[wxPython-users] Shaped window question

[Ken Seehart]

Robin Dunn wrote:
> Ken Seehart wrote:
>> Andrea Gavana wrote:
>
>> I'm on all platforms :-)
>>> myBitmap = wx.Bitmap("PNGWithAlpha.png", wx.BITMAP_TYPE_PNG)
>>> myRegion = wx.RegionFromBitmap(myBitmap)
>>> self.SetShape(myRegion)
>>>
>>> Where "self" is your frame.
>>>
>> Thanks.  It doesn't get the transparency though.  The image has 
>> variable alpha, but I am pretty certain most of the background is 0 
>> alpha.  The fully transparent area is unfortunately opaque.
>
> wx.RegionFromBitmap uses the bitmap's mask, however when a PNG image 
> is loaded it only gets a mask if all of the alpha channel bytes are 
> either 0 or 255.  If there are any pixels with partial transparency it 
> doesn't get a mask, but an alpha channel instead.  You can convert an 
> alpha channel to a mask using wx.Image.ConvertAlphaToMask, or you can 
> create another image that is only used to specify the mask to be used 
> to set the shape, but still draw the other bitmap with its alpha.
>
>
Ah, that explains it.  Thank you.
- Ken