is there alpa-transparency key in C#/WinForms

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Transparency key is easy to use - but that's not that what I need. For ex.: I have a sprite like this: http://spritedatabase.net/file/12735 (no alpha chanel) and I want to make buttons with image set to this - I want to set blue as transparency key, but on transparent parts of image I'd like to see the main form - not my desktop. How to achieve this kind of transparency?

Posted 29-Mar-14 8:38am

Pavel Pavlov

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2 solutions

Solution 2

or:
Bitmap bitmap = new Bitmap(...)
bitmap.MakeTransparent(some color)

Posted 30-Mar-14 3:45am

Pavel Pavlov

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Sergey Alexandrovich Kryukov · Accepted Answer · 2014-03-29T15:53:00

Sure. You can do graphics rendering using ARGB colors, with alpha channel:
http://msdn.microsoft.com/en-us/library/system.drawing.color.aspx[^],
http://msdn.microsoft.com/en-us/library/system.drawing.color.fromargb.aspx[^].
It is not related only to System.Windows.Forms, but to System.Drawing, which has wider applicability (for example, you can draw on bitmaps which are not shown on a form).

On top of that, you can set opacity for the whole form, but it cannot allow you do make one part of it more transparent than other. And I won't recommend to try to implement transparency to control (unless you do your own rendering as I mentioned above) — transparency for System.Windows.Forms is a total lame. If you need to apply transparency freely to anything you want, switch to WPF.

—SA