如何在Android中利用imageview实现一个图片缩放功能

package com.suo.image; 
 
import android.os.Build.VERSION; 
import android.os.Build.VERSION_CODES; 
import android.view.View; 
 
public class Compat { 
  
 private static final int SIXTY_FPS_INTERVAL = 1000 / 60; 
  
 public static void postOnAnimation(View view, Runnable runnable) { 
  if (VERSION.SDK_INT >= VERSION_CODES.JELLY_BEAN) { 
   SDK16.postOnAnimation(view, runnable); 
  } else { 
   view.postDelayed(runnable, SIXTY_FPS_INTERVAL); 
  } 
 } 
 
} 

package com.suo.image; 
 
import android.content.Context; 
import android.support.v4.view.ViewPager; 
import android.util.AttributeSet; 
import android.view.MotionEvent; 
 
/** 
 * Hacky fix for Issue #4 and 
 * http://code.google.com/p/android/issues/detail?id=18990 
 * 
 * ScaleGestureDetector seems to mess up the touch events, which means that 
 * ViewGroups which make use of onInterceptTouchEvent throw a lot of 
 * IllegalArgumentException: pointerIndex out of range. 
 * 
 * There's not much I can do in my code for now, but we can mask the result by 
 * just catching the problem and ignoring it. 
 * 
 * @author Chris Banes 
 */ 
public class HackyViewPager extends ViewPager { 
 
 public HackyViewPager(Context context) { 
  super(context); 
 } 
 
 public HackyViewPager(Context context, AttributeSet attrs) { 
  super(context, attrs); 
  // TODO Auto-generated constructor stub 
 } 
 
 @Override 
 public boolean onInterceptTouchEvent(MotionEvent ev) { 
  try { 
   return super.onInterceptTouchEvent(ev); 
  } catch (IllegalArgumentException e) { 
   e.printStackTrace(); 
   return false; 
  } 
 } 
 
} 

/******************************************************************************* 
 * Copyright 2011, 2012 Chris Banes. 
 * 
 * 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. 
 *******************************************************************************/ 
package com.suo.image; 
 
import android.graphics.RectF; 
import android.view.View; 
import android.widget.ImageView; 
 
 
public interface IScaleView { 
 /** 
  * Returns true if the ScaleView is set to allow zooming of Scales. 
  * 
  * @return true if the ScaleView allows zooming. 
  */ 
 boolean canZoom(); 
 
 /** 
  * Gets the Display Rectangle of the currently displayed Drawable. The 
  * Rectangle is relative to this View and includes all scaling and 
  * translations. 
  * 
  * @return - RectF of Displayed Drawable 
  */ 
 RectF getDisplayRect(); 
 
 /** 
  * @return The current minimum scale level. What this value represents depends on the current {@link android.widget.ImageView.ScaleType}. 
  */ 
 float getMinScale(); 
 
 /** 
  * @return The current middle scale level. What this value represents depends on the current {@link android.widget.ImageView.ScaleType}. 
  */ 
 float getMidScale(); 
 
 /** 
  * @return The current maximum scale level. What this value represents depends on the current {@link android.widget.ImageView.ScaleType}. 
  */ 
 float getMaxScale(); 
 
 /** 
  * Returns the current scale value 
  * 
  * @return float - current scale value 
  */ 
 float getScale(); 
 
 /** 
  * Return the current scale type in use by the ImageView. 
  */ 
 ImageView.ScaleType getScaleType(); 
 
 /** 
  * Whether to allow the ImageView's parent to intercept the touch event when the Scale is scroll to it's horizontal edge. 
  */ 
 void setAllowParentInterceptOnEdge(boolean allow); 
 
 /** 
  * Sets the minimum scale level. What this value represents depends on the current {@link android.widget.ImageView.ScaleType}. 
  */ 
 void setMinScale(float minScale); 
 
 /** 
  * Sets the middle scale level. What this value represents depends on the current {@link android.widget.ImageView.ScaleType}. 
  */ 
 void setMidScale(float midScale); 
 
 /** 
  * Sets the maximum scale level. What this value represents depends on the current {@link android.widget.ImageView.ScaleType}. 
  */ 
 void setMaxScale(float maxScale); 
 
 /** 
  * Register a callback to be invoked when the Scale displayed by this view is long-pressed. 
  * 
  * @param listener - Listener to be registered. 
  */ 
 void setOnLongClickListener(View.OnLongClickListener listener); 
 
 /** 
  * Register a callback to be invoked when the Matrix has changed for this 
  * View. An example would be the user panning or scaling the Scale. 
  * 
  * @param listener - Listener to be registered. 
  */ 
 void setOnMatrixChangeListener(ScaleViewAttacher.OnMatrixChangedListener listener); 
 
 /** 
  * Register a callback to be invoked when the Scale displayed by this View 
  * is tapped with a single tap. 
  * 
  * @param listener - Listener to be registered. 
  */ 
 void setOnScaleTapListener(ScaleViewAttacher.OnScaleTapListener listener); 
 
 /** 
  * Register a callback to be invoked when the View is tapped with a single 
  * tap. 
  * 
  * @param listener - Listener to be registered. 
  */ 
 void setOnViewTapListener(ScaleViewAttacher.OnViewTapListener listener); 
 
 /** 
  * Controls how the image should be resized or moved to match the size of 
  * the ImageView. Any scaling or panning will happen within the confines of 
  * this {@link android.widget.ImageView.ScaleType}. 
  * 
  * @param scaleType - The desired scaling mode. 
  */ 
 void setScaleType(ImageView.ScaleType scaleType); 
 
 /** 
  * Allows you to enable/disable the zoom functionality on the ImageView. 
  * When disable the ImageView reverts to using the FIT_CENTER matrix. 
  * 
  * @param zoomable - Whether the zoom functionality is enabled. 
  */ 
 void setZoomable(boolean zoomable); 
 
 /** 
  * Zooms to the specified scale, around the focal point given. 
  * 
  * @param scale - Scale to zoom to 
  * @param focalX - X Focus Point 
  * @param focalY - Y Focus Point 
  */ 
 void zoomTo(float scale, float focalX, float focalY); 
} 

/******************************************************************************* 
 * Copyright 2011, 2012 Chris Banes. 
 * 
 * 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. 
 *******************************************************************************/ 
package com.suo.image; 
 
import com.suo.image.ScaleViewAttacher.OnMatrixChangedListener; 
import com.suo.image.ScaleViewAttacher.OnScaleTapListener; 
import com.suo.image.ScaleViewAttacher.OnViewTapListener; 
 
import android.content.Context; 
import android.graphics.RectF; 
import android.graphics.drawable.Drawable; 
import android.net.Uri; 
import android.util.AttributeSet; 
import android.widget.ImageView; 
 
public class ScaleView extends ImageView implements IScaleView { 
 
 @SuppressWarnings("unused") 
 private static final String TAG = "ScaleView"; 
 private final ScaleViewAttacher mAttacher; 
 
 private ScaleType mPendingScaleType; 
 
 public ScaleView(Context context) { 
  this(context, null); 
  setZoomable(false); 
 } 
 
 public ScaleView(Context context, AttributeSet attr) { 
  this(context, attr, 0); 
 } 
  
 public ScaleView(Context context, AttributeSet attr, int defStyle) { 
  super(context, attr, defStyle); 
  super.setScaleType(ScaleType.MATRIX); 
  mAttacher = new ScaleViewAttacher(this); 
 
  if (null != mPendingScaleType) { 
   setScaleType(mPendingScaleType); 
   mPendingScaleType = null; 
  } 
 } 
  
 public void setOnClickListener(OnClickListener listener){ 
  mAttacher.setOnClickLinstener(listener); 
 } 
 
 @Override 
 public boolean canZoom() { 
  return mAttacher.canZoom(); 
 } 
  
 @Override 
 public RectF getDisplayRect() { 
  return mAttacher.getDisplayRect(); 
 } 
 
 @Override 
 public float getMinScale() { 
  return mAttacher.getMinScale(); 
 } 
 
 @Override 
 public float getMidScale() { 
  return mAttacher.getMidScale(); 
 } 
 
 @Override 
 public float getMaxScale() { 
  return mAttacher.getMaxScale(); 
 } 
 
 @Override 
 public float getScale() { 
  return mAttacher.getScale(); 
 } 
 
 @Override 
 public ScaleType getScaleType() { 
  return mAttacher.getScaleType(); 
 } 
 
 @Override 
 public void setAllowParentInterceptOnEdge(boolean allow) { 
  mAttacher.setAllowParentInterceptOnEdge(allow); 
 } 
 
 @Override 
 public void setMinScale(float minScale) { 
  mAttacher.setMinScale(minScale); 
 } 
 
 @Override 
 public void setMidScale(float midScale) { 
  mAttacher.setMidScale(midScale); 
 } 
 
 @Override 
 public void setMaxScale(float maxScale) { 
  mAttacher.setMaxScale(maxScale); 
 } 
 
 @Override 
 // setImageBitmap calls through to this method 
 public void setImageDrawable(Drawable drawable) { 
  super.setImageDrawable(drawable); 
  if (null != mAttacher) { 
   mAttacher.update(); 
  } 
 } 
 
 @Override 
 public void setImageResource(int resId) { 
  super.setImageResource(resId); 
  if (null != mAttacher) { 
   mAttacher.update(); 
  } 
 } 
 
 @Override 
 public void setImageURI(Uri uri) { 
  super.setImageURI(uri); 
  if (null != mAttacher) { 
   mAttacher.update(); 
  } 
 } 
 
 @Override 
 public void setOnMatrixChangeListener(OnMatrixChangedListener listener) { 
  mAttacher.setOnMatrixChangeListener(listener); 
 } 
 
 @Override 
 public void setOnLongClickListener(OnLongClickListener l) { 
  mAttacher.setOnLongClickListener(l); 
 } 
 
 @Override 
 public void setOnScaleTapListener(OnScaleTapListener listener) { 
  mAttacher.setOnScaleTapListener(listener); 
 } 
 
 @Override 
 public void setOnViewTapListener(OnViewTapListener listener) { 
  mAttacher.setOnViewTapListener(listener); 
 } 
 
 @Override 
 public void setScaleType(ScaleType scaleType) { 
  if (null != mAttacher) { 
   mAttacher.setScaleType(scaleType); 
  } else { 
   mPendingScaleType = scaleType; 
  } 
 } 
 
 @Override 
 public void setZoomable(boolean zoomable) { 
  mAttacher.setZoomable(zoomable); 
 } 
 
 @Override 
 public void zoomTo(float scale, float focalX, float focalY) { 
  mAttacher.zoomTo(scale, focalX, focalY); 
 } 
 
 @Override 
 protected void onDetachedFromWindow() { 
  mAttacher.cleanup(); 
  super.onDetachedFromWindow(); 
 } 
 
} 

/******************************************************************************* 
 * Copyright 2011, 2012 Chris Banes. 
 * 
 * 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. 
 *******************************************************************************/ 
package com.suo.image; 
 
import android.content.Context; 
import android.graphics.Matrix; 
import android.graphics.Matrix.ScaleToFit; 
import android.graphics.RectF; 
import android.graphics.drawable.Drawable; 
import android.util.Log; 
import android.view.GestureDetector; 
import android.view.MotionEvent; 
import android.view.View; 
import android.view.View.OnClickListener; 
import android.view.View.OnLongClickListener; 
import android.view.ViewTreeObserver; 
import android.widget.ImageView; 
import android.widget.ImageView.ScaleType; 
 
import java.lang.ref.WeakReference; 
 
public class ScaleViewAttacher implements IScaleView, View.OnTouchListener, VersionedGestureDetector.OnGestureListener, 
  GestureDetector.OnDoubleTapListener, ViewTreeObserver.OnGlobalLayoutListener { 
 
 static final String LOG_TAG = "ScaleViewAttacher"; 
 
 // let debug flag be dynamic, but still Proguard can be used to remove from release builds 
 static final boolean DEBUG = Log.isLoggable(LOG_TAG, Log.DEBUG); 
 
 static final int EDGE_NONE = -1; 
 static final int EDGE_LEFT = 0; 
 static final int EDGE_RIGHT = 1; 
 static final int EDGE_BOTH = 2; 
 
 public static final float DEFAULT_MAX_SCALE = 3.0f; 
 public static final float DEFAULT_MID_SCALE = 1.75f; 
 public static final float DEFAULT_MIN_SCALE = 1.0f; 
 
 private float mMinScale = DEFAULT_MIN_SCALE; 
 private float mMidScale = DEFAULT_MID_SCALE; 
 private float mMaxScale = DEFAULT_MAX_SCALE; 
 
 private boolean mAllowParentInterceptOnEdge = true; 
 
 private static void checkZoomLevels(float minZoom, float midZoom, float maxZoom) { 
  if (minZoom >= midZoom) { 
   throw new IllegalArgumentException("MinZoom should be less than MidZoom"); 
  } else if (midZoom >= maxZoom) { 
   throw new IllegalArgumentException("MidZoom should be less than MaxZoom"); 
  } 
 } 
 
 /** 
  * @return true if the ImageView exists, and it's Drawable existss 
  */ 
 private static boolean hasDrawable(ImageView imageView) { 
  return null != imageView && null != imageView.getDrawable(); 
 } 
 
 /** 
  * @return true if the ScaleType is supported. 
  */ 
 private static boolean isSupportedScaleType(final ScaleType scaleType) { 
  if (null == scaleType) { 
   return false; 
  } 
 
  switch (scaleType) { 
   case MATRIX: 
    throw new IllegalArgumentException(scaleType.name() + " is not supported in ScaleView"); 
 
   default: 
    return true; 
  } 
 } 
 
 /** 
  * Set's the ImageView's ScaleType to Matrix. 
  */ 
 private static void setImageViewScaleTypeMatrix(ImageView imageView) { 
  if (null != imageView) { 
   if (imageView instanceof ScaleView) { 
    /** 
     * ScaleView sets it's own ScaleType to Matrix, then diverts all 
     * calls setScaleType to this.setScaleType. Basically we don't 
     * need to do anything here 
     */ 
   } else { 
    imageView.setScaleType(ScaleType.MATRIX); 
   } 
  } 
 } 
 
 private WeakReference<ImageView> mImageView; 
 private ViewTreeObserver mViewTreeObserver; 
 
 // Gesture Detectors 
 private GestureDetector mGestureDetector; 
 private VersionedGestureDetector mScaleDragDetector; 
 
 // These are set so we don't keep allocating them on the heap 
 private final Matrix mBaseMatrix = new Matrix(); 
 private final Matrix mDrawMatrix = new Matrix(); 
 private final Matrix mSuppMatrix = new Matrix(); 
 private final RectF mDisplayRect = new RectF(); 
 private final float[] mMatrixValues = new float[9]; 
 
 // Listeners 
 private OnMatrixChangedListener mMatrixChangeListener; 
 private OnScaleTapListener mScaleTapListener; 
 private OnViewTapListener mViewTapListener; 
 private OnLongClickListener mLongClickListener; 
 
 private int mIvTop, mIvRight, mIvBottom, mIvLeft; 
 private FlingRunnable mCurrentFlingRunnable; 
 private int mScrollEdge = EDGE_BOTH; 
 
 private boolean mZoomEnabled; 
 private ScaleType mScaleType = ScaleType.FIT_CENTER; 
 private OnClickListener onClickListener; 
 
 public ScaleViewAttacher(ImageView imageView) { 
  mImageView = new WeakReference<ImageView>(imageView); 
 
  imageView.setOnTouchListener(this); 
 
  mViewTreeObserver = imageView.getViewTreeObserver(); 
  if (mViewTreeObserver != null) { 
   mViewTreeObserver.addOnGlobalLayoutListener(this); 
  } 
  onClickListener = null; 
 
  // Make sure we using MATRIX Scale Type 
  setImageViewScaleTypeMatrix(imageView); 
 
  if (!imageView.isInEditMode()) { 
   // Create Gesture Detectors... 
   mScaleDragDetector = VersionedGestureDetector.newInstance(imageView.getContext(), this); 
 
   mGestureDetector = new GestureDetector(imageView.getContext(), 
     new GestureDetector.SimpleOnGestureListener() { 
 
      // forward long click listener 
      @Override 
      public void onLongPress(MotionEvent e) { 
       if(null != mLongClickListener) { 
        mLongClickListener.onLongClick(mImageView.get()); 
       } 
      }}); 
 
   mGestureDetector.setOnDoubleTapListener(this); 
 
   // Finally, update the UI so that we're zoomable 
   setZoomable(true); 
  } 
 } 
 
 @Override 
 public final boolean canZoom() { 
  return mZoomEnabled; 
 } 
 
 /** 
  * Clean-up the resources attached to this object. This needs to be called 
  * when the ImageView is no longer used. A good example is from 
  * {@link android.view.View#onDetachedFromWindow()} or from {@link android.app.Activity#onDestroy()}. 
  * This is automatically called if you are using {@link ScaleView.co.senab.Scaleview.ScaleView}. 
  */ 
 @SuppressWarnings("deprecation") 
 public final void cleanup() { 
  if (null != mImageView) { 
   android.view.ViewTreeObserver obs = mImageView.get().getViewTreeObserver(); 
   if (obs != null) { 
    obs.removeGlobalOnLayoutListener(this); 
   } 
  } 
  mViewTreeObserver = null; 
 
  // Clear listeners too 
  mMatrixChangeListener = null; 
  mScaleTapListener = null; 
  mViewTapListener = null; 
 
  // Finally, clear ImageView 
  mImageView = null; 
 } 
 
 @Override 
 public final RectF getDisplayRect() { 
  checkMatrixBounds(); 
  return getDisplayRect(getDisplayMatrix()); 
 } 
 
 public final ImageView getImageView() { 
  ImageView imageView = null; 
 
  if (null != mImageView) { 
   imageView = mImageView.get(); 
  } 
 
  // If we don't have an ImageView, call cleanup() 
  if (null == imageView) { 
   cleanup(); 
//   throw new IllegalStateException( 
//     "ImageView no longer exists. You should not use this ScaleViewAttacher any more."); 
  } 
 
  return imageView; 
 } 
 
 @Override 
 public float getMinScale() { 
  return mMinScale; 
 } 
 
 @Override 
 public float getMidScale() { 
  return mMidScale; 
 } 
 
 @Override 
 public float getMaxScale() { 
  return mMaxScale; 
 } 
 
 @Override 
 public final float getScale() { 
  return getValue(mSuppMatrix, Matrix.MSCALE_X); 
 } 
 
 @Override 
 public final ScaleType getScaleType() { 
  return mScaleType; 
 } 
 
 public final boolean onDoubleTap(MotionEvent ev) { 
  try { 
   float scale = getScale(); 
   float x = ev.getX(); 
   float y = ev.getY(); 
 
   if (scale < mMidScale) { 
    zoomTo(mMidScale, x, y); 
   } else if (scale >= mMidScale && scale < mMaxScale) { 
    zoomTo(mMaxScale, x, y); 
   } else { 
    zoomTo(mMinScale, x, y); 
   } 
  } catch (ArrayIndexOutOfBoundsException e) { 
   // Can sometimes happen when getX() and getY() is called 
  } 
 
  return true; 
 } 
 
 public final boolean onDoubleTapEvent(MotionEvent e) { 
  // Wait for the confirmed onDoubleTap() instead 
  return false; 
 } 
 
 public final void onDrag(float dx, float dy) { 
  if (DEBUG) { 
   Log.d(LOG_TAG, String.format("onDrag: dx: %.2f. dy: %.2f", dx, dy)); 
  } 
 
  ImageView imageView = getImageView(); 
 
  if (null != imageView && hasDrawable(imageView)) { 
   mSuppMatrix.postTranslate(dx, dy); 
   checkAndDisplayMatrix(); 
 
   /** 
    * Here we decide whether to let the ImageView's parent to start 
    * taking over the touch event. 
    * 
    * First we check whether this function is enabled. We never want the 
    * parent to take over if we're scaling. We then check the edge we're 
    * on, and the direction of the scroll (i.e. if we're pulling against 
    * the edge, aka 'overscrolling', let the parent take over). 
    */ 
   if (mAllowParentInterceptOnEdge && !mScaleDragDetector.isScaling()) { 
    if (mScrollEdge == EDGE_BOTH || (mScrollEdge == EDGE_LEFT && dx >= 1f) 
      || (mScrollEdge == EDGE_RIGHT && dx <= -1f)) { 
      android.view.ViewParent vParent = imageView.getParent(); 
     if (vParent != null) { 
      vParent.requestDisallowInterceptTouchEvent(false); 
     } 
    } 
   } 
  } 
 } 
 
 @Override 
 public final void onFling(float startX, float startY, float velocityX, float velocityY) { 
  if (DEBUG) { 
   Log.d(LOG_TAG, "onFling. sX: " + startX + " sY: " + startY + " Vx: " + velocityX + " Vy: " + velocityY); 
  } 
 
  ImageView imageView = getImageView(); 
  if (hasDrawable(imageView)) { 
   mCurrentFlingRunnable = new FlingRunnable(imageView.getContext()); 
   mCurrentFlingRunnable.fling(imageView.getWidth(), imageView.getHeight(), (int) velocityX, (int) velocityY); 
   imageView.post(mCurrentFlingRunnable); 
  } 
 } 
 
 @Override 
 public final void onGlobalLayout() { 
  ImageView imageView = getImageView(); 
 
  if (null != imageView && mZoomEnabled) { 
   final int top = imageView.getTop(); 
   final int right = imageView.getRight(); 
   final int bottom = imageView.getBottom(); 
   final int left = imageView.getLeft(); 
 
   /** 
    * We need to check whether the ImageView's bounds have changed. 
    * This would be easier if we targeted API 11+ as we could just use 
    * View.OnLayoutChangeListener. Instead we have to replicate the 
    * work, keeping track of the ImageView's bounds and then checking 
    * if the values change. 
    */ 
   if (top != mIvTop || bottom != mIvBottom || left != mIvLeft || right != mIvRight) { 
    // Update our base matrix, as the bounds have changed 
    updateBaseMatrix(imageView.getDrawable()); 
 
    // Update values as something has changed 
    mIvTop = top; 
    mIvRight = right; 
    mIvBottom = bottom; 
    mIvLeft = left; 
   } 
  } 
 } 
  
 public final void setOnClickLinstener(OnClickListener listener){ 
  onClickListener = listener; 
 } 
 
 public final void onScale(float scaleFactor, float focusX, float focusY) { 
  if (DEBUG) { 
   Log.d(LOG_TAG, String.format("onScale: scale: %.2f. fX: %.2f. fY: %.2f", scaleFactor, focusX, focusY)); 
  } 
 
  if (hasDrawable(getImageView()) && (getScale() < mMaxScale || scaleFactor < 1f)) { 
   mSuppMatrix.postScale(scaleFactor, scaleFactor, focusX, focusY); 
   checkAndDisplayMatrix(); 
  } 
 } 
 
 public final boolean onSingleTapConfirmed(MotionEvent e) { 
  ImageView imageView = getImageView(); 
 
  if (null != imageView) { 
   if (null != mScaleTapListener) { 
    final RectF displayRect = getDisplayRect(); 
 
    if (null != displayRect) { 
     final float x = e.getX(), y = e.getY(); 
 
     // Check to see if the user tapped on the Scale 
     if (displayRect.contains(x, y)) { 
 
      float xResult = (x - displayRect.left) / displayRect.width(); 
      float yResult = (y - displayRect.top) / displayRect.height(); 
 
      mScaleTapListener.onScaleTap(imageView, xResult, yResult); 
      return true; 
     } 
    } 
   } 
   if (null != mViewTapListener) { 
    mViewTapListener.onViewTap(imageView, e.getX(), e.getY()); 
   } 
  } 
 
  return false; 
 } 
  
 private float lastPosX, lastPosY; 
 private long firClick = 0; 
 
 @Override 
 public final boolean onTouch(View v, MotionEvent ev) { 
  boolean handled = false; 
 
  if (mZoomEnabled) { 
   switch (ev.getAction()) { 
    case MotionEvent.ACTION_DOWN: 
     // First, disable the Parent from intercepting the touch 
     // event 
     android.view.ViewParent vParent = v.getParent(); 
     if (vParent != null) { 
      vParent.requestDisallowInterceptTouchEvent(true); 
     } 
 
     lastPosX = ev.getX(); 
     lastPosY = ev.getY(); 
     // If we're flinging, and the user presses down, cancel 
     // fling 
     cancelFling(); 
     break; 
 
    case MotionEvent.ACTION_CANCEL: 
    case MotionEvent.ACTION_UP: 
     // If the user has zoomed less than min scale, zoom back 
     // to min scale 
     if (getScale() < mMinScale) { 
      RectF rect = getDisplayRect(); 
      if (null != rect) { 
       v.post(new AnimatedZoomRunnable(getScale(), mMinScale, rect.centerX(), rect.centerY())); 
       handled = true; 
      } 
     } 
      
     if(ev.getX() == lastPosX && ev.getY() == lastPosY){ 
      long time = System.currentTimeMillis(); 
      if(time - firClick > 500){ 
       firClick = System.currentTimeMillis(); 
       if(onClickListener != null){ 
        onClickListener.onClick(getImageView()); 
       } 
      } 
     } 
     break; 
   } 
 
   // Check to see if the user double tapped 
   if (null != mGestureDetector && mGestureDetector.onTouchEvent(ev)) { 
    handled = true; 
   } 
 
   // Finally, try the Scale/Drag detector 
   if (null != mScaleDragDetector && mScaleDragDetector.onTouchEvent(ev)) { 
    handled = true; 
   } 
  } 
 
  return handled; 
 } 
 
 @Override 
 public void setAllowParentInterceptOnEdge(boolean allow) { 
  mAllowParentInterceptOnEdge = allow; 
 } 
 
 @Override 
 public void setMinScale(float minScale) { 
  checkZoomLevels(minScale, mMidScale, mMaxScale); 
  mMinScale = minScale; 
 } 
 
 @Override 
 public void setMidScale(float midScale) { 
  checkZoomLevels(mMinScale, midScale, mMaxScale); 
  mMidScale = midScale; 
 } 
 
 @Override 
 public void setMaxScale(float maxScale) { 
  checkZoomLevels(mMinScale, mMidScale, maxScale); 
  mMaxScale = maxScale; 
 } 
 
 @Override 
 public final void setOnLongClickListener(OnLongClickListener listener) { 
  mLongClickListener = listener; 
 } 
 
 @Override 
 public final void setOnMatrixChangeListener(OnMatrixChangedListener listener) { 
  mMatrixChangeListener = listener; 
 } 
 
 @Override 
 public final void setOnScaleTapListener(OnScaleTapListener listener) { 
  mScaleTapListener = listener; 
 } 
 
 @Override 
 public final void setOnViewTapListener(OnViewTapListener listener) { 
  mViewTapListener = listener; 
 } 
 
 @Override 
 public final void setScaleType(ScaleType scaleType) { 
  if (isSupportedScaleType(scaleType) && scaleType != mScaleType) { 
//   mScaleType = scaleType; 
 
   // Finally update 
   update(); 
  } 
 } 
 
 @Override 
 public final void setZoomable(boolean zoomable) { 
  mZoomEnabled = zoomable; 
  update(); 
 } 
 
 public final void update() { 
  ImageView imageView = getImageView(); 
 
  if (null != imageView) { 
   if (mZoomEnabled) { 
    // Make sure we using MATRIX Scale Type 
    setImageViewScaleTypeMatrix(imageView); 
 
    // Update the base matrix using the current drawable 
    updateBaseMatrix(imageView.getDrawable()); 
   } else { 
    // Reset the Matrix... 
    resetMatrix(); 
   } 
  } 
 } 
 
 @Override 
 public final void zoomTo(float scale, float focalX, float focalY) { 
  ImageView imageView = getImageView(); 
 
  if (null != imageView) { 
   imageView.post(new AnimatedZoomRunnable(getScale(), scale, focalX, focalY)); 
  } 
 } 
 
 protected Matrix getDisplayMatrix() { 
  mDrawMatrix.set(mBaseMatrix); 
  mDrawMatrix.postConcat(mSuppMatrix); 
  return mDrawMatrix; 
 } 
 
 private void cancelFling() { 
  if (null != mCurrentFlingRunnable) { 
   mCurrentFlingRunnable.cancelFling(); 
   mCurrentFlingRunnable = null; 
  } 
 } 
 
 /** 
  * Helper method that simply checks the Matrix, and then displays the result 
  */ 
 private void checkAndDisplayMatrix() { 
  checkMatrixBounds(); 
  setImageViewMatrix(getDisplayMatrix()); 
 } 
 
 private void checkImageViewScaleType() { 
  ImageView imageView = getImageView(); 
 
  /** 
   * ScaleView's getScaleType() will just divert to this.getScaleType() so 
   * only call if we're not attached to a ScaleView. 
   */ 
  if (null != imageView && !(imageView instanceof ScaleView)) { 
   if (imageView.getScaleType() != ScaleType.MATRIX) { 
    throw new IllegalStateException( 
      "The ImageView's ScaleType has been changed since attaching a ScaleViewAttacher"); 
   } 
  } 
 } 
 
 private void checkMatrixBounds() { 
  final ImageView imageView = getImageView(); 
  if (null == imageView) { 
   return; 
  } 
 
  final RectF rect = getDisplayRect(getDisplayMatrix()); 
  if (null == rect) { 
   return; 
  } 
 
  final float height = rect.height(), width = rect.width(); 
  float deltaX = 0, deltaY = 0; 
 
  final int viewHeight = imageView.getHeight(); 
  if (height <= viewHeight) { 
   switch (mScaleType) { 
    case FIT_START: 
     deltaY = -rect.top; 
     break; 
    case FIT_END: 
     deltaY = viewHeight - height - rect.top; 
     break; 
    default: 
     deltaY = (viewHeight - height) / 2 - rect.top; 
     break; 
   } 
  } else if (rect.top > 0) { 
   deltaY = -rect.top; 
  } else if (rect.bottom < viewHeight) { 
   deltaY = viewHeight - rect.bottom; 
  } 
 
  final int viewWidth = imageView.getWidth(); 
  if (width <= viewWidth) { 
   switch (mScaleType) { 
    case FIT_START: 
     deltaX = -rect.left; 
     break; 
    case FIT_END: 
     deltaX = viewWidth - width - rect.left; 
     break; 
    default: 
     deltaX = (viewWidth - width) / 2 - rect.left; 
     break; 
   } 
   mScrollEdge = EDGE_BOTH; 
  } else if (rect.left > 0) { 
   mScrollEdge = EDGE_LEFT; 
   deltaX = -rect.left; 
  } else if (rect.right < viewWidth) { 
   deltaX = viewWidth - rect.right; 
   mScrollEdge = EDGE_RIGHT; 
  } else { 
   mScrollEdge = EDGE_NONE; 
  } 
 
  // Finally actually translate the matrix 
  mSuppMatrix.postTranslate(deltaX, deltaY); 
 } 
 
 /** 
  * Helper method that maps the supplied Matrix to the current Drawable 
  * 
  * @param matrix - Matrix to map Drawable against 
  * @return RectF - Displayed Rectangle 
  */ 
 private RectF getDisplayRect(Matrix matrix) { 
  ImageView imageView = getImageView(); 
 
  if (null != imageView) { 
   Drawable d = imageView.getDrawable(); 
   if (null != d) { 
    mDisplayRect.set(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight()); 
    matrix.mapRect(mDisplayRect); 
    return mDisplayRect; 
   } 
  } 
  return null; 
 } 
 
 /** 
  * Helper method that 'unpacks' a Matrix and returns the required value 
  * 
  * @param matrix - Matrix to unpack 
  * @param whichValue - Which value from Matrix.M* to return 
  * @return float - returned value 
  */ 
 private float getValue(Matrix matrix, int whichValue) { 
  matrix.getValues(mMatrixValues); 
  return mMatrixValues[whichValue]; 
 } 
 
 /** 
  * Resets the Matrix back to FIT_CENTER, and then displays it.s 
  */ 
 private void resetMatrix() { 
  mSuppMatrix.reset(); 
  setImageViewMatrix(getDisplayMatrix()); 
  checkMatrixBounds(); 
 } 
 
 private void setImageViewMatrix(Matrix matrix) { 
  ImageView imageView = getImageView(); 
  if (null != imageView) { 
 
   checkImageViewScaleType(); 
   imageView.setImageMatrix(matrix); 
 
   // Call MatrixChangedListener if needed 
   if (null != mMatrixChangeListener) { 
    RectF displayRect = getDisplayRect(matrix); 
    if (null != displayRect) { 
     mMatrixChangeListener.onMatrixChanged(displayRect); 
    } 
   } 
  } 
 } 
 
 /** 
  * Calculate Matrix for FIT_CENTER 
  * 
  * @param d - Drawable being displayed 
  */ 
 private void updateBaseMatrix(Drawable d) { 
  ImageView imageView = getImageView(); 
  if (null == imageView || null == d) { 
   return; 
  } 
 
  final float viewWidth = imageView.getWidth(); 
  final float viewHeight = imageView.getHeight(); 
  final int drawableWidth = d.getIntrinsicWidth(); 
  final int drawableHeight = d.getIntrinsicHeight(); 
 
  mBaseMatrix.reset(); 
 
  final float widthScale = viewWidth / drawableWidth; 
  final float heightScale = viewHeight / drawableHeight; 
 
  if (mScaleType == ScaleType.CENTER) { 
   mBaseMatrix.postTranslate((viewWidth - drawableWidth) / 2F, (viewHeight - drawableHeight) / 2F); 
 
  } else if (mScaleType == ScaleType.CENTER_CROP) { 
   float scale = Math.max(widthScale, heightScale); 
   mBaseMatrix.postScale(scale, scale); 
   mBaseMatrix.postTranslate((viewWidth - drawableWidth * scale) / 2F, 
     (viewHeight - drawableHeight * scale) / 2F); 
 
  } else if (mScaleType == ScaleType.CENTER_INSIDE) { 
   float scale = Math.min(1.0f, Math.min(widthScale, heightScale)); 
   mBaseMatrix.postScale(scale, scale); 
   mBaseMatrix.postTranslate((viewWidth - drawableWidth * scale) / 2F, 
     (viewHeight - drawableHeight * scale) / 2F); 
 
  } else { 
   RectF mTempSrc = new RectF(0, 0, drawableWidth, drawableHeight); 
   RectF mTempDst = new RectF(0, 0, viewWidth, viewHeight); 
 
   switch (mScaleType) { 
    case FIT_CENTER: 
     mBaseMatrix.setRectToRect(mTempSrc, mTempDst, ScaleToFit.CENTER); 
     break; 
 
    case FIT_START: 
     mBaseMatrix.setRectToRect(mTempSrc, mTempDst, ScaleToFit.START); 
     break; 
 
    case FIT_END: 
     mBaseMatrix.setRectToRect(mTempSrc, mTempDst, ScaleToFit.END); 
     break; 
 
    case FIT_XY: 
     mBaseMatrix.setRectToRect(mTempSrc, mTempDst, ScaleToFit.FILL); 
     break; 
 
    default: 
     break; 
   } 
  } 
 
  resetMatrix(); 
 } 
 
 /** 
  * Interface definition for a callback to be invoked when the internal 
  * Matrix has changed for this View. 
  * 
  * @author Chris Banes 
  */ 
 public static interface OnMatrixChangedListener { 
  /** 
   * Callback for when the Matrix displaying the Drawable has changed. 
   * This could be because the View's bounds have changed, or the user has 
   * zoomed. 
   * 
   * @param rect - Rectangle displaying the Drawable's new bounds. 
   */ 
  void onMatrixChanged(RectF rect); 
 } 
 
 /** 
  * Interface definition for a callback to be invoked when the Scale is 
  * tapped with a single tap. 
  * 
  * @author Chris Banes 
  */ 
 public static interface OnScaleTapListener { 
 
  /** 
   * A callback to receive where the user taps on a Scale. You will only 
   * receive a callback if the user taps on the actual Scale, tapping on 
   * 'whitespace' will be ignored. 
   * 
   * @param view - View the user tapped. 
   * @param x - where the user tapped from the of the Drawable, as 
   *   percentage of the Drawable width. 
   * @param y - where the user tapped from the top of the Drawable, as 
   *   percentage of the Drawable height. 
   */ 
  void onScaleTap(View view, float x, float y); 
 } 
 
 /** 
  * Interface definition for a callback to be invoked when the ImageView is 
  * tapped with a single tap. 
  * 
  * @author Chris Banes 
  */ 
 public static interface OnViewTapListener { 
 
  /** 
   * A callback to receive where the user taps on a ImageView. You will 
   * receive a callback if the user taps anywhere on the view, tapping on 
   * 'whitespace' will not be ignored. 
   * 
   * @param view - View the user tapped. 
   * @param x - where the user tapped from the left of the View. 
   * @param y - where the user tapped from the top of the View. 
   */ 
  void onViewTap(View view, float x, float y); 
 } 
 
 private class AnimatedZoomRunnable implements Runnable { 
 
  // These are 'postScale' values, means they're compounded each iteration 
  static final float ANIMATION_SCALE_PER_ITERATION_IN = 1.07f; 
  static final float ANIMATION_SCALE_PER_ITERATION_OUT = 0.93f; 
 
  private final float mFocalX, mFocalY; 
  private final float mTargetZoom; 
  private final float mDeltaScale; 
 
  public AnimatedZoomRunnable(final float currentZoom, final float targetZoom, final float focalX, 
    final float focalY) { 
   mTargetZoom = targetZoom; 
   mFocalX = focalX; 
   mFocalY = focalY; 
 
   if (currentZoom < targetZoom) { 
    mDeltaScale = ANIMATION_SCALE_PER_ITERATION_IN; 
   } else { 
    mDeltaScale = ANIMATION_SCALE_PER_ITERATION_OUT; 
   } 
  } 
 
  public void run() { 
   ImageView imageView = getImageView(); 
 
   if (null != imageView) { 
    mSuppMatrix.postScale(mDeltaScale, mDeltaScale, mFocalX, mFocalY); 
    checkAndDisplayMatrix(); 
 
    final float currentScale = getScale(); 
 
    if ((mDeltaScale > 1f && currentScale < mTargetZoom) 
      || (mDeltaScale < 1f && mTargetZoom < currentScale)) { 
     // We haven't hit our target scale yet, so post ourselves 
     // again 
     Compat.postOnAnimation(imageView, this); 
 
    } else { 
     // We've scaled past our target zoom, so calculate the 
     // necessary scale so we're back at target zoom 
     final float delta = mTargetZoom / currentScale; 
     mSuppMatrix.postScale(delta, delta, mFocalX, mFocalY); 
     checkAndDisplayMatrix(); 
    } 
   } 
  } 
 } 
 
 private class FlingRunnable implements Runnable { 
 
  private final ScrollerProxy mScroller; 
  private int mCurrentX, mCurrentY; 
 
  public FlingRunnable(Context context) { 
   mScroller = ScrollerProxy.getScroller(context); 
  } 
 
  public void cancelFling() { 
   if (DEBUG) { 
    Log.d(LOG_TAG, "Cancel Fling"); 
   } 
   mScroller.forceFinished(true); 
  } 
 
  public void fling(int viewWidth, int viewHeight, int velocityX, int velocityY) { 
   final RectF rect = getDisplayRect(); 
   if (null == rect) { 
    return; 
   } 
 
   final int startX = Math.round(-rect.left); 
   final int minX, maxX, minY, maxY; 
 
   if (viewWidth < rect.width()) { 
    minX = 0; 
    maxX = Math.round(rect.width() - viewWidth); 
   } else { 
    minX = maxX = startX; 
   } 
 
   final int startY = Math.round(-rect.top); 
   if (viewHeight < rect.height()) { 
    minY = 0; 
    maxY = Math.round(rect.height() - viewHeight); 
   } else { 
    minY = maxY = startY; 
   } 
 
   mCurrentX = startX; 
   mCurrentY = startY; 
 
   if (DEBUG) { 
    Log.d(LOG_TAG, "fling. StartX:" + startX + " StartY:" + startY + " MaxX:" + maxX + " MaxY:" + maxY); 
   } 
 
   // If we actually can move, fling the scroller 
   if (startX != maxX || startY != maxY) { 
    mScroller.fling(startX, startY, velocityX, velocityY, minX, maxX, minY, maxY, 0, 0); 
   } 
  } 
 
  @Override 
  public void run() { 
   ImageView imageView = getImageView(); 
   if (null != imageView && mScroller.computeScrollOffset()) { 
 
    final int newX = mScroller.getCurrX(); 
    final int newY = mScroller.getCurrY(); 
 
    if (DEBUG) { 
     Log.d(LOG_TAG, "fling run(). CurrentX:" + mCurrentX + " CurrentY:" + mCurrentY + " NewX:" + newX 
       + " NewY:" + newY); 
    } 
 
    mSuppMatrix.postTranslate(mCurrentX - newX, mCurrentY - newY); 
    setImageViewMatrix(getDisplayMatrix()); 
 
    mCurrentX = newX; 
    mCurrentY = newY; 
 
    // Post On animation 
    Compat.postOnAnimation(imageView, this); 
   } 
  } 
 } 
} 

/******************************************************************************* 
 * Copyright 2011, 2012 Chris Banes. 
 * 
 * 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. 
 *******************************************************************************/ 
package com.suo.image; 
 
import android.annotation.TargetApi; 
import android.content.Context; 
import android.os.Build.VERSION; 
import android.os.Build.VERSION_CODES; 
import android.widget.OverScroller; 
import android.widget.Scroller; 
 
public abstract class ScrollerProxy { 
 
 public static ScrollerProxy getScroller(Context context) { 
  if (VERSION.SDK_INT < VERSION_CODES.GINGERBREAD) { 
   return new PreGingerScroller(context); 
  } else { 
   return new GingerScroller(context); 
  } 
 } 
 
 public abstract boolean computeScrollOffset(); 
 
 public abstract void fling(int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, 
   int maxY, int overX, int overY); 
 
 public abstract void forceFinished(boolean finished); 
 
 public abstract int getCurrX(); 
 
 public abstract int getCurrY(); 
 
 @TargetApi(9) 
 private static class GingerScroller extends ScrollerProxy { 
 
  private OverScroller mScroller; 
 
  public GingerScroller(Context context) { 
   mScroller = new OverScroller(context); 
  } 
 
  @Override 
  public boolean computeScrollOffset() { 
   return mScroller.computeScrollOffset(); 
  } 
 
  @Override 
  public void fling(int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, int maxY, 
    int overX, int overY) { 
   mScroller.fling(startX, startY, velocityX, velocityY, minX, maxX, minY, maxY, overX, overY); 
  } 
 
  @Override 
  public void forceFinished(boolean finished) { 
   mScroller.forceFinished(finished); 
  } 
 
  @Override 
  public int getCurrX() { 
   return mScroller.getCurrX(); 
  } 
 
  @Override 
  public int getCurrY() { 
   return mScroller.getCurrY(); 
  } 
 } 
 
 private static class PreGingerScroller extends ScrollerProxy { 
 
  private Scroller mScroller; 
 
  public PreGingerScroller(Context context) { 
   mScroller = new Scroller(context); 
  } 
 
  @Override 
  public boolean computeScrollOffset() { 
   return mScroller.computeScrollOffset(); 
  } 
 
  @Override 
  public void fling(int startX, int startY, int velocityX, int velocityY, int minX, int maxX, int minY, int maxY, 
    int overX, int overY) { 
   mScroller.fling(startX, startY, velocityX, velocityY, minX, maxX, minY, maxY); 
  } 
 
  @Override 
  public void forceFinished(boolean finished) { 
   mScroller.forceFinished(finished); 
  } 
 
  @Override 
  public int getCurrX() { 
   return mScroller.getCurrX(); 
  } 
 
  @Override 
  public int getCurrY() { 
   return mScroller.getCurrY(); 
  } 
 } 
} 

/******************************************************************************* 
 * Copyright 2011, 2012 Chris Banes. 
 * 
 * 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. 
 *******************************************************************************/ 
package com.suo.image; 
 
import android.annotation.TargetApi; 
import android.view.View; 
 
@TargetApi(16) 
public class SDK16 { 
 
 public static void postOnAnimation(View view, Runnable r) { 
  view.postOnAnimation(r); 
 } 
  
} 

package com.suo.image; 
 
/******************************************************************************* 
 * Copyright 2011, 2012 Chris Banes. 
 * 
 * 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. 
 *******************************************************************************/ 
 
import android.annotation.TargetApi; 
import android.content.Context; 
import android.os.Build; 
import android.view.MotionEvent; 
import android.view.ScaleGestureDetector; 
import android.view.ScaleGestureDetector.OnScaleGestureListener; 
import android.view.VelocityTracker; 
import android.view.ViewConfiguration; 
 
public abstract class VersionedGestureDetector { 
 static final String LOG_TAG = "VersionedGestureDetector"; 
 OnGestureListener mListener; 
 
 public static VersionedGestureDetector newInstance(Context context, OnGestureListener listener) { 
  final int sdkVersion = Build.VERSION.SDK_INT; 
  VersionedGestureDetector detector = null; 
 
  if (sdkVersion < Build.VERSION_CODES.ECLAIR) { 
   detector = new CupcakeDetector(context); 
  } else if (sdkVersion < Build.VERSION_CODES.FROYO) { 
   detector = new EclairDetector(context); 
  } else { 
   detector = new FroyoDetector(context); 
  } 
 
  detector.mListener = listener; 
 
  return detector; 
 } 
 
 public abstract boolean onTouchEvent(MotionEvent ev); 
 
 public abstract boolean isScaling(); 
 
 public static interface OnGestureListener { 
  public void onDrag(float dx, float dy); 
 
  public void onFling(float startX, float startY, float velocityX, float velocityY); 
 
  public void onScale(float scaleFactor, float focusX, float focusY); 
 } 
 
 private static class CupcakeDetector extends VersionedGestureDetector { 
 
  float mLastTouchX; 
  float mLastTouchY; 
  final float mTouchSlop; 
  final float mMinimumVelocity; 
 
  public CupcakeDetector(Context context) { 
   final ViewConfiguration configuration = ViewConfiguration.get(context); 
   mMinimumVelocity = configuration.getScaledMinimumFlingVelocity(); 
   mTouchSlop = configuration.getScaledTouchSlop(); 
  } 
 
  private VelocityTracker mVelocityTracker; 
  private boolean mIsDragging; 
 
  float getActiveX(MotionEvent ev) { 
   return ev.getX(); 
  } 
 
  float getActiveY(MotionEvent ev) { 
   return ev.getY(); 
  } 
 
  public boolean isScaling() { 
   return false; 
  } 
 
  @Override 
  public boolean onTouchEvent(MotionEvent ev) { 
   boolean result = true; 
   switch (ev.getAction()) { 
    case MotionEvent.ACTION_DOWN: { 
     mVelocityTracker = VelocityTracker.obtain(); 
     if (mVelocityTracker != null) { 
      mVelocityTracker.addMovement(ev); 
     } 
 
     mLastTouchX = getActiveX(ev); 
     mLastTouchY = getActiveY(ev); 
     mIsDragging = false; 
     break; 
    } 
 
    case MotionEvent.ACTION_MOVE: { 
     final float x = getActiveX(ev); 
     final float y = getActiveY(ev); 
     final float dx = x - mLastTouchX, dy = y - mLastTouchY; 
 
     if (!mIsDragging) { 
      // Use Pythagoras to see if drag length is larger than 
      // touch slop 
      mIsDragging = Math.sqrt((dx * dx) + (dy * dy)) >= mTouchSlop; 
     } 
 
     if (mIsDragging) { 
      mListener.onDrag(dx, dy); 
      mLastTouchX = x; 
      mLastTouchY = y; 
 
      if (null != mVelocityTracker) { 
       mVelocityTracker.addMovement(ev); 
      } 
     } 
     break; 
    } 
 
    case MotionEvent.ACTION_CANCEL: { 
     // Recycle Velocity Tracker 
      
     if (null != mVelocityTracker) { 
      mVelocityTracker.recycle(); 
      mVelocityTracker = null; 
     } 
     break; 
    } 
 
    case MotionEvent.ACTION_UP: { 
     if (mIsDragging) { 
      if (null != mVelocityTracker) { 
       mLastTouchX = getActiveX(ev); 
       mLastTouchY = getActiveY(ev); 
 
       // Compute velocity within the last 1000ms 
       mVelocityTracker.addMovement(ev); 
       mVelocityTracker.computeCurrentVelocity(1000); 
 
       final float vX = mVelocityTracker.getXVelocity(), vY = mVelocityTracker.getYVelocity(); 
 
       // If the velocity is greater than minVelocity, call 
       // listener 
       if (Math.max(Math.abs(vX), Math.abs(vY)) >= mMinimumVelocity) { 
        mListener.onFling(mLastTouchX, mLastTouchY, -vX, -vY); 
       } 
      } 
     } 
      
     // Recycle Velocity Tracker 
     if (null != mVelocityTracker) { 
      mVelocityTracker.recycle(); 
      mVelocityTracker = null; 
     } 
      
     break; 
    } 
   } 
 
   return result; 
  } 
 } 
 
 @TargetApi(5) 
 private static class EclairDetector extends CupcakeDetector { 
  private static final int INVALID_POINTER_ID = -1; 
  private int mActivePointerId = INVALID_POINTER_ID; 
  private int mActivePointerIndex = 0; 
 
  public EclairDetector(Context context) { 
   super(context); 
  } 
 
  @Override 
  float getActiveX(MotionEvent ev) { 
   try { 
    return ev.getX(mActivePointerIndex); 
   } catch (Exception e) { 
    return ev.getX(); 
   } 
  } 
 
  @Override 
  float getActiveY(MotionEvent ev) { 
   try { 
    return ev.getY(mActivePointerIndex); 
   } catch (Exception e) { 
    return ev.getY(); 
   } 
  } 
 
  @Override 
  public boolean onTouchEvent(MotionEvent ev) { 
   final int action = ev.getAction(); 
   switch (action & MotionEvent.ACTION_MASK) { 
    case MotionEvent.ACTION_DOWN: 
     mActivePointerId = ev.getPointerId(0); 
     break; 
    case MotionEvent.ACTION_CANCEL: 
    case MotionEvent.ACTION_UP: 
     mActivePointerId = INVALID_POINTER_ID; 
     break; 
    case MotionEvent.ACTION_POINTER_UP: 
     final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >> MotionEvent.ACTION_POINTER_INDEX_SHIFT; 
     final int pointerId = ev.getPointerId(pointerIndex); 
     if (pointerId == mActivePointerId) { 
      // This was our active pointer going up. Choose a new 
      // active pointer and adjust accordingly. 
      final int newPointerIndex = pointerIndex == 0 &#63; 1 : 0; 
      mActivePointerId = ev.getPointerId(newPointerIndex); 
      mLastTouchX = ev.getX(newPointerIndex); 
      mLastTouchY = ev.getY(newPointerIndex); 
     } 
     break; 
   } 
 
   mActivePointerIndex = ev.findPointerIndex(mActivePointerId != INVALID_POINTER_ID &#63; mActivePointerId : 0); 
   return super.onTouchEvent(ev); 
  } 
 } 
 
 @TargetApi(8) 
 private static class FroyoDetector extends EclairDetector { 
 
  private final ScaleGestureDetector mDetector; 
 
  // Needs to be an inner class so that we don't hit 
  // VerifyError's on API 4. 
  private final OnScaleGestureListener mScaleListener = new OnScaleGestureListener() { 
 
   @Override 
   public boolean onScale(ScaleGestureDetector detector) { 
    mListener.onScale(detector.getScaleFactor(), detector.getFocusX(), detector.getFocusY()); 
    return true; 
   } 
 
   @Override 
   public boolean onScaleBegin(ScaleGestureDetector detector) { 
    return true; 
   } 
 
   @Override 
   public void onScaleEnd(ScaleGestureDetector detector) { 
    // NO-OP 
   } 
  }; 
 
  public FroyoDetector(Context context) { 
   super(context); 
   mDetector = new ScaleGestureDetector(context, mScaleListener); 
  } 
 
  @Override 
  public boolean isScaling() { 
   return mDetector.isInProgress(); 
  } 
 
  @Override 
  public boolean onTouchEvent(MotionEvent ev) { 
   mDetector.onTouchEvent(ev); 
   return super.onTouchEvent(ev); 
  } 
 
 } 
} 

package com.suo.myimage; 
 
import android.os.Bundle; 
import android.app.Activity; 
import android.view.Menu; 
 
public class MainActivity extends Activity { 
 
 @Override 
 protected void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.activity_main); 
 } 
 
 @Override 
 public boolean onCreateOptionsMenu(Menu menu) { 
  // Inflate the menu; this adds items to the action bar if it is present. 
  getMenuInflater().inflate(R.menu.activity_main, menu); 
  return true; 
 } 
 
} 

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 xmlns:tools="http://schemas.android.com/tools" 
 android:layout_width="match_parent" 
 android:layout_height="match_parent" 
 tools:context=".MainActivity" > 
 
 <TextView 
  android:layout_width="wrap_content" 
  android:layout_height="wrap_content" 
  android:layout_centerHorizontal="true" 
  android:layout_centerVertical="true" 
  android:text="@string/hello_world" /> 
  
 <com.suo.image.ScaleView 
  android:layout_width="match_parent" 
  android:layout_height="match_parent" 
  android:src="@drawable/a"/> 
 
</RelativeLayout>