图片放大缩小

package com.example.testzoom;

import android.os.Bundle;

import android.app.Activity;

import android.view.MotionEvent;

import android.view.View;

import android.view.View.OnTouchListener;

import android.widget.ImageView;

import android.widget.RelativeLayout;

import android.widget.RelativeLayout.LayoutParams;

public class MainActivity extends Activity {

// 被缩放的图片

private ImageView imageView;

private float lastDistance = -1;

RelativeLayout root;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

imageView = (ImageView) findViewById(R.id.imageView1);

root = (RelativeLayout) findViewById(R.id.root);

// 设置触摸监听器

root.setOnTouchListener(new OnTouchListener() {

@Override

public boolean onTouch(View v, MotionEvent event) {

switch (event.getAction()) {

case MotionEvent.ACTION_POINTER_DOWN:

System.out.println("DOWN");

break;

case MotionEvent.ACTION_MOVE:

System.out.println("MOVE");

if (event.getPointerCount() > 1) {

float offsetX = event.getX(0) - event.getX(1);

float offsetY = event.getY(0) - event.getX(1);

RelativeLayout.LayoutParams layoutparams = (LayoutParams) imageView

.getLayoutParams();

float curDistance = (float) Math.sqrt(offsetX * offsetX

+ offsetY * offsetY);

if (lastDistance < 0) {

lastDistance = curDistance;

} else {

if (lastDistance - curDistance > 5) {

layoutparams.width = (int) (0.9f * imageView

.getWidth());

layoutparams.height = (int) (0.9f * imageView

.getHeight());

} else if (curDistance - lastDistance > 5) {

layoutparams.width = (int) (1.1f * imageView

.getWidth());

layoutparams.height = (int) (1.1f * imageView

.getWidth());

}

lastDistance = curDistance;

imageView.setLayoutParams(layoutparams);

}

}

break;

case MotionEvent.ACTION_UP:

System.out.println("UP");

break;

default:

break;

}

return true;

}

});

}

}

//感觉效果没有相册里面的图片放大缩小好