[C#] Image to Base64 後呈現
2012-10-04
最近有一些圖片控管的需求跟跨 Server 傳遞問題
剛好看到 點部落上面有 有人發一篇文章 img base64 顯示圖片 支援 IE、Firefox、Chorme
想說就順便側一下..
案例概述
按下按鈕後 Server 會讀取一張根目錄下面 sample.jpg 的圖案 之後轉碼為 base64 且設定為 imageSample 的 src 屬性..
程式實作
將圖片轉 base64
C# Code:
/// <summary>/// 自動判斷圖片格式/// </summary>/// <param name="img"></param>/// <returns></returns>public static System.Drawing.Imaging.ImageFormat GetImageFormat(System.Drawing.Image img)
{ if (img.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Jpeg)) return System.Drawing.Imaging.ImageFormat.Jpeg; if (img.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Bmp)) return System.Drawing.Imaging.ImageFormat.Bmp; if (img.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Png)) return System.Drawing.Imaging.ImageFormat.Png; if (img.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Emf)) return System.Drawing.Imaging.ImageFormat.Emf; if (img.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Exif)) return System.Drawing.Imaging.ImageFormat.Exif; if (img.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Gif)) return System.Drawing.Imaging.ImageFormat.Gif; if (img.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Icon)) return System.Drawing.Imaging.ImageFormat.Icon; if (img.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.MemoryBmp)) return System.Drawing.Imaging.ImageFormat.MemoryBmp; if (img.RawFormat.Equals(System.Drawing.Imaging.ImageFormat.Tiff)) return System.Drawing.Imaging.ImageFormat.Tiff; else return System.Drawing.Imaging.ImageFormat.Wmf;}
/// <summary>/// 將 Image 物件轉 Base64/// </summary>/// <param name="image"></param>/// <returns></returns>public string ImageToBase64(System.Drawing.Image image)
{ MemoryStream ms = new MemoryStream();System.Drawing.Imaging.ImageFormat format = GetImageFormat(image);
// 將圖片轉成 byte[]image.Save(ms, format);
byte[] imageBytes = ms.ToArray(); // 將 byte[] 轉 base64 string base64String = Convert.ToBase64String(imageBytes); return base64String;}
這裡面我是改寫 http://www.dailycoding.com/Posts/convert_image_to_base64_string_and_base64_string_to_image.aspx
讓其自動判斷格式
之後我們呼叫這 function
protected void Button1_Click(object sender, EventArgs e)
{// 讀取圖片並轉為 Image 物件var image= System.Drawing.Image.FromFile(AppDomain.CurrentDomain.BaseDirectory + "sample.jpg");// 設定至 imgSample 並且自動判定格式 imgSample.Src = "data:image/" + GetImageFormat(image) + ";base64," + ImageToBase64(image);
// 將 base64 寫檔案 比較檔案大小File.WriteAllText(AppDomain.CurrentDomain.BaseDirectory+"base64.txt",imgSample.Src);}
結果
補充
看一下檔案大小
圖片 從 67KB-> 89 KB 這成長量不容小覷..
Sample: