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）;
    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）;    public static void setOrientation（int display, int orientation） {
        setOrientation（display, orientation, 0）;
    }


    public native   void setLayer（int zorder）;
    public native   void setPosition（int x, int y）;
    public native   void setSize（int w, int h）;    public native   void hide（）;
    public native   void show（）;
    public native   void setTransparentRegionHint（Region region）;
    public native   void setAlpha（float alpha）;
    public native   void setMatrix（float dsdx, float dtdx,
                                   float dsdy, float dtdy）;    public native   void freeze（）;
    public native   void unfreeze（）;    public native   void setFreezeTint（int tint）;    public native   void setFlags（int flags, int mask）;    @Override
    public String toString（） {
        return "Surface（native-token=" + mSurface + "）";
    }    private Surface（Parcel source） throws OutOfResourcesException {
        init（source）;
    }

    public int describeContents（） {
        return 0;
    }    public native   void readFromParcel（Parcel source）;
    public native   void writeToParcel（Parcel dest, int flags）;    public static final Parcelable.Creator<Surface> CREATOR
            = new Parcelable.Creator<Surface>（）
    {
        public Surface createFromParcel（Parcel source） {
            try {
                return new Surface（source）;
            } catch （Exception e） {
                Log.e（LOG_TAG, "Exception creating surface from parcel", e）;
            }
            return null;
        }        public Surface[] newArray（int size） {
            return new Surface[size];
        }
    };    /* no user serviceable parts here ... */
    @Override
    protected void finalize（） throws Throwable {
        clear（）;
    }

    private native void init（SurfaceSession s,
            int pid, int display, int w, int h, int format, int flags）
            throws OutOfResourcesException;    private native void init（Parcel source）;
}