android多点触摸
今天带大家来看一下android里面的多指触摸开发;几根手指放上去就会出现几个原点,可以移动
首先先创建一个属性类Circle.java 用来设置圆的x,y,还有半径
package com.example.android_07_09;
import android.graphics.Canvas;
import android.graphics.Paint;
/**
* Created by admin on 2017/7/9.
*/
public class Circle {
public float x;
public float y;
public int r=100;
public int pointId;
public Circle(float x, float y, int pointId) {
this.x = x;
this.y = y;
this.pointId = pointId;
}
public void drawSelf(Canvas canvas, Paint paint){
canvas.drawCircle(x,y,r,paint);
}
}
创建MyView.java的主类;继承View
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import java.util.ArrayList;
import java.util.List;
/**
* Created by admin on 2017/7/9.
*/
public class MyView extends View{
List<Circle> circles=new ArrayList<>();
public MyView(Context context) {
super(context);
}
public MyView(Context context, @Nullable AttributeSet attrs) {
super(context, attrs);
}
public MyView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
}
public MyView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//实例化画笔
Paint paint=new Paint();
for (Circle circle : circles) {
circle.drawSelf(canvas,paint);
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//获取手机的行为
int action=event.getAction();
int action_code=action&0xff;
//获取手指的下标Index
int pointIndex=action>>8;
//获取手指的坐标
float x=event.getX(pointIndex);
float y=event.getY(pointIndex);
//获取手指的ID
int pointId=event.getPointerId(pointIndex);
if(action_code>=5){
action_code-=5;
}
switch (action_code) {
//手指点下
case MotionEvent.ACTION_DOWN:
//按下的时候 ,实例化一个圆
Circle circle=new Circle(x,y,pointId);
//将圆 添加到集合中
circles.add(circle);
break;
//手指拿走
case MotionEvent.ACTION_UP:
circles.remove(get(pointId));
break;
//手指滑动
case MotionEvent.ACTION_MOVE:
for (int i = 0; i <event.getPointerCount() ; i++) {
int id=event.getPointerId(i);
get(id).x= event.getX(i);
get(id).y= event.getY(i);
}
break;
}
//重新调用onDraw 重绘
invalidate();
return true;
}
public Circle get(int pointId){
for (Circle circle : circles) {
if(circle.pointId==pointId){
return circle;
}
}
return null;
}
}
最后再MainActivity类中更改一下 就OK啦
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new MyView(this));
}
}
最后运行就可以了,只能有自己的手机进行测试哦 电脑的模拟器不支持手点。