android 触摸手指动作放大和缩小图片

private RelativeLayout root;

private ImageView moveImage;

float lastDestance=-1;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);

setSupportActionBar(toolbar);

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

moveImage = (ImageView) findViewById(R.id.moveImage);

root.setOnTouchListener(new View.OnTouchListener() { //侦听控件的触摸事件

@Override

public boolean onTouch(View v, MotionEvent event) {

float currentDestance;

switch (event.getAction())

{

case MotionEvent.ACTION_DOWN ://监听点击一个点

System.out.println("按下");

break;

case MotionEvent.ACTION_MOVE ://触摸移动 手指移动时

if (event.getPointerCount()>=2)

{

float offSetX =event.getX(0)-event.getX(1);//获取

float offSetY =event.getY(0)-event.getY(1 );

currentDestance = (float) Math.sqrt(offSetX*offSetX+offSetY*offSetY);//获取两点间距离 然后运用勾股定理 算出两个手指点之间的距离

System.out.println(lastDestance);

if (lastDestance<0) {

System.out.println("初始化变量");

System.out.println(currentDestance);

lastDestance= (float)currentDestance;//将第一次获取的两点距离 复制给lastDestance

System.out.println(lastDestance);

}

else {

System.out.println("进入手指动作判断");

if (currentDestance-lastDestance>5)

{

System.out.println("手势 放大");

RelativeLayout.LayoutParams lv= (RelativeLayout.LayoutParams) moveImage.getLayoutParams();

lv.width = (int) (1.1f*moveImage.getWidth());//每一次两点间的距离放大 将图片的高和宽 分别*1.1 不停的放大

lv.height = (int) (1.1f*moveImage.getHeight());

moveImage.setLayoutParams(lv);//将每次放大的距离复制个image的高和宽

lastDestance =currentDestance;//将这一次的两点间距离赋值给lastDestance 以便每次比较

}

else if (lastDestance-currentDestance>5){

System.out.println("手势 缩小");

RelativeLayout.LayoutParams lv= (RelativeLayout.LayoutParams) moveImage.getLayoutParams();

lv.width = (int) (0.9f*moveImage.getWidth());//当两点间的距离在不断的缩小时

lv.height = (int) (0.9f*moveImage.getHeight());

moveImage.setLayoutParams(lv);

lastDestance =currentDestance;

}

}

}

break;

case MotionEvent.ACTION_UP ://手指离开屏幕事件

System.out.println("弹起");

break;

default:

System.out.println("无");

break;

}

return true;

}

});

}