src/views/SkTouchGesture.cpp - platform/external/skia - Gitiles

 /*
  * Copyright 2010 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #include <algorithm>

 #include "SkTouchGesture.h"
 #include "SkMatrix.h"
 #include "SkTime.h"

 #define DISCRETIZE_TRANSLATE_TO_AVOID_FLICKER   true

 static const SkScalar MAX_FLING_SPEED = SkIntToScalar(1500);

 static SkScalar pin_max_fling(SkScalar speed) {
     if (speed > MAX_FLING_SPEED) {
         speed = MAX_FLING_SPEED;
     }
     return speed;
 }

 static double getseconds() {
     return SkTime::GetMSecs() * 0.001;
 }

 // returns +1 or -1, depending on the sign of x
 // returns +1 if z is zero
 static SkScalar SkScalarSignNonZero(SkScalar x) {
     SkScalar sign = SK_Scalar1;
     if (x < 0) {
         sign = -sign;
     }
     return sign;
 }

 static void unit_axis_align(SkVector* unit) {
     const SkScalar TOLERANCE = SkDoubleToScalar(0.15);
     if (SkScalarAbs(unit->fX) < TOLERANCE) {
         unit->fX = 0;
         unit->fY = SkScalarSignNonZero(unit->fY);
     } else if (SkScalarAbs(unit->fY) < TOLERANCE) {
         unit->fX = SkScalarSignNonZero(unit->fX);
         unit->fY = 0;
     }
 }

 void SkFlingState::reset(float sx, float sy) {
     fActive = true;
     fDirection.set(sx, sy);
     fSpeed0 = SkPoint::Normalize(&fDirection);
     fSpeed0 = pin_max_fling(fSpeed0);
     fTime0 = getseconds();

     unit_axis_align(&fDirection);
 //    printf("---- speed %g dir %g %g\n", fSpeed0, fDirection.fX, fDirection.fY);
 }

 bool SkFlingState::evaluateMatrix(SkMatrix* matrix) {
     if (!fActive) {
         return false;
     }

     const float t =  (float)(getseconds() - fTime0);
     const float MIN_SPEED = 2;
     const float K0 = 5;
     const float K1 = 0.02f;
     const float speed = fSpeed0 * (sk_float_exp(- K0 * t) - K1);
     if (speed <= MIN_SPEED) {
         fActive = false;
         return false;
     }
     float dist = (fSpeed0 - speed) / K0;

 //    printf("---- time %g speed %g dist %g\n", t, speed, dist);
     float tx = fDirection.fX * dist;
     float ty = fDirection.fY * dist;
     if (DISCRETIZE_TRANSLATE_TO_AVOID_FLICKER) {
         tx = (float)sk_float_round2int(tx);
         ty = (float)sk_float_round2int(ty);
     }
     matrix->setTranslate(tx, ty);
 //    printf("---- evaluate (%g %g)\n", tx, ty);

     return true;
 }

 ///////////////////////////////////////////////////////////////////////////////

 static const SkMSec MAX_DBL_TAP_INTERVAL = 300;
 static const float MAX_DBL_TAP_DISTANCE = 100;
 static const float MAX_JITTER_RADIUS = 2;

 // if true, then ignore the touch-move, 'cause its probably just jitter
 static bool close_enough_for_jitter(float x0, float y0, float x1, float y1) {
     return  sk_float_abs(x0 - x1) <= MAX_JITTER_RADIUS &&
             sk_float_abs(y0 - y1) <= MAX_JITTER_RADIUS;
 }

 ///////////////////////////////////////////////////////////////////////////////

 SkTouchGesture::SkTouchGesture() {
     this->reset();
 }

 SkTouchGesture::~SkTouchGesture() {
 }

 void SkTouchGesture::reset() {
     fIsTransLimited = false;
     fTouches.reset();
     fState = kEmpty_State;
     fLocalM.reset();
     fGlobalM.reset();

     fLastUpMillis = SkTime::GetMSecs() - 2*MAX_DBL_TAP_INTERVAL;
     fLastUpP.set(0, 0);
 }

 void SkTouchGesture::flushLocalM() {
     fGlobalM.postConcat(fLocalM);
     fLocalM.reset();
 }

 const SkMatrix& SkTouchGesture::localM() {
     if (fFlinger.isActive()) {
         if (!fFlinger.evaluateMatrix(&fLocalM)) {
             this->flushLocalM();
         }
     }
     return fLocalM;
 }

 void SkTouchGesture::appendNewRec(void* owner, float x, float y) {
     Rec* rec = fTouches.append();
     rec->fOwner = owner;
     rec->fStartX = rec->fPrevX = rec->fLastX = x;
     rec->fStartY = rec->fPrevY = rec->fLastY = y;
     rec->fLastT = rec->fPrevT = static_cast<float>(SkTime::GetSecs());
 }

 void SkTouchGesture::touchBegin(void* owner, float x, float y) {
 //    SkDebugf("--- %d touchBegin %p %g %g\n", fTouches.count(), owner, x, y);

     int index = this->findRec(owner);
     if (index >= 0) {
         this->flushLocalM();
         fTouches.removeShuffle(index);
         SkDebugf("---- already exists, removing\n");
     }

     if (fTouches.count() == 2) {
         return;
     }

     this->flushLocalM();
     fFlinger.stop();

     this->appendNewRec(owner, x, y);

     switch (fTouches.count()) {
         case 1:
             fState = kTranslate_State;
             break;
         case 2:
             fState = kZoom_State;
             break;
         default:
             break;
     }
 }

 int SkTouchGesture::findRec(void* owner) const {
     for (int i = 0; i < fTouches.count(); i++) {
         if (owner == fTouches[i].fOwner) {
             return i;
         }
     }
     return -1;
 }

 static SkScalar center(float pos0, float pos1) {
     return (pos0 + pos1) * 0.5f;
 }

 static const float MAX_ZOOM_SCALE = 4;
 static const float MIN_ZOOM_SCALE = 0.25f;

 float SkTouchGesture::limitTotalZoom(float scale) const {
     // this query works 'cause we know that we're square-scale w/ no skew/rotation
     const float curr = SkScalarToFloat(fGlobalM[0]);

     if (scale > 1 && curr * scale > MAX_ZOOM_SCALE) {
         scale = MAX_ZOOM_SCALE / curr;
     } else if (scale < 1 && curr * scale < MIN_ZOOM_SCALE) {
         scale = MIN_ZOOM_SCALE / curr;
     }
     return scale;
 }

 void SkTouchGesture::touchMoved(void* owner, float x, float y) {
 //    SkDebugf("--- %d touchMoved %p %g %g\n", fTouches.count(), owner, x, y);

     if (kEmpty_State == fState) {
         return;
     }

     int index = this->findRec(owner);
     if (index < 0) {
         // not found, so I guess we should add it...
         SkDebugf("---- add missing begin\n");
         this->appendNewRec(owner, x, y);
         index = fTouches.count() - 1;
     }

     Rec& rec = fTouches[index];

     // not sure how valuable this is
     if (fTouches.count() == 2) {
         if (close_enough_for_jitter(rec.fLastX, rec.fLastY, x, y)) {
 //            SkDebugf("--- drop touchMove, withing jitter tolerance %g %g\n", rec.fLastX - x, rec.fLastY - y);
             return;
         }
     }

     rec.fPrevX = rec.fLastX; rec.fLastX = x;
     rec.fPrevY = rec.fLastY; rec.fLastY = y;
     rec.fPrevT = rec.fLastT;
     rec.fLastT = static_cast<float>(SkTime::GetSecs());

     switch (fTouches.count()) {
         case 1: {
             float dx = rec.fLastX - rec.fStartX;
             float dy = rec.fLastY - rec.fStartY;
             dx = (float)sk_float_round2int(dx);
             dy = (float)sk_float_round2int(dy);
             fLocalM.setTranslate(dx, dy);
         } break;
         case 2: {
             SkASSERT(kZoom_State == fState);
             const Rec& rec0 = fTouches[0];
             const Rec& rec1 = fTouches[1];

             float scale = this->computePinch(rec0, rec1);
             scale = this->limitTotalZoom(scale);

             fLocalM.setTranslate(-center(rec0.fStartX, rec1.fStartX),
                                  -center(rec0.fStartY, rec1.fStartY));
             fLocalM.postScale(scale, scale);
             fLocalM.postTranslate(center(rec0.fLastX, rec1.fLastX),
                                   center(rec0.fLastY, rec1.fLastY));
         } break;
         default:
             break;
     }
 }

 void SkTouchGesture::touchEnd(void* owner) {
 //    SkDebugf("--- %d touchEnd   %p\n", fTouches.count(), owner);

     int index = this->findRec(owner);
     if (index < 0) {
         SkDebugf("--- not found\n");
         return;
     }

     const Rec& rec = fTouches[index];
     if (this->handleDblTap(rec.fLastX, rec.fLastY)) {
         return;
     }

     // count() reflects the number before we removed the owner
     switch (fTouches.count()) {
         case 1: {
             this->flushLocalM();
             float dx = rec.fLastX - rec.fPrevX;
             float dy = rec.fLastY - rec.fPrevY;
             float dur = rec.fLastT - rec.fPrevT;
             if (dur > 0) {
                 fFlinger.reset(dx / dur, dy / dur);
             }
             fState = kEmpty_State;
         } break;
         case 2:
             this->flushLocalM();
             SkASSERT(kZoom_State == fState);
             fState = kEmpty_State;
             break;
         default:
             SkASSERT(kZoom_State == fState);
             break;
     }

     fTouches.removeShuffle(index);

     limitTrans();
 }

 float SkTouchGesture::computePinch(const Rec& rec0, const Rec& rec1) {
     double dx = rec0.fStartX - rec1.fStartX;
     double dy = rec0.fStartY - rec1.fStartY;
     double dist0 = sqrt(dx*dx + dy*dy);

     dx = rec0.fLastX - rec1.fLastX;
     dy = rec0.fLastY - rec1.fLastY;
     double dist1 = sqrt(dx*dx + dy*dy);

     double scale = dist1 / dist0;
     return (float)scale;
 }

 bool SkTouchGesture::handleDblTap(float x, float y) {
     bool found = false;
     double now = SkTime::GetMSecs();
     if (now - fLastUpMillis <= MAX_DBL_TAP_INTERVAL) {
         if (SkPoint::Length(fLastUpP.fX - x,
                             fLastUpP.fY - y) <= MAX_DBL_TAP_DISTANCE) {
             fFlinger.stop();
             fLocalM.reset();
             fGlobalM.reset();
             fTouches.reset();
             fState = kEmpty_State;
             found = true;
         }
     }

     fLastUpMillis = now;
     fLastUpP.set(x, y);
     return found;
 }

 void SkTouchGesture::setTransLimit(const SkRect& contentRect, const SkRect& windowRect) {
     fIsTransLimited = true;
     fContentRect = contentRect;
     fWindowRect = windowRect;
 }

 void SkTouchGesture::limitTrans() {
     if (!fIsTransLimited) {
         return;
     }

     SkRect scaledContent = fContentRect;
     fGlobalM.mapRect(&scaledContent);
     const SkScalar ZERO = 0;

     fGlobalM.postTranslate(ZERO, std::min(ZERO, fWindowRect.fBottom - scaledContent.fTop));
     fGlobalM.postTranslate(ZERO, std::max(ZERO, fWindowRect.fTop - scaledContent.fBottom));
     fGlobalM.postTranslate(std::min(ZERO, fWindowRect.fRight - scaledContent.fLeft), ZERO);
     fGlobalM.postTranslate(std::max(ZERO, fWindowRect.fLeft - scaledContent.fRight), ZERO);
 }
	/*
	* Copyright 2010 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#include <algorithm>

	#include "SkTouchGesture.h"
	#include "SkMatrix.h"
	#include "SkTime.h"

	#define DISCRETIZE_TRANSLATE_TO_AVOID_FLICKER true

	static const SkScalar MAX_FLING_SPEED = SkIntToScalar(1500);

	static SkScalar pin_max_fling(SkScalar speed) {
	if (speed > MAX_FLING_SPEED) {
	speed = MAX_FLING_SPEED;
	}
	return speed;
	}

	static double getseconds() {
	return SkTime::GetMSecs() * 0.001;
	}

	// returns +1 or -1, depending on the sign of x
	// returns +1 if z is zero
	static SkScalar SkScalarSignNonZero(SkScalar x) {
	SkScalar sign = SK_Scalar1;
	if (x < 0) {
	sign = -sign;
	}
	return sign;
	}

	static void unit_axis_align(SkVector* unit) {
	const SkScalar TOLERANCE = SkDoubleToScalar(0.15);
	if (SkScalarAbs(unit->fX) < TOLERANCE) {
	unit->fX = 0;
	unit->fY = SkScalarSignNonZero(unit->fY);
	} else if (SkScalarAbs(unit->fY) < TOLERANCE) {
	unit->fX = SkScalarSignNonZero(unit->fX);
	unit->fY = 0;
	}
	}

	void SkFlingState::reset(float sx, float sy) {
	fActive = true;
	fDirection.set(sx, sy);
	fSpeed0 = SkPoint::Normalize(&fDirection);
	fSpeed0 = pin_max_fling(fSpeed0);
	fTime0 = getseconds();

	unit_axis_align(&fDirection);
	// printf("---- speed %g dir %g %g\n", fSpeed0, fDirection.fX, fDirection.fY);
	}

	bool SkFlingState::evaluateMatrix(SkMatrix* matrix) {
	if (!fActive) {
	return false;
	}

	const float t = (float)(getseconds() - fTime0);
	const float MIN_SPEED = 2;
	const float K0 = 5;
	const float K1 = 0.02f;
	const float speed = fSpeed0 * (sk_float_exp(- K0 * t) - K1);
	if (speed <= MIN_SPEED) {
	fActive = false;
	return false;
	}
	float dist = (fSpeed0 - speed) / K0;

	// printf("---- time %g speed %g dist %g\n", t, speed, dist);
	float tx = fDirection.fX * dist;
	float ty = fDirection.fY * dist;
	if (DISCRETIZE_TRANSLATE_TO_AVOID_FLICKER) {
	tx = (float)sk_float_round2int(tx);
	ty = (float)sk_float_round2int(ty);
	}
	matrix->setTranslate(tx, ty);
	// printf("---- evaluate (%g %g)\n", tx, ty);

	return true;
	}

	///////////////////////////////////////////////////////////////////////////////

	static const SkMSec MAX_DBL_TAP_INTERVAL = 300;
	static const float MAX_DBL_TAP_DISTANCE = 100;
	static const float MAX_JITTER_RADIUS = 2;

	// if true, then ignore the touch-move, 'cause its probably just jitter
	static bool close_enough_for_jitter(float x0, float y0, float x1, float y1) {
	return sk_float_abs(x0 - x1) <= MAX_JITTER_RADIUS &&
	sk_float_abs(y0 - y1) <= MAX_JITTER_RADIUS;
	}

	///////////////////////////////////////////////////////////////////////////////

	SkTouchGesture::SkTouchGesture() {
	this->reset();
	}

	SkTouchGesture::~SkTouchGesture() {
	}

	void SkTouchGesture::reset() {
	fIsTransLimited = false;
	fTouches.reset();
	fState = kEmpty_State;
	fLocalM.reset();
	fGlobalM.reset();

	fLastUpMillis = SkTime::GetMSecs() - 2*MAX_DBL_TAP_INTERVAL;
	fLastUpP.set(0, 0);
	}

	void SkTouchGesture::flushLocalM() {
	fGlobalM.postConcat(fLocalM);
	fLocalM.reset();
	}

	const SkMatrix& SkTouchGesture::localM() {
	if (fFlinger.isActive()) {
	if (!fFlinger.evaluateMatrix(&fLocalM)) {
	this->flushLocalM();
	}
	}
	return fLocalM;
	}

	void SkTouchGesture::appendNewRec(void* owner, float x, float y) {
	Rec* rec = fTouches.append();
	rec->fOwner = owner;
	rec->fStartX = rec->fPrevX = rec->fLastX = x;
	rec->fStartY = rec->fPrevY = rec->fLastY = y;
	rec->fLastT = rec->fPrevT = static_cast<float>(SkTime::GetSecs());
	}

	void SkTouchGesture::touchBegin(void* owner, float x, float y) {
	// SkDebugf("--- %d touchBegin %p %g %g\n", fTouches.count(), owner, x, y);

	int index = this->findRec(owner);
	if (index >= 0) {
	this->flushLocalM();
	fTouches.removeShuffle(index);
	SkDebugf("---- already exists, removing\n");
	}

	if (fTouches.count() == 2) {
	return;
	}

	this->flushLocalM();
	fFlinger.stop();

	this->appendNewRec(owner, x, y);

	switch (fTouches.count()) {
	case 1:
	fState = kTranslate_State;
	break;
	case 2:
	fState = kZoom_State;
	break;
	default:
	break;
	}
	}

	int SkTouchGesture::findRec(void* owner) const {
	for (int i = 0; i < fTouches.count(); i++) {
	if (owner == fTouches[i].fOwner) {
	return i;
	}
	}
	return -1;
	}

	static SkScalar center(float pos0, float pos1) {
	return (pos0 + pos1) * 0.5f;
	}

	static const float MAX_ZOOM_SCALE = 4;
	static const float MIN_ZOOM_SCALE = 0.25f;

	float SkTouchGesture::limitTotalZoom(float scale) const {
	// this query works 'cause we know that we're square-scale w/ no skew/rotation
	const float curr = SkScalarToFloat(fGlobalM[0]);

	if (scale > 1 && curr * scale > MAX_ZOOM_SCALE) {
	scale = MAX_ZOOM_SCALE / curr;
	} else if (scale < 1 && curr * scale < MIN_ZOOM_SCALE) {
	scale = MIN_ZOOM_SCALE / curr;
	}
	return scale;
	}

	void SkTouchGesture::touchMoved(void* owner, float x, float y) {
	// SkDebugf("--- %d touchMoved %p %g %g\n", fTouches.count(), owner, x, y);

	if (kEmpty_State == fState) {
	return;
	}

	int index = this->findRec(owner);
	if (index < 0) {
	// not found, so I guess we should add it...
	SkDebugf("---- add missing begin\n");
	this->appendNewRec(owner, x, y);
	index = fTouches.count() - 1;
	}

	Rec& rec = fTouches[index];

	// not sure how valuable this is
	if (fTouches.count() == 2) {
	if (close_enough_for_jitter(rec.fLastX, rec.fLastY, x, y)) {
	// SkDebugf("--- drop touchMove, withing jitter tolerance %g %g\n", rec.fLastX - x, rec.fLastY - y);
	return;
	}
	}

	rec.fPrevX = rec.fLastX; rec.fLastX = x;
	rec.fPrevY = rec.fLastY; rec.fLastY = y;
	rec.fPrevT = rec.fLastT;
	rec.fLastT = static_cast<float>(SkTime::GetSecs());

	switch (fTouches.count()) {
	case 1: {
	float dx = rec.fLastX - rec.fStartX;
	float dy = rec.fLastY - rec.fStartY;
	dx = (float)sk_float_round2int(dx);
	dy = (float)sk_float_round2int(dy);
	fLocalM.setTranslate(dx, dy);
	} break;
	case 2: {
	SkASSERT(kZoom_State == fState);
	const Rec& rec0 = fTouches[0];
	const Rec& rec1 = fTouches[1];

	float scale = this->computePinch(rec0, rec1);
	scale = this->limitTotalZoom(scale);

	fLocalM.setTranslate(-center(rec0.fStartX, rec1.fStartX),
	-center(rec0.fStartY, rec1.fStartY));
	fLocalM.postScale(scale, scale);
	fLocalM.postTranslate(center(rec0.fLastX, rec1.fLastX),
	center(rec0.fLastY, rec1.fLastY));
	} break;
	default:
	break;
	}
	}

	void SkTouchGesture::touchEnd(void* owner) {
	// SkDebugf("--- %d touchEnd %p\n", fTouches.count(), owner);

	int index = this->findRec(owner);
	if (index < 0) {
	SkDebugf("--- not found\n");
	return;
	}

	const Rec& rec = fTouches[index];
	if (this->handleDblTap(rec.fLastX, rec.fLastY)) {
	return;
	}

	// count() reflects the number before we removed the owner
	switch (fTouches.count()) {
	case 1: {
	this->flushLocalM();
	float dx = rec.fLastX - rec.fPrevX;
	float dy = rec.fLastY - rec.fPrevY;
	float dur = rec.fLastT - rec.fPrevT;
	if (dur > 0) {
	fFlinger.reset(dx / dur, dy / dur);
	}
	fState = kEmpty_State;
	} break;
	case 2:
	this->flushLocalM();
	SkASSERT(kZoom_State == fState);
	fState = kEmpty_State;
	break;
	default:
	SkASSERT(kZoom_State == fState);
	break;
	}

	fTouches.removeShuffle(index);

	limitTrans();
	}

	float SkTouchGesture::computePinch(const Rec& rec0, const Rec& rec1) {
	double dx = rec0.fStartX - rec1.fStartX;
	double dy = rec0.fStartY - rec1.fStartY;
	double dist0 = sqrt(dxdx + dydy);

	dx = rec0.fLastX - rec1.fLastX;
	dy = rec0.fLastY - rec1.fLastY;
	double dist1 = sqrt(dxdx + dydy);

	double scale = dist1 / dist0;
	return (float)scale;
	}

	bool SkTouchGesture::handleDblTap(float x, float y) {
	bool found = false;
	double now = SkTime::GetMSecs();
	if (now - fLastUpMillis <= MAX_DBL_TAP_INTERVAL) {
	if (SkPoint::Length(fLastUpP.fX - x,
	fLastUpP.fY - y) <= MAX_DBL_TAP_DISTANCE) {
	fFlinger.stop();
	fLocalM.reset();
	fGlobalM.reset();
	fTouches.reset();
	fState = kEmpty_State;
	found = true;
	}
	}

	fLastUpMillis = now;
	fLastUpP.set(x, y);
	return found;
	}

	void SkTouchGesture::setTransLimit(const SkRect& contentRect, const SkRect& windowRect) {
	fIsTransLimited = true;
	fContentRect = contentRect;
	fWindowRect = windowRect;
	}

	void SkTouchGesture::limitTrans() {
	if (!fIsTransLimited) {
	return;
	}

	SkRect scaledContent = fContentRect;
	fGlobalM.mapRect(&scaledContent);
	const SkScalar ZERO = 0;

	fGlobalM.postTranslate(ZERO, std::min(ZERO, fWindowRect.fBottom - scaledContent.fTop));
	fGlobalM.postTranslate(ZERO, std::max(ZERO, fWindowRect.fTop - scaledContent.fBottom));
	fGlobalM.postTranslate(std::min(ZERO, fWindowRect.fRight - scaledContent.fLeft), ZERO);
	fGlobalM.postTranslate(std::max(ZERO, fWindowRect.fLeft - scaledContent.fRight), ZERO);
	}