Android的surface类源码深度剖析

surface用来处理一段单独的缓冲区，这段缓冲区是由屏幕合成器来管理的。

surface 包含安全的内容，使用一些特殊的措施来阻止在其他的进程中复制surface内容。尤其是截屏和VNC服务。surface不能被硬件加速。它创建的缓冲区有几种：BUFFERS，NORMAL，BLUR，DIM。

当surface不能被创建或更改大小时候，系统会抛出异常。surface创建过程中，创建了一个画布，并且在之后的程序设计中我们可以使用。我们可以锁定或解锁一个surface，但解锁时，只有调用post()或postAll() 是才会更新屏幕。

源码：

package Android.view;

import android.graphics.*;
import android.os.Parcelable;
import android.os.Parcel;
import android.util.Log;

public class Surface implements Parcelable {
    private static final String LOG_TAG = "Surface";
   
 
    public static final int HIDDEN              = 0x00000004;

public static final int HARDWARE            = 0x00000010;

public static final int GPU                 = 0x00000028;

public static final int SECURE              = 0x00000080;
   
   
    public static final int NON_PREMULTIPLIED   = 0x00000100;
   
   
    public static final int PUSH_BUFFERS        = 0x00000200;
   
  
    public static final int FX_SURFACE_NORMAL   = 0x00000000;
   
  
    public static final int FX_SURFACE_BLUR     = 0x00010000;
   
  
    public static final int FX_SURFACE_DIM     = 0x00020000;

    public static final int FX_SURFACE_MASK     = 0x000F0000;

   
  
    public static final int SURFACE_HIDDEN    = 0x01;
   
  
    public static final int SURACE_FROZEN     = 0x02;
   
    public static final int SURFACE_DITHER    = 0x04;

public static final int SURFACE_BLUR_FREEZE= 0x10;

    public static final int ROTATION_0       = 0;
    public static final int ROTATION_90      = 1;
    public static final int ROTATION_180     = 2;
    public static final int ROTATION_270     = 3;
   
  
    public static final int FLAGS_ORIENTATION_ANIMATION_DISABLE = 0x000000001;

@SuppressWarnings("unused")
    private int mSurface;
    @SuppressWarnings("unused")
    private int mSaveCount;
    @SuppressWarnings("unused")
    private Canvas mCanvas;

/**
     * Exception thrown when a surface couldn't be created or resized
     */
    public static class OutOfResourcesException extends Exception {
        public OutOfResourcesException() {
        }
        public OutOfResourcesException(String name) {
            super(name);
        }
    }

    native private static void nativeClassInit();
    static { nativeClassInit(); }

    public Surface(SurfaceSession s,
            int pid, int display, int w, int h, int format, int flags)
        throws OutOfResourcesException {
        mCanvas = new Canvas();
        init(s,pid,display,w,h,format,flags);
    }

    public Surface() {
        mCanvas = new Canvas();
    }
   
    public native   void copyFrom(Surface o);
   
   
    public native   boolean isValid();
   
    public native   void clear();
   
    public Canvas lockCanvas(Rect dirty) throws OutOfResourcesException {
     
        return lockCanvasNative(dirty);
    }

private native Canvas lockCanvasNative(Rect dirty);

    public native   void unlockCanvasAndPost(Canvas canvas);