[PATCH libinput 07/10] Add a basic pointer acceleration API

[Peter Hutterer]

Only exposes two knobs - speed and precision which have historically been the
only two knobs exposed anyway on most UIs. We could go for something fancier
but really, I think this will be enough.

The only open question is whether speed will be enough for high-dpi devices.

Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
---
 src/libinput-private.h | 12 ++++++++
 src/libinput.c         | 53 +++++++++++++++++++++++++++++++++
 src/libinput.h         | 80 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 145 insertions(+)

diff --git a/src/libinput-private.h b/src/libinput-private.h
index 0d2a1b1..85113bd 100644
--- a/src/libinput-private.h
+++ b/src/libinput-private.h
@@ -93,10 +93,22 @@ struct libinput_device_config_rotation {
 	void (*reset)(struct libinput_device *device);
 };
 
+struct libinput_device_config_accel {
+	int (*available)(struct libinput_device *device);
+	enum libinput_config_status (*set_speed)(struct libinput_device *device,
+						 unsigned int speed);
+	enum libinput_config_status (*set_precision)(struct libinput_device *device,
+						     unsigned int precision);
+	int (*get_speed)(struct libinput_device *device);
+	int (*get_precision)(struct libinput_device *device);
+	void (*reset)(struct libinput_device *device);
+};
+
 struct libinput_device_config {
 	struct libinput_device_config_tap *tap;
 	struct libinput_device_config_scroll *scroll;
 	struct libinput_device_config_rotation *rotation;
+	struct libinput_device_config_accel *accel;
 };
 
 struct libinput_device {
diff --git a/src/libinput.c b/src/libinput.c
index 2572f5b..5a068f1 100644
--- a/src/libinput.c
+++ b/src/libinput.c
@@ -1283,3 +1283,56 @@ libinput_device_config_rotation_reset(struct libinput_device *device)
 	if (libinput_device_config_rotation_get_increment(device) != 0)
 		device->config.rotation->reset(device);
 }
+
+
+LIBINPUT_EXPORT int
+libinput_device_config_accel_is_available(struct libinput_device *device)
+{
+	return device->config.accel ?
+		device->config.accel->available(device) : 0;
+}
+
+LIBINPUT_EXPORT enum libinput_config_status
+libinput_device_config_accel_set_speed(struct libinput_device *device,
+				       unsigned int speed)
+{
+	if (!libinput_device_config_accel_is_available(device))
+		return LIBINPUT_CONFIG_STATUS_UNSUPPORTED;
+
+	return device->config.accel->set_speed(device, speed);
+}
+
+LIBINPUT_EXPORT enum libinput_config_status
+libinput_device_config_accel_set_precision(struct libinput_device *device,
+					   unsigned int precision)
+{
+	if (!libinput_device_config_accel_is_available(device))
+		return LIBINPUT_CONFIG_STATUS_UNSUPPORTED;
+
+	return device->config.accel->set_precision(device, precision);
+}
+
+LIBINPUT_EXPORT unsigned int
+libinput_device_config_accel_get_speed(struct libinput_device *device)
+{
+	if (!libinput_device_config_accel_is_available(device))
+		return 0;
+
+	return device->config.accel->get_speed(device);
+}
+
+LIBINPUT_EXPORT unsigned int
+libinput_device_config_accel_get_precision(struct libinput_device *device)
+{
+	if (!libinput_device_config_accel_is_available(device))
+		return 0;
+
+	return device->config.accel->get_precision(device);
+}
+
+LIBINPUT_EXPORT void
+libinput_device_config_accel_reset(struct libinput_device *device)
+{
+	if (device->config.accel)
+		device->config.accel->reset(device);
+}
diff --git a/src/libinput.h b/src/libinput.h
index 328d050..1b6207c 100644
--- a/src/libinput.h
+++ b/src/libinput.h
@@ -1577,6 +1577,86 @@ libinput_device_config_rotation_get(struct libinput_device *device);
 void
 libinput_device_config_rotation_reset(struct libinput_device *device);
 
+/**
+ * @ingroup config
+ *
+ * Check if a device uses libinput-internal pointer-acceleration.
+ *
+ * @param device The device to configure
+ *
+ * @return 0 if the device is not accelerated, nonzero if it is accelerated
+ */
+int
+libinput_device_config_accel_is_available(struct libinput_device *device);
+
+/**
+ * @ingroup config
+ *
+ * Set the speed of this pointer device, where 0% is the minimum pointer
+ * acceleration to be applied (none or slowed down, depending on the device)
+ * and 100% is the maximum amount of acceleration to be applied.
+ *
+ * @param device The device to configure
+ * @param speed The abstract speed identifier, ranged 0% to 100%.
+ *
+ * @return A config status code
+ */
+enum libinput_config_status
+libinput_device_config_accel_set_speed(struct libinput_device *device,
+				       unsigned int speed);
+
+/**
+ * @ingroup config
+ *
+ * Set the precision or sensibility of this pointer device. This affects the
+ * movement of the pointer when moving relatively slowly towards a target.
+ * The range is an abstract range,  0% is the minimum pointer precision and
+ * 100% is the maximum precision).
+ *
+ * @param device The device to configure
+ * @param precision The abstract precision identifier, range 0% to 100%.
+ *
+ * @return A config status code
+ */
+enum libinput_config_status
+libinput_device_config_accel_set_precision(struct libinput_device *device,
+					   unsigned int precision);
+
+/**
+ * @ingroup config
+ *
+ * Get the current speed setting for this pointer device.
+ *
+ * @param device The device to configure
+ *
+ * @return The current speed, range 0% to 100%.
+ */
+unsigned int
+libinput_device_config_accel_get_speed(struct libinput_device *device);
+
+/**
+ * @ingroup config
+ *
+ * Get the current precision setting for this pointer device.
+ *
+ * @param device The device to configure
+ *
+ * @return The current precision, range 0% to 100%.
+ */
+unsigned int
+libinput_device_config_accel_get_precision(struct libinput_device *device);
+
+/**
+ * @ingroup config
+ *
+ * Reset the acceleration to the device's default setting. If the device
+ * does not support acceleration, this function does nothing.
+ *
+ * @param device The device to configure
+ */
+void
+libinput_device_config_accel_reset(struct libinput_device *device);
+
 #ifdef __cplusplus
 }
 #endif
-- 
1.9.0