Thumbnail 缩略图生成

using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Net;

namespace EasyFrame.Common
{
/// <summary>
/// Thumbnail 的摘要说明。
/// </summary>
public class Thumbnail
{
private Image srcImage;
private string srcFileName;

/// <summary>
/// 创建
/// </summary>
/// <param name="FileName">原始图片路径</param>
public bool SetImage(string FileName)
{
srcFileName = Utils.GetMapPath(FileName);
try
{
srcImage = Image.FromFile(srcFileName);
}
catch
{
return false;
}
return true;

}

/// <summary>
/// 回调
/// </summary>
/// <returns></returns>
public bool ThumbnailCallback()
{
return false;
}

/// <summary>
/// 生成缩略图,返回缩略图的Image对象
/// </summary>
/// <param name="Width">缩略图宽度</param>
/// <param name="Height">缩略图高度</param>
/// <returns>缩略图的Image对象</returns>
public Image GetImage(int Width, int Height)
{
Image img;
Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);
img = srcImage.GetThumbnailImage(Width, Height, callb, IntPtr.Zero);
return img;
}

/// <summary>
/// 保存缩略图
/// </summary>
/// <param name="Width"></param>
/// <param name="Height"></param>
public void SaveThumbnailImage(int Width, int Height)
{
switch (Path.GetExtension(srcFileName).ToLower())
{
case ".png":
SaveImage(Width, Height, ImageFormat.Png);
break;
case ".gif":
SaveImage(Width, Height, ImageFormat.Gif);
break;
default:
SaveImage(Width, Height, ImageFormat.Jpeg);
break;
}
}

/// <summary>
/// 生成缩略图并保存
/// </summary>
/// <param name="Width">缩略图的宽度</param>
/// <param name="Height">缩略图的高度</param>
/// <param name="imgformat">保存的图像格式</param>
/// <returns>缩略图的Image对象</returns>
public void SaveImage(int Width, int Height, ImageFormat imgformat)
{
if (imgformat != ImageFormat.Gif && (srcImage.Width > Width) || (srcImage.Height > Height))
{
Image img;
Image.GetThumbnailImageAbort callb = new Image.GetThumbnailImageAbort(ThumbnailCallback);
img = srcImage.GetThumbnailImage(Width, Height, callb, IntPtr.Zero);
srcImage.Dispose();
img.Save(srcFileName, imgformat);
img.Dispose();
}
}

#region Helper

/// <summary>
/// 保存图片
/// </summary>
/// <param name="image">Image 对象</param>
/// <param name="savePath">保存路径</param>
/// <param name="ici">指定格式的编解码参数</param>
private static void SaveImage(Image image, string savePath, ImageCodecInfo ici)
{
//设置 原图片 对象的 EncoderParameters 对象
EncoderParameters parameters = new EncoderParameters(1);
parameters.Param[0] = new EncoderParameter(Encoder.Quality, ((long)100));
image.Save(savePath, ici, parameters);
parameters.Dispose();
}

/// <summary>
/// 获取图像编码解码器的所有相关信息
/// </summary>
/// <param name="mimeType">包含编码解码器的多用途网际邮件扩充协议 (MIME) 类型的字符串</param>
/// <returns>返回图像编码解码器的所有相关信息</returns>
private static ImageCodecInfo GetCodecInfo(string mimeType)
{
ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders();
foreach (ImageCodecInfo ici in CodecInfo)
{
if (ici.MimeType == mimeType)
return ici;
}
return null;
}

/// <summary>
/// 计算新尺寸
/// </summary>
/// <param name="width">原始宽度</param>
/// <param name="height">原始高度</param>
/// <param name="maxWidth">最大新宽度</param>
/// <param name="maxHeight">最大新高度</param>
/// <returns></returns>
private static Size ResizeImage(int width, int height, int maxWidth, int maxHeight)
{
//此次2012-02-05修改过=================
if (maxWidth <= 0)
maxWidth = width;
if (maxHeight <= 0)
maxHeight = height;
//以上2012-02-05修改过=================
decimal MAX_WIDTH = (decimal)maxWidth;
decimal MAX_HEIGHT = (decimal)maxHeight;
decimal ASPECT_RATIO = MAX_WIDTH / MAX_HEIGHT;

int newWidth, newHeight;
decimal originalWidth = (decimal)width;
decimal originalHeight = (decimal)height;

if (originalWidth > MAX_WIDTH || originalHeight > MAX_HEIGHT)
{
decimal factor;
// determine the largest factor
if (originalWidth / originalHeight > ASPECT_RATIO)
{
factor = originalWidth / MAX_WIDTH;
newWidth = Convert.ToInt32(originalWidth / factor);
newHeight = Convert.ToInt32(originalHeight / factor);
}
else
{
factor = originalHeight / MAX_HEIGHT;
newWidth = Convert.ToInt32(originalWidth / factor);
newHeight = Convert.ToInt32(originalHeight / factor);
}
}
else
{
newWidth = width;
newHeight = height;
}
return new Size(newWidth, newHeight);
}

/// <summary>
/// 得到图片格式
/// </summary>
/// <param name="name">文件名称</param>
/// <returns></returns>
public static ImageFormat GetFormat(string name)
{
string ext = name.Substring(name.LastIndexOf(".") + 1);
switch (ext.ToLower())
{
case "jpg":
case "jpeg":
return ImageFormat.Jpeg;
case "bmp":
return ImageFormat.Bmp;
case "png":
return ImageFormat.Png;
case "gif":
return ImageFormat.Gif;
default:
return ImageFormat.Jpeg;
}
}
#endregion

/// <summary>
/// 制作小正方形
/// </summary>
/// <param name="image">图片对象</param>
/// <param name="newFileName">新地址</param>
/// <param name="newSize">长度或宽度</param>
public static void MakeSquareImage(Image image, string newFileName, int newSize)
{
int i = 0;
int width = image.Width;
int height = image.Height;
if (width > height)
i = height;
else
i = width;

Bitmap b = new Bitmap(newSize, newSize);

try
{
Graphics g = Graphics.FromImage(b);
//设置高质量插值法
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
//设置高质量,低速度呈现平滑程度
g.SmoothingMode = SmoothingMode.AntiAlias;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
//清除整个绘图面并以透明背景色填充
g.Clear(Color.Transparent);
if (width < height)
g.DrawImage(image, new Rectangle(0, 0, newSize, newSize), new Rectangle(0, (height - width) / 2, width, width), GraphicsUnit.Pixel);
else
g.DrawImage(image, new Rectangle(0, 0, newSize, newSize), new Rectangle((width - height) / 2, 0, height, height), GraphicsUnit.Pixel);

SaveImage(b, newFileName, GetCodecInfo("image/" + GetFormat(newFileName).ToString().ToLower()));
}
finally
{
image.Dispose();
b.Dispose();
}
}

/// <summary>
/// 制作小正方形
/// </summary>
/// <param name="fileName">图片文件名</param>
/// <param name="newFileName">新地址</param>
/// <param name="newSize">长度或宽度</param>
public static void MakeSquareImage(string fileName, string newFileName, int newSize)
{
MakeSquareImage(Image.FromFile(fileName), newFileName, newSize);
}

/// <summary>
/// 制作远程小正方形
/// </summary>
/// <param name="url">图片url</param>
/// <param name="newFileName">新地址</param>
/// <param name="newSize">长度或宽度</param>
public static void MakeRemoteSquareImage(string url, string newFileName, int newSize)
{
Stream stream = GetRemoteImage(url);
if (stream == null)
return;
Image original = Image.FromStream(stream);
stream.Close();
MakeSquareImage(original, newFileName, newSize);
}

/// <summary>
/// 制作缩略图
/// </summary>
/// <param name="original">图片对象</param>
/// <param name="newFileName">新图路径</param>
/// <param name="maxWidth">最大宽度</param>
/// <param name="maxHeight">最大高度</param>
public static void MakeThumbnailImage(Image original, string newFileName, int maxWidth, int maxHeight)
{
Size _newSize = ResizeImage(original.Width, original.Height, maxWidth, maxHeight);

using (Image displayImage = new Bitmap(original, _newSize))
{
try
{
displayImage.Save(newFileName, original.RawFormat);
}
finally
{
original.Dispose();
}
}
}

/// <summary>
/// 制作缩略图
/// </summary>
/// <param name="fileName">文件名</param>
/// <param name="newFileName">新图路径</param>
/// <param name="maxWidth">最大宽度</param>
/// <param name="maxHeight">最大高度</param>
public static void MakeThumbnailImage(string fileName, string newFileName, int maxWidth, int maxHeight)
{
//2012-02-05修改过，支持替换
byte[] imageBytes = File.ReadAllBytes(fileName);
Image img = Image.FromStream(new System.IO.MemoryStream(imageBytes));
MakeThumbnailImage(img, newFileName, maxWidth, maxHeight);
//原文
//MakeThumbnailImage(Image.FromFile(fileName), newFileName, maxWidth, maxHeight);
}

#region 2012-2-19 新增生成图片缩略图方法
/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="fileName">源图路径（绝对路径）</param>
/// <param name="newFileName">缩略图路径（绝对路径）</param>
/// <param name="width">缩略图宽度</param>
/// <param name="height">缩略图高度</param>
/// <param name="mode">生成缩略图的方式</param>
public static void MakeThumbnailImage(string fileName, string newFileName, int width, int height, string mode)
{
Image originalImage = Image.FromFile(fileName);
int towidth = width;
int toheight = height;

int x = 0;
int y = 0;
int ow = originalImage.Width;
int oh = originalImage.Height;

switch (mode)
{
case "HW"://指定高宽缩放（可能变形）
break;
case "W"://指定宽，高按比例
toheight = originalImage.Height * width / originalImage.Width;
break;
case "H"://指定高，宽按比例
towidth = originalImage.Width * height / originalImage.Height;
break;
case "Cut"://指定高宽裁减（不变形）
if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
{
oh = originalImage.Height;
ow = originalImage.Height * towidth / toheight;
y = 0;
x = (originalImage.Width - ow) / 2;
}
else
{
ow = originalImage.Width;
oh = originalImage.Width * height / towidth;
x = 0;
y = (originalImage.Height - oh) / 2;
}
break;
default:
break;
}

//新建一个bmp图片
Bitmap b = new Bitmap(towidth, toheight);
try
{
//新建一个画板
Graphics g = Graphics.FromImage(b);
//设置高质量插值法
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
//设置高质量,低速度呈现平滑程度
g.SmoothingMode = SmoothingMode.AntiAlias;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
//清空画布并以透明背景色填充
g.Clear(Color.Transparent);
//在指定位置并且按指定大小绘制原图片的指定部分
g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight), new Rectangle(x, y, ow, oh), GraphicsUnit.Pixel);

SaveImage(b, newFileName, GetCodecInfo("image/" + GetFormat(newFileName).ToString().ToLower()));
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
b.Dispose();
}
}
#endregion

#region 2012-10-30 新增图片裁剪方法
/// <summary>
/// 裁剪图片并保存
/// </summary>
/// <param name="fileName">源图路径（绝对路径）</param>
/// <param name="newFileName">缩略图路径（绝对路径）</param>
/// <param name="maxWidth">缩略图宽度</param>
/// <param name="maxHeight">缩略图高度</param>
/// <param name="cropWidth">裁剪宽度</param>
/// <param name="cropHeight">裁剪高度</param>
/// <param name="X">X轴</param>
/// <param name="Y">Y轴</param>
public static bool MakeThumbnailImage(string fileName, string newFileName, int maxWidth, int maxHeight, int cropWidth, int cropHeight, int X, int Y)
{
byte[] imageBytes = File.ReadAllBytes(fileName);
Image originalImage = Image.FromStream(new System.IO.MemoryStream(imageBytes));
Bitmap b = new Bitmap(cropWidth, cropHeight);
try
{
using (Graphics g = Graphics.FromImage(b))
{
//设置高质量插值法
g.InterpolationMode = InterpolationMode.HighQualityBicubic;
//设置高质量,低速度呈现平滑程度
g.SmoothingMode = SmoothingMode.AntiAlias;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
//清空画布并以透明背景色填充
g.Clear(Color.Transparent);
//在指定位置并且按指定大小绘制原图片的指定部分
g.DrawImage(originalImage, new Rectangle(0, 0, cropWidth, cropHeight), X, Y, cropWidth, cropHeight, GraphicsUnit.Pixel);
Image displayImage = new Bitmap(b, maxWidth, maxHeight);
SaveImage(displayImage, newFileName, GetCodecInfo("image/" + GetFormat(newFileName).ToString().ToLower()));
return true;
}
}
catch (System.Exception e)
{
throw e;
}
finally
{
originalImage.Dispose();
b.Dispose();
}
}
#endregion

/// <summary>
/// 制作远程缩略图
/// </summary>
/// <param name="url">图片URL</param>
/// <param name="newFileName">新图路径</param>
/// <param name="maxWidth">最大宽度</param>
/// <param name="maxHeight">最大高度</param>
public static void MakeRemoteThumbnailImage(string url, string newFileName, int maxWidth, int maxHeight)
{
Stream stream = GetRemoteImage(url);
if (stream == null)
return;
Image original = Image.FromStream(stream);
stream.Close();
MakeThumbnailImage(original, newFileName, maxWidth, maxHeight);
}

/// <summary>
/// 获取图片流
/// </summary>
/// <param name="url">图片URL</param>
/// <returns></returns>
private static Stream GetRemoteImage(string url)
{
HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(url);
request.Method = "GET";
request.ContentLength = 0;
request.Timeout = 20000;
HttpWebResponse response = null;

try
{
response = (HttpWebResponse)request.GetResponse();
return response.GetResponseStream();
}
catch
{
return null;
}
}
}
}