Exporting PNG or TIFF charts with transparent background

Old forum General discussion
1

I am using the VBA api to automatically export charts. Originally, I exported them as EMF files and by turning the chart background to ‘no fill’ I could get the backgrounds of the exported charts to be transparent. However, when I do the exact same export on the same charts but as PNGs instead, the charts come out with white backgrounds.

Does anyone know how I can get the charts to export as PNG files (or any web suitable image format), and keep their transparent background? As I am sure that this file format should be able to handle transparency.

Any help would be greatly appreciated. And thanks to the developer for this great piece of software!

Andrew

2

Hi Andrew,

the Toolbox currently cannot do this, unfortunately. Internally, it ‘asks’ Windows to draw the chart to be exported in memory, and then the FreeImage library is used to create a graphics file from this in-memory representation. Thus, the Toolbox currently has no means to interfere with the drawing of individual elements such as the chart background.

I am working on a revamped chart export engine, but it will take a while before it’s ready. I know that lots of people have come to like the Toolbox’ chart export feature, and I use it myself for my scientific work.

One workaround for the time being is to use an image manipulation software such as http://gimp.org to make the white background transparent.

Another workaround is to use http://inkscape.org to manually delete the background rectangle, then export the image to PNG. (Coincidentally I posted an http://xltoolbox.sf.net/blog/2014/02/export-excel-charts-to-svg-files about how to get Excel charts into Inkscape just yesterday.)

I know both of these methods are cumbersome if you need to export many charts, or update your charts often.

Kind regards

Daniel

3

Oh well, just realized you are using the API. So it’s probably not feasible to manually work with the exported charts…

4

Thanks Daniel. I’ll give your workarounds a shot. Cheers

5

Hi, if you’re still listening to this, try the new alpha versions (2 and higher), which support transparency.

xltoolbox.sourceforge.net/blog/2 … he-license