Correct gesture scale and translation

src/views/SkTouchGesture.cpp

 /*
  * 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) {
@@ skipping 83 matching lines @@
 ///////////////////////////////////////////////////////////////////////////////
 
 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() {
@@ skipping 164 matching lines @@
             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);
@@ skipping 14 matching lines @@
             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);
+}