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comparison: gfx/skia/trunk/src/views/SkTouchGesture.cpp

gfx/skia/trunk/src/views/SkTouchGesture.cpp

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1
2 /*
3 * Copyright 2010 Google Inc.
4 *
5 * Use of this source code is governed by a BSD-style license that can be
6 * found in the LICENSE file.
7 */
8
9
10
11 #include "SkTouchGesture.h"
12 #include "SkMatrix.h"
13 #include "SkTime.h"
14
15 #define DISCRETIZE_TRANSLATE_TO_AVOID_FLICKER true
16
17 static const SkScalar MAX_FLING_SPEED = SkIntToScalar(1500);
18
19 static SkScalar pin_max_fling(SkScalar speed) {
20 if (speed > MAX_FLING_SPEED) {
21 speed = MAX_FLING_SPEED;
22 }
23 return speed;
24 }
25
26 static double getseconds() {
27 return SkTime::GetMSecs() * 0.001;
28 }
29
30 // returns +1 or -1, depending on the sign of x
31 // returns +1 if z is zero
32 static SkScalar SkScalarSignNonZero(SkScalar x) {
33 SkScalar sign = SK_Scalar1;
34 if (x < 0) {
35 sign = -sign;
36 }
37 return sign;
38 }
39
40 static void unit_axis_align(SkVector* unit) {
41 const SkScalar TOLERANCE = SkDoubleToScalar(0.15);
42 if (SkScalarAbs(unit->fX) < TOLERANCE) {
43 unit->fX = 0;
44 unit->fY = SkScalarSignNonZero(unit->fY);
45 } else if (SkScalarAbs(unit->fY) < TOLERANCE) {
46 unit->fX = SkScalarSignNonZero(unit->fX);
47 unit->fY = 0;
48 }
49 }
50
51 void SkFlingState::reset(float sx, float sy) {
52 fActive = true;
53 fDirection.set(sx, sy);
54 fSpeed0 = SkPoint::Normalize(&fDirection);
55 fSpeed0 = pin_max_fling(fSpeed0);
56 fTime0 = getseconds();
57
58 unit_axis_align(&fDirection);
59 // printf("---- speed %g dir %g %g\n", fSpeed0, fDirection.fX, fDirection.fY);
60 }
61
62 bool SkFlingState::evaluateMatrix(SkMatrix* matrix) {
63 if (!fActive) {
64 return false;
65 }
66
67 const float t = (float)(getseconds() - fTime0);
68 const float MIN_SPEED = 2;
69 const float K0 = 5;
70 const float K1 = 0.02f;
71 const float speed = fSpeed0 * (sk_float_exp(- K0 * t) - K1);
72 if (speed <= MIN_SPEED) {
73 fActive = false;
74 return false;
75 }
76 float dist = (fSpeed0 - speed) / K0;
77
78 // printf("---- time %g speed %g dist %g\n", t, speed, dist);
79 float tx = fDirection.fX * dist;
80 float ty = fDirection.fY * dist;
81 if (DISCRETIZE_TRANSLATE_TO_AVOID_FLICKER) {
82 tx = (float)sk_float_round2int(tx);
83 ty = (float)sk_float_round2int(ty);
84 }
85 matrix->setTranslate(tx, ty);
86 // printf("---- evaluate (%g %g)\n", tx, ty);
87
88 return true;
89 }
90
91 ///////////////////////////////////////////////////////////////////////////////
92
93 static const SkMSec MAX_DBL_TAP_INTERVAL = 300;
94 static const float MAX_DBL_TAP_DISTANCE = 100;
95 static const float MAX_JITTER_RADIUS = 2;
96
97 // if true, then ignore the touch-move, 'cause its probably just jitter
98 static bool close_enough_for_jitter(float x0, float y0, float x1, float y1) {
99 return sk_float_abs(x0 - x1) <= MAX_JITTER_RADIUS &&
100 sk_float_abs(y0 - y1) <= MAX_JITTER_RADIUS;
101 }
102
103 ///////////////////////////////////////////////////////////////////////////////
104
105 SkTouchGesture::SkTouchGesture() {
106 this->reset();
107 }
108
109 SkTouchGesture::~SkTouchGesture() {
110 }
111
112 void SkTouchGesture::reset() {
113 fTouches.reset();
114 fState = kEmpty_State;
115 fLocalM.reset();
116 fGlobalM.reset();
117
118 fLastUpT = SkTime::GetMSecs() - 2*MAX_DBL_TAP_INTERVAL;
119 fLastUpP.set(0, 0);
120 }
121
122 void SkTouchGesture::flushLocalM() {
123 fGlobalM.postConcat(fLocalM);
124 fLocalM.reset();
125 }
126
127 const SkMatrix& SkTouchGesture::localM() {
128 if (fFlinger.isActive()) {
129 if (!fFlinger.evaluateMatrix(&fLocalM)) {
130 this->flushLocalM();
131 }
132 }
133 return fLocalM;
134 }
135
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 = SkTime::GetMSecs();
142 }
143
144 void SkTouchGesture::touchBegin(void* owner, float x, float y) {
145 // GrPrintf("--- %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
175 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
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
191 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
203 void SkTouchGesture::touchMoved(void* owner, float x, float y) {
204 // GrPrintf("--- %d touchMoved %p %g %g\n", fTouches.count(), owner, x, y);
205
206 SkASSERT(kEmpty_State != fState);
207
208 int index = this->findRec(owner);
209 if (index < 0) {
210 // not found, so I guess we should add it...
211 SkDebugf("---- add missing begin\n");
212 this->appendNewRec(owner, x, y);
213 index = fTouches.count() - 1;
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 // GrPrintf("--- drop touchMove, withing 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; rec.fLastT = SkTime::GetMSecs();
229
230 switch (fTouches.count()) {
231 case 1: {
232 float dx = rec.fLastX - rec.fStartX;
233 float dy = rec.fLastY - rec.fStartY;
234 dx = (float)sk_float_round2int(dx);
235 dy = (float)sk_float_round2int(dy);
236 fLocalM.setTranslate(dx, dy);
237 } break;
238 case 2: {
239 SkASSERT(kZoom_State == fState);
240 const Rec& rec0 = fTouches[0];
241 const Rec& rec1 = fTouches[1];
242
243 float scale = this->computePinch(rec0, rec1);
244 scale = this->limitTotalZoom(scale);
245
246 fLocalM.setTranslate(-center(rec0.fStartX, rec1.fStartX),
247 -center(rec0.fStartY, rec1.fStartY));
248 fLocalM.postScale(scale, scale);
249 fLocalM.postTranslate(center(rec0.fLastX, rec1.fLastX),
250 center(rec0.fLastY, rec1.fLastY));
251 } break;
252 default:
253 break;
254 }
255 }
256
257 void SkTouchGesture::touchEnd(void* owner) {
258 // GrPrintf("--- %d touchEnd %p\n", fTouches.count(), owner);
259
260 int index = this->findRec(owner);
261 if (index < 0) {
262 SkDebugf("--- not found\n");
263 return;
264 }
265
266 const Rec& rec = fTouches[index];
267 if (this->handleDblTap(rec.fLastX, rec.fLastY)) {
268 return;
269 }
270
271 // count() reflects the number before we removed the owner
272 switch (fTouches.count()) {
273 case 1: {
274 this->flushLocalM();
275 float dx = rec.fLastX - rec.fPrevX;
276 float dy = rec.fLastY - rec.fPrevY;
277 float dur = (rec.fLastT - rec.fPrevT) * 0.001f;
278 if (dur > 0) {
279 fFlinger.reset(dx / dur, dy / dur);
280 }
281 fState = kEmpty_State;
282 } break;
283 case 2:
284 this->flushLocalM();
285 SkASSERT(kZoom_State == fState);
286 fState = kEmpty_State;
287 break;
288 default:
289 SkASSERT(kZoom_State == fState);
290 break;
291 }
292
293 fTouches.removeShuffle(index);
294 }
295
296 float SkTouchGesture::computePinch(const Rec& rec0, const Rec& rec1) {
297 double dx = rec0.fStartX - rec1.fStartX;
298 double dy = rec0.fStartY - rec1.fStartY;
299 double dist0 = sqrt(dx*dx + dy*dy);
300
301 dx = rec0.fLastX - rec1.fLastX;
302 dy = rec0.fLastY - rec1.fLastY;
303 double dist1 = sqrt(dx*dx + dy*dy);
304
305 double scale = dist1 / dist0;
306 return (float)scale;
307 }
308
309 bool SkTouchGesture::handleDblTap(float x, float y) {
310 bool found = false;
311 SkMSec now = SkTime::GetMSecs();
312 if (now - fLastUpT <= MAX_DBL_TAP_INTERVAL) {
313 if (SkPoint::Length(fLastUpP.fX - x,
314 fLastUpP.fY - y) <= MAX_DBL_TAP_DISTANCE) {
315 fFlinger.stop();
316 fLocalM.reset();
317 fGlobalM.reset();
318 fTouches.reset();
319 fState = kEmpty_State;
320 found = true;
321 }
322 }
323
324 fLastUpT = now;
325 fLastUpP.set(x, y);
326 return found;
327 }

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