Add configuration option to select scroll mode

Add a configuration option to allow selecting between 2-finger / edge / none
scrolling (for touchpads).

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

3 files changed, 295 insertions, 0 deletions

diff --git a/src/libinput-private.h b/src/libinput-private.h
index 92bd96b8..53101609 100644
--- a/src/libinput-private.h
+++ b/src/libinput-private.h
@@ -132,6 +132,18 @@ struct libinput_device_config_left_handed {
 	int (*get_default)(struct libinput_device *device);
 };
 
+struct libinput_device_config_scroll_mode {
+	uint32_t (*get_modes)(struct libinput_device *device);
+	enum libinput_config_status (*set_mode)(struct libinput_device *device,
+						enum libinput_config_scroll_mode mode);
+	enum libinput_config_scroll_mode (*get_mode)(struct libinput_device *device);
+	enum libinput_config_scroll_mode (*get_default_mode)(struct libinput_device *device);
+	enum libinput_config_status (*set_button)(struct libinput_device *device,
+						  uint32_t button);
+	uint32_t (*get_button)(struct libinput_device *device);
+	uint32_t (*get_default_button)(struct libinput_device *device);
+};
+
 struct libinput_device_config {
 	struct libinput_device_config_tap *tap;
 	struct libinput_device_config_calibration *calibration;
@@ -139,6 +151,7 @@ struct libinput_device_config {
 	struct libinput_device_config_accel *accel;
 	struct libinput_device_config_natural_scroll *natural_scroll;
 	struct libinput_device_config_left_handed *left_handed;
+	struct libinput_device_config_scroll_mode *scroll_mode;
 };
 
 struct libinput_device {
diff --git a/src/libinput.c b/src/libinput.c
index a293f0ff..202c239a 100644
--- a/src/libinput.c
+++ b/src/libinput.c
@@ -1531,3 +1531,88 @@ libinput_device_config_buttons_get_default_left_handed(struct libinput_device *d
 
 	return device->config.left_handed->get_default(device);
 }
+
+LIBINPUT_EXPORT uint32_t
+libinput_device_config_scroll_get_modes(struct libinput_device *device)
+{
+	if (device->config.scroll_mode)
+		return device->config.scroll_mode->get_modes(device);
+	else
+		return 0;
+}
+
+LIBINPUT_EXPORT enum libinput_config_status
+libinput_device_config_scroll_set_mode(struct libinput_device *device,
+				       enum libinput_config_scroll_mode mode)
+{
+	if ((libinput_device_config_scroll_get_modes(device) & mode) != mode)
+		return LIBINPUT_CONFIG_STATUS_UNSUPPORTED;
+
+	/* Check mode is a single valid mode */
+	switch (mode) {
+	case LIBINPUT_CONFIG_SCROLL_NO_SCROLL:
+	case LIBINPUT_CONFIG_SCROLL_2FG:
+	case LIBINPUT_CONFIG_SCROLL_EDGE:
+	case LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN:
+		break;
+	default:
+		return LIBINPUT_CONFIG_STATUS_INVALID;
+	}
+
+	if (device->config.scroll_mode)
+		return device->config.scroll_mode->set_mode(device, mode);
+	else /* mode must be _NO_SCROLL to get here */
+		return LIBINPUT_CONFIG_STATUS_SUCCESS;
+}
+
+LIBINPUT_EXPORT enum libinput_config_scroll_mode
+libinput_device_config_scroll_get_mode(struct libinput_device *device)
+{
+	if (device->config.scroll_mode)
+		return device->config.scroll_mode->get_mode(device);
+	else
+		return LIBINPUT_CONFIG_SCROLL_NO_SCROLL;
+}
+
+LIBINPUT_EXPORT enum libinput_config_scroll_mode
+libinput_device_config_scroll_get_default_mode(struct libinput_device *device)
+{
+	if (device->config.scroll_mode)
+		return device->config.scroll_mode->get_default_mode(device);
+	else
+		return LIBINPUT_CONFIG_SCROLL_NO_SCROLL;
+}
+
+LIBINPUT_EXPORT enum libinput_config_status
+libinput_device_config_scroll_set_button(struct libinput_device *device,
+					 uint32_t button)
+{
+	if ((libinput_device_config_scroll_get_modes(device) &
+	     LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN) == 0)
+		return LIBINPUT_CONFIG_STATUS_UNSUPPORTED;
+
+	if (!libinput_device_has_button(device, button))
+		return LIBINPUT_CONFIG_STATUS_INVALID;
+
+	return device->config.scroll_mode->set_button(device, button);
+}
+
+LIBINPUT_EXPORT uint32_t
+libinput_device_config_scroll_get_button(struct libinput_device *device)
+{
+	if ((libinput_device_config_scroll_get_modes(device) &
+	     LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN) == 0)
+		return 0;
+
+	return device->config.scroll_mode->get_button(device);
+}
+
+LIBINPUT_EXPORT uint32_t
+libinput_device_config_scroll_get_default_button(struct libinput_device *device)
+{
+	if ((libinput_device_config_scroll_get_modes(device) &
+	     LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN) == 0)
+		return 0;
+
+	return device->config.scroll_mode->get_default_button(device);
+}
diff --git a/src/libinput.h b/src/libinput.h
index 8bb37800..1536b97c 100644
--- a/src/libinput.h
+++ b/src/libinput.h
@@ -2041,6 +2041,203 @@ libinput_device_config_buttons_get_left_handed(struct libinput_device *device);
 int
 libinput_device_config_buttons_get_default_left_handed(struct libinput_device *device);
 
+/**
+ * The scroll mode of a device selects when to generate scroll axis events
+ * instead of pointer motion events.
+ */
+enum libinput_config_scroll_mode {
+	/**
+	 * Never send scroll events instead of pointer motion events.
+	 * Note scroll wheels, etc. will still send scroll events.
+	 */
+	LIBINPUT_CONFIG_SCROLL_NO_SCROLL = 0,
+	/**
+	 * Send scroll events when 2 fingers are down on the device.
+	 */
+	LIBINPUT_CONFIG_SCROLL_2FG = (1 << 0),
+	/**
+	 * Send scroll events when a finger is moved along the bottom or
+	 * right edge of a device.
+	 */
+	LIBINPUT_CONFIG_SCROLL_EDGE = (1 << 1),
+	/**
+	 * Send scroll events when a button is down and the device moves
+	 * along a scroll-capable axis.
+	 */
+	LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN = (1 << 2),
+};
+
+/**
+ * @ingroup config
+ *
+ * Check which scroll modes a device supports. The mode defines when to
+ * generate scroll axis events instead of pointer motion events.
+ *
+ * @param device The device to configure
+ *
+ * @return A bitmask of possible modes.
+ *
+ * @see libinput_device_config_scroll_set_mode
+ * @see libinput_device_config_scroll_get_mode
+ * @see libinput_device_config_scroll_get_default_mode
+ * @see libinput_device_config_scroll_set_button
+ * @see libinput_device_config_scroll_get_button
+ * @see libinput_device_config_scroll_get_default_button
+ */
+uint32_t
+libinput_device_config_scroll_get_modes(struct libinput_device *device);
+
+/**
+ * @ingroup config
+ *
+ * Set the scroll mode for this device. The mode defines when to
+ * generate scroll axis events instead of pointer motion events.
+ *
+ * @note Setting @ref LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN enables
+ * the scroll mode, but scrolling is only activated when the configured
+ * button is held down. If no button is set, i.e.
+ * libinput_device_config_scroll_get_button() returns 0, scrolling
+ * cannot activate.
+ *
+ * @param device The device to configure
+ * @param mode The scroll mode for this device.
+ *
+ * @return A config status code.
+ *
+ * @see libinput_device_config_scroll_get_modes
+ * @see libinput_device_config_scroll_get_mode
+ * @see libinput_device_config_scroll_get_default_mode
+ * @see libinput_device_config_scroll_set_button
+ * @see libinput_device_config_scroll_get_button
+ * @see libinput_device_config_scroll_get_default_button
+ */
+enum libinput_config_status
+libinput_device_config_scroll_set_mode(struct libinput_device *device,
+				       enum libinput_config_scroll_mode mode);
+
+/**
+ * @ingroup config
+ *
+ * Get the scroll mode for this device. The mode defines when to
+ * generate scroll axis events instead of pointer motion events.
+ *
+ * @param device The device to configure
+ * @return The current scroll mode for this device.
+ *
+ * @see libinput_device_config_scroll_get_modes
+ * @see libinput_device_config_scroll_set_mode
+ * @see libinput_device_config_scroll_get_default_mode
+ * @see libinput_device_config_scroll_set_button
+ * @see libinput_device_config_scroll_get_button
+ * @see libinput_device_config_scroll_get_default_button
+ */
+enum libinput_config_scroll_mode
+libinput_device_config_scroll_get_mode(struct libinput_device *device);
+
+/**
+ * @ingroup config
+ *
+ * Get the default scroll mode for this device. The mode defines when to
+ * generate scroll axis events instead of pointer motion events.
+ *
+ * @param device The device to configure
+ * @return The default scroll mode for this device.
+ *
+ * @see libinput_device_config_scroll_get_modes
+ * @see libinput_device_config_scroll_set_mode
+ * @see libinput_device_config_scroll_get_mode
+ * @see libinput_device_config_scroll_set_button
+ * @see libinput_device_config_scroll_get_button
+ * @see libinput_device_config_scroll_get_default_button
+ */
+enum libinput_config_scroll_mode
+libinput_device_config_scroll_get_default_mode(struct libinput_device *device);
+
+/**
+ * @ingroup config
+ *
+ * Set the button for the @ref LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN mode
+ * for this device.
+ *
+ * When the current scroll mode is set to @ref
+ * LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN, no button press/release events
+ * will be send for the configured button.
+ *
+ * When the configured button is pressed, any motion events along a
+ * scroll-capable axis are turned into scroll axis events.
+ *
+ * @note Setting the button does not change the scroll mode. To change the
+ * scroll mode call libinput_device_config_scroll_set_mode().
+ *
+ * @param device The device to configure
+ * @param button The button which when pressed switches to sending scroll events
+ *
+ * @return a config status code
+ * @retval LIBINPUT_CONFIG_STATUS_SUCCESS on success
+ * @retval LIBINPUT_CONFIG_STATUS_UNSUPPORTED if @ref LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN is not supported
+ * @retval LIBINPUT_CONFIG_STATUS_INVALID the given button does not
+ * exist on this device
+ *
+ * @see libinput_device_config_scroll_get_modes
+ * @see libinput_device_config_scroll_set_mode
+ * @see libinput_device_config_scroll_get_mode
+ * @see libinput_device_config_scroll_get_default_mode
+ * @see libinput_device_config_scroll_get_button
+ * @see libinput_device_config_scroll_get_default_button
+ */
+enum libinput_config_status
+libinput_device_config_scroll_set_button(struct libinput_device *device,
+					 uint32_t button);
+
+/**
+ * @ingroup config
+ *
+ * Get the button for the @ref LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN mode for
+ * this device.
+ *
+ * If @ref LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN scroll mode is not supported,
+ * or no button is set, this function returns 0.
+ *
+ * @note The return value is independent of the currently selected
+ * scroll-mode. For button scrolling to activate, a device must have the
+ * @ref LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN mode enabled, and a non-zero
+ * button set as scroll button.
+ *
+ * @param device The device to configure
+ * @return The button which when pressed switches to sending scroll events
+ *
+ * @see libinput_device_config_scroll_get_modes
+ * @see libinput_device_config_scroll_set_mode
+ * @see libinput_device_config_scroll_get_mode
+ * @see libinput_device_config_scroll_get_default_mode
+ * @see libinput_device_config_scroll_set_button
+ * @see libinput_device_config_scroll_get_default_button
+ */
+uint32_t
+libinput_device_config_scroll_get_button(struct libinput_device *device);
+
+/**
+ * @ingroup config
+ *
+ * Get the default button for LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN mode
+ * for this device.
+ *
+ * If @ref LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN scroll mode is not supported,
+ * or no default button is set, this function returns 0.
+ *
+ * @param device The device to configure
+ * @return The default button for LIBINPUT_CONFIG_SCROLL_ON_BUTTON_DOWN mode
+ *
+ * @see libinput_device_config_scroll_get_modes
+ * @see libinput_device_config_scroll_set_mode
+ * @see libinput_device_config_scroll_get_mode
+ * @see libinput_device_config_scroll_get_default_mode
+ * @see libinput_device_config_scroll_set_button
+ * @see libinput_device_config_scroll_get_button
+ */
+uint32_t
+libinput_device_config_scroll_get_default_button(struct libinput_device *device);
+
 #ifdef __cplusplus
 }
 #endif