michael@0: 
michael@0: /*
michael@0:  * Copyright 2010 Google Inc.
michael@0:  *
michael@0:  * Use of this source code is governed by a BSD-style license that can be
michael@0:  * found in the LICENSE file.
michael@0:  */
michael@0: 
michael@0: 
michael@0: 
michael@0: #include "SkTouchGesture.h"
michael@0: #include "SkMatrix.h"
michael@0: #include "SkTime.h"
michael@0: 
michael@0: #define DISCRETIZE_TRANSLATE_TO_AVOID_FLICKER   true
michael@0: 
michael@0: static const SkScalar MAX_FLING_SPEED = SkIntToScalar(1500);
michael@0: 
michael@0: static SkScalar pin_max_fling(SkScalar speed) {
michael@0:     if (speed > MAX_FLING_SPEED) {
michael@0:         speed = MAX_FLING_SPEED;
michael@0:     }
michael@0:     return speed;
michael@0: }
michael@0: 
michael@0: static double getseconds() {
michael@0:     return SkTime::GetMSecs() * 0.001;
michael@0: }
michael@0: 
michael@0: // returns +1 or -1, depending on the sign of x
michael@0: // returns +1 if z is zero
michael@0: static SkScalar SkScalarSignNonZero(SkScalar x) {
michael@0:     SkScalar sign = SK_Scalar1;
michael@0:     if (x < 0) {
michael@0:         sign = -sign;
michael@0:     }
michael@0:     return sign;
michael@0: }
michael@0: 
michael@0: static void unit_axis_align(SkVector* unit) {
michael@0:     const SkScalar TOLERANCE = SkDoubleToScalar(0.15);
michael@0:     if (SkScalarAbs(unit->fX) < TOLERANCE) {
michael@0:         unit->fX = 0;
michael@0:         unit->fY = SkScalarSignNonZero(unit->fY);
michael@0:     } else if (SkScalarAbs(unit->fY) < TOLERANCE) {
michael@0:         unit->fX = SkScalarSignNonZero(unit->fX);
michael@0:         unit->fY = 0;
michael@0:     }
michael@0: }
michael@0: 
michael@0: void SkFlingState::reset(float sx, float sy) {
michael@0:     fActive = true;
michael@0:     fDirection.set(sx, sy);
michael@0:     fSpeed0 = SkPoint::Normalize(&fDirection);
michael@0:     fSpeed0 = pin_max_fling(fSpeed0);
michael@0:     fTime0 = getseconds();
michael@0: 
michael@0:     unit_axis_align(&fDirection);
michael@0: //    printf("---- speed %g dir %g %g\n", fSpeed0, fDirection.fX, fDirection.fY);
michael@0: }
michael@0: 
michael@0: bool SkFlingState::evaluateMatrix(SkMatrix* matrix) {
michael@0:     if (!fActive) {
michael@0:         return false;
michael@0:     }
michael@0: 
michael@0:     const float t =  (float)(getseconds() - fTime0);
michael@0:     const float MIN_SPEED = 2;
michael@0:     const float K0 = 5;
michael@0:     const float K1 = 0.02f;
michael@0:     const float speed = fSpeed0 * (sk_float_exp(- K0 * t) - K1);
michael@0:     if (speed <= MIN_SPEED) {
michael@0:         fActive = false;
michael@0:         return false;
michael@0:     }
michael@0:     float dist = (fSpeed0 - speed) / K0;
michael@0: 
michael@0: //    printf("---- time %g speed %g dist %g\n", t, speed, dist);
michael@0:     float tx = fDirection.fX * dist;
michael@0:     float ty = fDirection.fY * dist;
michael@0:     if (DISCRETIZE_TRANSLATE_TO_AVOID_FLICKER) {
michael@0:         tx = (float)sk_float_round2int(tx);
michael@0:         ty = (float)sk_float_round2int(ty);
michael@0:     }
michael@0:     matrix->setTranslate(tx, ty);
michael@0: //    printf("---- evaluate (%g %g)\n", tx, ty);
michael@0: 
michael@0:     return true;
michael@0: }
michael@0: 
michael@0: ///////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: static const SkMSec MAX_DBL_TAP_INTERVAL = 300;
michael@0: static const float MAX_DBL_TAP_DISTANCE = 100;
michael@0: static const float MAX_JITTER_RADIUS = 2;
michael@0: 
michael@0: // if true, then ignore the touch-move, 'cause its probably just jitter
michael@0: static bool close_enough_for_jitter(float x0, float y0, float x1, float y1) {
michael@0:     return  sk_float_abs(x0 - x1) <= MAX_JITTER_RADIUS &&
michael@0:             sk_float_abs(y0 - y1) <= MAX_JITTER_RADIUS;
michael@0: }
michael@0: 
michael@0: ///////////////////////////////////////////////////////////////////////////////
michael@0: 
michael@0: SkTouchGesture::SkTouchGesture() {
michael@0:     this->reset();
michael@0: }
michael@0: 
michael@0: SkTouchGesture::~SkTouchGesture() {
michael@0: }
michael@0: 
michael@0: void SkTouchGesture::reset() {
michael@0:     fTouches.reset();
michael@0:     fState = kEmpty_State;
michael@0:     fLocalM.reset();
michael@0:     fGlobalM.reset();
michael@0: 
michael@0:     fLastUpT = SkTime::GetMSecs() - 2*MAX_DBL_TAP_INTERVAL;
michael@0:     fLastUpP.set(0, 0);
michael@0: }
michael@0: 
michael@0: void SkTouchGesture::flushLocalM() {
michael@0:     fGlobalM.postConcat(fLocalM);
michael@0:     fLocalM.reset();
michael@0: }
michael@0: 
michael@0: const SkMatrix& SkTouchGesture::localM() {
michael@0:     if (fFlinger.isActive()) {
michael@0:         if (!fFlinger.evaluateMatrix(&fLocalM)) {
michael@0:             this->flushLocalM();
michael@0:         }
michael@0:     }
michael@0:     return fLocalM;
michael@0: }
michael@0: 
michael@0: void SkTouchGesture::appendNewRec(void* owner, float x, float y) {
michael@0:     Rec* rec = fTouches.append();
michael@0:     rec->fOwner = owner;
michael@0:     rec->fStartX = rec->fPrevX = rec->fLastX = x;
michael@0:     rec->fStartY = rec->fPrevY = rec->fLastY = y;
michael@0:     rec->fLastT = rec->fPrevT = SkTime::GetMSecs();
michael@0: }
michael@0: 
michael@0: void SkTouchGesture::touchBegin(void* owner, float x, float y) {
michael@0: //    GrPrintf("--- %d touchBegin %p %g %g\n", fTouches.count(), owner, x, y);
michael@0: 
michael@0:     int index = this->findRec(owner);
michael@0:     if (index >= 0) {
michael@0:         this->flushLocalM();
michael@0:         fTouches.removeShuffle(index);
michael@0:         SkDebugf("---- already exists, removing\n");
michael@0:     }
michael@0: 
michael@0:     if (fTouches.count() == 2) {
michael@0:         return;
michael@0:     }
michael@0: 
michael@0:     this->flushLocalM();
michael@0:     fFlinger.stop();
michael@0: 
michael@0:     this->appendNewRec(owner, x, y);
michael@0: 
michael@0:     switch (fTouches.count()) {
michael@0:         case 1:
michael@0:             fState = kTranslate_State;
michael@0:             break;
michael@0:         case 2:
michael@0:             fState = kZoom_State;
michael@0:             break;
michael@0:         default:
michael@0:             break;
michael@0:     }
michael@0: }
michael@0: 
michael@0: int SkTouchGesture::findRec(void* owner) const {
michael@0:     for (int i = 0; i < fTouches.count(); i++) {
michael@0:         if (owner == fTouches[i].fOwner) {
michael@0:             return i;
michael@0:         }
michael@0:     }
michael@0:     return -1;
michael@0: }
michael@0: 
michael@0: static SkScalar center(float pos0, float pos1) {
michael@0:     return (pos0 + pos1) * 0.5f;
michael@0: }
michael@0: 
michael@0: static const float MAX_ZOOM_SCALE = 4;
michael@0: static const float MIN_ZOOM_SCALE = 0.25f;
michael@0: 
michael@0: float SkTouchGesture::limitTotalZoom(float scale) const {
michael@0:     // this query works 'cause we know that we're square-scale w/ no skew/rotation
michael@0:     const float curr = SkScalarToFloat(fGlobalM[0]);
michael@0: 
michael@0:     if (scale > 1 && curr * scale > MAX_ZOOM_SCALE) {
michael@0:         scale = MAX_ZOOM_SCALE / curr;
michael@0:     } else if (scale < 1 && curr * scale < MIN_ZOOM_SCALE) {
michael@0:         scale = MIN_ZOOM_SCALE / curr;
michael@0:     }
michael@0:     return scale;
michael@0: }
michael@0: 
michael@0: void SkTouchGesture::touchMoved(void* owner, float x, float y) {
michael@0: //    GrPrintf("--- %d touchMoved %p %g %g\n", fTouches.count(), owner, x, y);
michael@0: 
michael@0:     SkASSERT(kEmpty_State != fState);
michael@0: 
michael@0:     int index = this->findRec(owner);
michael@0:     if (index < 0) {
michael@0:         // not found, so I guess we should add it...
michael@0:         SkDebugf("---- add missing begin\n");
michael@0:         this->appendNewRec(owner, x, y);
michael@0:         index = fTouches.count() - 1;
michael@0:     }
michael@0: 
michael@0:     Rec& rec = fTouches[index];
michael@0: 
michael@0:     // not sure how valuable this is
michael@0:     if (fTouches.count() == 2) {
michael@0:         if (close_enough_for_jitter(rec.fLastX, rec.fLastY, x, y)) {
michael@0: //            GrPrintf("--- drop touchMove, withing jitter tolerance %g %g\n", rec.fLastX - x, rec.fLastY - y);
michael@0:             return;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     rec.fPrevX = rec.fLastX; rec.fLastX = x;
michael@0:     rec.fPrevY = rec.fLastY; rec.fLastY = y;
michael@0:     rec.fPrevT = rec.fLastT; rec.fLastT = SkTime::GetMSecs();
michael@0: 
michael@0:     switch (fTouches.count()) {
michael@0:         case 1: {
michael@0:             float dx = rec.fLastX - rec.fStartX;
michael@0:             float dy = rec.fLastY - rec.fStartY;
michael@0:             dx = (float)sk_float_round2int(dx);
michael@0:             dy = (float)sk_float_round2int(dy);
michael@0:             fLocalM.setTranslate(dx, dy);
michael@0:         } break;
michael@0:         case 2: {
michael@0:             SkASSERT(kZoom_State == fState);
michael@0:             const Rec& rec0 = fTouches[0];
michael@0:             const Rec& rec1 = fTouches[1];
michael@0: 
michael@0:             float scale = this->computePinch(rec0, rec1);
michael@0:             scale = this->limitTotalZoom(scale);
michael@0: 
michael@0:             fLocalM.setTranslate(-center(rec0.fStartX, rec1.fStartX),
michael@0:                                  -center(rec0.fStartY, rec1.fStartY));
michael@0:             fLocalM.postScale(scale, scale);
michael@0:             fLocalM.postTranslate(center(rec0.fLastX, rec1.fLastX),
michael@0:                                   center(rec0.fLastY, rec1.fLastY));
michael@0:         } break;
michael@0:         default:
michael@0:             break;
michael@0:     }
michael@0: }
michael@0: 
michael@0: void SkTouchGesture::touchEnd(void* owner) {
michael@0: //    GrPrintf("--- %d touchEnd   %p\n", fTouches.count(), owner);
michael@0: 
michael@0:     int index = this->findRec(owner);
michael@0:     if (index < 0) {
michael@0:         SkDebugf("--- not found\n");
michael@0:         return;
michael@0:     }
michael@0: 
michael@0:     const Rec& rec = fTouches[index];
michael@0:     if (this->handleDblTap(rec.fLastX, rec.fLastY)) {
michael@0:         return;
michael@0:     }
michael@0: 
michael@0:     // count() reflects the number before we removed the owner
michael@0:     switch (fTouches.count()) {
michael@0:         case 1: {
michael@0:             this->flushLocalM();
michael@0:             float dx = rec.fLastX - rec.fPrevX;
michael@0:             float dy = rec.fLastY - rec.fPrevY;
michael@0:             float dur = (rec.fLastT - rec.fPrevT) * 0.001f;
michael@0:             if (dur > 0) {
michael@0:                 fFlinger.reset(dx / dur, dy / dur);
michael@0:             }
michael@0:             fState = kEmpty_State;
michael@0:         } break;
michael@0:         case 2:
michael@0:             this->flushLocalM();
michael@0:             SkASSERT(kZoom_State == fState);
michael@0:             fState = kEmpty_State;
michael@0:             break;
michael@0:         default:
michael@0:             SkASSERT(kZoom_State == fState);
michael@0:             break;
michael@0:     }
michael@0: 
michael@0:     fTouches.removeShuffle(index);
michael@0: }
michael@0: 
michael@0: float SkTouchGesture::computePinch(const Rec& rec0, const Rec& rec1) {
michael@0:     double dx = rec0.fStartX - rec1.fStartX;
michael@0:     double dy = rec0.fStartY - rec1.fStartY;
michael@0:     double dist0 = sqrt(dx*dx + dy*dy);
michael@0: 
michael@0:     dx = rec0.fLastX - rec1.fLastX;
michael@0:     dy = rec0.fLastY - rec1.fLastY;
michael@0:     double dist1 = sqrt(dx*dx + dy*dy);
michael@0: 
michael@0:     double scale = dist1 / dist0;
michael@0:     return (float)scale;
michael@0: }
michael@0: 
michael@0: bool SkTouchGesture::handleDblTap(float x, float y) {
michael@0:     bool found = false;
michael@0:     SkMSec now = SkTime::GetMSecs();
michael@0:     if (now - fLastUpT <= MAX_DBL_TAP_INTERVAL) {
michael@0:         if (SkPoint::Length(fLastUpP.fX - x,
michael@0:                             fLastUpP.fY - y) <= MAX_DBL_TAP_DISTANCE) {
michael@0:             fFlinger.stop();
michael@0:             fLocalM.reset();
michael@0:             fGlobalM.reset();
michael@0:             fTouches.reset();
michael@0:             fState = kEmpty_State;
michael@0:             found = true;
michael@0:         }
michael@0:     }
michael@0: 
michael@0:     fLastUpT = now;
michael@0:     fLastUpP.set(x, y);
michael@0:     return found;
michael@0: }