/*
* 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::resetTouchState() {
fIsTransLimited = false;
fTouches.reset();
fState = kEmpty_State;
fLocalM.reset();
fLastUpMillis = SkTime::GetMSecs() - 2*MAX_DBL_TAP_INTERVAL;
fLastUpP.set(0, 0);
}
void SkTouchGesture::reset() {
fGlobalM.reset();
this->resetTouchState();
}
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) {
SkDebugf("---- ignoring move without begin\n");
return;
}
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, within 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,
const SkMatrix& preTouchMatrix) {
fIsTransLimited = true;
fContentRect = contentRect;
fWindowRect = windowRect;
fPreTouchM = preTouchMatrix;
}
void SkTouchGesture::limitTrans() {
if (!fIsTransLimited) {
return;
}
SkRect scaledContent = fContentRect;
fPreTouchM.mapRect(&scaledContent);
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);
}