与SurfaceView的初次见面

浅浅的花香味﹌ 2022-06-11 09:22 131阅读 0赞

SurfaceView适用于被动更新，通过子线程来进行页面的刷新,使用双缓冲机制。  
一般实现SurfaceHolder.Callback 和 Runnable接口。  
当SurfaceHolder被销毁的时候回调  
surfaceCreated（SurfaceHolder holder）  
开始绘制

当SurfaceHolder的尺寸发生变化的时候被回调。  
surfaceChange(SurfaceHolder holder, int format, int width, int height)

当SurfaceHolder被创建的时候回调  
surfaceDestroyed(SurfaceHolder holder)  
一般用于释放资源，或者结束绘图

下面画了一个用SurfaceView画了一个正弦波。

package com.example.administrator.youku_animi;
    
    import android.content.Context;
    import android.graphics.Canvas;
    import android.graphics.Color;
    import android.graphics.Paint;
    import android.graphics.Path;
    import android.util.AttributeSet;
    import android.view.SurfaceHolder;
    import android.view.SurfaceView;
    
    
    /** * Created by Administrator on 2017/8/3 0003. */
    
    public class MySurfaceView extends SurfaceView implements SurfaceHolder.Callback, Runnable { 
    
        private SurfaceHolder mHolder;
        private Canvas mCanvas;
        private boolean mIsDrawing;
        private Paint mPaint;
        private Path path;
        int x = 0, y;
    
    
        public MySurfaceView(Context context){
            super(context);
            initView();
        }
        public MySurfaceView(Context context, AttributeSet attrs)
        {
            super(context, attrs);
            initView();
        }
    
        /* *@author * * *初始化函数 *create at 2017/8/3 0003 下午 23:11 */
        private  void initView()
        {
            mHolder = getHolder();
            mHolder.addCallback(this);
            setFocusable(true);
            setFocusableInTouchMode(true);
            this.setKeepScreenOn(true);
            path = new Path();
            path.setLastPoint(0, 400);
    
            mPaint = new Paint();
            mPaint.setColor(Color.BLACK);
            mPaint.setStrokeWidth(2);
            mPaint.setStyle(Paint.Style.STROKE);
        }
    
        /* *@author * * * *create at 2017/8/3 0003 下午 23:10 */
        @Override
        public void surfaceCreated(SurfaceHolder holder)
        {
            mIsDrawing = true;
            new Thread(this).start();
        }
    
        @Override
        public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)
        {
    
        }
    
    
        @Override
        public void surfaceDestroyed(SurfaceHolder holder)
        {
            mIsDrawing = false;
        }
    
        /* *@author * * *画正选波 *create at 2017/8/3 0003 下午 23:09 */
        @Override
        public void run()
        {
            while (mIsDrawing)
            {
                draw();
                x += 1;
                y = (int) (100 * Math.sin(x * 2 * Math.PI / 180) + 400);
                path.lineTo(x, y);
            }
    
        }
    
        private void draw()
        {
            try
            {
                //锁定画布
                mCanvas = mHolder.lockCanvas();
                //draw something
                //给画布设置颜色为白色
                mCanvas.drawColor(Color.WHITE);
                //画路径
                mCanvas.drawPath(path, mPaint);
            }
            catch (Exception e)
            {
    
            }
            finally {
                if (mCanvas != null)
                {
                    //解锁画布
                    mHolder.unlockCanvasAndPost(mCanvas);
                }
            }
        }
    }