PDFSharp-第二页为空

Question

For some reason, when I try to create a document with multiple pages the first page is ok but all others come out empty.

public PdfDocument toPdf()
{
    // Create new PDF document
    PdfDocument document = new PdfDocument();
    XGraphics gfx;
    PdfPage page;

    foreach (var p in pages)
    {
        // Create new page
        page = document.AddPage();
        page.Width = XUnit.FromMillimeter(width);
        page.Height = XUnit.FromMillimeter(height);
        gfx = XGraphics.FromPdfPage(page, XGraphicsUnit.Millimeter);
        p.drawItems(gfx);
    }
    return document;
}

Any clues?

Answer 1

AFAIK there is a problem with the XGraphics when you set a non-default unit (Millimeter in your case).

Maybe the second page is not empty, but content is outside the "viewport".

If my guess is correct, then first page will not be correct either.

See this case on the PDFsharp forum:
http://forum.pdfsharp.net/viewtopic.php?p=9642#p9642

Answer 2

Try to dispose the graphics object properly, like this:

public PdfDocument toPdf()
{
    // Create new PDF document
    PdfDocument document = new PdfDocument();
    PdfPage page;

    foreach (var p in pages)
    {
        // Create new page
        page = document.AddPage();
        page.Width = XUnit.FromMillimeter(width);
        page.Height = XUnit.FromMillimeter(height);

        using (var gfx = XGraphics.FromPdfPage(page, XGraphicsUnit.Millimeter))
        {
            p.drawItems(gfx);
        }
    }

    return document;
}

As general rule: all objects which implements IDisposable must be disposed by calling Dispose . The using statement does this implicit.

Since you are returning the document, it's the caller's responsibility to dispose that one.

As a side note: some people will tell you Dispose will be called in the Finalizer , so you don't need to call it. This argument is invalid because:

a) not everybody implements IDisposable properly, and

b) typical objects, especially graphics objects and IO objects (eg file locks), need to be disposed before they can be re-used in such a way.

If this doesn't help, please make sure you don't have empty pages :-)