android 多点触摸实例

package com.multi;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Shader;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.Window;

public class MainMulti extends Activity {
private float x1,y1,x2,y2;
private MyView myView;
@Override
public void onCreate(Bundle savedInstanceState) {
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 = new MyView(this);
setContentView(myView);
}

@Override
public boolean onTouchEvent(MotionEvent event)
{
if (event.getPointerCount() == 2)//当有两个触发点的时候执行xy2
{
x2 = event.getX(1);
y2 = event.getY(1);
}
x1 = event.getX(0);
y1 = event.getY(0);
myView.invalidate();
return super.onTouchEvent(event);
}

/* 自定义继承View的MyView */
private class MyView extends View
{
public MyView(Context context)
{
super(context);
}
/* 覆盖onDraw() */
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);

/* 设置背景为白色 */
canvas.drawColor(Color.WHITE);

Paint paint = new Paint();
/* 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 */
Shader mShader = new LinearGradient(0, 0, 100, 100, new int[]
{ 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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