aboutsummaryrefslogtreecommitdiff
path: root/xorg-server/dix/ptrveloc.c
blob: 684f2a8518282fde055e3f36ec527ba9bbf52bdd (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
/*
 *
 * Copyright © 2006-2009 Simon Thum             simon dot thum at gmx dot de
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 */

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#ifdef _MSC_VER
#define _USE_MATH_DEFINES
#endif

#include <math.h>
#include <ptrveloc.h>
#include <exevents.h>
#include <X11/Xatom.h>

#include <xserver-properties.h>


/*****************************************************************************
 * Predictable pointer acceleration
 *
 * 2006-2009 by Simon Thum (simon [dot] thum [at] gmx de)
 *
 * Serves 3 complementary functions:
 * 1) provide a sophisticated ballistic velocity estimate to improve
 *    the relation between velocity (of the device) and acceleration
 * 2) make arbitrary acceleration profiles possible
 * 3) decelerate by two means (constant and adaptive) if enabled
 *
 * Important concepts are the
 *
 * - Scheme
 *      which selects the basic algorithm
 *      (see devices.c/InitPointerAccelerationScheme)
 * - Profile
 *      which returns an acceleration
 *      for a given velocity
 *
 *  The profile can be selected by the user at runtime.
 *  The classic profile is intended to cleanly perform old-style
 *  function selection (threshold =/!= 0)
 *
 ****************************************************************************/

#ifdef _MSC_VER
#define inline __inline
#define lrintf(val) ((int)val)
#endif

/* fwds */
int
SetAccelerationProfile(DeviceVelocityPtr vel, int profile_num);
static float
SimpleSmoothProfile(DeviceIntPtr dev, DeviceVelocityPtr vel, float velocity,
                    float threshold, float acc);
static PointerAccelerationProfileFunc
GetAccelerationProfile(DeviceVelocityPtr vel, int profile_num);

/*#define PTRACCEL_DEBUGGING*/

#ifdef PTRACCEL_DEBUGGING
#define DebugAccelF ErrorF
#else
#define DebugAccelF(...) /* */
#endif

/********************************
 *  Init/Uninit
 *******************************/

/* some int which is not a profile number */
#define PROFILE_UNINITIALIZE (-100)

/**
 * Init struct so it should match the average case
 */
void
InitVelocityData(DeviceVelocityPtr vel)
{
    memset(vel, 0, sizeof(DeviceVelocityRec));

    vel->corr_mul = 10.0;      /* dots per 10 milisecond should be usable */
    vel->const_acceleration = 1.0;   /* no acceleration/deceleration  */
    vel->reset_time = 300;
    vel->use_softening = 1;
    vel->min_acceleration = 1.0; /* don't decelerate */
    vel->max_rel_diff = 0.2;
    vel->max_diff = 1.0;
    vel->initial_range = 2;
    vel->average_accel = TRUE;
    SetAccelerationProfile(vel, AccelProfileClassic);
    InitTrackers(vel, 16);
}


/**
 * Clean up
 */
void
FreeVelocityData(DeviceVelocityPtr vel){
    xfree(vel->tracker);
    SetAccelerationProfile(vel, PROFILE_UNINITIALIZE);
}


/*
 *  dix uninit helper, called through scheme
 */
void
AccelerationDefaultCleanup(DeviceIntPtr dev)
{
    /*sanity check*/
    if( dev->valuator->accelScheme.AccelSchemeProc == acceleratePointerPredictable
            && dev->valuator->accelScheme.accelData != NULL){
        dev->valuator->accelScheme.AccelSchemeProc = NULL;
        FreeVelocityData(dev->valuator->accelScheme.accelData);
        xfree(dev->valuator->accelScheme.accelData);
        dev->valuator->accelScheme.accelData = NULL;
    }
}


/*************************
 * Input property support
 ************************/

/**
 * choose profile
 */
static int
AccelSetProfileProperty(DeviceIntPtr dev, Atom atom,
                        XIPropertyValuePtr val, BOOL checkOnly)
{
    DeviceVelocityPtr vel;
    int profile, *ptr = &profile;
    int rc;
    int nelem = 1;

    if (atom != XIGetKnownProperty(ACCEL_PROP_PROFILE_NUMBER))
        return Success;

    vel = GetDevicePredictableAccelData(dev);
    if (!vel)
        return BadValue;
    rc = XIPropToInt(val, &nelem, &ptr);

    if(checkOnly)
    {
        if (rc)
            return rc;

        if (GetAccelerationProfile(vel, profile) == NULL)
            return BadValue;
    } else
	SetAccelerationProfile(vel, profile);

    return Success;
}

static void
AccelInitProfileProperty(DeviceIntPtr dev, DeviceVelocityPtr vel)
{
    int profile = vel->statistics.profile_number;
    Atom prop_profile_number = XIGetKnownProperty(ACCEL_PROP_PROFILE_NUMBER);

    XIChangeDeviceProperty(dev, prop_profile_number, XA_INTEGER, 32,
                           PropModeReplace, 1, &profile, FALSE);
    XISetDevicePropertyDeletable(dev, prop_profile_number, FALSE);
    XIRegisterPropertyHandler(dev, AccelSetProfileProperty, NULL, NULL);
}

/**
 * constant deceleration
 */
static int
AccelSetDecelProperty(DeviceIntPtr dev, Atom atom,
                      XIPropertyValuePtr val, BOOL checkOnly)
{
    DeviceVelocityPtr vel;
    float v, *ptr = &v;
    int rc;
    int nelem = 1;

    if (atom != XIGetKnownProperty(ACCEL_PROP_CONSTANT_DECELERATION))
        return Success;

    vel = GetDevicePredictableAccelData(dev);
    if (!vel)
        return BadValue;
    rc = XIPropToFloat(val, &nelem, &ptr);

    if(checkOnly)
    {
        if (rc)
            return rc;
	return (v >= 1.0f) ? Success : BadValue;
    }

    if(v >= 1.0f)
	vel->const_acceleration = 1/v;

    return Success;
}

static void
AccelInitDecelProperty(DeviceIntPtr dev, DeviceVelocityPtr vel)
{
    float fval = 1.0/vel->const_acceleration;
    Atom prop_const_decel = XIGetKnownProperty(ACCEL_PROP_CONSTANT_DECELERATION);
    XIChangeDeviceProperty(dev, prop_const_decel,
                           XIGetKnownProperty(XATOM_FLOAT), 32,
                           PropModeReplace, 1, &fval, FALSE);
    XISetDevicePropertyDeletable(dev, prop_const_decel, FALSE);
    XIRegisterPropertyHandler(dev, AccelSetDecelProperty, NULL, NULL);
}


/**
 * adaptive deceleration
 */
static int
AccelSetAdaptDecelProperty(DeviceIntPtr dev, Atom atom,
                           XIPropertyValuePtr val, BOOL checkOnly)
{
    DeviceVelocityPtr veloc;
    float v, *ptr = &v;
    int rc;
    int nelem = 1;

    if (atom != XIGetKnownProperty(ACCEL_PROP_ADAPTIVE_DECELERATION))
        return Success;

    veloc = GetDevicePredictableAccelData(dev);
    if (!veloc)
        return BadValue;
    rc = XIPropToFloat(val, &nelem, &ptr);

    if(checkOnly)
    {
        if (rc)
            return rc;
	return (v >= 1.0f) ? Success : BadValue;
    }

    if(v >= 1.0f)
	veloc->min_acceleration = 1/v;

    return Success;
}

static void
AccelInitAdaptDecelProperty(DeviceIntPtr dev, DeviceVelocityPtr vel)
{
    float fval = 1.0/vel->min_acceleration;
    Atom prop_adapt_decel = XIGetKnownProperty(ACCEL_PROP_ADAPTIVE_DECELERATION);

    XIChangeDeviceProperty(dev, prop_adapt_decel, XIGetKnownProperty(XATOM_FLOAT), 32,
                           PropModeReplace, 1, &fval, FALSE);
    XISetDevicePropertyDeletable(dev, prop_adapt_decel, FALSE);
    XIRegisterPropertyHandler(dev, AccelSetAdaptDecelProperty, NULL, NULL);
}


/**
 * velocity scaling
 */
static int
AccelSetScaleProperty(DeviceIntPtr dev, Atom atom,
                      XIPropertyValuePtr val, BOOL checkOnly)
{
    DeviceVelocityPtr vel;
    float v, *ptr = &v;
    int rc;
    int nelem = 1;

    if (atom != XIGetKnownProperty(ACCEL_PROP_VELOCITY_SCALING))
        return Success;

    vel = GetDevicePredictableAccelData(dev);
    if (!vel)
        return BadValue;
    rc = XIPropToFloat(val, &nelem, &ptr);

    if (checkOnly)
    {
        if (rc)
            return rc;

        return (v > 0) ? Success : BadValue;
    }

    if(v > 0)
	vel->corr_mul = v;

    return Success;
}

static void
AccelInitScaleProperty(DeviceIntPtr dev, DeviceVelocityPtr vel)
{
    float fval = vel->corr_mul;
    Atom prop_velo_scale = XIGetKnownProperty(ACCEL_PROP_VELOCITY_SCALING);

    XIChangeDeviceProperty(dev, prop_velo_scale, XIGetKnownProperty(XATOM_FLOAT), 32,
                           PropModeReplace, 1, &fval, FALSE);
    XISetDevicePropertyDeletable(dev, prop_velo_scale, FALSE);
    XIRegisterPropertyHandler(dev, AccelSetScaleProperty, NULL, NULL);
}

BOOL
InitializePredictableAccelerationProperties(DeviceIntPtr dev)
{
    DeviceVelocityPtr  vel = GetDevicePredictableAccelData(dev);

    if(!vel)
	return FALSE;

    AccelInitProfileProperty(dev, vel);
    AccelInitDecelProperty(dev, vel);
    AccelInitAdaptDecelProperty(dev, vel);
    AccelInitScaleProperty(dev, vel);
    return TRUE;
}

/*********************
 * Tracking logic
 ********************/

void
InitTrackers(DeviceVelocityPtr vel, int ntracker)
{
    if(ntracker < 1){
	ErrorF("(dix ptracc) invalid number of trackers\n");
	return;
    }
    xfree(vel->tracker);
    vel->tracker = (MotionTrackerPtr)xalloc(ntracker * sizeof(MotionTracker));
    memset(vel->tracker, 0, ntracker * sizeof(MotionTracker));
    vel->num_tracker = ntracker;
}

/**
 * return a bit field of possible directions.
 * 0 = N, 2 = E, 4 = S, 6 = W, in-between is as you guess.
 * There's no reason against widening to more precise directions (<45 degrees),
 * should it not perform well. All this is needed for is sort out non-linear
 * motion, so precision isn't paramount. However, one should not flag direction
 * too narrow, since it would then cut the linear segment to zero size way too
 * often.
 */
static int
DoGetDirection(int dx, int dy){
    float r;
    int i1, i2;
    /* on insignificant mickeys, flag 135 degrees */
    if(abs(dx) < 2 && abs(dy < 2)){
	/* first check diagonal cases */
	if(dx > 0 && dy > 0)
	    return 4+8+16;
	if(dx > 0 && dy < 0)
	    return 1+2+4;
	if(dx < 0 && dy < 0)
	    return 1+128+64;
	if(dx < 0 && dy > 0)
	    return 16+32+64;
        /* check axis-aligned directions */
	if(dx > 0)
            return 2+4+8; /*E*/
        if(dx < 0)
            return 128+64+32; /*W*/
        if(dy > 0)
            return 32+16+8; /*S*/
        if(dy < 0)
            return 128+1+2; /*N*/
        return 255; /* shouldn't happen */
    }
    /* else, compute angle and set appropriate flags */
#ifdef _ISOC99_SOURCE
    r = atan2f(dy, dx);
#else
    r = atan2(dy, dx);
#endif
    /* find direction. We avoid r to become negative,
     * since C has no well-defined modulo for such cases. */
    r = (r+(M_PI*2.5))/(M_PI/4);
    /* this intends to flag 2 directions (90 degrees),
     * except on very well-aligned mickeys. */
    i1 = (int)(r+0.1) % 8;
    i2 = (int)(r+0.9) % 8;
    if(i1 < 0 || i1 > 7 || i2 < 0 || i2 > 7)
	return 255; /* shouldn't happen */
    return 1 << i1 | 1 << i2;
}

#define DIRECTION_CACHE_RANGE 5
#define DIRECTION_CACHE_SIZE (DIRECTION_CACHE_RANGE*2+1)

/* cache DoGetDirection(). */
static int
GetDirection(int dx, int dy){
    static int cache[DIRECTION_CACHE_SIZE][DIRECTION_CACHE_SIZE];
    int i;
    if (abs(dx) <= DIRECTION_CACHE_RANGE &&
	abs(dy) <= DIRECTION_CACHE_RANGE) {
	/* cacheable */
	i = cache[DIRECTION_CACHE_RANGE+dx][DIRECTION_CACHE_RANGE+dy];
	if(i != 0){
	    return i;
	}else{
	    i = DoGetDirection(dx, dy);
	    cache[DIRECTION_CACHE_RANGE+dx][DIRECTION_CACHE_RANGE+dy] = i;
	    return i;
	}
    }else{
	/* non-cacheable */
	return DoGetDirection(dx, dy);
    }
}

#undef DIRECTION_CACHE_RANGE
#undef DIRECTION_CACHE_SIZE


/* convert offset (age) to array index */
#define TRACKER_INDEX(s, d) (((s)->num_tracker + (s)->cur_tracker - (d)) % (s)->num_tracker)

static inline void
FeedTrackers(DeviceVelocityPtr vel, int dx, int dy, int cur_t)
{
    int n;
    for(n = 0; n < vel->num_tracker; n++){
	vel->tracker[n].dx += dx;
	vel->tracker[n].dy += dy;
    }
    n = (vel->cur_tracker + 1) % vel->num_tracker;
    vel->tracker[n].dx = 0;
    vel->tracker[n].dy = 0;
    vel->tracker[n].time = cur_t;
    vel->tracker[n].dir = GetDirection(dx, dy);
    DebugAccelF("(dix prtacc) motion [dx: %i dy: %i dir:%i diff: %i]\n",
                dx, dy, vel->tracker[n].dir,
                cur_t - vel->tracker[vel->cur_tracker].time);
    vel->cur_tracker = n;
}

/**
 * calc velocity for given tracker, with
 * velocity scaling.
 * This assumes linear motion.
 */
static float
CalcTracker(DeviceVelocityPtr vel, int offset, int cur_t){
    int index = TRACKER_INDEX(vel, offset);
    float dist = sqrt(  vel->tracker[index].dx * vel->tracker[index].dx
                      + vel->tracker[index].dy * vel->tracker[index].dy);
    int dtime = cur_t - vel->tracker[index].time;
    if(dtime > 0)
	return (dist / dtime);
    else
	return 0;/* synonymous for NaN, since we're not C99 */
}

/* find the most plausible velocity. That is, the most distant
 * (in time) tracker which isn't too old, beyond a linear partition,
 * or simply too much off initial velocity.
 *
 * May return 0.
 */
static float
QueryTrackers(DeviceVelocityPtr vel, int cur_t){
    int n, offset, dir = 255, i = -1, age_ms;
    /* initial velocity: a low-offset, valid velocity */
    float iveloc = 0, res = 0, tmp, vdiff;
    float vfac =  vel->corr_mul * vel->const_acceleration; /* premultiply */
    /* loop from current to older data */
    for(offset = 1; offset < vel->num_tracker; offset++){
	n = TRACKER_INDEX(vel, offset);

	age_ms = cur_t - vel->tracker[n].time;

	/* bail out if data is too old and protect from overrun */
	if (age_ms >= vel->reset_time || age_ms < 0) {
	    DebugAccelF("(dix prtacc) query: tracker too old\n");
	    break;
	}

	/*
	 * this heuristic avoids using the linear-motion velocity formula
	 * in CalcTracker() on motion that isn't exactly linear. So to get
	 * even more precision we could subdivide as a final step, so possible
	 * non-linearities are accounted for.
	 */
	dir &= vel->tracker[n].dir;
	if(dir == 0){
	    DebugAccelF("(dix prtacc) query: no longer linear\n");
	    /* instead of breaking it we might also inspect the partition after,
	     * but actual improvement with this is probably rare. */
	    break;
	}

	tmp = CalcTracker(vel, offset, cur_t) * vfac;

	if ((iveloc == 0 || offset <= vel->initial_range) && tmp != 0) {
	    /* set initial velocity and result */
	    res = iveloc = tmp;
	    i = offset;
	} else if (iveloc != 0 && tmp != 0) {
	    vdiff = fabs(iveloc - tmp);
	    if (vdiff <= vel->max_diff ||
		vdiff/(iveloc + tmp) < vel->max_rel_diff) {
		/* we're in range with the initial velocity,
		 * so this result is likely better
		 * (it contains more information). */
		res = tmp;
		i = offset;
	    }else{
		/* we're not in range, quit - it won't get better. */
		DebugAccelF("(dix prtacc) query: tracker too different:"
		            " old %2.2f initial %2.2f diff: %2.2f\n",
		            tmp, iveloc, vdiff);
		break;
	    }
	}
    }
    if(offset == vel->num_tracker){
	DebugAccelF("(dix prtacc) query: last tracker in effect\n");
	i = vel->num_tracker-1;
    }
    if(i>=0){
        n = TRACKER_INDEX(vel, i);
	DebugAccelF("(dix prtacc) result: offset %i [dx: %i dy: %i diff: %i]\n",
	            i,
	            vel->tracker[n].dx,
	            vel->tracker[n].dy,
	            cur_t - vel->tracker[n].time);
    }
    return res;
}

#undef TRACKER_INDEX

/**
 * Perform velocity approximation based on 2D 'mickeys' (mouse motion delta).
 * return true if non-visible state reset is suggested
 */
short
ProcessVelocityData2D(
    DeviceVelocityPtr vel,
    int dx,
    int dy,
    int time)
{
    float velocity;

    vel->last_velocity = vel->velocity;

    FeedTrackers(vel, dx, dy, time);

    velocity = QueryTrackers(vel, time);

    vel->velocity = velocity;
    return velocity == 0;
}

/**
 * this flattens significant ( > 1) mickeys a little bit for more steady
 * constant-velocity response
 */
static inline float
ApplySimpleSoftening(int od, int d)
{
    float res = d;
    if (d <= 1 && d >= -1)
        return res;
    if (d > od)
        res -= 0.5;
    else if (d < od)
        res += 0.5;
    return res;
}


static void
ApplySofteningAndConstantDeceleration(
        DeviceVelocityPtr vel,
        int dx,
        int dy,
        float* fdx,
        float* fdy,
        short do_soften)
{
    if (do_soften && vel->use_softening) {
        *fdx = ApplySimpleSoftening(vel->last_dx, dx);
        *fdy = ApplySimpleSoftening(vel->last_dy, dy);
    } else {
        *fdx = dx;
        *fdy = dy;
    }

    *fdx *= vel->const_acceleration;
    *fdy *= vel->const_acceleration;
}

/*
 * compute the acceleration for given velocity and enforce min_acceleartion
 */
float
BasicComputeAcceleration(
    DeviceIntPtr dev,
    DeviceVelocityPtr vel,
    float velocity,
    float threshold,
    float acc){

    float result;
    result = vel->Profile(dev, vel, velocity, threshold, acc);

    /* enforce min_acceleration */
    if (result < vel->min_acceleration)
	result = vel->min_acceleration;
    return result;
}

/**
 * Compute acceleration. Takes into account averaging, nv-reset, etc.
 */
static float
ComputeAcceleration(
    DeviceIntPtr dev,
    DeviceVelocityPtr vel,
    float threshold,
    float acc){
    float res;

    if(vel->velocity <= 0){
	DebugAccelF("(dix ptracc) profile skipped\n");
        /*
         * If we have no idea about device velocity, don't pretend it.
         */
	return 1;
    }

    if(vel->average_accel && vel->velocity != vel->last_velocity){
	/* use simpson's rule to average acceleration between
	 * current and previous velocity.
	 * Though being the more natural choice, it causes a minor delay
	 * in comparison, so it can be disabled. */
	res = BasicComputeAcceleration(
	          dev, vel, vel->velocity, threshold, acc);
	res += BasicComputeAcceleration(
	          dev, vel, vel->last_velocity, threshold, acc);
	res += 4.0f * BasicComputeAcceleration(dev, vel,
	                   (vel->last_velocity + vel->velocity) / 2,
	                   threshold, acc);
	res /= 6.0f;
	DebugAccelF("(dix ptracc) profile average [%.2f ... %.2f] is %.3f\n",
	            vel->velocity, vel->last_velocity, res);
        return res;
    }else{
	res = BasicComputeAcceleration(dev, vel,
	                               vel->velocity, threshold, acc);
	DebugAccelF("(dix ptracc) profile sample [%.2f] is %.3f\n",
               vel->velocity, res);
	return res;
    }
}


/*****************************************
 *  Acceleration functions and profiles
 ****************************************/

/**
 * Polynomial function similar previous one, but with f(1) = 1
 */
static float
PolynomialAccelerationProfile(
    DeviceIntPtr dev,
    DeviceVelocityPtr vel,
    float velocity,
    float ignored,
    float acc)
{
   return pow(velocity, (acc - 1.0) * 0.5);
}


/**
 * returns acceleration for velocity.
 * This profile selects the two functions like the old scheme did
 */
static float
ClassicProfile(
    DeviceIntPtr dev,
    DeviceVelocityPtr vel,
    float velocity,
    float threshold,
    float acc)
{
    if (threshold > 0) {
	return SimpleSmoothProfile (dev,
	                            vel,
	                            velocity,
                                    threshold,
                                    acc);
    } else {
	return PolynomialAccelerationProfile (dev,
	                                      vel,
	                                      velocity,
                                              0,
                                              acc);
    }
}


/**
 * Power profile
 * This has a completely smooth transition curve, i.e. no jumps in the
 * derivatives.
 *
 * This has the expense of overall response dependency on min-acceleration.
 * In effect, min_acceleration mimics const_acceleration in this profile.
 */
static float
PowerProfile(
    DeviceIntPtr dev,
    DeviceVelocityPtr vel,
    float velocity,
    float threshold,
    float acc)
{
    float vel_dist;

    acc = (acc-1.0) * 0.1f + 1.0; /* without this, acc of 2 is unuseable */

    if (velocity <= threshold)
        return vel->min_acceleration;
    vel_dist = velocity - threshold;
    return (pow(acc, vel_dist)) * vel->min_acceleration;
}


/**
 * just a smooth function in [0..1] -> [0..1]
 *  - point symmetry at 0.5
 *  - f'(0) = f'(1) = 0
 *  - starts faster than a sinoid
 *  - smoothness C1 (Cinf if you dare to ignore endpoints)
 */
static inline float
CalcPenumbralGradient(float x){
    x *= 2.0f;
    x -= 1.0f;
    return 0.5f + (x * sqrt(1.0f - x*x) + asin(x))/M_PI;
}


/**
 * acceleration function similar to classic accelerated/unaccelerated,
 * but with smooth transition in between (and towards zero for adaptive dec.).
 */
static float
SimpleSmoothProfile(
    DeviceIntPtr dev,
    DeviceVelocityPtr vel,
    float velocity,
    float threshold,
    float acc)
{
    if(velocity < 1.0f)
        return CalcPenumbralGradient(0.5 + velocity*0.5) * 2.0f - 1.0f;
    if(threshold < 1.0f)
        threshold = 1.0f;
    if (velocity <= threshold)
        return 1;
    velocity /= threshold;
    if (velocity >= acc)
        return acc;
    else
        return 1.0f + (CalcPenumbralGradient(velocity/acc) * (acc - 1.0f));
}


/**
 * This profile uses the first half of the penumbral gradient as a start
 * and then scales linearly.
 */
static float
SmoothLinearProfile(
    DeviceIntPtr dev,
    DeviceVelocityPtr vel,
    float velocity,
    float threshold,
    float acc)
{
    float res, nv;

    if(acc > 1.0f)
        acc -= 1.0f; /*this is so acc = 1 is no acceleration */
    else
        return 1.0f;

    nv = (velocity - threshold) * acc * 0.5f;

    if(nv < 0){
        res = 0;
    }else if(nv < 2){
        res = CalcPenumbralGradient(nv*0.25f)*2.0f;
    }else{
        nv -= 2.0f;
        res = nv * 2.0f / M_PI  /* steepness of gradient at 0.5 */
              + 1.0f; /* gradient crosses 2|1 */
    }
    res += vel->min_acceleration;
    return res;
}


static float
LinearProfile(
    DeviceIntPtr dev,
    DeviceVelocityPtr vel,
    float velocity,
    float threshold,
    float acc)
{
    return acc * velocity;
}


static float
NoProfile(
    DeviceIntPtr dev,
    DeviceVelocityPtr vel,
    float velocity,
    float threshold,
    float acc)
{
    return 1.0f;
}

static PointerAccelerationProfileFunc
GetAccelerationProfile(
    DeviceVelocityPtr vel,
    int profile_num)
{
    switch(profile_num){
        case AccelProfileClassic:
            return ClassicProfile;
        case AccelProfileDeviceSpecific:
            return vel->deviceSpecificProfile;
        case AccelProfilePolynomial:
            return PolynomialAccelerationProfile;
        case AccelProfileSmoothLinear:
            return SmoothLinearProfile;
        case AccelProfileSimple:
            return SimpleSmoothProfile;
        case AccelProfilePower:
            return PowerProfile;
        case AccelProfileLinear:
            return LinearProfile;
        case AccelProfileNone:
            return NoProfile;
        default:
            return NULL;
    }
}

/**
 * Set the profile by number.
 * Intended to make profiles exchangeable at runtime.
 * If you created a profile, give it a number here and in the header to
 * make it selectable. In case some profile-specific init is needed, here
 * would be a good place, since FreeVelocityData() also calls this with
 * PROFILE_UNINITIALIZE.
 *
 * returns FALSE if profile number is unavailable, TRUE otherwise.
 */
int
SetAccelerationProfile(
    DeviceVelocityPtr vel,
    int profile_num)
{
    PointerAccelerationProfileFunc profile;
    profile = GetAccelerationProfile(vel, profile_num);

    if(profile == NULL && profile_num != PROFILE_UNINITIALIZE)
	return FALSE;

    if(vel->profile_private != NULL){
        /* Here one could free old profile-private data */
        xfree(vel->profile_private);
        vel->profile_private = NULL;
    }
    /* Here one could init profile-private data */
    vel->Profile = profile;
    vel->statistics.profile_number = profile_num;
    return TRUE;
}

/**********************************************
 * driver interaction
 **********************************************/


/**
 * device-specific profile
 *
 * The device-specific profile is intended as a hook for a driver
 * which may want to provide an own acceleration profile.
 * It should not rely on profile-private data, instead
 * it should do init/uninit in the driver (ie. with DEVICE_INIT and friends).
 * Users may override or choose it.
 */
void
SetDeviceSpecificAccelerationProfile(
        DeviceVelocityPtr vel,
        PointerAccelerationProfileFunc profile)
{
    if(vel)
	vel->deviceSpecificProfile = profile;
}

/**
 * Use this function to obtain a DeviceVelocityPtr for a device. Will return NULL if
 * the predictable acceleration scheme is not in effect.
 */
DeviceVelocityPtr
GetDevicePredictableAccelData(
	DeviceIntPtr dev)
{
    /*sanity check*/
    if(!dev){
	ErrorF("[dix] accel: DeviceIntPtr was NULL");
	return NULL;
    }
    if( dev->valuator &&
	dev->valuator->accelScheme.AccelSchemeProc ==
	    acceleratePointerPredictable &&
	dev->valuator->accelScheme.accelData != NULL){

	return (DeviceVelocityPtr)dev->valuator->accelScheme.accelData;
    }
    return NULL;
}

/********************************
 *  acceleration schemes
 *******************************/

/**
 * Modifies valuators in-place.
 * This version employs a velocity approximation algorithm to
 * enable fine-grained predictable acceleration profiles.
 */
void
acceleratePointerPredictable(
    DeviceIntPtr dev,
    int first_valuator,
    int num_valuators,
    int *valuators,
    int evtime)
{
    float mult = 0.0;
    int dx = 0, dy = 0;
    int *px = NULL, *py = NULL;
    DeviceVelocityPtr velocitydata =
	(DeviceVelocityPtr) dev->valuator->accelScheme.accelData;
    float fdx, fdy, tmp; /* no need to init */
    Bool soften = TRUE;

    if (!num_valuators || !valuators || !velocitydata)
        return;

    if (velocitydata->statistics.profile_number == AccelProfileNone &&
	velocitydata->const_acceleration == 1.0f) {
	return; /*we're inactive anyway, so skip the whole thing.*/
    }

    if (first_valuator == 0) {
        dx = valuators[0];
        px = &valuators[0];
    }
    if (first_valuator <= 1 && num_valuators >= (2 - first_valuator)) {
        dy = valuators[1 - first_valuator];
        py = &valuators[1 - first_valuator];
    }

    if (dx || dy){
        /* reset non-visible state? */
        if (ProcessVelocityData2D(velocitydata, dx , dy, evtime)) {
            soften = FALSE;
        }

        if (dev->ptrfeed && dev->ptrfeed->ctrl.num) {
            /* invoke acceleration profile to determine acceleration */
            mult = ComputeAcceleration (dev, velocitydata,
					dev->ptrfeed->ctrl.threshold,
					(float)dev->ptrfeed->ctrl.num /
					(float)dev->ptrfeed->ctrl.den);

            if(mult != 1.0 || velocitydata->const_acceleration != 1.0) {
                ApplySofteningAndConstantDeceleration( velocitydata,
						       dx, dy,
						       &fdx, &fdy,
						       (mult > 1.0) && soften);

                if (dx) {
                    tmp = mult * fdx + dev->last.remainder[0];
                    /* Since it may not be apparent: lrintf() does not offer
                     * strong statements about rounding; however because we
                     * process each axis conditionally, there's no danger
                     * of a toggling remainder. Its lack of guarantees likely
                     * makes it faster on the average target. */
                    *px = lrintf(tmp);
                    dev->last.remainder[0] = tmp - (float)*px;
                }
                if (dy) {
                    tmp = mult * fdy + dev->last.remainder[1];
                    *py = lrintf(tmp);
                    dev->last.remainder[1] = tmp - (float)*py;
                }
                DebugAccelF("pos (%i | %i) remainders x: %.3f y: %.3f delta x:%.3f y:%.3f\n",
                            *px, *py, dev->last.remainder[0], dev->last.remainder[1], fdx, fdy);
            }
        }
    }
    /* remember last motion delta (for softening/slow movement treatment) */
    velocitydata->last_dx = dx;
    velocitydata->last_dy = dy;
}



/**
 * Originally a part of xf86PostMotionEvent; modifies valuators
 * in-place. Retained mostly for embedded scenarios.
 */
void
acceleratePointerLightweight(
    DeviceIntPtr dev,
    int first_valuator,
    int num_valuators,
    int *valuators,
    int ignored)
{
    float mult = 0.0;
    int dx = 0, dy = 0;
    int *px = NULL, *py = NULL;

    if (!num_valuators || !valuators)
        return;

    if (first_valuator == 0) {
        dx = valuators[0];
        px = &valuators[0];
    }
    if (first_valuator <= 1 && num_valuators >= (2 - first_valuator)) {
        dy = valuators[1 - first_valuator];
        py = &valuators[1 - first_valuator];
    }

    if (!dx && !dy)
        return;

    if (dev->ptrfeed && dev->ptrfeed->ctrl.num) {
        /* modeled from xf86Events.c */
        if (dev->ptrfeed->ctrl.threshold) {
            if ((abs(dx) + abs(dy)) >= dev->ptrfeed->ctrl.threshold) {
                dev->last.remainder[0] = ((float)dx *
                                             (float)(dev->ptrfeed->ctrl.num)) /
                                             (float)(dev->ptrfeed->ctrl.den) +
                                            dev->last.remainder[0];
                if (px) {
                    *px = (int)dev->last.remainder[0];
                    dev->last.remainder[0] = dev->last.remainder[0] -
                                                (float)(*px);
                }

                dev->last.remainder[1] = ((float)dy *
                                             (float)(dev->ptrfeed->ctrl.num)) /
                                             (float)(dev->ptrfeed->ctrl.den) +
                                            dev->last.remainder[1];
                if (py) {
                    *py = (int)dev->last.remainder[1];
                    dev->last.remainder[1] = dev->last.remainder[1] -
                                                (float)(*py);
                }
            }
        }
        else {
	    mult = pow((float)dx * (float)dx + (float)dy * (float)dy,
                       ((float)(dev->ptrfeed->ctrl.num) /
                        (float)(dev->ptrfeed->ctrl.den) - 1.0) /
                       2.0) / 2.0;
            if (dx) {
                dev->last.remainder[0] = mult * (float)dx +
                                            dev->last.remainder[0];
                *px = (int)dev->last.remainder[0];
                dev->last.remainder[0] = dev->last.remainder[0] -
                                            (float)(*px);
            }
            if (dy) {
                dev->last.remainder[1] = mult * (float)dy +
                                            dev->last.remainder[1];
                *py = (int)dev->last.remainder[1];
                dev->last.remainder[1] = dev->last.remainder[1] -
                                            (float)(*py);
            }
        }
    }
}