Android应用开发揭秘之5.2.2 Canvas类介绍

 

 

 

 

package com.yarin.android.Examples_05_04;

 

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.Rect;

import android.view.KeyEvent;

import android.view.MotionEvent;

import android.view.View;

 

public class GameView extends View implements Runnable

{

    /* 声明Paint对象 */

    private Paint               mPaint  = null;

 

    public GameView(Context context)

    {

        super(context);

        /* 构建对象 */

        mPaint = new Paint();

 

        /* 开启线程 */

        new Thread(this).start();

    }

   

    public void onDraw(Canvas canvas)

    {

        super.onDraw(canvas);

       

        /* 设置画布的颜色 */

        canvas.drawColor(Color.BLACK);

       

        /* 设置取消锯齿效果 */

        mPaint.setAntiAlias(true);

       

        /* 设置裁剪区域 这里就是把可以操作的canvas裁剪成下面这么大*/

        canvas.clipRect(10, 10, 280, 260);

 

       

        /* 线锁定画布 */

        canvas.save();

        /* 旋转画布 */

        canvas.rotate(45.0f);

       

        /* 设置颜色及绘制矩形 */

        mPaint.setColor(Color.RED);

        canvas.drawRect(new Rect(15,15,140,70), mPaint);

       

        /* 解除画布的锁定 */

        canvas.restore();

       

        /* 设置颜色及绘制另一个矩形 */

        mPaint.setColor(Color.GREEN);

        canvas.drawRect(new Rect(150,75,260,120), mPaint);

    }

   

    // 触笔事件

    public boolean onTouchEvent(MotionEvent event)

    {

        return true;

    }

 

 

    // 按键按下事件

    public boolean onKeyDown(int keyCode, KeyEvent event)

    {

        return true;

    }

 

 

    // 按键弹起事件

    public boolean onKeyUp(int keyCode, KeyEvent event)

    {

        return false;

    }

 

 

    public boolean onKeyMultiple(int keyCode, int repeatCount, KeyEvent event)

    {

        return true;

    }

 

 

    public void run()

    {

        while (!Thread.currentThread().isInterrupted())

        {

            try

            {

                Thread.sleep(100);

            }

            catch (InterruptedException e)

            {

                Thread.currentThread().interrupt();

            }

            // 使用postInvalidate可以直接在线程中更新界面

            postInvalidate();

        }

    }

}