderer_impl wlr_renderer_impl = {
 	.render_ellipse = wlr_gles2_render_ellipse,
 	.formats = wlr_gles2_formats,
 	.buffer_is_drm = wlr_gles2_buffer_is_drm,
+	.read_pixels = wlr_gles2_read_pixels,
 };
 
 struct wlr_renderer *wlr_gles2_renderer_create(struct wlr_backend *backend) {
diff --git a/render/meson.build b/render/meson.build
index dc0ceeb9..749d1393 100644
--- a/render/meson.build
+++ b/render/meson.build
@@ -1,3 +1,16 @@
+glgen = find_program('../glgen.sh')
+
+glapi_c = custom_target('glapi.c',
+	input: 'glapi.txt',
+	output: '@BASENAME@.c',
+	command: [glgen, '@INPUT@', '@OUTPUT@'],
+)
+glapi_h = custom_target('glapi.h',
+	input: 'glapi.txt',
+	output: '@BASENAME@.h',
+	command: [glgen, '@INPUT@', '@OUTPUT@'],
+)
+
 lib_wlr_render = static_library(
 	'wlr_render',
 	files(
@@ -11,6 +24,13 @@ lib_wlr_render = static_library(
 		'wlr_renderer.c',
 		'wlr_texture.c',
 	),
+	glapi_c,
+	glapi_h,
 	include_directories: wlr_inc,
 	dependencies: [glesv2, egl],
 )
+
+wlr_render = declare_dependency(
+	link_with: lib_wlr_render,
+	sources: glapi_h,
+)
diff --git a/render/wlr_renderer.c b/render/wlr_renderer.c
index fec5e38a..ef0c31be 100644
--- a/render/wlr_renderer.c
+++ b/render/wlr_renderer.c
@@ -51,3 +51,8 @@ bool wlr_renderer_buffer_is_drm(struct wlr_renderer *r,
 		struct wl_resource *buffer) {
 	return r->impl->buffer_is_drm(r, buffer);
 }
+
+void wlr_renderer_read_pixels(struct wlr_renderer *r, int x, int y,
+		int width, int height, void *out_data) {
+	r->impl->read_pixels(r, x, y, width, height, out_data);
+}
diff --git a/rootston/desktop.c b/rootston/desktop.c
index 75030ad2..562ba6d0 100644
--- a/rootston/desktop.c
+++ b/rootston/desktop.c
@@ -238,16 +238,15 @@ struct roots_desktop *desktop_create(struct roots_server *server,
 	wl_list_init(&desktop->output_remove.link);
 	desktop->output_remove.notify = output_remove_notify;
 
-	wl_signal_add(&server->backend->events.output_add,
-			&desktop->output_add);
+	wl_signal_add(&server->backend->events.output_add, &desktop->output_add);
 	wl_signal_add(&server->backend->events.output_remove,
-			&desktop->output_remove);
+		&desktop->output_remove);
 
 	desktop->server = server;
 	desktop->config = config;
 	desktop->layout = wlr_output_layout_create();
-	desktop->compositor = wlr_compositor_create(
-			server->wl_display, server->renderer);
+	desktop->compositor = wlr_compositor_create(server->wl_display,
+		server->renderer);
 
 	desktop->xdg_shell_v6 = wlr_xdg_shell_v6_create(server->wl_display);
 	wl_signal_add(&desktop->xdg_shell_v6->events.new_surface,
@@ -266,7 +265,9 @@ struct roots_desktop *desktop_create(struct roots_server *server,
 	desktop->xwayland_surface.notify = handle_xwayland_surface;
 
 	desktop->gamma_control_manager = wlr_gamma_control_manager_create(
-			server->wl_display);
+		server->wl_display);
+	desktop->screenshooter = wlr_screenshooter_create(server->wl_display,
+		server->renderer);
 
 	return desktop;
 }
diff --git a/types/meson.build b/types/meson.build
index cff40150..a151e8a3 100644
--- a/types/meson.build
+++ b/types/meson.build
@@ -20,6 +20,7 @@ lib_wlr_types = static_library(
 		'wlr_compositor.c',
 		'wlr_box.c',
 		'wlr_gamma_control.c',
+		'wlr_screenshooter.c',
 	),
 	include_directories: wlr_inc,
 	dependencies: [wayland_server, pixman, wlr_protos],
diff --git a/types/wlr_output.c b/types/wlr_output.c
index f167a213..64f67f2d 100644
--- a/types/wlr_output.c
+++ b/types/wlr_output.c
@@ -105,6 +105,7 @@ void wlr_output_init(struct wlr_output *output,
 	output->transform = WL_OUTPUT_TRANSFORM_NORMAL;
 	output->scale = 1;
 	wl_signal_init(&output->events.frame);
+	wl_signal_init(&output->events.swap_buffers);
 	wl_signal_init(&output->events.resolution);
 	wl_signal_init(&output->events.destroy);
 }
@@ -231,6 +232,8 @@ void wlr_output_swap_buffers(struct wlr_output *output) {
 		wlr_render_with_matrix(output->cursor.renderer, output->cursor.texture, &matrix);
 	}
 
+	wl_signal_emit(&output->events.swap_buffers, &output);
+
 	output->impl->swap_buffers(output);
 }
 
diff --git a/types/wlr_screenshooter.c b/types/wlr_screenshooter.c
new file mode 100644
index 00000000..38204aa1
--- /dev/null
+++ b/types/wlr_screenshooter.c
@@ -0,0 +1,163 @@
+#include <assert.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wayland-server.h>
+#include <wlr/render.h>
+#include <wlr/types/wlr_screenshooter.h>
+#include <wlr/types/wlr_output.h>
+#include <wlr/util/log.h>
+#include "screenshooter-protocol.h"
+
+static void copy_yflip(uint8_t *dst, uint8_t *src, int32_t height,
+		int32_t stride) {
+	uint8_t *end = dst + height * stride;
+	while (dst < end) {
+		memcpy(dst, src, stride);
+		dst += stride;
+		src -= stride;
+	}
+}
+
+struct screenshot_state {
+	int32_t width, height, stride;
+	uint8_t *pixels;
+	struct wl_shm_buffer *shm_buffer;
+	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);
+	struct wlr_renderer *renderer = state->screenshot->screenshooter->renderer;
+	struct wlr_output *output = state->screenshot->output;
+
+	wlr_output_make_current(output);
+	wlr_renderer_read_pixels(renderer, 0, 0, output->width, output->height,
+		state->pixels);
+
+	void *data = wl_shm_buffer_get_data(state->shm_buffer);
+	wl_shm_buffer_begin_access(state->shm_buffer);
+	copy_yflip(data, state->pixels + state->stride * (state->height - 1),
+		state->height, state->stride);
+	wl_shm_buffer_end_access(state->shm_buffer);
+
+	free(state->pixels);
+	wl_list_remove(&listener->link);
+
+	orbital_screenshot_send_done(state->screenshot->resource);
+
+	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_screenshooter *screenshooter =
+		wl_resource_get_user_data(_screenshooter);
+	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);
+	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;
+	}
+
+	uint32_t format = wl_shm_buffer_get_format(shm_buffer);
+	if (format != WL_SHM_FORMAT_XRGB8888) {
+		wlr_log(L_ERROR, "Invalid buffer: unsupported format");
+		return;
+	}
+
+	uint8_t *pixels = malloc(stride * height);
+	if (pixels == NULL) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+
+	struct wlr_screenshot *screenshot =
+		calloc(1, sizeof(struct wlr_screenshot));
+	if (!screenshot) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+	screenshot->output_resource = _output;
+	screenshot->output = output;
+	screenshot->screenshooter = screenshooter;
+	screenshot->resource = wl_resource_create(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);
+
+	struct screenshot_state *state = calloc(1, sizeof(struct screenshot_state));
+	if (!state) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+	state->width = width;
+	state->height = height;
+	state->stride = stride;
+	state->pixels = pixels;
+	state->shm_buffer = shm_buffer;
+	state->screenshot = screenshot;
+	state->frame_listener.notify = output_frame_notify;
+	wl_signal_add(&output->events.swap_buffers, &state->frame_listener);
+}
+
+static struct orbital_screenshooter_interface screenshooter_impl = {
+	.shoot = screenshooter_shoot,
+};
+
+static void screenshooter_bind(struct wl_client *wl_client,
+		void *_screenshooter, uint32_t version, uint32_t id) {
+	struct wlr_screenshooter *screenshooter = _screenshooter;
+	assert(wl_client && screenshooter);
+	if (version > 1) {
+		wlr_log(L_ERROR, "Client requested unsupported screenshooter version,"
+			"disconnecting");
+		wl_client_destroy(wl_client);
+		return;
+	}
+	struct wl_resource *wl_resource = wl_resource_create(wl_client,
+		&orbital_screenshooter_interface, version, id);
+	wl_resource_set_implementation(wl_resource, &screenshooter_impl,
+		screenshooter, NULL);
+}
+
+struct wlr_screenshooter *wlr_screenshooter_create(struct wl_display *display,
+		struct wlr_renderer *renderer) {
+	struct wlr_screenshooter *screenshooter =
+		calloc(1, sizeof(struct wlr_screenshooter));
+	if (!screenshooter) {
+		return NULL;
+	}
+	screenshooter->renderer = renderer;
+
+	struct wl_global *wl_global = wl_global_create(display,
+		&orbital_screenshooter_interface, 1, screenshooter, screenshooter_bind);
+	if (!wl_global) {
+		free(screenshooter);
+		return NULL;
+	}
+	screenshooter->wl_global = wl_global;
+
+	return screenshooter;
+}
+
+void wlr_screenshooter_destroy(struct wlr_screenshooter *screenshooter) {
+	if (!screenshooter) {
+		return;
+	}
+	// TODO: this segfault (wl_display->registry_resource_list is not init)
+	// wl_global_destroy(screenshooter->wl_global);
+	free(screenshooter);
+}