C#图片处理基本应用(裁剪,缩放,清晰度,水印)

代码

封装了几个通用的方法，如发现有BUG或漏洞还请及时指正。

 

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using System;

using System.Collections.Generic;

using System.Text;

using System.IO;

using System.Drawing;

using System.Drawing.Drawing2D;

using System.Drawing.Imaging;

namespace WuJian.Common

{

/// <summary>

/// 图片处理类

/// 吴剑 2008-07-02 创建

/// 吴剑 2011-01-21 修改

/// </summary>

public class PTImage

{

#region 正方型裁剪并缩放

/// <summary>

/// 正方型裁剪

/// 以图片中心为轴心，截取正方型，然后等比缩放

/// 用于头像处理

/// </summary>

/// <remarks>吴剑 2010-11-23</remarks>

/// <param name="postedFile">原图HttpPostedFile对象</param>

/// <param name="fileSaveUrl">缩略图存放地址</param>

/// <param name="side">指定的边长（正方型）</param>

/// <param name="quality">质量（范围0-100）</param>

public static void CutForSquare(System.Web.HttpPostedFile postedFile, string fileSaveUrl, int side, int quality)

{

//创建目录

string dir = Path.GetDirectoryName(fileSaveUrl);

if (!Directory.Exists(dir))

Directory.CreateDirectory(dir);

//原始图片（获取原始图片创建对象，并使用流中嵌入的颜色管理信息）

System.Drawing.Image initImage = System.Drawing.Image.FromStream(postedFile.InputStream, true);

//原图宽高均小于模版，不作处理，直接保存

if (initImage.Width <= side && initImage.Height <= side)

{

initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);

}

else

{

//原始图片的宽、高

int initWidth = initImage.Width;

int initHeight = initImage.Height;

//非正方型先裁剪为正方型

if (initWidth != initHeight)

{

//截图对象

System.Drawing.Image pickedImage = null;

System.Drawing.Graphics pickedG = null;

//宽大于高的横图

if (initWidth > initHeight)

{

//对象实例化

pickedImage = new System.Drawing.Bitmap(initHeight, initHeight);

pickedG = System.Drawing.Graphics.FromImage(pickedImage);

//设置质量

pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//定位

Rectangle fromR = new Rectangle((initWidth - initHeight) / 2, 0, initHeight, initHeight);

Rectangle toR = new Rectangle(0, 0, initHeight, initHeight);

//画图

pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);

//重置宽

initWidth = initHeight;

}

//高大于宽的竖图

else

{

//对象实例化

pickedImage = new System.Drawing.Bitmap(initWidth, initWidth);

pickedG = System.Drawing.Graphics.FromImage(pickedImage);

//设置质量

pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//定位

Rectangle fromR = new Rectangle(0, (initHeight - initWidth) / 2, initWidth, initWidth);

Rectangle toR = new Rectangle(0, 0, initWidth, initWidth);

//画图

pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);

//重置高

initHeight = initWidth;

}

//将截图对象赋给原图

initImage = (System.Drawing.Image)pickedImage.Clone();

//释放截图资源

pickedG.Dispose();

pickedImage.Dispose();

}

//缩略图对象

System.Drawing.Image resultImage = new System.Drawing.Bitmap(side, side);

System.Drawing.Graphics resultG = System.Drawing.Graphics.FromImage(resultImage);

//设置质量

resultG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

resultG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//用指定背景色清空画布

resultG.Clear(Color.White);

//绘制缩略图

resultG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, side, side), new System.Drawing.Rectangle(0, 0, initWidth, initHeight), System.Drawing.GraphicsUnit.Pixel);

//关键质量控制

//获取系统编码类型数组,包含了jpeg,bmp,png,gif,tiff

ImageCodecInfo[] icis = ImageCodecInfo.GetImageEncoders();

ImageCodecInfo ici = null;

foreach (ImageCodecInfo i in icis)

{

if (i.MimeType == "image/jpeg" || i.MimeType == "image/bmp" || i.MimeType == "image/png" || i.MimeType == "image/gif")

{

ici = i;

}

}

EncoderParameters ep = new EncoderParameters(1);

ep.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)quality);

//保存缩略图

resultImage.Save(fileSaveUrl, ici, ep);

//释放关键质量控制所用资源

ep.Dispose();

//释放缩略图资源

resultG.Dispose();

resultImage.Dispose();

//释放原始图片资源

initImage.Dispose();

}

}

/// <summary>

/// 正方型裁剪

/// 以图片中心为轴心，截取正方型，然后等比缩放

/// 用于头像处理

/// </summary>

/// <remarks>吴剑 2010-11-23</remarks>

/// <param name="postedFile">原图HttpPostedFile对象</param>

/// <param name="fileSaveUrl">缩略图存放地址</param>

/// <param name="side">指定的边长（正方型）</param>

/// <param name="quality">质量（范围0-100）</param>

public static void CutForSquare(System.IO.Stream fromFile, string fileSaveUrl, int side, int quality)

{

//创建目录

string dir = Path.GetDirectoryName(fileSaveUrl);

if (!Directory.Exists(dir))

Directory.CreateDirectory(dir);

//原始图片（获取原始图片创建对象，并使用流中嵌入的颜色管理信息）

System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true);

//原图宽高均小于模版，不作处理，直接保存

if (initImage.Width <= side && initImage.Height <= side)

{

initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);

}

else

{

//原始图片的宽、高

int initWidth = initImage.Width;

int initHeight = initImage.Height;

//非正方型先裁剪为正方型

if (initWidth != initHeight)

{

//截图对象

System.Drawing.Image pickedImage = null;

System.Drawing.Graphics pickedG = null;

//宽大于高的横图

if (initWidth > initHeight)

{

//对象实例化

pickedImage = new System.Drawing.Bitmap(initHeight, initHeight);

pickedG = System.Drawing.Graphics.FromImage(pickedImage);

//设置质量

pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//定位

Rectangle fromR = new Rectangle((initWidth - initHeight) / 2, 0, initHeight, initHeight);

Rectangle toR = new Rectangle(0, 0, initHeight, initHeight);

//画图

pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);

//重置宽

initWidth = initHeight;

}

//高大于宽的竖图

else

{

//对象实例化

pickedImage = new System.Drawing.Bitmap(initWidth, initWidth);

pickedG = System.Drawing.Graphics.FromImage(pickedImage);

//设置质量

pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//定位

Rectangle fromR = new Rectangle(0, (initHeight - initWidth) / 2, initWidth, initWidth);

Rectangle toR = new Rectangle(0, 0, initWidth, initWidth);

//画图

pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);

//重置高

initHeight = initWidth;

}

//将截图对象赋给原图

initImage = (System.Drawing.Image)pickedImage.Clone();

//释放截图资源

pickedG.Dispose();

pickedImage.Dispose();

}

//缩略图对象

System.Drawing.Image resultImage = new System.Drawing.Bitmap(side, side);

System.Drawing.Graphics resultG = System.Drawing.Graphics.FromImage(resultImage);

//设置质量

resultG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;

resultG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

//用指定背景色清空画布

resultG.Clear(Color.White);

//绘制缩略图

resultG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, side, side), new System.Drawing.Rectangle(0, 0, initWidth, initHeight), System.Drawing.GraphicsUnit.Pixel);