1 /*
2 * Copyright 2010 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7
8 #include <algorithm>
9
10 #include "SkTouchGesture.h"
11 #include "SkMatrix.h"
12 #include "SkTime.h"
13
14 #define DISCRETIZE_TRANSLATE_TO_AVOID_FLICKER true
15
16 static const SkScalar MAX_FLING_SPEED = SkIntToScalar(1500);
17
pin_max_fling(SkScalar speed)18 static SkScalar pin_max_fling(SkScalar speed) {
19 if (speed > MAX_FLING_SPEED) {
20 speed = MAX_FLING_SPEED;
21 }
22 return speed;
23 }
24
getseconds()25 static double getseconds() {
26 return SkTime::GetMSecs() * 0.001;
27 }
28
29 // returns +1 or -1, depending on the sign of x
30 // returns +1 if z is zero
SkScalarSignNonZero(SkScalar x)31 static SkScalar SkScalarSignNonZero(SkScalar x) {
32 SkScalar sign = SK_Scalar1;
33 if (x < 0) {
34 sign = -sign;
35 }
36 return sign;
37 }
38
unit_axis_align(SkVector * unit)39 static void unit_axis_align(SkVector* unit) {
40 const SkScalar TOLERANCE = SkDoubleToScalar(0.15);
41 if (SkScalarAbs(unit->fX) < TOLERANCE) {
42 unit->fX = 0;
43 unit->fY = SkScalarSignNonZero(unit->fY);
44 } else if (SkScalarAbs(unit->fY) < TOLERANCE) {
45 unit->fX = SkScalarSignNonZero(unit->fX);
46 unit->fY = 0;
47 }
48 }
49
reset(float sx,float sy)50 void SkFlingState::reset(float sx, float sy) {
51 fActive = true;
52 fDirection.set(sx, sy);
53 fSpeed0 = SkPoint::Normalize(&fDirection);
54 fSpeed0 = pin_max_fling(fSpeed0);
55 fTime0 = getseconds();
56
57 unit_axis_align(&fDirection);
58 // printf("---- speed %g dir %g %g\n", fSpeed0, fDirection.fX, fDirection.fY);
59 }
60
evaluateMatrix(SkMatrix * matrix)61 bool SkFlingState::evaluateMatrix(SkMatrix* matrix) {
62 if (!fActive) {
63 return false;
64 }
65
66 const float t = (float)(getseconds() - fTime0);
67 const float MIN_SPEED = 2;
68 const float K0 = 5;
69 const float K1 = 0.02f;
70 const float speed = fSpeed0 * (sk_float_exp(- K0 * t) - K1);
71 if (speed <= MIN_SPEED) {
72 fActive = false;
73 return false;
74 }
75 float dist = (fSpeed0 - speed) / K0;
76
77 // printf("---- time %g speed %g dist %g\n", t, speed, dist);
78 float tx = fDirection.fX * dist;
79 float ty = fDirection.fY * dist;
80 if (DISCRETIZE_TRANSLATE_TO_AVOID_FLICKER) {
81 tx = (float)sk_float_round2int(tx);
82 ty = (float)sk_float_round2int(ty);
83 }
84 matrix->setTranslate(tx, ty);
85 // printf("---- evaluate (%g %g)\n", tx, ty);
86
87 return true;
88 }
89
90 ///////////////////////////////////////////////////////////////////////////////
91
92 static const SkMSec MAX_DBL_TAP_INTERVAL = 300;
93 static const float MAX_DBL_TAP_DISTANCE = 100;
94 static const float MAX_JITTER_RADIUS = 2;
95
96 // if true, then ignore the touch-move, 'cause its probably just jitter
close_enough_for_jitter(float x0,float y0,float x1,float y1)97 static bool close_enough_for_jitter(float x0, float y0, float x1, float y1) {
98 return sk_float_abs(x0 - x1) <= MAX_JITTER_RADIUS &&
99 sk_float_abs(y0 - y1) <= MAX_JITTER_RADIUS;
100 }
101
102 ///////////////////////////////////////////////////////////////////////////////
103
SkTouchGesture()104 SkTouchGesture::SkTouchGesture() {
105 this->reset();
106 }
107
~SkTouchGesture()108 SkTouchGesture::~SkTouchGesture() {
109 }
110
reset()111 void SkTouchGesture::reset() {
112 fIsTransLimited = false;
113 fTouches.reset();
114 fState = kEmpty_State;
115 fLocalM.reset();
116 fGlobalM.reset();
117
118 fLastUpMillis = SkTime::GetMSecs() - 2*MAX_DBL_TAP_INTERVAL;
119 fLastUpP.set(0, 0);
120 }
121
flushLocalM()122 void SkTouchGesture::flushLocalM() {
123 fGlobalM.postConcat(fLocalM);
124 fLocalM.reset();
125 }
126
localM()127 const SkMatrix& SkTouchGesture::localM() {
128 if (fFlinger.isActive()) {
129 if (!fFlinger.evaluateMatrix(&fLocalM)) {
130 this->flushLocalM();
131 }
132 }
133 return fLocalM;
134 }
135
appendNewRec(void * owner,float x,float y)136 void SkTouchGesture::appendNewRec(void* owner, float x, float y) {
137 Rec* rec = fTouches.append();
138 rec->fOwner = owner;
139 rec->fStartX = rec->fPrevX = rec->fLastX = x;
140 rec->fStartY = rec->fPrevY = rec->fLastY = y;
141 rec->fLastT = rec->fPrevT = static_cast<float>(SkTime::GetSecs());
142 }
143
touchBegin(void * owner,float x,float y)144 void SkTouchGesture::touchBegin(void* owner, float x, float y) {
145 // SkDebugf("--- %d touchBegin %p %g %g\n", fTouches.count(), owner, x, y);
146
147 int index = this->findRec(owner);
148 if (index >= 0) {
149 this->flushLocalM();
150 fTouches.removeShuffle(index);
151 SkDebugf("---- already exists, removing\n");
152 }
153
154 if (fTouches.count() == 2) {
155 return;
156 }
157
158 this->flushLocalM();
159 fFlinger.stop();
160
161 this->appendNewRec(owner, x, y);
162
163 switch (fTouches.count()) {
164 case 1:
165 fState = kTranslate_State;
166 break;
167 case 2:
168 fState = kZoom_State;
169 break;
170 default:
171 break;
172 }
173 }
174
findRec(void * owner) const175 int SkTouchGesture::findRec(void* owner) const {
176 for (int i = 0; i < fTouches.count(); i++) {
177 if (owner == fTouches[i].fOwner) {
178 return i;
179 }
180 }
181 return -1;
182 }
183
center(float pos0,float pos1)184 static SkScalar center(float pos0, float pos1) {
185 return (pos0 + pos1) * 0.5f;
186 }
187
188 static const float MAX_ZOOM_SCALE = 4;
189 static const float MIN_ZOOM_SCALE = 0.25f;
190
limitTotalZoom(float scale) const191 float SkTouchGesture::limitTotalZoom(float scale) const {
192 // this query works 'cause we know that we're square-scale w/ no skew/rotation
193 const float curr = SkScalarToFloat(fGlobalM[0]);
194
195 if (scale > 1 && curr * scale > MAX_ZOOM_SCALE) {
196 scale = MAX_ZOOM_SCALE / curr;
197 } else if (scale < 1 && curr * scale < MIN_ZOOM_SCALE) {
198 scale = MIN_ZOOM_SCALE / curr;
199 }
200 return scale;
201 }
202
touchMoved(void * owner,float x,float y)203 void SkTouchGesture::touchMoved(void* owner, float x, float y) {
204 // SkDebugf("--- %d touchMoved %p %g %g\n", fTouches.count(), owner, x, y);
205
206 if (kEmpty_State == fState) {
207 return;
208 }
209
210 int index = this->findRec(owner);
211 if (index < 0) {
212 SkDebugf("---- ignoring move without begin\n");
213 return;
214 }
215
216 Rec& rec = fTouches[index];
217
218 // not sure how valuable this is
219 if (fTouches.count() == 2) {
220 if (close_enough_for_jitter(rec.fLastX, rec.fLastY, x, y)) {
221 // SkDebugf("--- drop touchMove, within jitter tolerance %g %g\n", rec.fLastX - x, rec.fLastY - y);
222 return;
223 }
224 }
225
226 rec.fPrevX = rec.fLastX; rec.fLastX = x;
227 rec.fPrevY = rec.fLastY; rec.fLastY = y;
228 rec.fPrevT = rec.fLastT;
229 rec.fLastT = static_cast<float>(SkTime::GetSecs());
230
231 switch (fTouches.count()) {
232 case 1: {
233 float dx = rec.fLastX - rec.fStartX;
234 float dy = rec.fLastY - rec.fStartY;
235 dx = (float)sk_float_round2int(dx);
236 dy = (float)sk_float_round2int(dy);
237 fLocalM.setTranslate(dx, dy);
238 } break;
239 case 2: {
240 SkASSERT(kZoom_State == fState);
241 const Rec& rec0 = fTouches[0];
242 const Rec& rec1 = fTouches[1];
243
244 float scale = this->computePinch(rec0, rec1);
245 scale = this->limitTotalZoom(scale);
246
247 fLocalM.setTranslate(-center(rec0.fStartX, rec1.fStartX),
248 -center(rec0.fStartY, rec1.fStartY));
249 fLocalM.postScale(scale, scale);
250 fLocalM.postTranslate(center(rec0.fLastX, rec1.fLastX),
251 center(rec0.fLastY, rec1.fLastY));
252 } break;
253 default:
254 break;
255 }
256 }
257
touchEnd(void * owner)258 void SkTouchGesture::touchEnd(void* owner) {
259 // SkDebugf("--- %d touchEnd %p\n", fTouches.count(), owner);
260
261 int index = this->findRec(owner);
262 if (index < 0) {
263 SkDebugf("--- not found\n");
264 return;
265 }
266
267 const Rec& rec = fTouches[index];
268 if (this->handleDblTap(rec.fLastX, rec.fLastY)) {
269 return;
270 }
271
272 // count() reflects the number before we removed the owner
273 switch (fTouches.count()) {
274 case 1: {
275 this->flushLocalM();
276 float dx = rec.fLastX - rec.fPrevX;
277 float dy = rec.fLastY - rec.fPrevY;
278 float dur = rec.fLastT - rec.fPrevT;
279 if (dur > 0) {
280 fFlinger.reset(dx / dur, dy / dur);
281 }
282 fState = kEmpty_State;
283 } break;
284 case 2:
285 this->flushLocalM();
286 SkASSERT(kZoom_State == fState);
287 fState = kEmpty_State;
288 break;
289 default:
290 SkASSERT(kZoom_State == fState);
291 break;
292 }
293
294 fTouches.removeShuffle(index);
295
296 limitTrans();
297 }
298
computePinch(const Rec & rec0,const Rec & rec1)299 float SkTouchGesture::computePinch(const Rec& rec0, const Rec& rec1) {
300 double dx = rec0.fStartX - rec1.fStartX;
301 double dy = rec0.fStartY - rec1.fStartY;
302 double dist0 = sqrt(dx*dx + dy*dy);
303
304 dx = rec0.fLastX - rec1.fLastX;
305 dy = rec0.fLastY - rec1.fLastY;
306 double dist1 = sqrt(dx*dx + dy*dy);
307
308 double scale = dist1 / dist0;
309 return (float)scale;
310 }
311
handleDblTap(float x,float y)312 bool SkTouchGesture::handleDblTap(float x, float y) {
313 bool found = false;
314 double now = SkTime::GetMSecs();
315 if (now - fLastUpMillis <= MAX_DBL_TAP_INTERVAL) {
316 if (SkPoint::Length(fLastUpP.fX - x,
317 fLastUpP.fY - y) <= MAX_DBL_TAP_DISTANCE) {
318 fFlinger.stop();
319 fLocalM.reset();
320 fGlobalM.reset();
321 fTouches.reset();
322 fState = kEmpty_State;
323 found = true;
324 }
325 }
326
327 fLastUpMillis = now;
328 fLastUpP.set(x, y);
329 return found;
330 }
331
setTransLimit(const SkRect & contentRect,const SkRect & windowRect,const SkMatrix & preTouchMatrix)332 void SkTouchGesture::setTransLimit(const SkRect& contentRect, const SkRect& windowRect,
333 const SkMatrix& preTouchMatrix) {
334 fIsTransLimited = true;
335 fContentRect = contentRect;
336 fWindowRect = windowRect;
337 fPreTouchM = preTouchMatrix;
338 }
339
limitTrans()340 void SkTouchGesture::limitTrans() {
341 if (!fIsTransLimited) {
342 return;
343 }
344
345 SkRect scaledContent = fContentRect;
346 fPreTouchM.mapRect(&scaledContent);
347 fGlobalM.mapRect(&scaledContent);
348 const SkScalar ZERO = 0;
349
350 fGlobalM.postTranslate(ZERO, std::min(ZERO, fWindowRect.fBottom - scaledContent.fTop));
351 fGlobalM.postTranslate(ZERO, std::max(ZERO, fWindowRect.fTop - scaledContent.fBottom));
352 fGlobalM.postTranslate(std::min(ZERO, fWindowRect.fRight - scaledContent.fLeft), ZERO);
353 fGlobalM.postTranslate(std::max(ZERO, fWindowRect.fLeft - scaledContent.fRight), ZERO);
354 }
355