Android中的多点触摸可以实现图片的放大、缩小和旋转等处理，供大家参考，具体内容如下
主要通过setOnTouchListener方法来监听用户的触摸事件，通过event.getX(0)和 event.getX(1)来获取第一个触控点和第二个触控点的x轴（或者y轴）坐标，接下来在MotionEvent.ACTION_DOWN、MotionEvent.ACTION_MOVE、MotionEvent.ACTION_UP这几种情况中来对获取到的x轴或者y轴进行处理，就能实现我们想要的效果了。
下面这个小Demo实现了对图片的放大和缩小处理：
package com.example.administrator.translation;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.RelativeLayout;
public class MainActivity extends ActionBarActivity {
private RelativeLayout layout;
private ImageView iv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
layout = (RelativeLayout) findViewById(R.id.layout);
iv = (ImageView) findViewById(R.id.iv);
layout.setOnTouchListener(new View.OnTouchListener() {
float currentDistance;
float lastDistance = -1;
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
break;
case MotionEvent.ACTION_MOVE:
//判断几个触控点
if (event.getPointerCount() >= 2) {
//两点之间x的坐标差
float offsetX = event.getX(0) - event.getX(1);
//两点之间y的坐标差
float offsetY = event.getY(0) - event.getY(1);
//两点之间的距离
currentDistance = (float) Math.sqrt(offsetX * offsetX + offsetY * offsetY);
if (lastDistance < 0) {
//没有缩放
lastDistance = currentDistance;
} else {
if (currentDistance - lastDistance > 5) {//放大
RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams) iv.getLayoutParams();
lp.width = (int) (1.1f * iv.getWidth());
lp.height = (int) (1.1f * iv.getHeight());
iv.setLayoutParams(lp);
lastDistance = currentDistance;
} else if (currentDistance - lastDistance < -5) {//缩小
int currentIvWidth = iv.getWidth();
int currentIvHeight = iv.getHeight();
if (currentIvWidth > 50 && currentIvHeight >50) {
RelativeLayout.LayoutParams lp = (RelativeLayout.LayoutParams) iv.getLayoutParams();
lp.width = (int) (0.9f * iv.getWidth());
lp.height = (int) (0.9f * iv.getHeight());
iv.setLayoutParams(lp);
lastDistance = currentDistance;
}
}
}
}
break;
case MotionEvent.ACTION_UP:
break;
}
return true;
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_main, menu);
return true;
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}xml代码：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/layout"
xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
android:layout_height="match_parent" tools:context=".MainActivity">
<ImageView
android:id="@+id/iv"
android:layout_width="wrap_content"
android:src="@mipmap/a"
android:layout_height="wrap_content" />
</RelativeLayout>
