add fling

git-svn-id: http://skia.googlecode.com/svn/trunk@946 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 336 insertions, 0 deletions

diff --git a/src/views/SkTouchGesture.cpp b/src/views/SkTouchGesture.cpp
new file mode 100644
index 0000000000..70eb6d3c9d
--- /dev/null
+++ b/src/views/SkTouchGesture.cpp
@@ -0,0 +1,336 @@
+/*
+    Copyright 2010 Google Inc.
+
+    Licensed under the Apache License, Version 2.0 (the "License");
+    you may not use this file except in compliance with the License.
+    You may obtain a copy of the License at
+
+         http://www.apache.org/licenses/LICENSE-2.0
+
+    Unless required by applicable law or agreed to in writing, software
+    distributed under the License is distributed on an "AS IS" BASIS,
+    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+    See the License for the specific language governing permissions and
+    limitations under the License.
+ */
+
+
+#include "SkTouchGesture.h"
+#include "SkMatrix.h"
+#include "SkTime.h"
+
+#define DISCRETIZE_TRANSLATE_TO_AVOID_FLICKER   true
+
+static const float MAX_FLING_SPEED = 1500;
+
+static float pin_max_fling(float 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 x is zero
+static SkScalar SkScalarSign(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 = SkScalarSign(unit->fY);
+    } else if (SkScalarAbs(unit->fY) < TOLERANCE) {
+        unit->fX = SkScalarSign(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 =  getseconds() - fTime0;
+    const float MIN_SPEED = 2;
+    const float K0 = 5.0;
+    const float K1 = 0.02;
+    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 = sk_float_round2int(tx);
+        ty = 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() {
+    fTouches.reset();
+    fState = kEmpty_State;
+    fLocalM.reset();
+    fGlobalM.reset();
+
+    fLastUpT = 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 = SkTime::GetMSecs();
+}
+
+void SkTouchGesture::touchBegin(void* owner, float x, float y) {
+//    GrPrintf("--- %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 float 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 = 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) {
+//    GrPrintf("--- %d touchMoved %p %g %g\n", fTouches.count(), owner, x, y);
+
+    SkASSERT(kEmpty_State != fState);
+
+    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)) {
+//            GrPrintf("--- 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 = SkTime::GetMSecs();
+
+    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) {
+//    GrPrintf("--- %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) * 0.001f;
+            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);
+}
+
+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;
+    SkMSec now = SkTime::GetMSecs();
+    if (now - fLastUpT <= 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;
+        }
+    }
+
+    fLastUpT = now;
+    fLastUpP.set(x, y);
+    return found;
+}
+
+