android图像绘制(四)自定义一个SurfaceView控件

下面我将为你详细讲解“android图像绘制(四)自定义一个SurfaceView控件”的完整攻略。

一、SurfaceView简介

SurfaceView是Android系统中常用的视图控件之一，它提供了一个可以在子线程中进行绘制操作的Canvas，使得我们可以方便地绘制动画、视频等复杂的图形内容，同时还可以提高绘制的效率和流畅度。

二、自定义SurfaceView控件

在Android应用中，我们经常需要自定义一些控件来满足自己的需求，而自定义SurfaceView控件是其中的一种常见方式。下面就介绍一下如何自定义一个SurfaceView控件。

1. 定义自定义SurfaceView控件类

public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback, Runnable {

    private SurfaceHolder mHolder;
    private Thread mThread;
    private boolean mIsRunning;

    public MySurfaceView(Context context) {
        super(context);
        init();
    }

    public MySurfaceView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public MySurfaceView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        mHolder = getHolder();
        mHolder.addCallback(this);
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder) {}

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {}

    @Override
    public void run() {}

}

2. 实现SurfaceHolder.Callback接口

    @Override
    public void surfaceCreated(SurfaceHolder holder) {
        mIsRunning = true;
        mThread = new Thread(this);
        mThread.start();
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {}

    @Override
    public void surfaceDestroyed(SurfaceHolder holder) {
        mIsRunning = false;
        try {
            mThread.join();
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }

3. 实现Runnable接口

    @Override
    public void run() {
        while (mIsRunning) {
            Canvas canvas = mHolder.lockCanvas();
            if (canvas != null) {
                // 在这里进行绘制操作
                mHolder.unlockCanvasAndPost(canvas);
            }
        }
    }

三、示例说明

1. 绘制一个矩形

    @Override
    public void run() {
        while (mIsRunning) {
            Canvas canvas = mHolder.lockCanvas();
            if (canvas != null) {
                Paint paint = new Paint();
                paint.setColor(Color.RED);
                canvas.drawRect(100, 100, 200, 200, paint);
                mHolder.unlockCanvasAndPost(canvas);
            }
        }
    }

2. 绘制一个移动的圆形

    private int mX = 100;
    private int mY = 100;
    private int mRadius = 50;
    private int mSpeed = 10;

    @Override
    public void run() {
        while (mIsRunning) {
            Canvas canvas = mHolder.lockCanvas();
            if (canvas != null) {
                Paint paint = new Paint();
                paint.setColor(Color.BLUE);
                canvas.drawCircle(mX, mY, mRadius, paint);
                mX += mSpeed;
                if (mX > getWidth() - mRadius) {
                    mSpeed = -10;
                } else if (mX < mRadius) {
                    mSpeed = 10;
                }
                mHolder.unlockCanvasAndPost(canvas);
            }
        }
    }

以上就是自定义一个SurfaceView控件并进行绘制的攻略。希望对你有所帮助。