Android手势控制实现缩放、移动图片

package com.liyong.btprinter; import android.graphics.Matrix; import android.graphics.PointF; import android.util.FloatMath; import android.view.MotionEvent; import android.view.View; import android.view.View.OnTouchListener; import android.widget.ImageView; 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?", "8?", "9?" };       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 < event.getPointerCount(); i++) {           sb.append("#").append(i);           sb.append("(pid ").append(event.getPointerId(i));           sb.append(")=").append((int) event.getX(i));           sb.append(",").append((int) event.getY(i));           if (i + 1 < event.getPointerCount())               sb.append(";");       }       sb.append("]");       //Log.d(TAG, sb.toString());   }     private float spacing(MotionEvent event) {       float x = event.getX(0) - event.getX(1);       float y = event.getY(0) - event.getY(1);       return FloatMath.sqrt(x * x + y * y);   }     private void midPoint(PointF point, MotionEvent event) {       float x = event.getX(0) + event.getX(1);       float y = event.getY(0) + event.getY(1);       point.set(x / 2, y / 2);   } }

<?xml version="1.0" encoding="UTF-8"?>   <LinearLayout   xmlns:android="http://schemas.android.com/apk/res/android"   android:orientation="vertical"   android:layout_height="fill_parent"   android:layout_width="fill_parent"   android:id="@+id/linearLayout1"   android:weightSum="1">     <ImageView android:layout_width="fill_parent"     android:id="@+id/priviewimage"     android:layout_height="fill_parent"     android:layout_gravity="center"     android:scaleType="matrix"     >    </ImageView>   </LinearLayout> 

priviewimage.setImageBitmap(ActivityPreviewImage.click_bitmap); priviewimage=(ImageView)findViewById(R.id.priviewimage); priviewimage.setOnTouchListener(new MulitPointTouchListener());