Android手势滑动实现ImageView缩放图片大小

public class MulitPointTouchListener implements OnTouchListener { 
  private static final String TAG = "Touch"; 
  // These matrices will be used to move and zoom image 
  Matrix matrix = new Matrix(); 
  Matrix savedMatrix = new Matrix(); 
 
  // We can be in one of these 3 states 
  static final int NOnE= 0; 
  static final int DRAG = 1; 
  static final int ZOOM = 2; 
  int mode = NONE; 
 
  // Remember some things for zooming 
  PointF start = new PointF(); 
  PointF mid = new PointF(); 
  float oldDist = 1f; 
 
  @Override 
  public boolean onTouch(View v, MotionEvent event) { 
 
    ImageView view = (ImageView) v; 
    // Log.e("view_width", 
    // view.getImageMatrix()..toString()+"*"+v.getWidth()); 
    // Dump touch event to log 
    dumpEvent(event); 
 
    // Handle touch events here... 
    switch (event.getAction() & MotionEvent.ACTION_MASK) { 
    case MotionEvent.ACTION_DOWN: 
 
      matrix.set(view.getImageMatrix()); 
      savedMatrix.set(matrix); 
      start.set(event.getX(), event.getY()); 
      //Log.d(TAG, "mode=DRAG"); 
      mode = DRAG; 
 
       
      //Log.d(TAG, "mode=NONE"); 
      break; 
    case MotionEvent.ACTION_POINTER_DOWN: 
      oldDist = spacing(event); 
      //Log.d(TAG, "oldDist=" + oldDist); 
      if (oldDist > 10f) { 
        savedMatrix.set(matrix); 
        midPoint(mid, event); 
        mode = ZOOM; 
        //Log.d(TAG, "mode=ZOOM"); 
      } 
      break; 
    case MotionEvent.ACTION_UP: 
    case MotionEvent.ACTION_POINTER_UP: 
      mode = NONE; 
      //Log.e("view.getWidth", view.getWidth() + ""); 
      //Log.e("view.getHeight", view.getHeight() + ""); 
 
      break; 
    case MotionEvent.ACTION_MOVE: 
      if (mode == DRAG) { 
        // ... 
        matrix.set(savedMatrix); 
        matrix.postTranslate(event.getX() - start.x, event.getY() 
            - start.y); 
      } else if (mode == ZOOM) { 
        float newDist = spacing(event); 
        //Log.d(TAG, "newDist=" + newDist); 
        if (newDist > 10f) { 
          matrix.set(savedMatrix); 
          float scale = newDist / oldDist; 
          matrix.postScale(scale, scale, mid.x, mid.y); 
        } 
      } 
      break; 
    } 
 
    view.setImageMatrix(matrix); 
    return true; // indicate event was handled 
  } 
 
  private void dumpEvent(MotionEvent event) { 
    String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE", 
        "POINTER_DOWN", "POINTER_UP", "7&＃63;", "8&＃63;", "9&＃63;" }; 
    StringBuilder sb = new StringBuilder(); 
    int action = event.getAction(); 
    int actiOnCode= action & MotionEvent.ACTION_MASK; 
    sb.append("event ACTION_").append(names[actionCode]); 
    if (actiOnCode== MotionEvent.ACTION_POINTER_DOWN 
        || actiOnCode== MotionEvent.ACTION_POINTER_UP) { 
      sb.append("(pid ").append( 
          action >> MotionEvent.ACTION_POINTER_ID_SHIFT); 
      sb.append(")"); 
    } 
    sb.append("["); 
    for (int i = 0; i 

import android.content.Context;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.ImageView;

public class TouchImageView extends ImageView {

 Matrix matrix;

 // We can be in one of these 3 states
 static final int NOnE= 0;
 static final int DRAG = 1;
 static final int ZOOM = 2;
 int mode = NONE;

 // Remember some things for zooming
 PointF last = new PointF();
 PointF start = new PointF();
 float minScale = 1f;
 float maxScale = 3f;
 float[] m;


 int viewWidth, viewHeight;
 static final int CLICK = 3;
 float saveScale = 1f;
 protected float origWidth, origHeight;
 int oldMeasuredWidth, oldMeasuredHeight;


 ScaleGestureDetector mScaleDetector;

 Context context;

 public TouchImageView(Context context) {
  super(context);
  sharedConstructing(context);
 }

 public TouchImageView(Context context, AttributeSet attrs) {
  super(context, attrs);
  sharedConstructing(context);
 }
 
 private void sharedConstructing(Context context) {
  super.setClickable(true);
  this.cOntext= context;
  mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
  matrix = new Matrix();
  m = new float[9];
  setImageMatrix(matrix);
  setScaleType(ScaleType.MATRIX);

  setOnTouchListener(new OnTouchListener() {

   @Override
   public boolean onTouch(View v, MotionEvent event) {
    mScaleDetector.onTouchEvent(event);
    PointF curr = new PointF(event.getX(), event.getY());

    switch (event.getAction()) {
     case MotionEvent.ACTION_DOWN:
      last.set(curr);
      start.set(last);
      mode = DRAG;
      break;
      
     case MotionEvent.ACTION_MOVE:
      if (mode == DRAG) {
       float deltaX = curr.x - last.x;
       float deltaY = curr.y - last.y;
       float fixTransX = getFixDragTrans(deltaX, viewWidth, origWidth * saveScale);
       float fixTransY = getFixDragTrans(deltaY, viewHeight, origHeight * saveScale);
       matrix.postTranslate(fixTransX, fixTransY);
       fixTrans();
       last.set(curr.x, curr.y);
      }
      break;

     case MotionEvent.ACTION_UP:
      mode = NONE;
      int xDiff = (int) Math.abs(curr.x - start.x);
      int yDiff = (int) Math.abs(curr.y - start.y);
      if (xDiff  maxScale) {
    saveScale = maxScale;
    mScaleFactor = maxScale / origScale;
   } else if (saveScale  maxTrans)
   return -trans + maxTrans;
  return 0;
 }
 
 float getFixDragTrans(float delta, float viewSize, float contentSize) {
  if (contentSize <= viewSize) {
   return 0;
  }
  return delta;
 }

 @Override
 protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
  super.onMeasure(widthMeasureSpec, heightMeasureSpec);
  viewWidth = MeasureSpec.getSize(widthMeasureSpec);
  viewHeight = MeasureSpec.getSize(heightMeasureSpec);
  
  //
  // Rescales image on rotation
  //
  if (oldMeasuredHeight == viewWidth && oldMeasuredHeight == viewHeight
    || viewWidth == 0 || viewHeight == 0)
   return;
  oldMeasuredHeight = viewHeight;
  oldMeasuredWidth = viewWidth;

  if (saveScale == 1) {
   //Fit to screen.
   float scale;

   Drawable drawable = getDrawable();
   if (drawable == null || drawable.getIntrinsicWidth() == 0 || drawable.getIntrinsicHeight() == 0)
    return;
   int bmWidth = drawable.getIntrinsicWidth();
   int bmHeight = drawable.getIntrinsicHeight();
   
   Log.d("bmSize", "bmWidth: " + bmWidth + " bmHeight : " + bmHeight);

   float scaleX = (float) viewWidth / (float) bmWidth;
   float scaleY = (float) viewHeight / (float) bmHeight;
   scale = Math.min(scaleX, scaleY);
   matrix.setScale(scale, scale);

   // Center the image
   float redundantYSpace = (float) viewHeight - (scale * (float) bmHeight);
   float redundantXSpace = (float) viewWidth - (scale * (float) bmWidth);
   redundantYSpace /= (float) 2;
   redundantXSpace /= (float) 2;

   matrix.postTranslate(redundantXSpace, redundantYSpace);

   origWidth = viewWidth - 2 * redundantXSpace;
   origHeight = viewHeight - 2 * redundantYSpace;
   setImageMatrix(matrix);
  }
  fixTrans();
 }
}

public class TouchImageViewActivity extends Activity {
 /** Called when the activity is first created. */
 @Override
 public void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.main);
  TouchImageView img = (TouchImageView) findViewById(R.id.snoop);
  img.setImageResource(R.drawable.snoopy);
  img.setMaxZoom(4f);
 }
}