WPF DataGrid GridLines not visible when saved as PDF

问题

I'm using a DataGrid to represent some data in a WPF application. In a feature where I'm saving a particular WPF Window which has the DataGrid into a PDF using PDFSharp, I'm facing an issue that the DataGrid GridLines are not visible when the saved PDF is viewed in smaller viewing percentages. (Refer attached images, only when the PDF view is set at 139%, the GridLines are visible. However, in smaller viewing %, some grid lines get omitted.)

Here's the PDF Saving Code:-

MemoryStream lMemoryStream = new MemoryStream();
Package package = Package.Open(lMemoryStream, FileMode.Create);
var doc = new System.Windows.Xps.Packaging.XpsDocument(package);
XpsDocumentWriter writer = System.Windows.Xps.Packaging.XpsDocument.CreateXpsDocumentWriter(doc);

VisualBrush sourceBrush = new VisualBrush(this);
DrawingVisual drawingVisual = new DrawingVisual();

using (var drawingContext = drawingVisual.RenderOpen())
{
    drawingContext.DrawRectangle(sourceBrush, null, new Rect(new Point(0, 0), new Point(this.ActualWidth, this.ActualHeight)));
}

writer.Write(drawingVisual);
doc.Close();
package.Close();

var pdfXpsDoc = PdfSharp.Xps.XpsModel.XpsDocument.Open(lMemoryStream);
XpsConverter.Convert(pdfXpsDoc, sFileName, 0);

I believe it has to do with the quality with which the visual is drawn. Then I tried this snippet where I'm using DrawImage to make the visual at a higher resolution. Here's the snippet:-

MemoryStream lMemoryStream = new MemoryStream();
Package package = Package.Open(lMemoryStream, FileMode.Create);
var doc = new System.Windows.Xps.Packaging.XpsDocument(package);
XpsDocumentWriter writer = System.Windows.Xps.Packaging.XpsDocument.CreateXpsDocumentWriter(doc);

double dpiScale = 600.0 / 96.0;
var renderBitmap = new RenderTargetBitmap(Convert.ToInt32(this.Width * dpiScale),
                       Convert.ToInt32(this.Height * dpiScale),
                       600.0,
                       600.0,
                       PixelFormats.Pbgra32);
renderBitmap.Render(this);
var visual = new DrawingVisual();
using (var dc = visual.RenderOpen())
{
    dc.DrawImage(renderBitmap, new Rect(0, 0, this.Width, this.Height));
}                

writer.Write(visual);
doc.Close();
package.Close();

var pdfXpsDoc = PdfSharp.Xps.XpsModel.XpsDocument.Open(lMemoryStream);
XpsConverter.Convert(pdfXpsDoc, _pdfFileName, 0);

This snippet is working as in the grid lines are visible even in smaller viewing percentages but it makes my application stuck at the PDF save operation and also it throws System.OutofMemoryException with message "Insufficient memory to continue the execution of the program." However, the application doesn't crash.

To check the behavior of PDF viewer, I generated a table with multiple rows and columns in MS Word and saved it as a PDF. In that case, the table grid lines are clearly visible even at small viewing percentages.

Can anyone help me with this?

回答1:

I assume the first code snippet creates a table in vector format (you do not supply a PDF that allows to verify this).

The second code snippet attempts to create a bitmap image (raster format).

Either way: with both vector and raster images it depends on the PDF viewer whether thin lines are visible. Adobe Reader has many options (like "Enhance thin lines", "Smooth line art", "Smooth images") that will have an effect on the actual display - to be set on the client computer, nothing to be set in the PDF.

I assume your test with MS Word also created a table in vector format, but maybe with thicker lines. So this test proofs nothing.

来源：https://stackoverflow.com/questions/47871928/wpf-datagrid-gridlines-not-visible-when-saved-as-pdf

标签

wpf

datagrid

resolution

pdfsharp

gridlines