【IT168 技术文档】本文旨在与各位朋友们分享我是如何在项目中用C# “ps图片” 为网站生成同比例微缩图的解决方案。如有不足之处欢迎您指出。
一、技术概述：
1.Ajax无刷新上传图片,详情请阅我的这篇文章。(jquery + c# ashx)
2.C#位图处理 System.Drawing。
3.最新demo支持IE7,IE8,FireFox。
二、微缩图处理方法：
生成微缩图的核心方法：
CreateThumbnailPicture
/// <summary>
/// 图片微缩图处理
/// </summary>
/// <param name="srcPath">源图片</param>
/// <param name="destPath">目标图片</param>
/// <param name="width">宽度</param>
/// <param name="height">高度</param>
public static void CreateThumbnailPicture(string srcPath, string destPath, int width, int height)
{
//根据图片的磁盘绝对路径获取 源图片 的Image对象
System.Drawing.Image img = System.Drawing.Image.FromFile(srcPath);
//bmp： 最终要建立的 微缩图 位图对象。 Bitmap bmp = new Bitmap(width, height);
//g: 绘制 bmp Graphics 对象
Graphics g = Graphics.FromImage(bmp);
g.Clear(Color.Transparent);
//为Graphics g 对象 初始化必要参数，很容易理解。
g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
//源图片宽和高
int imgWidth = img.Width;
int imgHeight = img.Height;
//绘制微缩图
g.DrawImage(img, new System.Drawing.Rectangle(0, 0, width, height), new System.Drawing.Rectangle(0, 0, imgWidth, imgHeight) , GraphicsUnit.Pixel);
ImageFormat format = img.RawFormat;
ImageCodecInfo info = ImageCodecInfo.GetImageEncoders().SingleOrDefault(i => i.FormatID == format.Guid);
EncoderParameter param = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
EncoderParameters parameters = new EncoderParameters(1);
parameters.Param[0] = param;
img.Dispose();
//保存已生成微缩图，这里将GIF格式转化成png格式。
if (format == ImageFormat.Gif)
{
destPath = destPath.ToLower().Replace(".gif", ".png");
bmp.Save(destPath, ImageFormat.Png);
}
else
{
if (info != null)
{
bmp.Save(destPath, info, parameters);
}
else
{
bmp.Save(destPath, format);
}
}
img.Dispose();
g.Dispose();
bmp.Dispose();
}
/// 图片微缩图处理
/// </summary>
/// <param name="srcPath">源图片</param>
/// <param name="destPath">目标图片</param>
/// <param name="width">宽度</param>
/// <param name="height">高度</param>
public static void CreateThumbnailPicture(string srcPath, string destPath, int width, int height)
{
//根据图片的磁盘绝对路径获取 源图片 的Image对象
System.Drawing.Image img = System.Drawing.Image.FromFile(srcPath);
//bmp： 最终要建立的 微缩图 位图对象。 Bitmap bmp = new Bitmap(width, height);
//g: 绘制 bmp Graphics 对象
Graphics g = Graphics.FromImage(bmp);
g.Clear(Color.Transparent);
//为Graphics g 对象 初始化必要参数，很容易理解。
g.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
//源图片宽和高
int imgWidth = img.Width;
int imgHeight = img.Height;
//绘制微缩图
g.DrawImage(img, new System.Drawing.Rectangle(0, 0, width, height), new System.Drawing.Rectangle(0, 0, imgWidth, imgHeight) , GraphicsUnit.Pixel);
ImageFormat format = img.RawFormat;
ImageCodecInfo info = ImageCodecInfo.GetImageEncoders().SingleOrDefault(i => i.FormatID == format.Guid);
EncoderParameter param = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
EncoderParameters parameters = new EncoderParameters(1);
parameters.Param[0] = param;
img.Dispose();
//保存已生成微缩图，这里将GIF格式转化成png格式。
if (format == ImageFormat.Gif)
{
destPath = destPath.ToLower().Replace(".gif", ".png");
bmp.Save(destPath, ImageFormat.Png);
}
else
{
if (info != null)
{
bmp.Save(destPath, info, parameters);
}
else
{
bmp.Save(destPath, format);
}
}
img.Dispose();
g.Dispose();
bmp.Dispose();
}
