Draw onto the transparent area of an image.

TGT · Post by **TGT** » Sun Mar 05, 2006 10:12 am

Hi,

is it somehow possible to draw onto the transparent area of an image!?

Thanks, Tom

Izhaki · Post by **Izhaki** » Sun Mar 05, 2006 2:35 pm

Yes, but you will need to change the alpha channel of the area onto which you are drawing. A transparent area will have its alpha channel set to 0 for all transparent pixels - no matter what values exist on the RGB channels these pixels will not be drawn.

Look at wxImage SetAlpha() and GetAlpha()

You can also try to draw into an off screen bitmap and them copy it onto the image.

TGT · Post by **TGT** » Sun Mar 05, 2006 6:13 pm

Hmm - I wasn't able to test this

...quite strange situation:

error: 'class wxImage' has no member named 'GetAlpha'

Today this is the second time something like that happend to me

(Set/GetMinSize, Set/GetMaxSize)
Of course both are mentioned in the online documentation.... and no I'm not using wx < 2.5 (regarding the note in the docu)

Any ideas