C#裁剪,縮放,清楚度,水印處置操作示例

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媒介

需求源自項目中的一些運用，好比相冊功效，平日用戶上傳相片後我們都邑針對該相片再生成一張縮略圖，用於其它頁面上的列表顯示。隨意看一下，年夜部門網站根本都是將原圖等比縮放來生成縮略圖。但完善主義者會發明一些成績，好比顯示排版時想讓相片縮略圖列表異常同一、整潔、和雅觀，好比請求每張縮略圖年夜小固定為120 x 90且不拉伸變形怎樣辦？再好比用戶頭像若何讓縮略圖比原圖更清楚？或是若何在上傳的圖片下加一個半通明的LOGO水印？

OK，本文依據本身的項目代碼描寫以上成績的處理計劃，全體基於.Net Framework類庫完成，代碼中包括了C#圖片處置的一些基本常識，與年夜家分享，小我才能無限，缺乏的地方還請實時斧正。

進步縮略圖清楚度

(原圖200*200,12.3k)(處置後80*80,17.7k)

之前一向以為縮略圖弗成能比原圖清楚，直到某天一名產物的同事給我看某網站的後果。因而開端尋覓.NET下完成代碼，細心不雅察縮略圖確切比原圖更清楚了一些，但價值是縮略圖文件比原圖更年夜，所以假如你想讓一張占滿顯示器屏幕的超年夜圖片更清楚，那末圖片占用空間和收集流量就必須斟酌了，假如是互聯網運用，建議縮略圖在200像素之內的應用該辦法。固然假如哪位有更好的代碼即能讓圖片文件年夜小變更不年夜又讓圖片更清楚還請分享。

圖片裁剪

(原圖256*192)(裁剪請求100*100)

(原圖256*192)(裁剪請求90*120)

(原圖256*192)(裁剪請求120*90)

(原圖146*256)(裁剪請求100*100)

(原圖146*256)(裁剪請求90*120)

(原圖146*256)(裁剪請求120*90)

算法：以原圖中間作為裁剪中間，最年夜規模的對原圖停止裁剪，然後對裁剪成果等比縮放。

圖片水印

僅演示了後果，如須要變革字體、水印通明度、地位等可自行在代碼或辦法中擴大。

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>
 /// 圖片處置
 /// http://www.cnblogs.com/wu-jian/
 /// 
 /// 吳劍 2011-02-20 創立
 /// 吳劍 2012-08-08 修正
 /// </summary>
 public class Image
 {
  #region 正方型裁剪並縮放

  /// <summary>
  /// 正方型裁剪
  /// 以圖片中間為軸心，截取正方型，然後等比縮放
  /// 用於頭像處置
  /// </summary>
  /// <remarks>吳劍 2012-08-08</remarks>
  /// <param name="fromFile">原圖Stream對象</param>
  /// <param name="fileSaveUrl">縮略圖寄存地址</param>
  /// <param name="side">指定的邊長（正方型）</param>
  /// <param name="quality">質量（規模0-100）</param>
  public static void CutForSquare(System.IO.Stream fromFile, string fileSaveUrl, int side, int quality)
  {
   //創立目次
   string dir = Path.GetDirectoryName(fileSaveUrl);
   if (!Directory.Exists(dir))
    Directory.CreateDirectory(dir);

   //原始圖片（獲得原始圖片創立對象，並應用流中嵌入的色彩治理信息）
   System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true);

   //原圖寬高均小於模版，不作處置，直接保留
   if (initImage.Width <= side && initImage.Height <= side)
   {
    initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
   }
   else
   {
    //原始圖片的寬、高
    int initWidth = initImage.Width;
    int initHeight = initImage.Height;

    //非正方型先裁剪為正方型
    if (initWidth != initHeight)
    {
     //截圖對象
     System.Drawing.Image pickedImage = null;
     System.Drawing.Graphics pickedG = null;

     //廣大於高的橫圖
     if (initWidth > initHeight)
     {
      //對象實例化
      pickedImage = new System.Drawing.Bitmap(initHeight, initHeight);
      pickedG = System.Drawing.Graphics.FromImage(pickedImage);
      //設置質量
      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);
      //繪圖
      pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
      //重置寬
      initWidth = initHeight;
     }
     //嵬峨於寬的豎圖
     else
     {
      //對象實例化
      pickedImage = new System.Drawing.Bitmap(initWidth, initWidth);
      pickedG = System.Drawing.Graphics.FromImage(pickedImage);
      //設置質量
      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);
      //繪圖
      pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel);
      //重置高
      initHeight = initWidth;
     }

     //將截圖對象賦給原圖
     initImage = (System.Drawing.Image)pickedImage.Clone();
     //釋放截圖資本
     pickedG.Dispose();
     pickedImage.Dispose();
    }

    //縮略圖對象
    System.Drawing.Image resultImage = new System.Drawing.Bitmap(side, side);
    System.Drawing.Graphics resultG = System.Drawing.Graphics.FromImage(resultImage);
    //設置質量
    resultG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
    resultG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
    //用指定配景色清空畫布
    resultG.Clear(Color.White);
    //繪制縮略圖
    resultG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, side, side), new System.Drawing.Rectangle(0, 0, initWidth, initHeight), System.Drawing.GraphicsUnit.Pixel);

    //症結質量掌握
    //獲得體系編碼類型數組,包括了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);

    //保留縮略圖
    resultImage.Save(fileSaveUrl, ici, ep);

    //釋放症結質量掌握所用資本
    ep.Dispose();

    //釋放縮略圖資本
    resultG.Dispose();
    resultImage.Dispose();

    //釋放原始圖片資本
    initImage.Dispose();
   }
  }

  #endregion

  #region 自界說裁剪並縮放

  /// <summary>
  /// 指定長寬裁剪
  /// 按模版比例最年夜規模的裁剪圖片並縮放至模版尺寸
  /// </summary>
  /// <remarks>吳劍 2012-08-08</remarks>
  /// <param name="fromFile">原圖Stream對象</param>
  /// <param name="fileSaveUrl">保留途徑</param>
  /// <param name="maxWidth">最年夜寬(單元:px)</param>
  /// <param name="maxHeight">最年夜高(單元:px)</param>
  /// <param name="quality">質量（規模0-100）</param>
  public static void CutForCustom(System.IO.Stream fromFile, string fileSaveUrl, int maxWidth, int maxHeight, int quality)
  {
   //從文件獲得原始圖片，並應用流中嵌入的色彩治理信息
   System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true);

   //原圖寬高均小於模版，不作處置，直接保留
   if (initImage.Width <= maxWidth && initImage.Height <= maxHeight)
   {
    initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
   }
   else
   {
    //模版的寬高比例
    double templateRate = (double)maxWidth / maxHeight;
    //原圖片的寬高比例
    double initRate = (double)initImage.Width / initImage.Height;

    //原圖與模版比例相等，直接縮放
    if (templateRate == initRate)
    {
     //按模版年夜小生成終究圖片
     System.Drawing.Image templateImage = new System.Drawing.Bitmap(maxWidth, maxHeight);
     System.Drawing.Graphics templateG = System.Drawing.Graphics.FromImage(templateImage);
     templateG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
     templateG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
     templateG.Clear(Color.White);
     templateG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, maxWidth, maxHeight), new System.Drawing.Rectangle(0, 0, initImage.Width, initImage.Height), System.Drawing.GraphicsUnit.Pixel);
     templateImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);
    }
    //原圖與模版比例不等，裁剪後縮放
    else
    {
     //裁剪對象
     System.Drawing.Image pickedImage = null;
     System.Drawing.Graphics pickedG = null;

     //定位
     Rectangle fromR = new Rectangle(0, 0, 0, 0);//原圖裁剪定位
     Rectangle toR = new Rectangle(0, 0, 0, 0);//目的定位

     //寬為尺度停止裁剪
     if (templateRate > initRate)
     {
      //裁剪對象實例化
      pickedImage = new System.Drawing.Bitmap(initImage.Width, (int)System.Math.Floor(initImage.Width / templateRate));
      pickedG = System.Drawing.Graphics.FromImage(pickedImage);

      //裁剪源定位
      fromR.X = 0;
      fromR.Y = (int)System.Math.Floor((initImage.Height - initImage.Width / templateRate) / 2);
      fromR.Width = initImage.Width;
      fromR.Height = (int)System.Math.Floor(initImage.Width / templateRate);

      //裁剪目的定位
      toR.X = 0;
      toR.Y = 0;
      toR.Width = initImage.Width;
      toR.Height = (int)System.Math.Floor(initImage.Width / templateRate);
     }
     //高為尺度停止裁剪
     else
     {
      pickedImage = new System.Drawing.Bitmap((int)System.Math.Floor(initImage.Height * templateRate), initImage.Height);
      pickedG = System.Drawing.Graphics.FromImage(pickedImage);

      fromR.X = (int)System.Math.Floor((initImage.Width - initImage.Height * templateRate) / 2);
      fromR.Y = 0;
      fromR.Width = (int)System.Math.Floor(initImage.Height * templateRate);
      fromR.Height = initImage.Height;

      toR.X = 0;
      toR.Y = 0;
      toR.Width = (int)System.Math.Floor(initImage.Height * templateRate);
      toR.Height = initImage.Height;
     }

     //設置質量
     pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
     pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

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

     //按模版年夜小生成終究圖片
     System.Drawing.Image templateImage = new System.Drawing.Bitmap(maxWidth, maxHeight);
     System.Drawing.Graphics templateG = System.Drawing.Graphics.FromImage(templateImage);
     templateG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
     templateG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
     templateG.Clear(Color.White);
     templateG.DrawImage(pickedImage, new System.Drawing.Rectangle(0, 0, maxWidth, maxHeight), new System.Drawing.Rectangle(0, 0, pickedImage.Width, pickedImage.Height), System.Drawing.GraphicsUnit.Pixel);

     //症結質量掌握
     //獲得體系編碼類型數組,包括了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);

     //保留縮略圖
     templateImage.Save(fileSaveUrl, ici, ep);
     //templateImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg);

     //釋放資本
     templateG.Dispose();
     templateImage.Dispose();

     pickedG.Dispose();
     pickedImage.Dispose();
    }
   }

   //釋放資本
   initImage.Dispose();
  }
  #endregion

  #region 等比縮放

  /// <summary>
  /// 圖片等比縮放
  /// </summary>
  /// <remarks>吳劍 2012-08-08</remarks>
  /// <param name="fromFile">原圖Stream對象</param>
  /// <param name="savePath">縮略圖寄存地址</param>
  /// <param name="targetWidth">指定的最年夜寬度</param>
  /// <param name="targetHeight">指定的最年夜高度</param>
  /// <param name="watermarkText">水印文字(為""表現不應用水印)</param>
  /// <param name="watermarkImage">水印圖片途徑(為""表現不應用水印)</param>
  public static void ZoomAuto(System.IO.Stream fromFile, string savePath, System.Double targetWidth, System.Double targetHeight, string watermarkText, string watermarkImage)
  {
   //創立目次
   string dir = Path.GetDirectoryName(savePath);
   if (!Directory.Exists(dir))
    Directory.CreateDirectory(dir);

   //原始圖片（獲得原始圖片創立對象，並應用流中嵌入的色彩治理信息）
   System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true);

   //原圖寬高均小於模版，不作處置，直接保留
   if (initImage.Width <= targetWidth && initImage.Height <= targetHeight)
   {
    //文字水印
    if (watermarkText != "")
    {
     using (System.Drawing.Graphics gWater = System.Drawing.Graphics.FromImage(initImage))
     {
      System.Drawing.Font fontWater = new Font("黑體", 10);
      System.Drawing.Brush brushWater = new SolidBrush(Color.White);
      gWater.DrawString(watermarkText, fontWater, brushWater, 10, 10);
      gWater.Dispose();
     }
    }

    //通明圖片水印
    if (watermarkImage != "")
    {
     if (File.Exists(watermarkImage))
     {
      //獲得水印圖片
      using (System.Drawing.Image wrImage = System.Drawing.Image.FromFile(watermarkImage))
      {
       //水印繪制前提：原始圖片寬高均年夜於或等於水印圖片
       if (initImage.Width >= wrImage.Width && initImage.Height >= wrImage.Height)
       {
        Graphics gWater = Graphics.FromImage(initImage);

        //通明屬性
        ImageAttributes imgAttributes = new ImageAttributes();
        ColorMap colorMap = new ColorMap();
        colorMap.OldColor = Color.FromArgb(255, 0, 255, 0);
        colorMap.NewColor = Color.FromArgb(0, 0, 0, 0);
        ColorMap[] remapTable = { colorMap };
        imgAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);

        float[][] colorMatrixElements = { 
         new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f},
         new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f},
         new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f},
         new float[] {0.0f, 0.0f, 0.0f, 0.5f, 0.0f},//通明度:0.5
         new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}
        };

        ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements);
        imgAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
        gWater.DrawImage(wrImage, new Rectangle(initImage.Width - wrImage.Width, initImage.Height - wrImage.Height, wrImage.Width, wrImage.Height), 0, 0, wrImage.Width, wrImage.Height, GraphicsUnit.Pixel, imgAttributes);

        gWater.Dispose();
       }
       wrImage.Dispose();
      }
     }
    }

    //保留
    initImage.Save(savePath, System.Drawing.Imaging.ImageFormat.Jpeg);
   }
   else
   {
    //縮略圖寬、高盤算
    double newWidth = initImage.Width;
    double newHeight = initImage.Height;

    //廣大於高或寬等於高（橫圖或正方）
    if (initImage.Width > initImage.Height || initImage.Width == initImage.Height)
    {
     //假如廣大於模版
     if (initImage.Width > targetWidth)
     {
      //寬按模版，高按比例縮放
      newWidth = targetWidth;
      newHeight = initImage.Height * (targetWidth / initImage.Width);
     }
    }
    //嵬峨於寬（豎圖）
    else
    {
     //假如嵬峨於模版
     if (initImage.Height > targetHeight)
     {
      //高按模版，寬按比例縮放
      newHeight = targetHeight;
      newWidth = initImage.Width * (targetHeight / initImage.Height);
     }
    }

    //生成新圖
    //新建一個bmp圖片
    System.Drawing.Image newImage = new System.Drawing.Bitmap((int)newWidth, (int)newHeight);
    //新建一個畫板
    System.Drawing.Graphics newG = System.Drawing.Graphics.FromImage(newImage);

    //設置質量
    newG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
    newG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

    //置配景色
    newG.Clear(Color.White);
    //繪圖
    newG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, newImage.Width, newImage.Height), new System.Drawing.Rectangle(0, 0, initImage.Width, initImage.Height), System.Drawing.GraphicsUnit.Pixel);

    //文字水印
    if (watermarkText != "")
    {
     using (System.Drawing.Graphics gWater = System.Drawing.Graphics.FromImage(newImage))
     {
      System.Drawing.Font fontWater = new Font("宋體", 10);
      System.Drawing.Brush brushWater = new SolidBrush(Color.White);
      gWater.DrawString(watermarkText, fontWater, brushWater, 10, 10);
      gWater.Dispose();
     }
    }

    //通明圖片水印
    if (watermarkImage != "")
    {
     if (File.Exists(watermarkImage))
     {
      //獲得水印圖片
      using (System.Drawing.Image wrImage = System.Drawing.Image.FromFile(watermarkImage))
      {
       //水印繪制前提：原始圖片寬高均年夜於或等於水印圖片
       if (newImage.Width >= wrImage.Width && newImage.Height >= wrImage.Height)
       {
        Graphics gWater = Graphics.FromImage(newImage);

        //通明屬性
        ImageAttributes imgAttributes = new ImageAttributes();
        ColorMap colorMap = new ColorMap();
        colorMap.OldColor = Color.FromArgb(255, 0, 255, 0);
        colorMap.NewColor = Color.FromArgb(0, 0, 0, 0);
        ColorMap[] remapTable = { colorMap };
        imgAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);

        float[][] colorMatrixElements = { 
         new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f},
         new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f},
         new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f},
         new float[] {0.0f, 0.0f, 0.0f, 0.5f, 0.0f},//通明度:0.5
         new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}
        };

        ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements);
        imgAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
        gWater.DrawImage(wrImage, new Rectangle(newImage.Width - wrImage.Width, newImage.Height - wrImage.Height, wrImage.Width, wrImage.Height), 0, 0, wrImage.Width, wrImage.Height, GraphicsUnit.Pixel, imgAttributes);
        gWater.Dispose();
       }
       wrImage.Dispose();
      }
     }
    }

    //保留縮略圖
    newImage.Save(savePath, System.Drawing.Imaging.ImageFormat.Jpeg);

    //釋放資本
    newG.Dispose();
    newImage.Dispose();
    initImage.Dispose();
   }
  }

  #endregion

  #region 其它

  /// <summary>
  /// 斷定文件類型能否為WEB格局圖片
  /// (注：JPG,GIF,BMP,PNG)
  /// </summary>
  /// <param name="contentType">HttpPostedFile.ContentType</param>
  /// <returns></returns>
  public static bool IsWebImage(string contentType)
  {
   if (contentType == "image/pjpeg" || contentType == "image/jpeg" || contentType == "image/gif" || contentType == "image/bmp" || contentType == "image/png")
   {
    return true;
   }
   else
   {
    return false;
   }
  }

  #endregion

 }//end class
}

以上就是本文的全體內容，願望對年夜家的進修有所贊助，也願望年夜家多多支撐。