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Exporting transparent gradients

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PdfProcessing
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Chris
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Chris asked on 12 Sep 2016, 08:32 PM

Hi,

Is it possible to generate PDFs containing transparent gradients?

Setting the alpha component on a solid object (RgbColor) works as expected; it's not fully opaque and any colours behind the show though.  Setting the alpha component on GradientStops appears to have no effect; the colors are shown at full opacity

This can be demonstrated with the API documentation example http://docs.telerik.com/devtools/document-processing/libraries/radpdfprocessing/concepts/colors-and-color-spaces#patterncolor and simply changing the LinearGradient stops to include an alpha value that is less than 255:

linearGradient.GradientStops.Add(new GradientStop(new RgbColor(10, 0, 207, 0), 0));
linearGradient.GradientStops.Add(new GradientStop(new RgbColor(10, 0, 102, 204), 1));

When rendered this shows a gradient with full opacity (attached) when it would be expected to be near transparent.

Thanks,
Chris

UI for WPF R2 2016 SP1

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Tanya
Telerik team
answered on 15 Sep 2016, 03:55 PM
Hello Chris,

I tested the behavior and can confirm that the alpha channel is not respected. I added the issue to our backlog and you could subscribe to the related public item in order to track its progress. Your Telerik points are updated as a token of appreciation for reporting this.

Regards,
Tanya
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Chris
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answered on 16 Sep 2016, 08:19 AM

Hi Tanya, thanks for investing the cause of the problem.  I'll track the fix progress.

 

Chris

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