Implement pointer-constraints protocol in wlroots and rootston

examples/meson.build

@@ -70,6 +70,10 @@ examples = {
 		'src': 'gamma-control.c',
 		'dep': [wayland_client, wayland_cursor, wlr_protos, wlroots],
 	},
+	'pointer-constraints': {
+		'src': 'pointer-constraints.c',
+		'dep': [wayland_client, wlr_protos, wlroots],
+	},
 	'dmabuf-capture': {
 		'src': 'dmabuf-capture.c',
 		'dep': [

examples/pointer-constraints.c

@@ -0,0 +1,254 @@
+#include <GLES2/gl2.h>
+#include <linux/input-event-codes.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <wayland-client.h>
+#include <wayland-egl.h>
+#include <wlr/render/egl.h>
+#include "xdg-shell-client-protocol.h"
+#include "pointer-constraints-unstable-v1-client-protocol.h"
+
+static int width = 512, height = 512;
+
+static struct wl_compositor *compositor = NULL;
+static struct wl_seat *seat = NULL;
+static struct xdg_wm_base *wm_base = NULL;
+static struct zwp_pointer_constraints_v1 *pointer_constraints = NULL;
+
+struct wlr_egl egl;
+struct wl_egl_window *egl_window;
+struct wlr_egl_surface *egl_surface;
+struct zwp_locked_pointer_v1* locked_pointer;
+struct zwp_confined_pointer_v1* confined_pointer;
+
+enum {
+	REGION_TYPE_NONE,
+	REGION_TYPE_DISJOINT,
+	REGION_TYPE_JOINT,
+	REGION_TYPE_MAX
+} region_type = REGION_TYPE_NONE;
+
+struct wl_region *regions[3];
+
+static void draw(void) {
+	eglMakeCurrent(egl.display, egl_surface, egl_surface, egl.context);
+
+	float color[] = {1.0, 1.0, 0.0, 1.0};
+
+	glViewport(0, 0, width, height);
+	glClearColor(color[0], color[1], color[2], 1.0);
+	glClear(GL_COLOR_BUFFER_BIT);
+
+	eglSwapBuffers(egl.display, egl_surface);
+}
+
+static void pointer_handle_button(void *data, struct wl_pointer *pointer, uint32_t serial,
+		uint32_t time, uint32_t button, uint32_t state_w) {
+	struct wl_surface *surface = data;
+
+	if (button == BTN_LEFT && state_w == WL_POINTER_BUTTON_STATE_PRESSED) {
+		region_type = (region_type + 1) % REGION_TYPE_MAX;
+
+		if (locked_pointer) {
+			zwp_locked_pointer_v1_set_region(locked_pointer, regions[region_type]);
+		} else if (confined_pointer) {
+			zwp_confined_pointer_v1_set_region(confined_pointer, regions[region_type]);
+		}
+
+		wl_surface_commit(surface);
+	}
+}
+
+static void pointer_handle_enter(void *data, struct wl_pointer *wl_pointer,
+		uint32_t serial, struct wl_surface *surface,
+		wl_fixed_t surface_x, wl_fixed_t surface_y) {
+	// This space intentionally left blank
+}
+
+static void pointer_handle_leave(void *data, struct wl_pointer *wl_pointer,
+		uint32_t serial, struct wl_surface *surface) {
+	// This space intentionally left blank
+}
+
+static void pointer_handle_motion(void *data, struct wl_pointer *wl_pointer,
+		uint32_t time, wl_fixed_t surface_x, wl_fixed_t surface_y) {
+	// This space intentionally left blank
+}
+
+static void pointer_handle_axis(void *data, struct wl_pointer *wl_pointer,
+		uint32_t time, uint32_t axis, wl_fixed_t value) {
+	// This space intentionally left blank
+}
+
+static void pointer_handle_frame(void *data, struct wl_pointer *wl_pointer) {
+	// This space intentionally left blank
+}
+
+static void pointer_handle_axis_source(void *data,
+		struct wl_pointer *wl_pointer, uint32_t axis_source) {
+	// This space intentionally left blank
+}
+
+static void pointer_handle_axis_stop(void *data,
+		struct wl_pointer *wl_pointer, uint32_t time, uint32_t axis) {
+	// This space intentionally left blank
+}
+
+static void pointer_handle_axis_discrete(void *data,
+		struct wl_pointer *wl_pointer, uint32_t axis, int32_t discrete) {
+	// This space intentionally left blank
+}
+
+static const struct wl_pointer_listener pointer_listener = {
+	.enter = pointer_handle_enter,
+	.leave = pointer_handle_leave,
+	.motion = pointer_handle_motion,
+	.button = pointer_handle_button,
+	.axis = pointer_handle_axis,
+	.frame = pointer_handle_frame,
+	.axis_source = pointer_handle_axis_source,
+	.axis_stop = pointer_handle_axis_stop,
+	.axis_discrete = pointer_handle_axis_discrete,
+};
+
+static void xdg_surface_handle_configure(void *data,
+		struct xdg_surface *xdg_surface, uint32_t serial) {
+	xdg_surface_ack_configure(xdg_surface, serial);
+	wl_egl_window_resize(egl_window, width, height, 0, 0);
+	draw();
+}
+
+static const struct xdg_surface_listener xdg_surface_listener = {
+	.configure = xdg_surface_handle_configure,
+};
+
+static void xdg_toplevel_handle_configure(void *data,
+		struct xdg_toplevel *xdg_toplevel, int32_t w, int32_t h,
+		struct wl_array *states) {
+	width = w;
+	height = h;
+}
+
+static void xdg_toplevel_handle_close(void *data,
+		struct xdg_toplevel *xdg_toplevel) {
+	exit(EXIT_SUCCESS);
+}
+
+static const struct xdg_toplevel_listener xdg_toplevel_listener = {
+	.configure = xdg_toplevel_handle_configure,
+	.close = xdg_toplevel_handle_close,
+};
+
+static void handle_global(void *data, struct wl_registry *registry,
+		uint32_t name, const char *interface, uint32_t version) {
+	if (strcmp(interface, wl_compositor_interface.name) == 0) {
+		compositor = wl_registry_bind(registry, name,
+			&wl_compositor_interface, 1);
+	} else if (strcmp(interface, xdg_wm_base_interface.name) == 0) {
+		wm_base = wl_registry_bind(registry, name, &xdg_wm_base_interface, 1);
+	} else if (strcmp(interface, wl_seat_interface.name) == 0) {
+		seat = wl_registry_bind(registry, name, &wl_seat_interface, version);
+	} else if (strcmp(interface, zwp_pointer_constraints_v1_interface.name) == 0) {
+		pointer_constraints = wl_registry_bind(registry, name,
+				&zwp_pointer_constraints_v1_interface, version);
+	}
+}
+
+static const struct wl_registry_listener registry_listener = {
+	.global = handle_global,
+	.global_remove = NULL,
+};
+
+int main(int argc, char **argv) {
+	if (argc != 4) {
+		goto invalid_args;
+	}
+
+	bool lock;
+	if (strcmp(argv[1], "lock") == 0) {
+		lock = true;
+	} else if (strcmp(argv[1], "confine") == 0) {
+		lock = false;
+	} else {
+		goto invalid_args;
+	}
+
+	enum zwp_pointer_constraints_v1_lifetime lifetime;
+	if (strcmp(argv[2], "oneshot") == 0) {
+		lifetime = ZWP_POINTER_CONSTRAINTS_V1_LIFETIME_ONESHOT;
+	} else if (strcmp(argv[2], "persistent") == 0) {
+		lifetime = ZWP_POINTER_CONSTRAINTS_V1_LIFETIME_PERSISTENT;
+	} else {
+		goto invalid_args;
+	}
+
+	if (strcmp(argv[3], "no-region") == 0) {
+		region_type = REGION_TYPE_NONE;
+	} else if (strcmp(argv[3], "disjoint-region") == 0) {
+		region_type = REGION_TYPE_DISJOINT;
+	} else if (strcmp(argv[3], "joint-region") == 0) {
+		region_type = REGION_TYPE_JOINT;
+	}
+
+	struct wl_display *display = wl_display_connect(NULL);
+
+	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);
+
+	struct wl_region *disjoint_region = wl_compositor_create_region(compositor);
+	wl_region_add(disjoint_region, 0, 0, 255, 256);
+	wl_region_add(disjoint_region, 257, 0, 255, 256);
+	regions[REGION_TYPE_DISJOINT] = disjoint_region;
+
+	struct wl_region *joint_region = wl_compositor_create_region(compositor);
+	wl_region_add(joint_region, 0, 0, 256, 256);
+	wl_region_add(joint_region, 256, 0, 256, 256);
+	wl_region_add(joint_region, 256, 256, 256, 256);
+	regions[REGION_TYPE_JOINT] = joint_region;
+
+	wlr_egl_init(&egl, EGL_PLATFORM_WAYLAND_EXT, display, NULL,
+		WL_SHM_FORMAT_ARGB8888);
+
+	struct wl_surface *surface = wl_compositor_create_surface(compositor);
+	struct xdg_surface *xdg_surface =
+		xdg_wm_base_get_xdg_surface(wm_base, surface);
+	struct xdg_toplevel *xdg_toplevel = xdg_surface_get_toplevel(xdg_surface);
+
+	xdg_surface_add_listener(xdg_surface, &xdg_surface_listener, NULL);
+	xdg_toplevel_add_listener(xdg_toplevel, &xdg_toplevel_listener, NULL);
+
+	struct wl_pointer *pointer = wl_seat_get_pointer(seat);
+	wl_pointer_add_listener(pointer, &pointer_listener, surface);
+
+	if (lock) {
+		locked_pointer = zwp_pointer_constraints_v1_lock_pointer(
+				pointer_constraints, surface, pointer, regions[region_type], lifetime);
+
+		zwp_locked_pointer_v1_set_cursor_position_hint(locked_pointer, wl_fixed_from_int(128), wl_fixed_from_int(128));
+	} else {
+		confined_pointer = zwp_pointer_constraints_v1_confine_pointer(
+			pointer_constraints, surface, pointer, regions[region_type], lifetime);
+	}
+
+	wl_surface_commit(surface);
+
+	egl_window = wl_egl_window_create(surface, width, height);
+	egl_surface = wlr_egl_create_surface(&egl, egl_window);
+
+	wl_display_roundtrip(display);
+
+	draw();
+
+	while (wl_display_dispatch(display) != -1) {}
+
+	return EXIT_SUCCESS;
+
+	invalid_args: {
+		fprintf(stderr, "pointer-constraints <lock | confine> <oneshot | persistent> "
+			"<no-region | disjoint-rejoin | joint-region>\n");
+		exit(EXIT_FAILURE);
+	}
+}

include/rootston/cursor.h

@@ -1,6 +1,7 @@
 #ifndef ROOTSTON_CURSOR_H
 #define ROOTSTON_CURSOR_H
 
+#include <wlr/types/wlr_pointer_constraints_v1.h>
 #include "rootston/seat.h"
 
 enum roots_cursor_mode {
@@ -14,6 +15,9 @@ struct roots_cursor {
 	struct roots_seat *seat;
 	struct wlr_cursor *cursor;
 
+	struct wlr_pointer_constraint_v1 *active_constraint;
+	pixman_region32_t confine; // invalid if active_constraint == NULL
+
 	const char *default_xcursor;
 
 	enum roots_cursor_mode mode;
@@ -45,6 +49,10 @@ struct roots_cursor {
 	struct wl_listener tool_button;
 
 	struct wl_listener request_set_cursor;
+
+	struct wl_listener focus_change;
+
+	struct wl_listener constraint_commit;
 };
 
 struct roots_cursor *roots_cursor_create(struct roots_seat *seat);
@@ -81,9 +89,17 @@ void roots_cursor_handle_tool_tip(struct roots_cursor *cursor,
 void roots_cursor_handle_request_set_cursor(struct roots_cursor *cursor,
 	struct wlr_seat_pointer_request_set_cursor_event *event);
 
+void roots_cursor_handle_focus_change(struct roots_cursor *cursor,
+	struct wlr_seat_pointer_focus_change_event *event);
+
+void roots_cursor_handle_constraint_commit(struct roots_cursor *cursor);
+
 void roots_cursor_update_position(struct roots_cursor *cursor,
 	uint32_t time);
 
 void roots_cursor_update_focus(struct roots_cursor *cursor);
 
+void roots_cursor_constrain(struct roots_cursor *cursor,
+	struct wlr_pointer_constraint_v1 *constraint, double sx, double sy);
+
 #endif

include/rootston/desktop.h

@@ -56,6 +56,7 @@ struct roots_desktop {
 	struct wlr_virtual_keyboard_manager_v1 *virtual_keyboard;
 	struct wlr_screencopy_manager_v1 *screencopy;
 	struct wlr_tablet_manager_v2 *tablet_v2;
+	struct wlr_pointer_constraints_v1 *pointer_constraints;
 
 	struct wl_listener new_output;
 	struct wl_listener layout_change;
@@ -67,6 +68,8 @@ struct roots_desktop {
 	struct wl_listener input_inhibit_activate;
 	struct wl_listener input_inhibit_deactivate;
 	struct wl_listener virtual_keyboard_new;
+	struct wl_listener constraint_create;
+	struct wl_listener constraint_destroy;
 
 #ifdef WLR_HAS_XWAYLAND
 	struct wlr_xwayland *xwayland;

include/rootston/input.h

@@ -16,7 +16,7 @@ struct roots_input {
 
 	struct wl_listener new_input;
 
-	struct wl_list seats;
+	struct wl_list seats; // roots_seat::link
 };
 
 struct roots_input *input_create(struct roots_server *server,

include/rootston/seat.h

@@ -10,7 +10,7 @@ struct roots_seat {
 	struct roots_input *input;
 	struct wlr_seat *seat;
 	struct roots_cursor *cursor;
-	struct wl_list link;
+	struct wl_list link; // roots_input::seats
 
 	// coordinates of the first touch point if it exists
 	int32_t touch_id;

include/wlr/types/wlr_box.h

@@ -9,6 +9,7 @@
 #ifndef WLR_TYPES_WLR_BOX_H
 #define WLR_TYPES_WLR_BOX_H
 
+#include <pixman.h>
 #include <stdbool.h>
 #include <wayland-server.h>
 
@@ -40,4 +41,6 @@ void wlr_box_transform(const struct wlr_box *box,
 void wlr_box_rotated_bounds(const struct wlr_box *box, float rotation,
 	struct wlr_box *dest);
 
+void wlr_box_from_pixman_box32(const pixman_box32_t box, struct wlr_box *dest);
+
 #endif

include/wlr/types/wlr_cursor.h

@@ -91,6 +91,18 @@ bool wlr_cursor_warp(struct wlr_cursor *cur, struct wlr_input_device *dev,
 void wlr_cursor_absolute_to_layout_coords(struct wlr_cursor *cur,
 	struct wlr_input_device *dev, double x, double y, double *lx, double *ly);
 
+
+/**
+ * Warp the cursor to the given x and y coordinates. If the given point is out
+ * of the layout boundaries or constraints, the closest point will be used.
+ * If one coordinate is NAN, it will be ignored.
+ *
+ * `dev` may be passed to respect device mapping constraints. If `dev` is NULL,
+ * device mapping constraints will be ignored.
+ */
+void wlr_cursor_warp_closest(struct wlr_cursor *cur,
+	struct wlr_input_device *dev, double x, double y);
+
 /**
  * Warp the cursor to the given x and y in absolute 0..1 coordinates. If the
  * given point is out of the layout boundaries or constraints, the closest point

include/wlr/types/wlr_pointer_constraints_v1.h

@@ -0,0 +1,88 @@
+#ifndef WLR_TYPES_WLR_POINTER_CONSTRAINTS_V1_H
+#define WLR_TYPES_WLR_POINTER_CONSTRAINTS_V1_H
+
+#include <stdint.h>
+#include <wayland-server.h>
+#include <pixman.h>
+#include <wlr/types/wlr_box.h>
+#include <wlr/types/wlr_seat.h>
+#include "pointer-constraints-unstable-v1-protocol.h"
+
+struct wlr_seat;
+
+enum wlr_pointer_constraint_v1_type {
+	WLR_POINTER_CONSTRAINT_V1_LOCKED,
+	WLR_POINTER_CONSTRAINT_V1_CONFINED,
+};
+
+struct wlr_pointer_constraint_v1_state {
+	pixman_region32_t *region;
+
+	// only valid for locked_pointer
+	struct {
+		double x, y;
+		bool valid;
+	} cursor_hint;
+};
+
+struct wlr_pointer_constraint_v1 {
+	struct wlr_pointer_constraints_v1 *pointer_constraints;
+
+	struct wl_resource *resource;
+	struct wlr_surface *surface;
+	struct wlr_seat *seat;
+	enum zwp_pointer_constraints_v1_lifetime lifetime;
+	enum wlr_pointer_constraint_v1_type type;
+	pixman_region32_t region;
+
+	struct wlr_pointer_constraint_v1_state current, pending;
+
+	struct wl_listener surface_commit;
+	struct wl_listener surface_destroy;
+	struct wl_listener seat_destroy;
+
+	struct wl_list link; // wlr_pointer_constraints_v1::constraints
+
+	void *data;
+};
+
+struct wlr_pointer_constraints_v1 {
+	struct wl_list wl_resources; // wl_resource_get_link
+	struct wl_global *wl_global;
+
+	struct {
+		/**
+		 * Called when a new pointer constraint is created.
+		 *
+		 * data: wlr_pointer_constraint_v1*
+		 */
+		struct wl_signal constraint_create;
+		/**
+		 * Called when a pointer constraint is destroyed.
+		 *
+		 * data: wlr_pointer_constraint_v1*
+		 */
+		struct wl_signal constraint_destroy;
+	} events;
+
+	struct wl_list constraints; // wlr_pointer_constraint_v1::link
+
+	void *data;
+};
+
+struct wlr_pointer_constraints_v1 *wlr_pointer_constraints_v1_create(
+	struct wl_display *display);
+void wlr_pointer_constraints_v1_destroy(
+	struct wlr_pointer_constraints_v1 *wlr_pointer_constraints_v1);
+
+struct wlr_pointer_constraint_v1 *wlr_pointer_constraints_v1_constraint_for_surface(
+	struct wlr_pointer_constraints_v1 *wlr_pointer_constraints_v1,
+	struct wlr_surface *surface, struct wlr_seat *seat);
+
+void wlr_pointer_constraint_v1_send_activated(
+	struct wlr_pointer_constraint_v1 *constraint);
+void wlr_pointer_constraint_v1_send_deactivated(
+	struct wlr_pointer_constraint_v1 *constraint);
+
+
+#endif

include/wlr/types/wlr_region.h

@@ -10,8 +10,7 @@
 #define WLR_TYPES_WLR_REGION_H
 
 #include <pixman.h>
-
+#include <wayland-server-protocol.h>
-struct wl_resource;
 
 /*
  * Creates a new region resource with the provided new ID. If `resource_list` is

include/wlr/util/region.h

@@ -16,6 +16,8 @@
 
 #ifndef WLR_UTIL_REGION_H
 #define WLR_UTIL_REGION_H
+
+#include <stdbool.h>
 #include <pixman.h>
 #include <wayland-server.h>
 
@@ -48,4 +50,7 @@ void wlr_region_expand(pixman_region32_t *dst, pixman_region32_t *src,
 void wlr_region_rotated_bounds(pixman_region32_t *dst, pixman_region32_t *src,
 	float rotation, int ox, int oy);
 
+bool wlr_region_confine(pixman_region32_t *region, double x1, double y1, double x2,
+	double y2, double *x2_out, double *y2_out);
+
 #endif

protocol/meson.build

@@ -18,6 +18,7 @@ protocols = [
 	[wl_protocol_dir, 'unstable/xdg-decoration/xdg-decoration-unstable-v1.xml'],
 	[wl_protocol_dir, 'unstable/xdg-output/xdg-output-unstable-v1.xml'],
 	[wl_protocol_dir, 'unstable/xdg-shell/xdg-shell-unstable-v6.xml'],
+	[wl_protocol_dir, 'unstable/pointer-constraints/pointer-constraints-unstable-v1.xml'],
 	'gamma-control.xml',
 	'gtk-primary-selection.xml',
 	'idle.xml',
@@ -36,6 +37,7 @@ client_protocols = [
 	[wl_protocol_dir, 'unstable/idle-inhibit/idle-inhibit-unstable-v1.xml'],
 	[wl_protocol_dir, 'unstable/xdg-decoration/xdg-decoration-unstable-v1.xml'],
 	[wl_protocol_dir, 'unstable/xdg-shell/xdg-shell-unstable-v6.xml'],
+	[wl_protocol_dir, 'unstable/pointer-constraints/pointer-constraints-unstable-v1.xml'],
 	'idle.xml',
 	'screenshooter.xml',
 	'wlr-export-dmabuf-unstable-v1.xml',

rootston/config.c

@@ -506,6 +506,7 @@ struct roots_config *roots_config_create_from_args(int argc, char *argv[]) {
 		add_binding_config(&config->bindings, "Logo+Shift+E", "exit");
 		add_binding_config(&config->bindings, "Ctrl+q", "close");
 		add_binding_config(&config->bindings, "Alt+Tab", "next_window");
+		add_binding_config(&config->bindings, "Logo+Escape", "break_pointer_constraint");
 		struct roots_keyboard_config *kc =
 			calloc(1, sizeof(struct roots_keyboard_config));
 		kc->meta_key = WLR_MODIFIER_LOGO;

rootston/cursor.c

@@ -1,9 +1,12 @@
 #define _XOPEN_SOURCE 700
+#include <assert.h>
 #include <math.h>
 #include <stdlib.h>
+#include <wlr/types/wlr_region.h>
 #include <wlr/types/wlr_xcursor_manager.h>
 #include <wlr/util/edges.h>
 #include <wlr/util/log.h>
+#include <wlr/util/region.h>
 #ifdef __linux__
 #include <linux/input-event-codes.h>
 #elif __FreeBSD__
@@ -11,6 +14,7 @@
 #endif
 #include "rootston/cursor.h"
 #include "rootston/desktop.h"
+#include "rootston/view.h"
 #include "rootston/xcursor.h"
 
 struct roots_cursor *roots_cursor_create(struct roots_seat *seat) {
@@ -303,15 +307,86 @@ static void roots_cursor_press_button(struct roots_cursor *cursor,
 
 void roots_cursor_handle_motion(struct roots_cursor *cursor,
 		struct wlr_event_pointer_motion *event) {
-	wlr_cursor_move(cursor->cursor, event->device,
+	double dx = event->delta_x;
-			event->delta_x, event->delta_y);
+	double dy = event->delta_y;
+
+	if (cursor->active_constraint) {
+		struct roots_view *view = cursor->pointer_view->view;
+		assert(view);
+
+		double center_x = view->x + view->width / 2.;
+		double center_y = view->y + view->height / 2.;
+
+		double lx1 = cursor->cursor->x;
+		double ly1 = cursor->cursor->y;
+
+		double lx2 = lx1 + dx;
+		double ly2 = ly1 + dy;
+
+		// Optimization for most common case.
+		// This also makes sure that we don't encounter
+		// precision bugs in the most common case.
+		if (view->rotation == 0.0) {
+			double sx1 = lx1 - view->x;
+			double sy1 = ly1 - view->y;
+
+			double sx2 = lx2 - view->x;
+			double sy2 = ly2 - view->y;
+
+			double sx2_confined, sy2_confined;
+			if (!wlr_region_confine(&cursor->confine, sx1, sy1, sx2, sy2, &sx2_confined, &sy2_confined)) {
+				return;
+			}
+
+			dx = sx2_confined - sx1;
+			dy = sy2_confined - sy1;
+		} else {
+			assert(false);
+			double c = cos(view->rotation);
+			double s = sin(view->rotation);
+
+			double sx1 = c * (lx1 - center_x) - s * (ly1 - center_y) + view->width / 2.;
+			double sy1 = s * (lx1 - center_x) + c * (ly1 - center_y) + view->height / 2.;
+
+			double sx2 = c * (lx2 - center_x) - s * (ly2 - center_y) + view->width / 2.;
+			double sy2 = s * (lx2 - center_x) + c * (ly2 - center_y) + view->height / 2.;
+
+			double sx2_confined, sy2_confined;
+			if (!wlr_region_confine(&cursor->confine, sx1, sy1, sx2, sy2, &sx2_confined, &sy2_confined)) {
+				return;
+			}
+
+			// avoid NaNs
+			double fraction = (sx2 - sx1) > (sy2 - sy1) ?
+				(sx2_confined - sx1) / (sx2 - sx1) :
+				(sy2_confined - sy1) / (sy2 - sy1);
+
+			dx *= fraction;
+			dy *= fraction;
+		}
+	}
+
+	wlr_cursor_move(cursor->cursor, event->device, dx, dy);
 	roots_cursor_update_position(cursor, event->time_msec);
 }
 
 void roots_cursor_handle_motion_absolute(struct roots_cursor *cursor,
 		struct wlr_event_pointer_motion_absolute *event) {
-	wlr_cursor_warp_absolute(cursor->cursor,
+	double lx, ly;
-			event->device, event->x, event->y);
+	wlr_cursor_absolute_to_layout_coords(cursor->cursor, event->device, event->x,
+		event->y, &lx, &ly);
+
+	if (cursor->pointer_view) {
+		struct roots_view *view = cursor->pointer_view->view;
+
+		if (cursor->active_constraint &&
+				!pixman_region32_contains_point(&cursor->confine,
+					lx - view->x, ly - view->y, NULL)) {
+			return;
+		}
+	}
+
+	wlr_cursor_warp_closest(cursor->cursor, event->device, lx, ly);
 	roots_cursor_update_position(cursor, event->time_msec);
 }
 
@@ -405,18 +480,34 @@ void roots_cursor_handle_touch_motion(struct roots_cursor *cursor,
 
 void roots_cursor_handle_tool_axis(struct roots_cursor *cursor,
 		struct wlr_event_tablet_tool_axis *event) {
+	double x = NAN, y = NAN;
 	if ((event->updated_axes & WLR_TABLET_TOOL_AXIS_X) &&
 			(event->updated_axes & WLR_TABLET_TOOL_AXIS_Y)) {
-		wlr_cursor_warp_absolute(cursor->cursor, event->device,
+		x = event->x;
-			event->x, event->y);
+		y = event->y;
-		roots_cursor_update_position(cursor, event->time_msec);
 	} else if ((event->updated_axes & WLR_TABLET_TOOL_AXIS_X)) {
-		wlr_cursor_warp_absolute(cursor->cursor, event->device, event->x, -1);
+		x = event->x;
-		roots_cursor_update_position(cursor, event->time_msec);
 	} else if ((event->updated_axes & WLR_TABLET_TOOL_AXIS_Y)) {
-		wlr_cursor_warp_absolute(cursor->cursor, event->device, -1, event->y);
+		y = event->y;
-		roots_cursor_update_position(cursor, event->time_msec);
 	}
+
+	double lx, ly;
+	wlr_cursor_absolute_to_layout_coords(cursor->cursor, event->device,
+		x, y, &lx, &ly);
+
+
+	if (cursor->pointer_view) {
+		struct roots_view *view = cursor->pointer_view->view;
+
+		if (cursor->active_constraint &&
+				!pixman_region32_contains_point(&cursor->confine,
+					lx - view->x, ly - view->y, NULL)) {
+			return;
+		}
+	}
+
+	wlr_cursor_warp_closest(cursor->cursor, event->device, lx, ly);
+	roots_cursor_update_position(cursor, event->time_msec);
 }
 
 void roots_cursor_handle_tool_tip(struct roots_cursor *cursor,
@@ -446,3 +537,102 @@ void roots_cursor_handle_request_set_cursor(struct roots_cursor *cursor,
 		event->hotspot_y);
 	cursor->cursor_client = event->seat_client->client;
 }
+
+void roots_cursor_handle_focus_change(struct roots_cursor *cursor,
+		struct wlr_seat_pointer_focus_change_event *event) {
+	double sx = event->sx;
+	double sy = event->sy;
+
+	double lx = cursor->cursor->x;
+	double ly = cursor->cursor->y;
+
+	wlr_log(WLR_DEBUG, "entered surface %p, lx: %f, ly: %f, sx: %f, sy: %f",
+		event->new_surface, lx, ly, sx, sy);
+
+	roots_cursor_constrain(cursor,
+		wlr_pointer_constraints_v1_constraint_for_surface(
+			cursor->seat->input->server->desktop->pointer_constraints,
+			event->new_surface, cursor->seat->seat),
+		sx, sy);
+}
+
+void roots_cursor_handle_constraint_commit(struct roots_cursor *cursor) {
+	struct roots_desktop *desktop = cursor->seat->input->server->desktop;
+
+	struct roots_view *view;
+	double sx, sy;
+	struct wlr_surface *surface = desktop_surface_at(desktop,
+			cursor->cursor->x, cursor->cursor->y, &sx, &sy, &view);
+	// This should never happen but views move around right when they're
+	// created from (0, 0) to their actual coordinates.
+	if (surface != cursor->active_constraint->surface) {
+		roots_cursor_update_focus(cursor);
+	} else {
+		roots_cursor_constrain(cursor, cursor->active_constraint, sx, sy);
+	}
+}
+
+void roots_cursor_constrain(struct roots_cursor *cursor,
+		struct wlr_pointer_constraint_v1 *constraint, double sx, double sy) {
+	if (cursor->active_constraint != constraint) {
+		wlr_log(WLR_DEBUG, "roots_cursor_constrain(%p, %p)", cursor, constraint);
+		wlr_log(WLR_DEBUG, "cursor->active_constraint: %p", cursor->active_constraint);
+
+		if (cursor->active_constraint) {
+			wlr_pointer_constraint_v1_send_deactivated(cursor->active_constraint);
+			if (cursor->constraint_commit.link.next) {
+				wl_list_remove(&cursor->constraint_commit.link);
+			}
+		}
+
+		cursor->active_constraint = constraint;
+
+		if (!constraint) {
+			return;
+		}
+
+		wlr_pointer_constraint_v1_send_activated(constraint);
+		wl_signal_add(&constraint->surface->events.commit,
+			&cursor->constraint_commit);
+	} else if (constraint == NULL) {
+		return;
+	}
+
+	pixman_region32_clear(&cursor->confine);
+
+	pixman_region32_t *region = &constraint->region;
+
+	if (!pixman_region32_contains_point(region, sx, sy, NULL)) {
+		// Warp into region if possible
+		int nboxes;
+		pixman_box32_t *boxes = pixman_region32_rectangles(region, &nboxes);
+		if (nboxes > 0) {
+			struct roots_view *view = cursor->pointer_view->view;
+
+			double sx = (boxes[0].x1 + boxes[0].x2) / 2.;
+			double sy = (boxes[0].y1 + boxes[0].y2) / 2.;
+
+			double lx, ly;
+			if (view->rotation == 0.0) {
+				lx = sx + view->x;
+				ly = sy + view->y;
+			} else {
+				double c = cos(view->rotation);
+				double s = sin(view->rotation);
+
+				double center_x = view->width / 2.;
+				double center_y = view->height / 2.;
+
+				lx = c * (sx - center_x) - s * (sy - center_y) + center_x + view->x;
+				ly = s * (sx - center_x) + c * (sy - center_y) + center_y + view->y;
+			}
+
+			wlr_cursor_warp_closest(cursor->cursor, NULL, lx, ly);
+		}
+	}
+
+	// A locked pointer will result in an empty region, thus disallowing all movement
+	if (constraint->type == WLR_POINTER_CONSTRAINT_V1_CONFINED) {
+		pixman_region32_copy(&cursor->confine, region);
+	}
+}

rootston/desktop.c

@@ -15,6 +15,7 @@
 #include <wlr/types/wlr_input_inhibitor.h>
 #include <wlr/types/wlr_layer_shell_v1.h>
 #include <wlr/types/wlr_output_layout.h>
+#include <wlr/types/wlr_pointer_constraints_v1.h>
 #include <wlr/types/wlr_primary_selection.h>
 #include <wlr/types/wlr_server_decoration.h>
 #include <wlr/types/wlr_wl_shell.h>
@@ -776,6 +777,53 @@ static void input_inhibit_deactivate(struct wl_listener *listener, void *data) {
 	}
 }
 
+static void handle_constraint_create(
+		struct wl_listener *listener,
+		struct wlr_pointer_constraint_v1 *constraint) {
+	struct roots_seat* seat = constraint->seat->data;
+
+	double sx, sy;
+	struct wlr_surface *surface = desktop_surface_at(seat->input->server->desktop,
+		seat->cursor->cursor->x, seat->cursor->cursor->y, &sx, &sy, NULL);
+
+	if (surface == constraint->surface) {
+		assert(!seat->cursor->active_constraint);
+		roots_cursor_constrain(seat->cursor, constraint, sx, sy);
+	}
+}
+
+static void handle_constraint_destroy(
+		struct wl_listener *listener,
+		struct wlr_pointer_constraint_v1 *constraint) {
+	struct roots_seat* seat = constraint->seat->data;
+	if (seat->cursor->active_constraint == constraint) {
+		roots_cursor_constrain(seat->cursor, NULL, NAN, NAN);
+		if (constraint->current.cursor_hint.valid && seat->cursor->pointer_view) {
+			double sx = constraint->current.cursor_hint.x;
+			double sy = constraint->current.cursor_hint.y;
+
+			struct roots_view *view = seat->cursor->pointer_view->view;
+
+			double lx, ly;
+			if (view->rotation == 0.0) {
+				lx = sx + view->x;
+				ly = sy + view->y;
+			} else {
+				double c = cos(view->rotation);
+				double s = sin(view->rotation);
+
+				double center_x = view->width / 2.;
+				double center_y = view->height / 2.;
+
+				lx = c * (sx - center_x) - s * (sy - center_y) + center_x + view->x;
+				ly = s * (sx - center_x) + c * (sy - center_y) + center_y + view->y;
+			}
+
+			wlr_cursor_warp(seat->cursor->cursor, NULL, lx, ly);
+		}
+	}
+}
+
 struct roots_desktop *desktop_create(struct roots_server *server,
 		struct roots_config *config) {
 	wlr_log(WLR_DEBUG, "Initializing roots desktop");
@@ -906,6 +954,14 @@ struct roots_desktop *desktop_create(struct roots_server *server,
 		&desktop->xdg_toplevel_decoration);
 	desktop->xdg_toplevel_decoration.notify = handle_xdg_toplevel_decoration;
 
+	desktop->pointer_constraints = wlr_pointer_constraints_v1_create(server->wl_display);
+	desktop->constraint_destroy.notify = (wl_notify_func_t)handle_constraint_destroy;
+	wl_signal_add(&desktop->pointer_constraints->events.constraint_destroy,
+		&desktop->constraint_destroy);
+	desktop->constraint_create.notify = (wl_notify_func_t)handle_constraint_create;
+	wl_signal_add(&desktop->pointer_constraints->events.constraint_create,
+		&desktop->constraint_create);
+
 	return desktop;
 }
 

rootston/keyboard.c

@@ -8,6 +8,7 @@
 #include <wlr/backend/multi.h>
 #include <wlr/backend/session.h>
 #include <wlr/types/wlr_input_device.h>
+#include <wlr/types/wlr_pointer_constraints_v1.h>
 #include <wlr/types/wlr_pointer.h>
 #include <wlr/util/log.h>
 #include <xkbcommon/xkbcommon.h>
@@ -176,6 +177,13 @@ static void keyboard_binding_execute(struct roots_keyboard *keyboard,
 					decoration->wlr_decoration, mode);
 			}
 		}
+	} else if (strcmp(command, "break_pointer_constraint") == 0) {
+		struct wl_list *list =
+			&keyboard->input->seats;
+		struct roots_seat *seat;
+		wl_list_for_each(seat, list, link) {
+			roots_cursor_constrain(seat->cursor, NULL, NAN, NAN);
+		}
 	} else {
 		wlr_log(WLR_ERROR, "unknown binding command: %s", command);
 	}

rootston/rootston.ini.example

@@ -53,9 +53,11 @@ meta-key = Logo
 # - "close" to close the current view
 # - "next_window" to cycle through windows
 # - "alpha" to cycle a window's alpha channel
+# - "break_pointer_constraint" to decline and deactivate all pointer constraints
 [bindings]
 Logo+Shift+e = exit
 Logo+q = close
 Logo+m = maximize
+Logo+Escape = break_pointer_constraint
 Alt+Tab = next_window
 Ctrl+Shift+a = alpha

rootston/seat.c

@@ -299,6 +299,22 @@ static void handle_request_set_cursor(struct wl_listener *listener,
 	roots_cursor_handle_request_set_cursor(cursor, event);
 }
 
+static void handle_pointer_focus_change(struct wl_listener *listener,
+		void *data) {
+	struct roots_cursor *cursor =
+		wl_container_of(listener, cursor, focus_change);
+	struct wlr_seat_pointer_focus_change_event *event = data;
+	roots_cursor_handle_focus_change(cursor, event);
+}
+
+static void handle_constraint_commit(struct wl_listener *listener,
+		void *data) {
+	struct roots_cursor *cursor =
+		wl_container_of(listener, cursor, constraint_commit);
+	assert(cursor->active_constraint->surface == data);
+	roots_cursor_handle_constraint_commit(cursor);
+}
+
 static void seat_reset_device_mappings(struct roots_seat *seat,
 		struct wlr_input_device *device) {
 	struct wlr_cursor *cursor = seat->cursor->cursor;
@@ -434,6 +450,13 @@ static void roots_seat_init_cursor(struct roots_seat *seat) {
 	wl_signal_add(&seat->seat->events.request_set_cursor,
 		&seat->cursor->request_set_cursor);
 	seat->cursor->request_set_cursor.notify = handle_request_set_cursor;
+
+	wl_signal_add(&seat->seat->pointer_state.events.focus_change,
+		&seat->cursor->focus_change);
+	seat->cursor->focus_change.notify = handle_pointer_focus_change;
+
+	wl_list_init(&seat->cursor->constraint_commit.link);
+	seat->cursor->constraint_commit.notify = handle_constraint_commit;
 }
 
 static void roots_drag_icon_handle_surface_commit(struct wl_listener *listener,
@@ -1188,8 +1211,10 @@ void roots_seat_set_focus(struct roots_seat *seat, struct roots_view *view) {
 			NULL, 0, NULL);
 	}
 
+	if (seat->cursor) {
 		roots_cursor_update_focus(seat->cursor);
 	}
+}
 
 /**
  * Focus semantics of layer surfaces are somewhat detached from the normal focus
@@ -1224,8 +1249,11 @@ void roots_seat_set_focus_layer(struct roots_seat *seat,
 			NULL, 0, NULL);
 	}
 
+
+	if (seat->cursor) {
 		roots_cursor_update_focus(seat->cursor);
 	}
+}
 
 void roots_seat_set_exclusive_client(struct roots_seat *seat,
 		struct wl_client *client) {

types/meson.build

@@ -39,6 +39,7 @@ lib_wlr_types = static_library(
 		'wlr_output_layout.c',
 		'wlr_output.c',
 		'wlr_pointer.c',
+		'wlr_pointer_constraints_v1.c',
 		'wlr_primary_selection.c',
 		'wlr_region.c',
 		'wlr_screenshooter.c',

types/wlr_box.c

@@ -143,3 +143,12 @@ void wlr_box_rotated_bounds(const struct wlr_box *box, float rotation,
 	dest->y = floor(fmin(y1, y2));
 	dest->height = ceil(fmax(y1, y2) - fmin(y1, y2));
 }
+
+void wlr_box_from_pixman_box32(const pixman_box32_t box, struct wlr_box *dest) {
+	*dest = (struct wlr_box){
+		.x = box.x1,
+		.y = box.y1,
+		.width = box.x2 - box.x1,
+		.height = box.y2 - box.y1,
+	};
+}

types/wlr_cursor.c

@@ -252,7 +252,7 @@ bool wlr_cursor_warp(struct wlr_cursor *cur, struct wlr_input_device *dev,
 	return result;
 }
 
-static void cursor_warp_closest(struct wlr_cursor *cur,
+void wlr_cursor_warp_closest(struct wlr_cursor *cur,
 		struct wlr_input_device *dev, double lx, double ly) {
 	struct wlr_box *mapping = get_mapping(cur, dev);
 	if (mapping) {
@@ -286,7 +286,7 @@ void wlr_cursor_warp_absolute(struct wlr_cursor *cur,
 	double lx, ly;
 	wlr_cursor_absolute_to_layout_coords(cur, dev, x, y, &lx, &ly);
 
-	cursor_warp_closest(cur, dev, lx, ly);
+	wlr_cursor_warp_closest(cur, dev, lx, ly);
 }
 
 void wlr_cursor_move(struct wlr_cursor *cur, struct wlr_input_device *dev,
@@ -296,7 +296,7 @@ void wlr_cursor_move(struct wlr_cursor *cur, struct wlr_input_device *dev,
 	double lx = !isnan(delta_x) ? cur->x + delta_x : cur->x;
 	double ly = !isnan(delta_y) ? cur->y + delta_y : cur->y;
 
-	cursor_warp_closest(cur, dev, lx, ly);
+	wlr_cursor_warp_closest(cur, dev, lx, ly);
 }
 
 void wlr_cursor_set_image(struct wlr_cursor *cur, const uint8_t *pixels,

types/wlr_pointer_constraints_v1.c

@@ -0,0 +1,362 @@
+#include <assert.h>
+#include <limits.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <pixman.h>
+#include <wayland-server.h>
+#include <wlr/types/wlr_box.h>
+#include <wlr/types/wlr_pointer_constraints_v1.h>
+#include <wlr/types/wlr_region.h>
+#include <wlr/util/log.h>
+
+#include "util/signal.h"
+
+static const struct zwp_locked_pointer_v1_interface locked_pointer_impl;
+static const struct zwp_confined_pointer_v1_interface confined_pointer_impl;
+static const struct zwp_pointer_constraints_v1_interface pointer_constraints_impl;
+static void pointer_constraint_destroy(struct wlr_pointer_constraint_v1 *constraint);
+
+static struct wlr_pointer_constraint_v1 *pointer_constraint_from_resource(
+		struct wl_resource *resource) {
+	assert(
+		wl_resource_instance_of(
+			resource, &zwp_confined_pointer_v1_interface,
+				&confined_pointer_impl) ||
+		wl_resource_instance_of(
+			resource, &zwp_locked_pointer_v1_interface,
+				&locked_pointer_impl));
+	return wl_resource_get_user_data(resource);
+}
+
+static struct wlr_pointer_constraints_v1 *pointer_constraints_from_resource(
+		struct wl_resource *resource) {
+	assert(wl_resource_instance_of(resource, &zwp_pointer_constraints_v1_interface,
+		&pointer_constraints_impl));
+	return wl_resource_get_user_data(resource);
+}
+
+static void resource_destroy(struct wl_client *client,
+		struct wl_resource *resource) {
+	wl_resource_destroy(resource);
+}
+
+static void pointer_constraint_destroy(struct wlr_pointer_constraint_v1 *constraint) {
+	if (constraint == NULL) {
+		return;
+	}
+
+	wlr_log(WLR_DEBUG, "destroying constraint %p", constraint);
+
+	wl_resource_set_user_data(constraint->resource, NULL);
+	wl_list_remove(&constraint->link);
+	wl_list_remove(&constraint->surface_commit.link);
+	wl_list_remove(&constraint->surface_destroy.link);
+	wl_list_remove(&constraint->seat_destroy.link);
+
+	wlr_signal_emit_safe(
+		&constraint->pointer_constraints->events.constraint_destroy,
+		constraint);
+
+	if (constraint->current.region) {
+		pixman_region32_fini(constraint->current.region);
+		free(constraint->current.region);
+	}
+	if (constraint->pending.region &&
+			constraint->current.region != constraint->pending.region) {
+		pixman_region32_fini(constraint->pending.region);
+		free(constraint->pending.region);
+	}
+	pixman_region32_fini(&constraint->region);
+	free(constraint);
+}
+
+static void pointer_constraint_destroy_resource(struct wl_resource *resource) {
+	struct wlr_pointer_constraint_v1 *constraint =
+		pointer_constraint_from_resource(resource);
+
+	pointer_constraint_destroy(constraint);
+}
+
+static void pointer_constraint_set_region(
+		struct wlr_pointer_constraint_v1 *constraint,
+		struct wl_resource *region_resource) {
+	if (constraint->pending.region &&
+			constraint->current.region != constraint->pending.region) {
+		pixman_region32_fini(constraint->pending.region);
+		free(constraint->pending.region);
+	}
+
+	if (region_resource) {
+		constraint->pending.region = calloc(1, sizeof(pixman_region32_t));
+		pixman_region32_init(constraint->pending.region);
+
+		pixman_region32_t *region = wlr_region_from_resource(region_resource);
+		pixman_region32_copy(constraint->pending.region, region);
+	} else {
+		constraint->pending.region = NULL;
+	}
+}
+
+static void pointer_constraint_set_region_wrapper(struct wl_client *client,
+		struct wl_resource *resource, struct wl_resource *region_resource) {
+	struct wlr_pointer_constraint_v1 *constraint =
+		pointer_constraint_from_resource(resource);
+
+	pointer_constraint_set_region(constraint, region_resource);
+}
+
+static void pointer_constraint_set_cursor_position_hint(struct wl_client *client,
+		struct wl_resource *resource, wl_fixed_t x, wl_fixed_t y) {
+	struct wlr_pointer_constraint_v1 *constraint =
+		pointer_constraint_from_resource(resource);
+
+	constraint->pending.cursor_hint.x = wl_fixed_to_double(x);
+	constraint->pending.cursor_hint.y = wl_fixed_to_double(y);
+	constraint->pending.cursor_hint.valid = true;
+}
+
+static void pointer_constraint_handle_commit(
+		struct wlr_pointer_constraint_v1 *constraint) {
+	constraint->current.cursor_hint = constraint->pending.cursor_hint;
+
+	if (constraint->current.region != constraint->pending.region) {
+		if (constraint->current.region) {
+			pixman_region32_fini(constraint->current.region);
+			free(constraint->current.region);
+		}
+
+		constraint->current.region = constraint->pending.region;
+	}
+
+	pixman_region32_clear(&constraint->region);
+
+	if (constraint->current.region) {
+		pixman_region32_intersect(&constraint->region,
+			&constraint->surface->input_region, constraint->current.region);
+	} else {
+		pixman_region32_copy(&constraint->region,
+			&constraint->surface->input_region);
+	}
+}
+
+static void handle_surface_commit(struct wl_listener *listener, void *data) {
+	struct wlr_pointer_constraint_v1 *constraint =
+		wl_container_of(listener, constraint, surface_commit);
+
+	pointer_constraint_handle_commit(constraint);
+}
+
+static void handle_surface_destroy(struct wl_listener *listener, void *data) {
+	struct wlr_pointer_constraint_v1 *constraint =
+		wl_container_of(listener, constraint, surface_destroy);
+
+	pointer_constraint_destroy(constraint);
+}
+
+static void handle_seat_destroy(struct wl_listener *listener, void *data) {
+	struct wlr_pointer_constraint_v1 *constraint =
+		wl_container_of(listener, constraint, seat_destroy);
+
+	pointer_constraint_destroy(constraint);
+}
+
+static const struct zwp_confined_pointer_v1_interface confined_pointer_impl = {
+	.destroy = resource_destroy,
+	.set_region = pointer_constraint_set_region_wrapper,
+};
+
+static const struct zwp_locked_pointer_v1_interface locked_pointer_impl = {
+	.destroy = resource_destroy,
+	.set_region = pointer_constraint_set_region_wrapper,
+	.set_cursor_position_hint = pointer_constraint_set_cursor_position_hint,
+};
+
+static void pointer_constraint_create(struct wl_client *client,
+		struct wl_resource *pointer_constraints_resource, uint32_t id,
+		struct wl_resource *surface_resource, struct wl_resource *pointer_resource,
+		struct wl_resource *region_resource,
+		enum zwp_pointer_constraints_v1_lifetime lifetime,
+		enum wlr_pointer_constraint_v1_type type) {
+	struct wlr_pointer_constraints_v1 *pointer_constraints =
+		pointer_constraints_from_resource(pointer_constraints_resource);
+
+	struct wlr_surface *surface = wlr_surface_from_resource(surface_resource);
+	struct wlr_seat *seat = wlr_seat_client_from_pointer_resource(pointer_resource)->seat;
+
+	if (wlr_pointer_constraints_v1_constraint_for_surface(pointer_constraints,
+			surface, seat)) {
+		wl_resource_post_error(pointer_constraints_resource,
+			ZWP_POINTER_CONSTRAINTS_V1_ERROR_ALREADY_CONSTRAINED,
+			"a pointer constraint with a wl_pointer of the same wl_seat"
+			" is already on this surface");
+		return;
+	}
+
+	uint32_t version = wl_resource_get_version(pointer_constraints_resource);
+
+	bool locked_pointer = type == WLR_POINTER_CONSTRAINT_V1_LOCKED;
+
+	struct wl_resource *resource = locked_pointer ?
+		wl_resource_create(client, &zwp_locked_pointer_v1_interface, version, id) :
+		wl_resource_create(client, &zwp_confined_pointer_v1_interface, version, id);
+
+	if (resource == NULL) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+
+	struct wlr_pointer_constraint_v1 *constraint = calloc(1, sizeof(*constraint));
+	if (constraint == NULL) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+
+	constraint->resource = resource;
+	constraint->surface = surface;
+	constraint->seat = seat;
+	constraint->lifetime = lifetime;
+	constraint->type = type;
+	constraint->pointer_constraints = pointer_constraints;
+
+	pixman_region32_init(&constraint->region);
+
+	pointer_constraint_set_region(constraint, region_resource);
+	pointer_constraint_handle_commit(constraint);
+
+	constraint->surface_commit.notify = handle_surface_commit;
+	wl_signal_add(&surface->events.commit, &constraint->surface_commit);
+
+	constraint->surface_destroy.notify = handle_surface_destroy;
+	wl_signal_add(&surface->events.destroy, &constraint->surface_destroy);
+
+	constraint->seat_destroy.notify = handle_seat_destroy;
+	wl_signal_add(&seat->events.destroy, &constraint->seat_destroy);
+
+	wl_resource_set_implementation(constraint->resource,
+		locked_pointer ? (void*)&locked_pointer_impl : (void*)&confined_pointer_impl,
+		constraint, pointer_constraint_destroy_resource);
+
+	wlr_log(WLR_DEBUG, "new %s_pointer %p (res %p)",
+		locked_pointer ? "locked" : "confined", constraint, constraint->resource);
+
+	wl_list_insert(&pointer_constraints->constraints, &constraint->link);
+
+	wlr_signal_emit_safe(&pointer_constraints->events.constraint_create,
+		constraint);
+}
+
+static void pointer_constraints_lock_pointer(struct wl_client *client,
+		struct wl_resource *cons_resource, uint32_t id,
+		struct wl_resource *surface, struct wl_resource *pointer,
+		struct wl_resource *region, enum zwp_pointer_constraints_v1_lifetime lifetime) {
+	pointer_constraint_create(client, cons_resource, id, surface, pointer,
+		region, lifetime, WLR_POINTER_CONSTRAINT_V1_LOCKED);
+}
+
+static void pointer_constraints_confine_pointer(struct wl_client *client,
+		struct wl_resource *cons_resource, uint32_t id,
+		struct wl_resource *surface, struct wl_resource *pointer,
+		struct wl_resource *region, enum zwp_pointer_constraints_v1_lifetime lifetime) {
+	pointer_constraint_create(client, cons_resource, id, surface, pointer,
+		region, lifetime, WLR_POINTER_CONSTRAINT_V1_CONFINED);
+}
+
+static const struct zwp_pointer_constraints_v1_interface pointer_constraints_impl = {
+	.destroy = resource_destroy,
+	.lock_pointer = pointer_constraints_lock_pointer,
+	.confine_pointer = pointer_constraints_confine_pointer,
+};
+
+static void pointer_constraints_destroy(struct wl_resource *resource) {
+	wl_list_remove(wl_resource_get_link(resource));
+}
+
+static void pointer_constraints_bind(struct wl_client *client, void *data,
+		uint32_t version, uint32_t id) {
+	struct wlr_pointer_constraints_v1 *pointer_constraints = data;
+	assert(client && pointer_constraints);
+
+	struct wl_resource *resource = wl_resource_create(client,
+		&zwp_pointer_constraints_v1_interface, version, id);
+	if (resource == NULL) {
+		wl_client_post_no_memory(client);
+		return;
+	}
+
+	wl_list_insert(&pointer_constraints->wl_resources, wl_resource_get_link(resource));
+	wl_resource_set_implementation(resource, &pointer_constraints_impl,
+		pointer_constraints, pointer_constraints_destroy);
+}
+
+struct wlr_pointer_constraints_v1 *wlr_pointer_constraints_v1_create(
+		struct wl_display *display) {
+	struct wlr_pointer_constraints_v1 *pointer_constraints =
+		calloc(1, sizeof(*pointer_constraints));
+
+	if (!pointer_constraints) {
+		return NULL;
+	}
+
+	struct wl_global *wl_global = wl_global_create(display,
+		&zwp_pointer_constraints_v1_interface, 1, pointer_constraints,
+		pointer_constraints_bind);
+	if (!wl_global) {
+		free(pointer_constraints);
+		return NULL;
+	}
+	pointer_constraints->wl_global = wl_global;
+
+	wl_list_init(&pointer_constraints->wl_resources);
+	wl_list_init(&pointer_constraints->constraints);
+	wl_signal_init(&pointer_constraints->events.constraint_create);
+	wl_signal_init(&pointer_constraints->events.constraint_destroy);
+
+	return pointer_constraints;
+}
+
+void wlr_pointer_constraints_v1_destroy(
+		struct wlr_pointer_constraints_v1 *pointer_constraints) {
+	struct wl_resource *resource, *_tmp_res;
+	wl_resource_for_each_safe(resource, _tmp_res, &pointer_constraints->wl_resources) {
+		wl_resource_destroy(resource);
+	}
+
+	struct wlr_pointer_constraint_v1 *constraint, *_tmp_cons;
+	wl_list_for_each_safe(constraint, _tmp_cons, &pointer_constraints->constraints, link) {
+		wl_resource_destroy(constraint->resource);
+	}
+
+	wl_global_destroy(pointer_constraints->wl_global);
+	free(pointer_constraints);
+}
+
+struct wlr_pointer_constraint_v1 *wlr_pointer_constraints_v1_constraint_for_surface(
+		struct wlr_pointer_constraints_v1 *pointer_constraints,
+		struct wlr_surface *surface, struct wlr_seat *seat) {
+	struct wlr_pointer_constraint_v1 *constraint;
+	wl_list_for_each(constraint, &pointer_constraints->constraints, link) {
+		if (constraint->surface == surface && constraint->seat == seat) {
+			return constraint;
+		}
+	}
+
+	return NULL;
+}
+
+// Thankfully zwp_confined_pointer_v1_send_{un,}confined work
+// on both locked and confined pointer constraints.
+void wlr_pointer_constraint_v1_send_activated(
+		struct wlr_pointer_constraint_v1 *constraint) {
+	wlr_log(WLR_DEBUG, "constrained %p", constraint);
+	zwp_confined_pointer_v1_send_confined(constraint->resource);
+}
+
+void wlr_pointer_constraint_v1_send_deactivated(struct wlr_pointer_constraint_v1 *constraint) {
+	if (wl_resource_get_user_data(constraint->resource)) {
+		wlr_log(WLR_DEBUG, "unconstrained %p", constraint);
+		zwp_confined_pointer_v1_send_unconfined(constraint->resource);
+		if (constraint->lifetime == ZWP_POINTER_CONSTRAINTS_V1_LIFETIME_ONESHOT) {
+			pointer_constraint_destroy(constraint);
+		}
+	}
+}

util/region.c

@@ -1,5 +1,8 @@
+#include <assert.h>
 #include <math.h>
+#include <limits.h>
 #include <stdlib.h>
+#include <wlr/types/wlr_box.h>
 #include <wlr/util/region.h>
 
 void wlr_region_scale(pixman_region32_t *dst, pixman_region32_t *src,
@@ -177,3 +180,71 @@ void wlr_region_rotated_bounds(pixman_region32_t *dst, pixman_region32_t *src,
 	pixman_region32_init_rects(dst, dst_rects, nrects);
 	free(dst_rects);
 }
+
+static void region_confine(pixman_region32_t *region, double x1, double y1, double x2,
+		double y2, double *x2_out, double *y2_out, pixman_box32_t box) {
+	double x_clamped = fmax(fmin(x2, box.x2 - 1), box.x1);
+	double y_clamped = fmax(fmin(y2, box.y2 - 1), box.y1);
+
+	// If the target coordinates are above box.{x,y}2 - 1, but less than
+	// box.{x,y}2, then they are still within the box.
+	if (floor(x_clamped) == floor(x2) && floor(y_clamped) == floor(y2)) {
+		*x2_out = x2;
+		*y2_out = y2;
+		return;
+	}
+
+	double dx = x2 - x1;
+	double dy = y2 - y1;
+
+	// We use fabs to avoid negative zeroes and thus avoid a bug
+	// with negative infinity.
+	double delta = fmin(fabs(x_clamped - x1) / fabs(dx), fabs(y_clamped - y1) / fabs(dy));
+
+	// We clamp it again due to precision errors.
+	double x = fmax(fmin(delta * dx + x1, box.x2 - 1), box.x1);
+	double y = fmax(fmin(delta * dy + y1, box.y2 - 1), box.y1);
+
+	// Go one unit past the boundary to find an adjacent box.
+	int x_ext = floor(x) + (dx == 0 ? 0 : dx > 0 ? 1 : -1);
+	int y_ext = floor(y) + (dy == 0 ? 0 : dy > 0 ? 1 : -1);
+
+	if (pixman_region32_contains_point(region, x_ext, y_ext, &box)) {
+		return region_confine(region, x1, y1, x2, y2, x2_out, y2_out, box);
+	} else if (dx == 0 || dy == 0) {
+		*x2_out = x;
+		*y2_out = y;
+	} else {
+		bool bordering_x = x == box.x1 || x == box.x2 - 1;
+		bool bordering_y = y == box.y1 || y == box.y2 - 1;
+
+		if ((bordering_x && bordering_y) || (!bordering_x && !bordering_y)) {
+			double x2_potential, y2_potential;
+			double tmp1, tmp2;
+			region_confine(region, x, y, x, y2, &tmp1, &y2_potential, box);
+			region_confine(region, x, y, x2, y, &x2_potential, &tmp2, box);
+			if (fabs(x2_potential - x) > fabs(y2_potential - y)) {
+				*x2_out = x2_potential;
+				*y2_out = y;
+			} else {
+				*x2_out = x;
+				*y2_out = y2_potential;
+			}
+		} else if (bordering_x) {
+			return region_confine(region, x, y, x, y2, x2_out, y2_out, box);
+		} else if (bordering_y) {
+			return region_confine(region, x, y, x2, y, x2_out, y2_out, box);
+		}
+	}
+}
+
+bool wlr_region_confine(pixman_region32_t *region, double x1, double y1, double x2,
+		double y2, double *x2_out, double *y2_out) {
+	pixman_box32_t box;
+	if (pixman_region32_contains_point(region, x1, y1, &box)) {
+		region_confine(region, x1, y1, x2, y2, x2_out, y2_out, box);
+		return true;
+	} else {
+		return false;
+	}
+}