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：

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);

public native void unlockCanvas(Canvas canvas);

public static native void openTransaction();

public static native void closeTransaction();

public static native void freezeDisplay(int display);

public static native void unfreezeDisplay(int display);

public static native void setOrientation(int display, int orientation, int flags);