C#創立縮略圖操作類實例

C#創立縮略圖操作類實例。本站提示廣大學習愛好者：（C#創立縮略圖操作類實例）文章只能為提供參考，不一定能成為您想要的結果。以下是C#創立縮略圖操作類實例正文

本文實例講述了C#創立縮略圖操作類。分享給年夜家供年夜家參考。詳細剖析以下：

這個C#類可以生成各類情勢的縮略圖，可以主動堅持圖片比例縮略，可以依據百分比取得圖片尺寸等

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Imaging;
namespace HtmlSnap
{
 public static class ImageHelper
 {
  /// <summary>
  /// 獲得縮略圖
  /// </summary>
  /// <param name="image"></param>
  /// <param name="width"></param>
  /// <param name="height"></param>
  /// <returns></returns>
  public static Image GetThumbnailImage(Image image, int width, int height)
  {
   if (image == null || width < 1 || height < 1)
    return null;
   // 新建一個bmp圖片
   //
   Image bitmap = new System.Drawing.Bitmap(width, height);
   // 新建一個畫板
   //
   using (Graphics g = System.Drawing.Graphics.FromImage(bitmap))
   {
    // 設置高質量插值法
    //
    g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
    // 設置高質量,低速度出現膩滑水平
    //
    g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
    // 高質量、低速度復合
    //
    g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
    // 清空畫布並以通明配景色填充
    //
    g.Clear(Color.Transparent);
    // 在指定地位而且按指定年夜小繪制原圖片的指定部門
    //
    g.DrawImage(image, new Rectangle(0, 0, width, height),
     new Rectangle(0, 0, image.Width, image.Height),
     GraphicsUnit.Pixel);
    return bitmap;
   }
  }
  /// <summary>
  /// 生成縮略圖，並堅持縱橫比
  /// </summary>
  /// <param name="image"></param>
  /// <param name="width"></param>
  /// <param name="height"></param>
  /// <returns>生成縮略圖後對象</returns>
  public static Image GetThumbnailImageKeepRatio(Image image, int width, int height)
  {
   Size imageSize = GetImageSize(image, width, height);
   return GetThumbnailImage(image, imageSize.Width, imageSize.Height);
  }
  /// <summary>
  /// 依據百分比獲得圖片的尺寸
  /// </summary>
  /// <param name="picture"></param>
  /// <param name="percent"></param>
  /// <returns></returns>
  public static Size GetImageSize(Image picture, int percent)
  {
   if (picture == null || percent < 1)
    return Size.Empty;
   int width = picture.Width * percent / 100;
   int height = picture.Height * percent / 100;
   return GetImageSize(picture, width, height);
  }
  /// <summary>
  /// 依據設定的年夜小前往圖片的年夜小，斟酌圖片長寬的比例成績
  /// </summary>
  /// <param name="picture"></param>
  /// <param name="width"></param>
  /// <param name="height"></param>
  /// <returns></returns>
  public static Size GetImageSize(Image picture, int width, int height)
  {
   if (picture == null || width < 1 || height < 1)
    return Size.Empty;
   Size imageSize;
   imageSize = new Size(width, height);
   double heightRatio = (double)picture.Height / picture.Width;
   double widthRatio = (double)picture.Width / picture.Height;
   int desiredHeight = imageSize.Height;
   int desiredWidth = imageSize.Width;
 
   imageSize.Height = desiredHeight;
   if (widthRatio > 0)
    imageSize.Width = Convert.ToInt32(imageSize.Height * widthRatio);
   if (imageSize.Width > desiredWidth)
   {
    imageSize.Width = desiredWidth;
    imageSize.Height = Convert.ToInt32(imageSize.Width * heightRatio);
   }
   return imageSize;
  }
 
  /// <summary>
  /// 獲得圖象編碼解碼器的一切相干信息
  /// </summary>
  /// <param name="mimeType">包括編碼解碼器的多用處網際郵件擴大協定 (MIME) 類型的字符串</param>
  /// <returns>前往圖象編碼解碼器的一切相干信息</returns>
  public static ImageCodecInfo GetCodecInfo(string mimeType)
  {
   ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders();
   foreach (ImageCodecInfo ici in CodecInfo)
   {
    if (ici.MimeType == mimeType) return ici;
   }
   return null;
  }
  public static ImageCodecInfo GetImageCodecInfo(ImageFormat format)
  {
   ImageCodecInfo[] encoders = ImageCodecInfo.GetImageEncoders();
   foreach (ImageCodecInfo icf in encoders)
   {
    if (icf.FormatID == format.Guid)
    {
     return icf;
    }
   }
   return null;
  }
  public static void SaveImage(Image image, string savePath, ImageFormat format)
  {
   SaveImage(image, savePath, GetImageCodecInfo(format));
  }
  /// <summary>
  /// 高質量保留圖片
  /// </summary>
  /// <param name="image"></param>
  /// <param name="savePath"></param>
  /// <param name="ici"></param>
  private static void SaveImage(Image image, string savePath, ImageCodecInfo ici)
  {
   // 設置 原圖片 對象的 EncoderParameters 對象
   //
   EncoderParameters parms = new EncoderParameters(1);
   EncoderParameter parm = new EncoderParameter(Encoder.Quality, ((long)95));
   parms.Param[0] = parm;
   image.Save(savePath, ici, parms);
   parms.Dispose();
  }
 }
}

願望本文所述對年夜家的C#法式設計有所贊助。