1.知识图谱
A.单点触摸
自己写一个MyView实体类继承view
代码如下:
public class MyView extends View {
private float x;
private float y;
private int r=100;
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);
Paint paint=new Paint();
canvas.drawCircle(x,y,r,paint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//获取手指的行为
int action=event.getAction();
//获取手指的坐标
x=event.getX();
y=event.getY();
switch (action) {
case MotionEvent.ACTION_DOWN:
break;
case MotionEvent.ACTION_UP:
break;
case MotionEvent.ACTION_MOVE:
break;
}
//重新调用onDraw 重绘
invalidate();
return true;
}
}
2.多点触摸
首先要写一个Circle的实体类
package com.example.cookie.android0709twopointstouch;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import java.util.Random;
/**
* Created by Administrator on 2017/7/9 0009.
*/
public class Circle {
public float x;
public float y;
public int r=100;
public int pointId;
public int red;
public int green;
public int blue;
Random random=new Random();
public Circle(float x, float y, int pointId) {
this.x = x;
this.y = y;
this.pointId = pointId;
red=random.nextInt(255);
green=random.nextInt(255);
blue=random.nextInt(255);
}
public void drawSelf(Canvas canvas, Paint paint){
//设置随机画笔的颜色
paint.setColor(Color.rgb(red,green,blue));
paint.setStyle(Paint.Style.STROKE);
canvas.drawCircle(x,y,r,paint);
}
}
再写一个MyView继承View
package com.example.cookie.android0709twopointstouch;
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 Administrator on 2017/7/9 0009.
*/
public class MyView extends View {
public 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);
Paint paint=new Paint();
for (Circle circle : circles) {
circle.drawSelf(canvas,paint);
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//获取手指的行为
int action=event.getAction();
int action_code=action&0xff;
//手指的下标
int pointIndex=action>>8;
//获取手指的下标
float x=event.getX(pointIndex);
float y=event.getY(pointIndex);
//获取手指的名字ID
int pointId=event.getPointerId(pointIndex);
if (action_code>=5){
action_code-=5;
}
switch (action_code) {
case MotionEvent.ACTION_DOWN:
//实例化圆
Circle circle=new Circle(x,y,pointId);
circles.add(circle);
break;
case MotionEvent.ACTION_UP:
circles.remove(get(pointId));
break;
case MotionEvent.ACTION_MOVE:
for (int i = 0; i < event.getPointerCount(); i++) {
int id=event.getPointerId(i);
get(id).x=event.getX();
get(id).y=event.getY();
}
break;
}
//重新绘制
invalidate();
return true;
}
public Circle get(int pointId){
for (Circle circle : circles) {
if (circle.pointId==pointId){
return circle;
}
}
return null;
}
}