SurfaceHolder源代码分析

package android.view;import android.graphics.Canvas;import android.graphics.Rect;public interface SurfaceHolder {    @Deprecated    public static final int SURFACE_TYPE_NORMAL = 0;    @Deprecated    public static final int SURFACE_TYPE_HARDWARE = 1;    @Deprecated    public static final int SURFACE_TYPE_GPU = 2;    @Deprecated    public static final int SURFACE_TYPE_PUSH_BUFFERS = 3;        public static class BadSurfaceTypeException extends RuntimeException {        public BadSurfaceTypeException() {        }        public BadSurfaceTypeException(String name) {            super(name);        }    }    public interface Callback {        public void surfaceCreated(SurfaceHolder holder);        public void surfaceChanged(SurfaceHolder holder, int format, int width,                int height);        public void surfaceDestroyed(SurfaceHolder holder);    }    public interface Callback2 extends Callback {        public void surfaceRedrawNeeded(SurfaceHolder holder);    }    public void addCallback(Callback callback);    public void removeCallback(Callback callback);    public boolean isCreating();    @Deprecated    public void setType(int type);    public void setFixedSize(int width, int height);    public void setSizeFromLayout();    public void setFormat(int format);    public void setKeepScreenOn(boolean screenOn);    public Canvas lockCanvas();    public Canvas lockCanvas(Rect dirty);    public void unlockCanvasAndPost(Canvas canvas);    public Rect getSurfaceFrame();    public Surface getSurface();}

在看SurfaceView时，得知利用SurfaceHolder来控制Surface，所以对这个Holder进行了了解。以上就是source for sdk中关于SurfaceHolder的源代码。

通过阅读该代码段，我们了解到在该接口中，主要就是需要实现Callback接口以及重写其中的created、changed和destroyed方法。对于画布Canvas的操作主要就是LOCK和UNLOCK