1 /*
2 * Copyright © 2006-2009 Simon Thum
3 * Copyright © 2012 Jonas Ådahl
4 * Copyright © 2014-2015 Red Hat, Inc.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the "Software"),
8 * to deal in the Software without restriction, including without limitation
9 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
10 * and/or sell copies of the Software, and to permit persons to whom the
11 * Software is furnished to do so, subject to the following conditions:
12 *
13 * The above copyright notice and this permission notice (including the next
14 * paragraph) shall be included in all copies or substantial portions of the
15 * Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
22 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
23 * DEALINGS IN THE SOFTWARE.
24 */
25
26 #include "config.h"
27
28 #include <assert.h>
29 #include <stdlib.h>
30 #include <stdint.h>
31 #include <math.h>
32
33 #include "filter.h"
34 #include "libinput-util.h"
35 #include "filter-private.h"
36
37 /* Once normalized, touchpads see the same acceleration as mice. that is
38 * technically correct but subjectively wrong, we expect a touchpad to be a
39 * lot slower than a mouse. Apply a magic factor to slow down all movements
40 */
41 #define TP_MAGIC_SLOWDOWN 0.2968 /* unitless factor */
42
43 struct touchpad_accelerator {
44 struct motion_filter base;
45
46 accel_profile_func_t profile;
47
48 double velocity; /* units/us */
49 double last_velocity; /* units/us */
50
51 struct pointer_trackers trackers;
52
53 double threshold; /* units/us */
54 double accel; /* unitless factor */
55
56 int dpi;
57
58 double speed_factor; /* factor based on speed setting */
59 };
60
61 /**
62 * Calculate the acceleration factor for the given delta with the timestamp.
63 *
64 * @param accel The acceleration filter
65 * @param unaccelerated The raw delta in the device's dpi
66 * @param data Caller-specific data
67 * @param time Current time in µs
68 *
69 * @return A unitless acceleration factor, to be applied to the delta
70 */
71 static inline double
calculate_acceleration_factor(struct touchpad_accelerator * accel,const struct device_float_coords * unaccelerated,void * data,uint64_t time)72 calculate_acceleration_factor(struct touchpad_accelerator *accel,
73 const struct device_float_coords *unaccelerated,
74 void *data,
75 uint64_t time)
76 {
77 double velocity; /* units/us in device-native dpi*/
78 double accel_factor;
79
80 trackers_feed(&accel->trackers, unaccelerated, time);
81 velocity = trackers_velocity(&accel->trackers, time);
82 accel_factor = calculate_acceleration_simpsons(&accel->base,
83 accel->profile,
84 data,
85 velocity,
86 accel->last_velocity,
87 time);
88 accel->last_velocity = velocity;
89
90 return accel_factor;
91 }
92
93 /**
94 * Generic filter that calculates the acceleration factor and applies it to
95 * the coordinates.
96 *
97 * @param filter The acceleration filter
98 * @param unaccelerated The raw delta in the device's dpi
99 * @param data Caller-specific data
100 * @param time Current time in µs
101 *
102 * @return An accelerated tuple of coordinates representing accelerated
103 * motion, still in device units.
104 */
105 static struct device_float_coords
accelerator_filter_generic(struct motion_filter * filter,const struct device_float_coords * unaccelerated,void * data,uint64_t time)106 accelerator_filter_generic(struct motion_filter *filter,
107 const struct device_float_coords *unaccelerated,
108 void *data, uint64_t time)
109 {
110 struct touchpad_accelerator *accel =
111 (struct touchpad_accelerator *) filter;
112 double accel_value; /* unitless factor */
113 struct device_float_coords accelerated;
114
115 accel_value = calculate_acceleration_factor(accel,
116 unaccelerated,
117 data,
118 time);
119
120 accelerated.x = accel_value * unaccelerated->x;
121 accelerated.y = accel_value * unaccelerated->y;
122
123 return accelerated;
124 }
125
126 static struct normalized_coords
accelerator_filter_post_normalized(struct motion_filter * filter,const struct device_float_coords * unaccelerated,void * data,uint64_t time)127 accelerator_filter_post_normalized(struct motion_filter *filter,
128 const struct device_float_coords *unaccelerated,
129 void *data, uint64_t time)
130 {
131 struct touchpad_accelerator *accel =
132 (struct touchpad_accelerator *) filter;
133 struct device_float_coords accelerated;
134
135 /* Accelerate for device units, normalize afterwards */
136 accelerated = accelerator_filter_generic(filter,
137 unaccelerated,
138 data,
139 time);
140 return normalize_for_dpi(&accelerated, accel->dpi);
141 }
142
143 /* Maps the [-1, 1] speed setting into a constant acceleration
144 * range. This isn't a linear scale, we keep 0 as the 'optimized'
145 * mid-point and scale down to 0 for setting -1 and up to 5 for
146 * setting 1. On the premise that if you want a faster cursor, it
147 * doesn't matter as much whether you have 0.56789 or 0.56790,
148 * but for lower settings it does because you may lose movements.
149 * *shrug*.
150 *
151 * Magic numbers calculated by MyCurveFit.com, data points were
152 * 0.0 0.0
153 * 0.1 0.1 (because we need 4 points)
154 * 1 1
155 * 2 5
156 *
157 * This curve fits nicely into the range necessary.
158 */
159 static inline double
speed_factor(double s)160 speed_factor(double s)
161 {
162 s += 1; /* map to [0, 2] */
163 return 435837.2 + (0.04762636 - 435837.2)/(1 + pow(s/240.4549,
164 2.377168));
165 }
166
167 static bool
touchpad_accelerator_set_speed(struct motion_filter * filter,double speed_adjustment)168 touchpad_accelerator_set_speed(struct motion_filter *filter,
169 double speed_adjustment)
170 {
171 struct touchpad_accelerator *accel_filter =
172 (struct touchpad_accelerator *)filter;
173
174 assert(speed_adjustment >= -1.0 && speed_adjustment <= 1.0);
175
176 filter->speed_adjustment = speed_adjustment;
177 accel_filter->speed_factor = speed_factor(speed_adjustment);
178
179 return true;
180 }
181
182 static struct normalized_coords
touchpad_constant_filter(struct motion_filter * filter,const struct device_float_coords * unaccelerated,void * data,uint64_t time)183 touchpad_constant_filter(struct motion_filter *filter,
184 const struct device_float_coords *unaccelerated,
185 void *data, uint64_t time)
186 {
187 struct touchpad_accelerator *accel =
188 (struct touchpad_accelerator *)filter;
189 struct normalized_coords normalized;
190 /* We need to use the same baseline here as the accelerated code,
191 * otherwise our unaccelerated speed is different to the accelerated
192 * speed on the plateau.
193 *
194 * This is a hack, the baseline should be incorporated into the
195 * TP_MAGIC_SLOWDOWN so we only have one number here but meanwhile
196 * this will do.
197 */
198 const double baseline = 0.9;
199
200 normalized = normalize_for_dpi(unaccelerated, accel->dpi);
201 normalized.x = baseline * TP_MAGIC_SLOWDOWN * normalized.x;
202 normalized.y = baseline * TP_MAGIC_SLOWDOWN * normalized.y;
203
204 return normalized;
205 }
206
207 static void
touchpad_accelerator_restart(struct motion_filter * filter,void * data,uint64_t time)208 touchpad_accelerator_restart(struct motion_filter *filter,
209 void *data,
210 uint64_t time)
211 {
212 struct touchpad_accelerator *accel =
213 (struct touchpad_accelerator *) filter;
214
215 trackers_reset(&accel->trackers, time);
216 }
217
218 static void
touchpad_accelerator_destroy(struct motion_filter * filter)219 touchpad_accelerator_destroy(struct motion_filter *filter)
220 {
221 struct touchpad_accelerator *accel =
222 (struct touchpad_accelerator *) filter;
223
224 trackers_free(&accel->trackers);
225 free(accel);
226 }
227
228 double
touchpad_accel_profile_linear(struct motion_filter * filter,void * data,double speed_in,uint64_t time)229 touchpad_accel_profile_linear(struct motion_filter *filter,
230 void *data,
231 double speed_in, /* in device units/µs */
232 uint64_t time)
233 {
234 struct touchpad_accelerator *accel_filter =
235 (struct touchpad_accelerator *)filter;
236 const double threshold = accel_filter->threshold; /* units/us */
237 const double baseline = 0.9;
238 double factor; /* unitless */
239
240 /* Convert to mm/s because that's something one can understand */
241 speed_in = v_us2s(speed_in) * 25.4/accel_filter->dpi;
242
243 /*
244 Our acceleration function calculates a factor to accelerate input
245 deltas with. The function is a double incline with a plateau,
246 with a rough shape like this:
247
248 accel
249 factor
250 ^ ______
251 | )
252 | _____)
253 | /
254 |/
255 +-------------> speed in
256
257 Except the second incline is a curve, but well, asciiart.
258
259 The first incline is a linear function in the form
260 y = ax + b
261 where y is speed_out
262 x is speed_in
263 a is the incline of acceleration
264 b is minimum acceleration factor
265 for speeds up to the lower threshold, we decelerate, down to 30%
266 of input speed.
267 hence 1 = a * 7 + 0.3
268 0.7 = a * 7 => a := 0.1
269 deceleration function is thus:
270 y = 0.1x + 0.3
271
272 The first plateau is the baseline.
273
274 The second incline is a curve up, based on magic numbers
275 obtained by trial-and-error.
276
277 Above the second incline we have another plateau because
278 by then you're moving so fast that extra acceleration doesn't
279 help.
280
281 Note:
282 * The minimum threshold is a result of trial-and-error and
283 has no other special meaning.
284 * 0.3 is chosen simply because it is above the Nyquist frequency
285 for subpixel motion within a pixel.
286 */
287
288 if (speed_in < 7.0) {
289 factor = min(baseline, 0.1 * speed_in + 0.3);
290 /* up to the threshold, we keep factor 1, i.e. 1:1 movement */
291 } else if (speed_in < threshold) {
292 factor = baseline;
293 } else {
294
295 /* Acceleration function above the threshold is a curve up
296 to four times the threshold, because why not.
297
298 Don't assume anything about the specific numbers though, this was
299 all just trial and error by tweaking numbers here and there, then
300 the formula was optimized doing basic maths.
301
302 You could replace this with some other random formula that gives
303 the same numbers and it would be just as correct.
304
305 */
306 const double upper_threshold = threshold * 4.0;
307 speed_in = min(speed_in, upper_threshold);
308
309 factor = 0.0025 * (speed_in/threshold) * (speed_in - threshold) + baseline;
310 }
311
312 factor *= accel_filter->speed_factor;
313 return factor * TP_MAGIC_SLOWDOWN;
314 }
315
316 struct motion_filter_interface accelerator_interface_touchpad = {
317 .type = LIBINPUT_CONFIG_ACCEL_PROFILE_ADAPTIVE,
318 .filter = accelerator_filter_post_normalized,
319 .filter_constant = touchpad_constant_filter,
320 .restart = touchpad_accelerator_restart,
321 .destroy = touchpad_accelerator_destroy,
322 .set_speed = touchpad_accelerator_set_speed,
323 };
324
325 struct motion_filter *
create_pointer_accelerator_filter_touchpad(int dpi,uint64_t event_delta_smooth_threshold,uint64_t event_delta_smooth_value,bool use_velocity_averaging)326 create_pointer_accelerator_filter_touchpad(int dpi,
327 uint64_t event_delta_smooth_threshold,
328 uint64_t event_delta_smooth_value,
329 bool use_velocity_averaging)
330 {
331 struct touchpad_accelerator *filter;
332 struct pointer_delta_smoothener *smoothener;
333
334 filter = zalloc(sizeof *filter);
335 filter->last_velocity = 0.0;
336
337 trackers_init(&filter->trackers, use_velocity_averaging ? 16 : 2);
338
339 filter->threshold = 130;
340 filter->dpi = dpi;
341
342 filter->base.interface = &accelerator_interface_touchpad;
343 filter->profile = touchpad_accel_profile_linear;
344
345 smoothener = zalloc(sizeof(*smoothener));
346 smoothener->threshold = event_delta_smooth_threshold,
347 smoothener->value = event_delta_smooth_value,
348 filter->trackers.smoothener = smoothener;
349
350 return &filter->base;
351 }
352