compositor-drm: Enable seat constraining when configured in weston.ini

This change tweaks weston_pointer_clamp to take into consideration if a
seat is constrained to a particular output by only considering the
pointer position valid if it is within the output we a constrained to.
This function is also used for the initial warping of the pointer when a
constraint is first established.

The other two changes are the application of the constraint when either
a new device added or a new output created and therefore outputs and
input devices can be brought up in either order.

v2: the code in create_output_for_connector has been spun off into a
new function setup_output_seat_constraint (Ander). The inappropriate
warping behaviour has been resolved by using weston_pointer_clamp
(Pekka).

src/compositor-drm.c

@@ -1728,6 +1728,25 @@ parse_transform(const char *transform, const char *output_name)
 	return WL_OUTPUT_TRANSFORM_NORMAL;
 }
 
+static void
+setup_output_seat_constraint(struct drm_compositor *ec,
+			     struct weston_output *output,
+			     const char *s)
+{
+	if (strcmp(s, "") != 0) {
+		struct udev_seat *seat;
+
+		seat = udev_seat_get_named(&ec->base, s);
+		if (seat)
+			seat->base.output = output;
+
+		if (seat && seat->base.pointer)
+			weston_pointer_clamp(seat->base.pointer,
+					     &seat->base.pointer->x,
+					     &seat->base.pointer->y);
+	}
+}
+
 static int
 create_output_for_connector(struct drm_compositor *ec,
 			    drmModeRes *resources,
@@ -1796,6 +1815,10 @@ create_output_for_connector(struct drm_compositor *ec,
 	transform = parse_transform(s, output->base.name);
 	free(s);
 
+	weston_config_section_get_string(section, "seat", &s, "");
+	setup_output_seat_constraint(ec, &output->base, s);
+	free(s);
+
 	output->crtc_id = resources->crtcs[i];
 	output->pipe = i;
 	ec->crtc_allocator |= (1 << output->crtc_id);

src/compositor.h

@@ -437,6 +437,8 @@ struct weston_seat {
 	struct weston_keyboard *keyboard;
 	struct weston_touch *touch;
 
+	struct weston_output *output; /* constraint */
+
 	struct wl_signal destroy_signal;
 
 	struct weston_compositor *compositor;

src/input.c

@@ -574,6 +574,8 @@ weston_pointer_clamp(struct weston_pointer *pointer, wl_fixed_t *fx, wl_fixed_t
 	old_y = wl_fixed_to_int(pointer->y);
 
 	wl_list_for_each(output, &ec->output_list, link) {
+		if (pointer->seat->output && pointer->seat->output != output)
+			continue;
 		if (pixman_region32_contains_point(&output->region,
 						   x, y, NULL))
 			valid = 1;
@@ -582,7 +584,10 @@ weston_pointer_clamp(struct weston_pointer *pointer, wl_fixed_t *fx, wl_fixed_t
 			prev = output;
 	}
 
-	if (!valid) {
+	if (!prev)
+		prev = pointer->seat->output;
+
+	if (prev && !valid) {
 		if (x < prev->x)
 			*fx = wl_fixed_from_int(prev->x);
 		else if (x >= prev->x + prev->width)

src/udev-seat.c

@@ -115,6 +115,11 @@ device_added(struct udev_device *udev_device, struct udev_input *input)
 
 	wl_list_insert(seat->devices_list.prev, &device->link);
 
+	if (seat->base.output && seat->base.pointer)
+		weston_pointer_clamp(seat->base.pointer,
+				     &seat->base.pointer->x,
+				     &seat->base.pointer->y);
+
 	return 0;
 }