1.Activity

package com.fit.touchimage;

import android.app.Activity;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Matrix;

import android.graphics.PointF;

import android.os.Bundle;

import android.util.FloatMath;

import android.view.MotionEvent;

import android.view.View;

import android.view.View.OnTouchListener;

import android.view.ViewGroup.MarginLayoutParams;

import android.widget.ImageView;

public class MainActivity extends Activity implements OnTouchListener {

/** Called when the activity is first created. */

//放大缩小

Matrix matrix=new Matrix();

Matrix savedMatrix=new Matrix();

PointF start=new PointF();

PointF mid=new PointF();

float oldDist;

private ImageView myImageView;

//模式

static final int NONE=0;

static final int DRAG=1;

static final int ZOOM=2;

int mode=NONE;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.main);

myImageView=(ImageView) findViewById(R.id.myImage);

myImageView.setOnTouchListener(this);

}

@Override

public boolean onTouch(View v, MotionEvent event) {

ImageView myImageView=(ImageView) v;

switch(event.getAction()&MotionEvent.ACTION_MASK){

//设置拖拉模式

case MotionEvent.ACTION_DOWN:

matrix.set(myImageView.getImageMatrix());

savedMatrix.set(matrix);

start.set(event.getX(),event.getY());

mode=DRAG;

break;

case MotionEvent.ACTION_UP:

case MotionEvent.ACTION_POINTER_UP:

mode=NONE;

break;

//设置多点触摸模式

case MotionEvent.ACTION_POINTER_DOWN:

oldDist=spacing(event);

if(oldDist>10f){

savedMatrix.set(matrix);

midPoint(mid, event);

mode=ZOOM;

}

break;

//若为DRAG模式，则点击移动图片

case MotionEvent.ACTION_MOVE:

if(mode==DRAG){

matrix.set(savedMatrix);

matrix.postTranslate(event.getX()-start.x,event.getY()-start.y);

}

//若为ZOOM模式，则点击触摸缩放

else if(mode==ZOOM){

float newDist=spacing(event);

if(newDist>10f){

matrix.set(savedMatrix);

float scale=newDist/oldDist;

//设置硕放比例和图片的中点位置

matrix.postScale(scale,scale, mid.x,mid.y);

}

}

break;

}

myImageView.setImageMatrix(matrix);

return true;

}

//计算移动距离

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);

}

//计算中点位置

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);

}

}

2.布局

android:orientation="vertical" android:layout_width="fill_parent"

android:layout_height="fill_parent" android:gravity="center">

android:layout_height="fill_parent" android:scaleType="matrix"

android:id="@+id/myImage" android:src="@drawable/xiaoxiong"/>

原文：http://www.cnblogs.com/xgjblog/p/3874854.html