如何使用 PDFClown 添加图像？

Question

我尝试使用 PDFClown 0.1.2.0 使用 C# 创建一个 pdf 文件，其中包含一个图像。
但我无法让它工作。

我得到的错误是：

An attempt was made to move the file pointer before the beginning of the file.

       at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
       at System.IO.FileStream.SeekCore(Int64 offset, SeekOrigin origin)
       at System.IO.FileStream.Seek(Int64 offset, SeekOrigin origin)
       at org.pdfclown.documents.contents.entities.JpegImage.Load()
       at org.pdfclown.documents.contents.entities.Image.Get(Stream stream)
       at org.pdfclown.documents.contents.entities.Image.Get(String path)
       at TestPdf.MainForm.createPDF() in c:\Users\Demo\Documents\SharpDevelop Projects\TestPdf\TestPdf\MainForm.cs:line 43

出现此错误的代码行是：

org.pdfclown.documents.contents.entities.Image image = org.pdfclown.documents.contents.entities.Image.Get("test.jpg");

我用的"test.jpg"是：

我使用的代码是：

public void createPDF()
    {
        try {
            org.pdfclown.files.File file = new org.pdfclown.files.File();
            org.pdfclown.documents.Document document = file.Document;
            org.pdfclown.documents.Page page = new org.pdfclown.documents.Page(document);
            document.Pages.Add(page);
            org.pdfclown.documents.contents.composition.PrimitiveComposer composer = new org.pdfclown.documents.contents.composition.PrimitiveComposer(page);
            composer.SetFont(new org.pdfclown.documents.contents.fonts.StandardType1Font(document, org.pdfclown.documents.contents.fonts.StandardType1Font.FamilyEnum.Courier, true, false), 32);
            composer.ShowText("Hello World!", new System.Drawing.PointF(32, 48));               
            org.pdfclown.documents.contents.entities.Image image = org.pdfclown.documents.contents.entities.Image.Get("test.jpg");
            org.pdfclown.documents.contents.xObjects.XObject imageXObject = image.ToXObject(document);
            composer.ShowXObject(imageXObject, new System.Drawing.PointF(32, 80));
            composer.Flush();
            file.Save("test.pdf", org.pdfclown.files.SerializationModeEnum.Incremental);            
            System.Diagnostics.Process.Start("explorer", System.IO.Directory.GetParent(System.Diagnostics.Process.GetCurrentProcess().MainModule.FileName).ToString());
        } catch (System.Exception e) {
            System.Windows.Forms.MessageBox.Show(e.Message + "\r\n" + e.StackTrace);
        }
    }

我做错了什么？

Answer 1

问题是，PdfClown 无法处理以渐进模式保存的 jpg 文件。解决问题最简单的方法是将jpg文件保存为非渐进式。

另一种方法是转换文件：

    public void createPDF()
    {
        try {
            org.pdfclown.files.File file = new org.pdfclown.files.File();
            org.pdfclown.documents.Document document = file.Document;
            org.pdfclown.documents.Page page = new org.pdfclown.documents.Page(document);
            document.Pages.Add(page);
            org.pdfclown.documents.contents.composition.PrimitiveComposer composer = new org.pdfclown.documents.contents.composition.PrimitiveComposer(page);
            composer.SetFont(new org.pdfclown.documents.contents.fonts.StandardType1Font(document, org.pdfclown.documents.contents.fonts.StandardType1Font.FamilyEnum.Courier, true, false), 32);
            composer.ShowText("Hello World!", new System.Drawing.PointF(32, 48));               
            org.pdfclown.documents.contents.entities.Image image = LoadImageFile("test.jpg");
            org.pdfclown.documents.contents.xObjects.XObject imageXObject = image.ToXObject(document);
            composer.ShowXObject(imageXObject, new System.Drawing.PointF(32, 80));              
            composer.Flush();
            file.Save("test.pdf", org.pdfclown.files.SerializationModeEnum.Incremental);
            System.Diagnostics.Process.Start("explorer", System.IO.Directory.GetParent(System.Diagnostics.Process.GetCurrentProcess().MainModule.FileName).ToString());
        } catch (System.Exception e) {
            System.Windows.Forms.MessageBox.Show(e.Message + "\r\n" + e.StackTrace);
        }
    }

    public org.pdfclown.documents.contents.entities.Image LoadImageFile(string path)
    {
        System.Drawing.Image image = System.Drawing.Image.FromFile(path);
        var ep = new System.Drawing.Imaging.EncoderParameters(3);
        ep.Param[0] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
        ep.Param[1] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.ScanMethod, (int)System.Drawing.Imaging.EncoderValue.ScanMethodInterlaced);
        ep.Param[2] = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.RenderMethod, (int)System.Drawing.Imaging.EncoderValue.RenderNonProgressive);
        System.IO.MemoryStream memStream = new System.IO.MemoryStream();

        System.Drawing.Imaging.ImageCodecInfo encoder_info = null;
        int j;
        System.Drawing.Imaging.ImageCodecInfo[] encoders;
        encoders = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders();
        for (j = 0; j < encoders.Length; ++j) {
            if (encoders[j].MimeType.Equals("image/jpeg"))
                encoder_info = encoders[j];
        }

        image.Save(memStream, encoder_info, ep);
        memStream.Position = 0;
        return org.pdfclown.documents.contents.entities.Image.Get(memStream);
    }

方法LoadImageFile在C#中打开一个图像并将其转换为JPG非渐进式文件。
这个非渐进式jpg文件被保存到pdf文档中。
这个也适用于 png 和 tiff。

如何使用 PDFClown 添加图像？

How to add an Image with PDFClown?

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