Export Chart to Metafile format in Stream

[Bertrand_D]

Hi,

I want to export a Winform chart to a .png or .gif file format, using Metafile first (rather than bitmap) to ensure a better quality of the output image. Also, I am working with MemoryStream rather than saving files on disk. I have the following Chart Exportation crashing, could you pelase help? (it works fine when I save files to disk, not with streams)

private

static MemoryStream ExportChartToStream(ChartFX.WinForms.Chart chart){  MemoryStream imgStream = new MemoryStream();  MemoryStream metafileStream = new MemoryStream();  chart.Export(FileFormat.Metafile, metafileStream);  var meta = new Metafile(metafileStream);  <----------- Generic Error occured in GDI+ ...  meta.Save(imgStream, ImageFormat.Png);  return imgStream;}

Thank you,

Bertrand

[AndreG]

I dont have an answer to your question, but I might have a better way if all you are trying to do is export charts in higher quality. Try the following:

  int desiredDPI = 300;   Rectangle r = new Rectangle(0, 0, (chart1.Width * desiredDPI) / 96, (chart1.Height * desiredDPI) / 96);   Bitmap bmp = new Bitmap (r.Width, r.Height);   bmp.SetResolution(desiredDPI, desiredDPI);   Graphics g = Graphics .FromImage(bmp);   chart1.Paint(g, r, PaintStyles .Background | PaintStyles .Border | PaintStyles .Print);   bmp.Save(@"c:\temp\cfx.png", ImageFormat.Png);   g.Dispose();   bmp.Dispose(); 

[Bertrand_D]

Hi,

 

Thank you for your answer.I have been trying to use your method but i am getting a smaller graph in the Rectangle with a lower definition.I am finnally using the basic following code (simplier and shorter) providing a very good quality of the chart.

 

private MemoryStream ExportChartToStream(ChartFX.WinForms.Chart chart) {   try   {   MemoryStream imgStream = new MemoryStream();   chart.Export(FileFormat.Bitmap, imgStream);   return imgStream;   }   catch (Exception e)   {   throw new Exception ("Error in ExportChartToStream()", e);   }

}

Thanks for your help.Bertrand

[AndreG]

 Great. Wonder why my code is not working for you, but thanks for sharing!

[Ozzard]

A late response, I accept - but the trick is to reset the stream's position to 0 before reading from it.

MemoryStream stream = new MemoryStream();

chart.Export(

FileFormat.Metafile, stream);

stream.Position = 0;

Image metaImage = Image.FromStream(stream);

stream.Close();

[Bertrand_D]

I have a similar issue and I just read your answer which solved the original problem.

Thanks a lot for sharing it.

Bertrand