Android图片预览效果，支持缩放、平移切换

package com.fcar.datamanager.view;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Matrix;
import android.graphics.RectF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.GestureDetector.SimpleOnGestureListener;
import android.view.ScaleGestureDetector.OnScaleGestureListener;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.ViewTreeObserver;
import android.widget.ImageView;
/**
 *
 *
 */
public class ZoomImageView extends ImageView implements OnScaleGestureListener,
      OnTouchListener, ViewTreeObserver.OnGlobalLayoutListener

{
   private static final String TAG = ZoomImageView.class.getSimpleName();
   public static final float SCALE_MAX = 4.0f;
   private static final float SCALE_MID = 2.0f;

   /**
    * 初始化时的缩放比例，如果图片宽或高大于屏幕，此值将小于0
    */
   private float initScale = 1.0f;
   private boolean once = true;

   /**
    * 用于存放矩阵的9个值
    */
   private final float[] matrixValues = new float[9];

   /**
    * 缩放的手势检测
    */
   private ScaleGestureDetector mScaleGestureDetector = null;
   private final Matrix mScaleMatrix = new Matrix();

   /**
    * 用于双击检测
    */
   private GestureDetector mGestureDetector;
   private boolean isAutoScale;

   private int mTouchSlop;

   private float mLastX;
   private float mLastY;

   private boolean isCanDrag;
   private int lastPointerCount;

   private boolean isCheckTopAndBottom = true;
   private boolean isCheckLeftAndRight = true;

   public ZoomImageView(Context context)
   {
      this(context, null);
   }

   public ZoomImageView(Context context, AttributeSet attrs)
   {
      super(context, attrs);
      super.setScaleType(ScaleType.MATRIX);
      mGestureDetector = new GestureDetector(context,
            new SimpleOnGestureListener()
            {
               @Override
               public boolean onDoubleTap(MotionEvent e)
               {
                  if (isAutoScale == true)
                     return true;

                  float x = e.getX();
                  float y = e.getY();
                  Log.e("DoubleTap", getScale() + " , " + initScale);
                  if (getScale() < SCALE_MID)
                  {
                     ZoomImageView.this.postDelayed(
                           new AutoScaleRunnable(SCALE_MID, x, y), 16);
                     isAutoScale = true;
                  } else if (getScale() >= SCALE_MID
                        && getScale() < SCALE_MAX)
                  {
                     ZoomImageView.this.postDelayed(
                           new AutoScaleRunnable(SCALE_MAX, x, y), 16);
                     isAutoScale = true;
                  } else
                  {
                     ZoomImageView.this.postDelayed(
                           new AutoScaleRunnable(initScale, x, y), 16);
                     isAutoScale = true;
                  }

                  return true;
               }
            });
      mScaleGestureDetector = new ScaleGestureDetector(context, this);
      this.setOnTouchListener(this);
   }

   /**
    * 自动缩放的任务
    * 
    * @author zhy
    * 
    */
   private class AutoScaleRunnable implements Runnable
   {
      static final float BIGGER = 1.07f;
      static final float SMALLER = 0.93f;
      private float mTargetScale;
      private float tmpScale;

      /**
       * 缩放的中心
       */
      private float x;
      private float y;

      /**
       * 传入目标缩放值，根据目标值与当前值，判断应该放大还是缩小
       * 
       * @param targetScale
       */
      public AutoScaleRunnable(float targetScale, float x, float y)
      {
         this.mTargetScale = targetScale;
         this.x = x;
         this.y = y;
         if (getScale() < mTargetScale)
         {
            tmpScale = BIGGER;
         } else
         {
            tmpScale = SMALLER;
         }

      }

      @Override
      public void run()
      {
         // 进行缩放
         mScaleMatrix.postScale(tmpScale, tmpScale, x, y);
         checkBorderAndCenterWhenScale();
         setImageMatrix(mScaleMatrix);

         final float currentScale = getScale();
         // 如果值在合法范围内，继续缩放
         if (((tmpScale > 1f) && (currentScale < mTargetScale))
               || ((tmpScale < 1f) && (mTargetScale < currentScale)))
         {
            ZoomImageView.this.postDelayed(this, 16);
         } else
         // 设置为目标的缩放比例
         {
            final float deltaScale = mTargetScale / currentScale;
            mScaleMatrix.postScale(deltaScale, deltaScale, x, y);
            checkBorderAndCenterWhenScale();
            setImageMatrix(mScaleMatrix);
            isAutoScale = false;
         }

      }
   }

   @SuppressLint("NewApi")
   @Override
   public boolean onScale(ScaleGestureDetector detector)
   {
      float scale = getScale();
      float scaleFactor = detector.getScaleFactor();

      if (getDrawable() == null)
         return true;

      /**
       * 缩放的范围控制
       */
      if ((scale < SCALE_MAX && scaleFactor > 1.0f)
            || (scale > initScale && scaleFactor < 1.0f))
      {
         /**
          * 最大值最小值判断
          */
         if (scaleFactor * scale < initScale)
         {
            scaleFactor = initScale / scale;
         }
         if (scaleFactor * scale > SCALE_MAX)
         {
            scaleFactor = SCALE_MAX / scale;
         }
         /**
          * 设置缩放比例
          */
         mScaleMatrix.postScale(scaleFactor, scaleFactor,
               detector.getFocusX(), detector.getFocusY());
         checkBorderAndCenterWhenScale();
         setImageMatrix(mScaleMatrix);
      }
      return true;

   }

   /**
    * 在缩放时，进行图片显示范围的控制
    */
   private void checkBorderAndCenterWhenScale()
   {

      RectF rect = getMatrixRectF();
      float deltaX = 0;
      float deltaY = 0;

      int width = getWidth();
      int height = getHeight();

      // 如果宽或高大于屏幕，则控制范围
      if (rect.width() >= width)
      {
         if (rect.left > 0)
         {
            deltaX = -rect.left;
         }
         if (rect.right < width)
         {
            deltaX = width - rect.right;
         }
      }
      if (rect.height() >= height)
      {
         if (rect.top > 0)
         {
            deltaY = -rect.top;
         }
         if (rect.bottom < height)
         {
            deltaY = height - rect.bottom;
         }
      }
      // 如果宽或高小于屏幕，则让其居中
      if (rect.width() < width)
      {
         deltaX = width * 0.5f - rect.right + 0.5f * rect.width();
      }
      if (rect.height() < height)
      {
         deltaY = height * 0.5f - rect.bottom + 0.5f * rect.height();
      }
      Log.e(TAG, "deltaX = " + deltaX + " , deltaY = " + deltaY);

      mScaleMatrix.postTranslate(deltaX, deltaY);

   }

   /**
    * 根据当前图片的Matrix获得图片的范围
    * 
    * @return
    */
   private RectF getMatrixRectF()
   {
      Matrix matrix = mScaleMatrix;
      RectF rect = new RectF();
      Drawable d = getDrawable();
      if (null != d)
      {
         rect.set(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());
         matrix.mapRect(rect);
      }
      return rect;
   }

   @Override
   public boolean onScaleBegin(ScaleGestureDetector detector)
   {
      return true;
   }

   @Override
   public void onScaleEnd(ScaleGestureDetector detector)
   {
   }

   @Override
   public boolean onTouch(View v, MotionEvent event)
   {

      if (mGestureDetector.onTouchEvent(event))
         return true;
      mScaleGestureDetector.onTouchEvent(event);

      float x = 0, y = 0;
      // 拿到触摸点的个数
      final int pointerCount = event.getPointerCount();
      // 得到多个触摸点的x与y均值
      for (int i = 0; i < pointerCount; i++)
      {
         x += event.getX(i);
         y += event.getY(i);
      }
      x = x / pointerCount;
      y = y / pointerCount;

      /**
       * 每当触摸点发生变化时，重置mLasX , mLastY
       */
      if (pointerCount != lastPointerCount)
      {
         isCanDrag = false;
         mLastX = x;
         mLastY = y;
      }

      lastPointerCount = pointerCount;
      RectF rectF = getMatrixRectF();
      switch (event.getAction())
      {
      case MotionEvent.ACTION_DOWN:
         if (rectF.width() > getWidth() || rectF.height() > getHeight())
         {
            getParent().requestDisallowInterceptTouchEvent(true);
         }
         break;
      case MotionEvent.ACTION_MOVE:
         if (rectF.width() > getWidth() || rectF.height() > getHeight())
         {
            getParent().requestDisallowInterceptTouchEvent(true);
         }
         Log.e(TAG, "ACTION_MOVE");
         float dx = x - mLastX;
         float dy = y - mLastY;

         if (!isCanDrag)
         {
            isCanDrag = isCanDrag(dx, dy);
         }
         if (isCanDrag)
         {

            if (getDrawable() != null)
            {
               // if (getMatrixRectF().left == 0 && dx > 0)
               // {
               // getParent().requestDisallowInterceptTouchEvent(false);
               // }
               //
               // if (getMatrixRectF().right == getWidth() && dx < 0)
               // {
               // getParent().requestDisallowInterceptTouchEvent(false);
               // }
               isCheckLeftAndRight = isCheckTopAndBottom = true;
               // 如果宽度小于屏幕宽度，则禁止左右移动
               if (rectF.width() < getWidth())
               {
                  dx = 0;
                  isCheckLeftAndRight = false;
               }
               // 如果高度小雨屏幕高度，则禁止上下移动
               if (rectF.height() < getHeight())
               {
                  dy = 0;
                  isCheckTopAndBottom = false;
               }
               

               mScaleMatrix.postTranslate(dx, dy);
               checkMatrixBounds();
               setImageMatrix(mScaleMatrix);
            }
         }
         mLastX = x;
         mLastY = y;
         break;

      case MotionEvent.ACTION_UP:
      case MotionEvent.ACTION_CANCEL:
         Log.e(TAG, "ACTION_UP");
         lastPointerCount = 0;
         break;
      }

      return true;
   }

   /**
    * 获得当前的缩放比例
    * 
    * @return
    */
   public final float getScale()
   {
      mScaleMatrix.getValues(matrixValues);
      return matrixValues[Matrix.MSCALE_X];
   }

   @Override
   protected void onAttachedToWindow()
   {
      super.onAttachedToWindow();
      getViewTreeObserver().addOnGlobalLayoutListener(this);
   }

   @SuppressWarnings("deprecation")
   @Override
   protected void onDetachedFromWindow()
   {
      super.onDetachedFromWindow();
      getViewTreeObserver().removeGlobalOnLayoutListener(this);
   }

   @Override
   public void onGlobalLayout()
   {
      if (once)
      {
         Drawable d = getDrawable();
         if (d == null)
            return;
         Log.e(TAG, d.getIntrinsicWidth() + " , " + d.getIntrinsicHeight());
         int width = getWidth();
         int height = getHeight();
         // 拿到图片的宽和高
         int dw = d.getIntrinsicWidth();
         int dh = d.getIntrinsicHeight();
         float scale = 1.0f;
         // 如果图片的宽或者高大于屏幕，则缩放至屏幕的宽或者高
         if (dw > width && dh <= height)
         {
            scale = width * 1.0f / dw;
         }
         if (dh > height && dw <= width)
         {
            scale = height * 1.0f / dh;
         }
         // 如果宽和高都大于屏幕，则让其按按比例适应屏幕大小
         if (dw > width && dh > height)
         {
            scale = Math.min(width * 1.0f / dw, height * 1.0f / dh);
         }
         initScale = scale;

         Log.e(TAG, "initScale = " + initScale);
         mScaleMatrix.postTranslate((width - dw) / 2, (height - dh) / 2);
         mScaleMatrix.postScale(scale, scale, getWidth() / 2,
               getHeight() / 2);
         // 图片移动至屏幕中心
         setImageMatrix(mScaleMatrix);
         once = false;
      }

   }

   /**
    * 移动时，进行边界判断，主要判断宽或高大于屏幕的
    */
   private void checkMatrixBounds()
   {
      RectF rect = getMatrixRectF();

      float deltaX = 0, deltaY = 0;
      final float viewWidth = getWidth();
      final float viewHeight = getHeight();
      // 判断移动或缩放后，图片显示是否超出屏幕边界
      if (rect.top > 0 && isCheckTopAndBottom)
      {
         deltaY = -rect.top;
      }
      if (rect.bottom < viewHeight && isCheckTopAndBottom)
      {
         deltaY = viewHeight - rect.bottom;
      }
      if (rect.left > 0 && isCheckLeftAndRight)
      {
         deltaX = -rect.left;
      }
      if (rect.right < viewWidth && isCheckLeftAndRight)
      {
         deltaX = viewWidth - rect.right;
      }
      mScaleMatrix.postTranslate(deltaX, deltaY);
   }

   /**
    * 是否是推动行为
    * 
    * @param dx
    * @param dy
    * @return
    */
   private boolean isCanDrag(float dx, float dy)
   {
      return Math.sqrt((dx * dx) + (dy * dy)) >= mTouchSlop;
   }

}

package com.fcar.datamanager;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

import com.fcar.datamanager.utils.BitmapUtils;
import com.fcar.datamanager.view.ZoomImageView;
import com.fcar.frameworks.core.GlobalVar;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;


public class ShowImageActivity1 extends Activity
{
   private ViewPager mViewPager;
   /*private int[] mImgs = new int[] { R.drawable.tbug, R.drawable.a,
         R.drawable.xx };*/
   private ImageView[] mImageViews;
   private ArrayList imagePaths;
   private int position;

   @Override
   protected void onCreate(Bundle savedInstanceState)
   {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.vp);

      Intent intent = getIntent();
      position = intent.getIntExtra("position", 0);
      imagePaths = intent.getStringArrayListExtra("imagePaths");
      mImageViews = new ImageView[imagePaths.size()];

      mViewPager = (ViewPager) findViewById(R.id.id_viewpager);
      mViewPager.setAdapter(new PagerAdapter()
      {

         @Override
         public Object instantiateItem(ViewGroup container, int position)
         {
            ZoomImageView imageView = new ZoomImageView(
                  getApplicationContext());
//          imageView.setImageResource(mImgs[position]);
            Bitmap bitmap = null;
            try {
               bitmap = BitmapUtils.compressImage(new File(imagePaths.get(position)), GlobalVar.getWidth(), GlobalVar.getHeight(), 100);
            } catch (IOException e) {
               e.printStackTrace();
            }
            if (bitmap != null) {
               imageView.setImageBitmap(bitmap);
            }
            container.addView(imageView);
            mImageViews[position] = imageView;
            return imageView;
         }

         @Override
         public void destroyItem(ViewGroup container, int position,
               Object object)
         {
            container.removeView(mImageViews[position]);
         }

         @Override
         public boolean isViewFromObject(View arg0, Object arg1)
         {
            return arg0 == arg1;
         }

         @Override
         public int getCount()
         {
            return imagePaths.size();
         }
      });
      mViewPager.setCurrentItem(position);
   }
}

ArrayList imagePaths = new ArrayList();
for (ItemInfo itemInfo:mList){
    String imagePath = itemInfo.getmPath();
    imagePaths.add(imagePath);
}
Intent intent = new Intent(ScreenShotManageActivity.this, ShowImageActivity1.class);
intent.putExtra("position", position);
intent.putStringArrayListExtra("imagePaths", imagePaths);
startActivity(intent);