Silverlight &Windows phone7 中使用Isolated Storage存储与读取图片

1 将ImageSource转化成WriteableBitmap

   var bitmap= new System.Windows.Media.Imaging.WriteableBitmap((System.Windows.Media.Imaging.BitmapSource)this.imgCreatedTag.Source);

2 代码：

 

///<summary>
      /// 载入指定名称的图片
      ///</summary>
      ///<param name="fileName"></param>
      ///<returns>返回指定文件的byte[]流</returns>
privatestaticbyte[] _LoadIfExists(string fileName)
        {
            byte[] retVal;

            using (IsolatedStorageFile iso = IsolatedStorageFile.GetUserStoreForApplication())
            {
                if (iso.FileExists(fileName))
                {
                    using (IsolatedStorageFileStream stream =
                    iso.OpenFile(fileName, FileMode.Open))
                    {
                        retVal =newbyte[stream.Length];
                        stream.Read(retVal, 0, retVal.Length);
                    }
                }
                else
                {
                    retVal =newbyte[0];
                }
            }
            return retVal;
        }
        ///<summary>
        /// 保存byte[]流到Storage
        ///</summary>
        ///<param name="buffer"></param>
        ///<param name="fileName"></param>
privatestaticvoid _SaveToDisk(byte[] buffer, string fileName)
        {
            using (IsolatedStorageFile iso =
                IsolatedStorageFile.GetUserStoreForApplication())
            {
                using (
                    IsolatedStorageFileStream stream =
                new IsolatedStorageFileStream(fileName, FileMode.CreateNew,
                                iso))
                {
                    stream.Write(buffer, 0, buffer.Length);
                }
            }
        }
        ///<summary>
        /// 从Storage获取图片
        ///</summary>
        ///<param name="buffer">图片的byte[]流</param>
        ///<returns></returns>
privatestatic WriteableBitmap _GetImage(byte[] buffer)
        {
            int width = buffer[0] *256+ buffer[1];
            int height = buffer[2] *256+ buffer[3];

            long matrixSize = width * height;

            WriteableBitmap retVal =new WriteableBitmap(width, height);

            int bufferPos =4;

            for (int matrixPos =0; matrixPos < matrixSize; matrixPos++)
            {
                int pixel = buffer[bufferPos++];
                pixel = pixel <<8| buffer[bufferPos++];
                pixel = pixel <<8| buffer[bufferPos++];
                pixel = pixel <<8| buffer[bufferPos++];
                retVal.Pixels[matrixPos] = pixel;
            }

            return retVal;
        }
        
        ///<summary>
        /// 将图片转换成byte[]流
        ///</summary>
        ///<param name="bitmap"></param>
        ///<returns></returns>
privatestaticbyte[] _GetSaveBuffer(WriteableBitmap bitmap)
        {
            long matrixSize = bitmap.PixelWidth * bitmap.PixelHeight;

            long byteSize = matrixSize *4+4;

            byte[] retVal =newbyte[byteSize];

            long bufferPos =0;

            retVal[bufferPos++] = (byte)((bitmap.PixelWidth /256) &0xff);
            retVal[bufferPos++] = (byte)((bitmap.PixelWidth %256) &0xff);
            retVal[bufferPos++] = (byte)((bitmap.PixelHeight /256) &0xff);
            retVal[bufferPos++] = (byte)((bitmap.PixelHeight %256) &0xff);

            for (int matrixPos =0; matrixPos < matrixSize; matrixPos++)
            {
                retVal[bufferPos++] = (byte)((bitmap.Pixels[matrixPos] >>24) &0xff);
                retVal[bufferPos++] = (byte)((bitmap.Pixels[matrixPos] >>16) &0xff);
                retVal[bufferPos++] = (byte)((bitmap.Pixels[matrixPos] >>8) &0xff);
                retVal[bufferPos++] = (byte)((bitmap.Pixels[matrixPos]) &0xff);
            }

            return retVal;
        }