Replace output screen size callback with transform helpers

Instead of automatically transforming absolute coordinates of touch and
pointer events to screen coordinates, the user now uses the corresponding
transform helper function. This means the coordinates returned by
libinput_event_pointer_get_absolute_x(),
libinput_event_pointer_get_absolute_y(), libinput_touch_get_x() and
libinput_touch_get_y() has changed from being in output screen coordinate
space to being in device specific coordinate space.

For example, where one before would call libinput_event_touch_get_x(event),
one now calls libinput_event_touch_get_x_transformed(event, output_width).

Signed-off-by: Jonas Ådahl <jadahl@gmail.com>

src/evdev.c

@@ -86,6 +86,24 @@ transform_absolute(struct evdev_device *device, int32_t *x, int32_t *y)
 	}
 }
 
+li_fixed_t
+evdev_device_transform_x(struct evdev_device *device,
+			 li_fixed_t x,
+			 uint32_t width)
+{
+	return (x - device->abs.min_x) * width /
+		(device->abs.max_x - device->abs.min_x);
+}
+
+li_fixed_t
+evdev_device_transform_y(struct evdev_device *device,
+			 li_fixed_t y,
+			 uint32_t height)
+{
+	return (y - device->abs.min_y) * height /
+		(device->abs.max_y - device->abs.min_y);
+}
+
 static void
 evdev_flush_pending_event(struct evdev_device *device, uint32_t time)
 {
@@ -242,16 +260,6 @@ evdev_process_touch(struct evdev_device *device,
 		    struct input_event *e,
 		    uint32_t time)
 {
-	struct libinput *libinput = device->base.seat->libinput;
-	int screen_width;
-	int screen_height;
-
-	libinput->interface->get_current_screen_dimensions(
-		&device->base,
-		&screen_width,
-		&screen_height,
-		libinput->user_data);
-
 	switch (e->code) {
 	case ABS_MT_SLOT:
 		evdev_flush_pending_event(device, time);
@@ -267,16 +275,12 @@ evdev_process_touch(struct evdev_device *device,
 			device->pending_event = EVDEV_ABSOLUTE_MT_UP;
 		break;
 	case ABS_MT_POSITION_X:
-		device->mt.slots[device->mt.slot].x =
-			(e->value - device->abs.min_x) * screen_width /
-			(device->abs.max_x - device->abs.min_x);
+		device->mt.slots[device->mt.slot].x = e->value;
 		if (device->pending_event == EVDEV_NONE)
 			device->pending_event = EVDEV_ABSOLUTE_MT_MOTION;
 		break;
 	case ABS_MT_POSITION_Y:
-		device->mt.slots[device->mt.slot].y =
-			(e->value - device->abs.min_y) * screen_height /
-			(device->abs.max_y - device->abs.min_y);
+		device->mt.slots[device->mt.slot].y = e->value;
 		if (device->pending_event == EVDEV_NONE)
 			device->pending_event = EVDEV_ABSOLUTE_MT_MOTION;
 		break;
@@ -287,28 +291,14 @@ static inline void
 evdev_process_absolute_motion(struct evdev_device *device,
 			      struct input_event *e)
 {
-	struct libinput *libinput = device->base.seat->libinput;
-	int screen_width;
-	int screen_height;
-
-	libinput->interface->get_current_screen_dimensions(
-		&device->base,
-		&screen_width,
-		&screen_height,
-		libinput->user_data);
-
 	switch (e->code) {
 	case ABS_X:
-		device->abs.x =
-			(e->value - device->abs.min_x) * screen_width /
-			(device->abs.max_x - device->abs.min_x);
+		device->abs.x = e->value;
 		if (device->pending_event == EVDEV_NONE)
 			device->pending_event = EVDEV_ABSOLUTE_MOTION;
 		break;
 	case ABS_Y:
-		device->abs.y =
-			(e->value - device->abs.min_y) * screen_height /
-			(device->abs.max_y - device->abs.min_y);
+		device->abs.y = e->value;
 		if (device->pending_event == EVDEV_NONE)
 			device->pending_event = EVDEV_ABSOLUTE_MOTION;
 		break;

src/evdev.h

@@ -146,6 +146,16 @@ int
 evdev_device_has_capability(struct evdev_device *device,
 			    enum libinput_device_capability capability);
 
+li_fixed_t
+evdev_device_transform_x(struct evdev_device *device,
+			 li_fixed_t x,
+			 uint32_t width);
+
+li_fixed_t
+evdev_device_transform_y(struct evdev_device *device,
+			 li_fixed_t y,
+			 uint32_t height);
+
 void
 evdev_device_remove(struct evdev_device *device);
 

src/libinput.c

@@ -245,6 +245,28 @@ libinput_event_pointer_get_absolute_y(
 	return event->y;
 }
 
+LIBINPUT_EXPORT li_fixed_t
+libinput_event_pointer_get_absolute_x_transformed(
+	struct libinput_event_pointer *event,
+	uint32_t width)
+{
+	struct evdev_device *device =
+		(struct evdev_device *) event->base.device;
+
+	return evdev_device_transform_x(device, event->x, width);
+}
+
+LIBINPUT_EXPORT li_fixed_t
+libinput_event_pointer_get_absolute_y_transformed(
+	struct libinput_event_pointer *event,
+	uint32_t height)
+{
+	struct evdev_device *device =
+		(struct evdev_device *) event->base.device;
+
+	return evdev_device_transform_y(device, event->y, height);
+}
+
 LIBINPUT_EXPORT uint32_t
 libinput_event_pointer_get_button(
 	struct libinput_event_pointer *event)
@@ -294,6 +316,28 @@ libinput_event_touch_get_x(
 	return event->x;
 }
 
+LIBINPUT_EXPORT li_fixed_t
+libinput_event_touch_get_x_transformed(
+	struct libinput_event_touch *event,
+	uint32_t width)
+{
+	struct evdev_device *device =
+		(struct evdev_device *) event->base.device;
+
+	return evdev_device_transform_x(device, event->x, width);
+}
+
+LIBINPUT_EXPORT li_fixed_t
+libinput_event_touch_get_y_transformed(
+	struct libinput_event_touch *event,
+	uint32_t height)
+{
+	struct evdev_device *device =
+		(struct evdev_device *) event->base.device;
+
+	return evdev_device_transform_y(device, event->y, height);
+}
+
 LIBINPUT_EXPORT li_fixed_t
 libinput_event_touch_get_y(
 	struct libinput_event_touch *event)

src/libinput.h

@@ -395,16 +395,19 @@ libinput_event_pointer_get_dy(
 /**
  * @ingroup event_pointer
  *
- * Return the absolute x coordinate of the device, scaled to screen
- * coordinates.
- * The axes' positive direction is device-specific. For pointer events that
- * are not of type LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE, this function
- * returns 0.
+ * Return the current absolute x coordinate of the pointer event.
+ *
+ * The coordinate is in a device specific coordinate space; to get the
+ * corresponding output screen coordinate, use
+ * libinput_event_pointer_get_x_transformed().
+ *
+ * For pointer events that are not of type
+ * LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE, this function returns 0.
  *
  * @note It is an application bug to call this function for events other than
  * LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE.
  *
- * @return the current absolute x coordinate scaled to screen coordinates.
+ * @return the current absolute x coordinate
  */
 li_fixed_t
 libinput_event_pointer_get_absolute_x(
@@ -413,20 +416,68 @@ libinput_event_pointer_get_absolute_x(
 /**
  * @ingroup event_pointer
  *
- * Return the absolute y coordinate of the device, scaled to screen coordinates.
- * The axes' positive direction is device-specific. For pointer events that
- * are not of type LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE, this function
- * returns 0.
+ * Return the current absolute y coordinate of the pointer event.
+ *
+ * The coordinate is in a device specific coordinate space; to get the
+ * corresponding output screen coordinate, use
+ * libinput_event_pointer_get_y_transformed().
+ *
+ * For pointer events that are not of type
+ * LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE, this function returns 0.
  *
  * @note It is an application bug to call this function for events other than
  * LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE.
  *
- * @return the current absolute y coordinate scaled to screen coordinates.
+ * @return the current absolute y coordinate
  */
 li_fixed_t
 libinput_event_pointer_get_absolute_y(
 	struct libinput_event_pointer *event);
 
+/**
+ * @ingroup event_pointer
+ *
+ * Return the current absolute x coordinate of the pointer event, transformed to
+ * screen coordinates.
+ *
+ * For pointer events that are not of type
+ * LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE, the return value of this function is
+ * undefined.
+ *
+ * @note It is an application bug to call this function for events other than
+ * LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE.
+ *
+ * @param event The libinput pointer event
+ * @param width The current output screen width
+ * @return the current absolute x coordinate transformed to a screen coordinate
+ */
+li_fixed_t
+libinput_event_pointer_get_absolute_x_transformed(
+	struct libinput_event_pointer *event,
+	uint32_t width);
+
+/**
+ * @ingroup event_pointer
+ *
+ * Return the current absolute y coordinate of the pointer event, transformed to
+ * screen coordinates.
+ *
+ * For pointer events that are not of type
+ * LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE, the return value of this function is
+ * undefined.
+ *
+ * @note It is an application bug to call this function for events other than
+ * LIBINPUT_EVENT_POINTER_MOTION_ABSOLUTE.
+ *
+ * @param event The libinput pointer event
+ * @param height The current output screen height
+ * @return the current absolute y coordinate transformed to a screen coordinate
+ */
+li_fixed_t
+libinput_event_pointer_get_absolute_y_transformed(
+	struct libinput_event_pointer *event,
+	uint32_t height);
+
 /**
  * @ingroup event_pointer
  *
@@ -531,9 +582,16 @@ libinput_event_touch_get_slot(
 /**
  * @ingroup event_touch
  *
+ * Return the current absolute x coordinate of the touch event.
+ *
+ * The coordinate is in a device specific coordinate space; to get the
+ * corresponding output screen coordinate, use
+ * libinput_event_touch_get_x_transformed().
+ *
  * @note this function should not be called for LIBINPUT_EVENT_TOUCH_FRAME.
  *
- * @return the absolute X coordinate on this touch device, scaled to screen coordinates.
+ * @param event The libinput touch event
+ * @return the current absolute x coordinate
  */
 li_fixed_t
 libinput_event_touch_get_x(
@@ -542,14 +600,53 @@ libinput_event_touch_get_x(
 /**
  * @ingroup event_touch
  *
+ * Return the current absolute y coordinate of the touch event.
+ *
+ * The coordinate is in a device specific coordinate space; to get the
+ * corresponding output screen coordinate, use
+ * libinput_event_touch_get_y_transformed().
+ *
  * @note this function should not be called for LIBINPUT_EVENT_TOUCH_FRAME.
  *
- * @return the absolute X coordinate on this touch device, scaled to screen coordinates.
+ * @param event The libinput touch event
+ * @return the current absolute y coordinate
  */
 li_fixed_t
 libinput_event_touch_get_y(
 	struct libinput_event_touch *event);
 
+/**
+ * @ingroup event_touch
+ *
+ * Return the current absolute x coordinate of the touch event, transformed to
+ * screen coordinates.
+ *
+ * @note this function should not be called for LIBINPUT_EVENT_TOUCH_FRAME.
+ *
+ * @param event The libinput touch event
+ * @param width The current output screen width
+ * @return the current absolute x coordinate transformed to a screen coordinate
+ */
+li_fixed_t
+libinput_event_touch_get_x_transformed(struct libinput_event_touch *event,
+				       uint32_t width);
+
+/**
+ * @ingroup event_touch
+ *
+ * Return the current absolute y coordinate of the touch event, transformed to
+ * screen coordinates.
+ *
+ * @note this function should not be called for LIBINPUT_EVENT_TOUCH_FRAME.
+ *
+ * @param event The libinput touch event
+ * @param height The current output screen height
+ * @return the current absolute y coordinate transformed to a screen coordinate
+ */
+li_fixed_t
+libinput_event_touch_get_y_transformed(struct libinput_event_touch *event,
+				       uint32_t height);
+
 /**
  * @ingroup event_touch
  *
@@ -586,11 +683,6 @@ struct libinput_interface {
 	 * libinput_create_from_udev()
 	 */
 	void (*close_restricted)(int fd, void *user_data);
-
-	void (*get_current_screen_dimensions)(struct libinput_device *device,
-					      int *width,
-					      int *height,
-					      void *user_data);
 };
 
 /**

test/litest.c

@@ -318,20 +318,9 @@ close_restricted(int fd, void *userdata)
 	close(fd);
 }
 
-static void
-get_current_screen_dimensions(struct libinput_device *device,
-			      int *width,
-			      int *height,
-			      void *user_data)
-{
-	*width = 1024;
-	*height = 768;
-}
-
 const struct libinput_interface interface = {
 	.open_restricted = open_restricted,
 	.close_restricted = close_restricted,
-	.get_current_screen_dimensions = get_current_screen_dimensions,
 };
 
 struct litest_device *

tools/event-debug.c

@@ -44,6 +44,8 @@ static const char *device;
 static const char *seat = "seat0";
 static struct udev *udev;
 uint32_t start_time;
+static const uint32_t screen_width = 100;
+static const uint32_t screen_height = 100;
 
 static void
 usage(void)
@@ -123,20 +125,9 @@ close_restricted(int fd, void *user_data)
 	close(fd);
 }
 
-static void get_current_screen_dimensions(struct libinput_device *device,
-					  int *width,
-					  int *height,
-					  void *user_data)
-{
-	/* display absdata in % of the screen */
-	*width = 100;
-	*height = 100;
-}
-
 const static struct libinput_interface interface = {
 	.open_restricted = open_restricted,
 	.close_restricted = close_restricted,
-	.get_current_screen_dimensions = get_current_screen_dimensions,
 };
 
 static int
@@ -257,8 +248,10 @@ static void
 print_absmotion_event(struct libinput_event *ev)
 {
 	struct libinput_event_pointer *p = libinput_event_get_pointer_event(ev);
-	li_fixed_t x = libinput_event_pointer_get_absolute_x(p),
-		   y = libinput_event_pointer_get_absolute_y(p);
+	li_fixed_t x = libinput_event_pointer_get_absolute_x_transformed(
+		p, screen_width);
+	li_fixed_t y = libinput_event_pointer_get_absolute_y_transformed(
+		p, screen_height);
 
 	print_event_time(libinput_event_pointer_get_time(p));
 	printf("%6.2f/%6.2f\n",
@@ -318,8 +311,8 @@ static void
 print_touch_event(struct libinput_event *ev)
 {
 	struct libinput_event_touch *t = libinput_event_get_touch_event(ev);
-	li_fixed_t x = libinput_event_touch_get_x(t),
-		   y = libinput_event_touch_get_y(t);
+	li_fixed_t x = libinput_event_touch_get_x_transformed(t, screen_width),
+		   y = libinput_event_touch_get_y_transformed(t, screen_height);
 	const char *type;
 
 	switch (libinput_event_touch_get_touch_type(t)) {