[C#] 圖片存檔(在 GDI+ 中發生泛型錯誤)

2010-01-13

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Introduction

今天在實做圖片存檔的時候 image.Save() 出現 GDI+ 中發生泛型錯誤，如圖

這邊紀錄一下，利用專案來模擬當時的情況。

Example

sample1 存檔時出現錯誤(如上圖)


using System.IO;
namespace TestImageSave {
    public partial class Form1 : Form {

        byte[] _SourceImage;

        public Form1() {
            InitializeComponent();
        }

        private void btnReadImage_Click(object sender, EventArgs e) {
            Image image = Image.FromFile("test.jpeg");
            this.pictureBox1.Image = image;
            //將 Image 轉換 Byte 陣列
            _SourceImage = this.ImageToBuffer(image);
        }

        private void btnSaveImage_Click(object sender, EventArgs e) {
            //模擬接到 Byte 陣列值 ，轉換為 Image 物件
            Image image = this.BufferToImage(_SourceImage);
            //將圖片存檔
            image.Save("test2.jpeg");
        }

        private byte[] ImageToBuffer(Image image) {
            byte[] buffer = null;
            using (Bitmap oBitmap = new Bitmap(image)) {
                using (MemoryStream MS = new MemoryStream()) {
                    oBitmap.Save(MS, System.Drawing.Imaging.ImageFormat.Jpeg);
                    MS.Position = 0;
                    buffer = new byte[MS.Length];
                    MS.Read(buffer, 0, Convert.ToInt32(MS.Length));
                    MS.Flush();
                }
            }

            return buffer;
        }

        private Image BufferToImage(byte[] Buffer) {
            byte[] data = null;
            Image oImage = null;
            MemoryStream oMemoryStream = null;
            Bitmap oBitmap = null;
            //建立副本
            data = (byte[])Buffer.Clone();
            try {
                oMemoryStream = new MemoryStream(data);
                //設定資料流位置
                oMemoryStream.Position = 0;                
                oImage = System.Drawing.Image.FromStream(oMemoryStream);
                //建立副本
                //oBitmap = new Bitmap(oImage);                
            }
            catch {
                throw;
            }
            finally {
                oMemoryStream.Close();
                oMemoryStream.Dispose();
                oMemoryStream = null;
            }
            return oImage;
            //return oBitmap;
        }
    }
}

觀察檔案資料是否有真正存取?

sample2

上網搜尋，發現當 Image 物件的來源為串流的時候，當串流關閉時，

資料來源也就遺失，所以，當圖片要儲存成檔案時，就會出現錯誤。

將程式修改如下


        private Image BufferToImage(byte[] Buffer) {
            byte[] data = null;
            Image oImage = null;
            MemoryStream oMemoryStream = null;
            Bitmap oBitmap = null;
            //建立副本
            data = (byte[])Buffer.Clone();
            try {
                oMemoryStream = new MemoryStream(data);
                //設定資料流位置
                oMemoryStream.Position = 0;                
                oImage = System.Drawing.Image.FromStream(oMemoryStream);
                //建立副本
                oBitmap = new Bitmap(oImage);                
            }
            catch {
                throw;
            }
            finally {
                oMemoryStream.Close();
                oMemoryStream.Dispose();
                oMemoryStream = null;
            }
            //return oImage;
            return oBitmap;
        }

觀察檔案資料是否有真正存取?

程式碼下載 TestImageSave.rar

Refrence

http://blog.miniasp.com/post/2009/05/A-generic-error-occurred-in-GDI-plus.aspx

備註

修改 [C#] Image 與 byte[] 互轉 - .NET 隨筆- 點部落程式碼

三小俠小弟獻醜，歡迎指教

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