Silverlight导出图片需要的几个类

1、EditableImage.cs类，代码如下：

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.IO;

namespace MapClient.CommonClass
{
public class EditableImage
{
private int _width = 0;
private int _height = 0;
private bool _init = false;
private byte[] _buffer;
private int _rowLength;

public event EventHandler<EditableImageErrorEventArgs> ImageError;

public EditableImage(int width, int height)
{
this.Width = width;
this.Height = height;
}

public int Width
{
get
{
return _width;
}
set
{
if (_init)
{
OnImageError("Error: Cannot change Width after the EditableImage has been initialized");
}
else if ((value <= 0) || (value > 2047))
{
OnImageError("Error: Width must be between 0 and 2047");
}
else
{
_width = value;
}
}
}

public int Height
{
get
{
return _height;
}
set
{
if (_init)
{
OnImageError("Error: Cannot change Height after the EditableImage has been initialized");
}
else if ((value <= 0) || (value > 2047))
{
OnImageError("Error: Height must be between 0 and 2047");
}
else
{
_height = value;
}
}
}

public void SetPixel(int col, int row, Color color)
{
SetPixel(col, row, color.R, color.G, color.B, color.A);
}

public void SetPixel(int col, int row, byte red, byte green, byte blue, byte alpha)
{
if (!_init)
{
_rowLength = _width * 4 + 1;
_buffer = new byte[_rowLength * _height];

// Initialize
for (int idx = 0; idx < _height; idx++)
{
_buffer[idx * _rowLength] = 0;      // Filter bit
}

_init = true;
}

if ((col > _width) || (col < 0))
{
OnImageError("Error: Column must be greater than 0 and less than the Width");
}
else if ((row > _height) || (row < 0))
{
OnImageError("Error: Row must be greater than 0 and less than the Height");
}

// Set the pixel
int start = _rowLength * row + col * 4 + 1;
_buffer[start] = red;
_buffer[start + 1] = green;
_buffer[start + 2] = blue;
_buffer[start + 3] = alpha;
}

public Color GetPixel(int col, int row)
{
if ((col > _width) || (col < 0))
{
OnImageError("Error: Column must be greater than 0 and less than the Width");
}
else if ((row > _height) || (row < 0))
{
OnImageError("Error: Row must be greater than 0 and less than the Height");
}

Color color = new Color();
int _base = _rowLength * row + col + 1;

color.R = _buffer[_base];
color.G = _buffer[_base + 1];
color.B = _buffer[_base + 2];
color.A = _buffer[_base + 3];

return color;
}

public Stream GetStream()
{
Stream stream;

if (!_init)
{
OnImageError("Error: Image has not been initialized");
stream = null;
}
else
{
stream = PngEncoder.Encode(_buffer, _width, _height);
}

return stream;
}

private void OnImageError(string msg)
{
if (null != ImageError)
{
EditableImageErrorEventArgs args = new EditableImageErrorEventArgs();
args.ErrorMessage = msg;
ImageError(this, args);
}
}

public class EditableImageErrorEventArgs : EventArgs
{
private string _errorMessage = string.Empty;

public string ErrorMessage
{
get { return _errorMessage; }
set { _errorMessage = value; }
}
}

}
}

2、ElementToPNG.cs类，代码如下：using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.Windows.Media.Imaging;
using System.IO;

namespace MapClient.CommonClass
{
/// <summary>
/// Based on:
///
/// Andy Beaulieu
/// http://www.andybeaulieu.com/Home/tabid/67/EntryID/161/Default.aspx ///
///
/// Tom Giam
/// http://silverlight.net/forums/t/108713.aspx /// </summary>
public class ElementToPNG
{
public void ShowSaveDialog(UIElement elementToExport)
{

//Canvas canvasToExport = e as Canvas;
// Instantiate SaveFileDialog
// and set defautl settings (just PNG export)

SaveFileDialog sfd = new SaveFileDialog()
{
DefaultExt = "png",
Filter = "Png files (*.png)|*.png|All files (*.*)|*.*",
FilterIndex = 1
};

if (sfd.ShowDialog() == true)
{
SaveAsPNG(sfd, elementToExport);
}
}

private void SaveAsPNG(SaveFileDialog sfd, UIElement elementToExport)
{
WriteableBitmap bitmap = new WriteableBitmap(elementToExport, new TranslateTransform());
EditableImage imageData = new EditableImage(bitmap.PixelWidth, bitmap.PixelHeight);

try
{
for (int y = 0; y < bitmap.PixelHeight; ++y)
{

for (int x = 0; x < bitmap.PixelWidth; ++x)
{

int pixel = bitmap.Pixels[bitmap.PixelWidth * y + x];
imageData.SetPixel(x, y,

(byte)((pixel >> 16) & 0xFF),
(byte)((pixel >> 8) & 0xFF),

(byte)(pixel & 0xFF), (byte)((pixel >> 24) & 0xFF)
);

}

}

}
catch (System.Security.SecurityException)
{
throw new Exception("Cannot print images from other domains");
}

// Save it to disk
Stream pngStream = imageData.GetStream();

//StreamReader sr = new StreamReader(pngStream);
byte[] binaryData = new Byte[pngStream.Length];

long bytesRead = pngStream.Read(binaryData, 0, (int)pngStream.Length);

//using (Stream stream = sfd.OpenFile())
//{

// stream.Write(binaryData, 0, binaryData.Length);

// stream.Close();

//}

Stream stream = sfd.OpenFile();

stream.Write(binaryData, 0, binaryData.Length);

stream.Close();

}
}
}


3、PngEncoder.cs类，代码如下：

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using System.IO;
using System.Windows.Browser;
using System.Reflection;

namespace MapClient.CommonClass
{
public class PngEncoder
{
private const int _ADLER32_BASE = 65521;
private const int _MAXBLOCK = 0xFFFF;
private static byte[] _HEADER = { 0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A };
private static byte[] _IHDR = { (byte)'I', (byte)'H', (byte)'D', (byte)'R' };
private static byte[] _GAMA = { (byte)'g', (byte)'A', (byte)'M', (byte)'A' };
private static byte[] _IDAT = { (byte)'I', (byte)'D', (byte)'A', (byte)'T' };
private static byte[] _IEND = { (byte)'I', (byte)'E', (byte)'N', (byte)'D' };
private static byte[] _4BYTEDATA = { 0, 0, 0, 0 };
private static byte[] _ARGB = { 0, 0, 0, 0, 0, 0, 0, 0, 8, 6, 0, 0, 0 };

public static Stream Encode(byte[] data, int width, int height)
{
MemoryStream ms = new MemoryStream();
byte[] size;

// Write PNG header
ms.Write(_HEADER, 0, _HEADER.Length);

// Write IHDR
//  Width:              4 bytes
//  Height:             4 bytes
//  Bit depth:          1 byte
//  Color type:         1 byte
//  Compression method: 1 byte
//  Filter method:      1 byte
//  Interlace method:   1 byte

size = BitConverter.GetBytes(width);
_ARGB[0] = size[3]; _ARGB[1] = size[2]; _ARGB[2] = size[1]; _ARGB[3] = size[0];

size = BitConverter.GetBytes(height);
_ARGB[4] = size[3]; _ARGB[5] = size[2]; _ARGB[6] = size[1]; _ARGB[7] = size[0];

// Write IHDR chunk
WriteChunk(ms, _IHDR, _ARGB);

// Set gamma = 1
size = BitConverter.GetBytes(1 * 100000);
_4BYTEDATA[0] = size[3]; _4BYTEDATA[1] = size[2]; _4BYTEDATA[2] = size[1]; _4BYTEDATA[3] = size[0];

// Write gAMA chunk
WriteChunk(ms, _GAMA, _4BYTEDATA);

// Write IDAT chunk
uint widthLength = (uint)(width * 4) + 1;
uint dcSize = widthLength * (uint)height;

// First part of ZLIB header is 78 1101 1010 (DA) 0000 00001 (01)
// ZLIB info
//
// CMF Byte: 78
//  CINFO = 7 (32K window size)
//  CM = 8 = (deflate compression)
// FLG Byte: DA
//  FLEVEL = 3 (bits 6 and 7 - ignored but signifies max compression)
//  FDICT = 0 (bit 5, 0 - no preset dictionary)
//  FCHCK = 26 (bits 0-4 - ensure CMF*256+FLG / 31 has no remainder)
// Compressed data
//  FLAGS: 0 or 1
//    00000 00 (no compression) X (X=1 for last block, 0=not the last block)
//    LEN = length in bytes (equal to ((width*4)+1)*height
//    NLEN = one's compliment of LEN
//    Example: 1111 1011 1111 1111 (FB), 0000 0100 0000 0000 (40)
//    Data for each line: 0 [RGBA] [RGBA] [RGBA] ...
//    ADLER32

uint adler = ComputeAdler32(data);
MemoryStream comp = new MemoryStream();

// Calculate number of 64K blocks
uint rowsPerBlock = _MAXBLOCK / widthLength;
uint blockSize = rowsPerBlock * widthLength;
uint blockCount;
ushort length;
uint remainder = dcSize;

if ((dcSize % blockSize) == 0)
{
blockCount = dcSize / blockSize;
}
else
{
blockCount = (dcSize / blockSize) + 1;
}

// Write headers
comp.WriteByte(0x78);
comp.WriteByte(0xDA);

for (uint blocks = 0; blocks < blockCount; blocks++)
{
// Write LEN
length = (ushort)((remainder < blockSize) ? remainder : blockSize);

if (length == remainder)
{
comp.WriteByte(0x01);
}
else
{
comp.WriteByte(0x00);
}

comp.Write(BitConverter.GetBytes(length), 0, 2);

// Write one's compliment of LEN
comp.Write(BitConverter.GetBytes((ushort)~length), 0, 2);

// Write blocks
comp.Write(data, (int)(blocks * blockSize), length);

// Next block
remainder -= blockSize;
}

WriteReversedBuffer(comp, BitConverter.GetBytes(adler));
comp.Seek(0, SeekOrigin.Begin);

byte[] dat = new byte[comp.Length];
comp.Read(dat, 0, (int)comp.Length);

WriteChunk(ms, _IDAT, dat);

// Write IEND chunk
WriteChunk(ms, _IEND, new byte[0]);

// Reset stream
ms.Seek(0, SeekOrigin.Begin);

return ms;

// See http://www.libpng.org/pub/png//spec/1.2/PNG-Chunks.html // See http://www.libpng.org/pub/png/book/chapter08.html#png.ch08.div.4 // See http://www.gzip.org/zlib/rfc-zlib.html (ZLIB format)
// See ftp://ftp.uu.net/pub/archiving/zip/doc/rfc1951.txt (ZLIB compression format)
}

private static void WriteReversedBuffer(Stream stream, byte[] data)
{
int size = data.Length;
byte[] reorder = new byte[size];

for (int idx = 0; idx < size; idx++)
{
reorder[idx] = data[size - idx - 1];
}
stream.Write(reorder, 0, size);
}

private static void WriteChunk(Stream stream, byte[] type, byte[] data)
{
int idx;
int size = type.Length;
byte[] buffer = new byte[type.Length + data.Length];

// Initialize buffer
for (idx = 0; idx < type.Length; idx++)
{
buffer[idx] = type[idx];
}

for (idx = 0; idx < data.Length; idx++)
{
buffer[idx + size] = data[idx];
}

// Write length
WriteReversedBuffer(stream, BitConverter.GetBytes(data.Length));

// Write type and data
stream.Write(buffer, 0, buffer.Length);   // Should always be 4 bytes

// Compute and write the CRC
WriteReversedBuffer(stream, BitConverter.GetBytes(GetCRC(buffer)));
}

private static uint[] _crcTable = new uint[256];
private static bool _crcTableComputed = false;

private static void MakeCRCTable()
{
uint c;

for (int n = 0; n < 256; n++)
{
c = (uint)n;
for (int k = 0; k < 8; k++)
{
if ((c & (0x00000001)) > 0)
c = 0xEDB88320 ^ (c >> 1);
else
c = c >> 1;
}
_crcTable
= c;
}

_crcTableComputed = true;
}

private static uint UpdateCRC(uint crc, byte[] buf, int len)
{
uint c = crc;

if (!_crcTableComputed)
{
MakeCRCTable();
}

for (int n = 0; n < len; n++)
{
c = _crcTable[(c ^ buf
) & 0xFF] ^ (c >> 8);
}

return c;
}

/* Return the CRC of the bytes buf[0..len-1]. */
private static uint GetCRC(byte[] buf)
{
return UpdateCRC(0xFFFFFFFF, buf, buf.Length) ^ 0xFFFFFFFF;
}

private static uint ComputeAdler32(byte[] buf)
{
uint s1 = 1;
uint s2 = 0;
int length = buf.Length;

for (int idx = 0; idx < length; idx++)
{
s1 = (s1 + (uint)buf[idx]) % _ADLER32_BASE;
s2 = (s2 + s1) % _ADLER32_BASE;
}

return (s2 << 16) + s1;
}
}
}

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