Android之多点触控实例

直接上代码，代码内容上有相应的注释。效果作简短介绍，有一个圆形一个方形，当一只手指触控的时候只有圆形随着移动；当两只手指触控的时候圆形与方形各自随着手指移动。不要忘记使用View.invalidate()对绘图进行更新。

/* import相关class */
importandroid.app.Activity;
importandroid.content.Context;
importandroid.graphics.Canvas;
importandroid.graphics.Color;
importandroid.graphics.LinearGradient;
importandroid.graphics.Paint;
importandroid.graphics.Shader;
importandroid.os.Bundle;
importandroid.util.Log;
importandroid.view.MotionEvent;
importandroid.view.View;
importandroid.view.Window;

public classmulti extendsActivity
{
//x1,y1是第一个触控点；x2,y2是第二个触控点

publicfloatx1,x2,y1,y2;
privateMyViewmyView;

@Override
publicvoidonCreate(BundlesavedInstanceState)
{
//设置没有title
requestWindowFeature(Window.FEATURE_NO_TITLE);
//getWindow().setFlags(flags,mask)
x1=30;
y1=30;
x2=200;
y2=30;
super.onCreate(savedInstanceState);
/*设置ContentView为自定义的MyView*/
myView=newMyView(this);
setContentView(myView);

}

@Override
publicbooleanonTouchEvent(MotionEventevent)
{
//if(event.getX(1)==event.getX(0)&&event.getY(1)==event.getY(0))、
//如果有两个点接触才执行该代码段
if(event.getPointerCount()==2)
{
x2=event.getX(1);
y2=event.getY(1);
}
x1=event.getX(0);
y1=event.getY(0);
//用于更新view

myView.invalidate();

//Log.d("multi01",event.getPointerCount()+"xy1:"+x1+","
//+y1+"xy2:"+x2+","+y2);
returnsuper.onTouchEvent(event);
}

/*自定义继承View的MyView*/
privateclassMyViewextendsView
{
publicMyView(Contextcontext)
{
super(context);
}

/*覆盖onDraw()*/
@Override
protectedvoidonDraw(Canvascanvas)
{
super.onDraw(canvas);
/*设置背景为白色*/
canvas.drawColor(Color.WHITE);

Paintpaint=newPaint();
/*去锯齿*/
paint.setAntiAlias(true);

/*设置paint的style为FILL：实心*/
paint.setStyle(Paint.Style.FILL);
/*设置paint的颜色*/
paint.setColor(Color.BLUE);

/*画一个实心圆*/
canvas.drawCircle(x1,y1,30,paint);
/*画一个实心正方形*/
canvas.drawRect(x2-30,y2-30,x2+30,y2+30,paint);
paint.setColor(Color.RED);
canvas.drawLine(x1,y1,x2,y2,paint);
/*设置渐变色*/
ShadermShader=newLinearGradient(0,0,100,100,newint[]
{Color.RED,Color.GREEN,Color.BLUE,Color.YELLOW},null,
Shader.TileMode.REPEAT);
paint.setShader(mShader);

/*写字*/
paint.setTextSize(14);
canvas.drawText("xy1:"+x1+";"+y1,80,50,paint);
canvas.drawText("xy2:"+x2+";"+y2,80,120,paint);
}
}

}

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