Following Bert's advice, I see that HaloMorph overrides #drawSubmorphsOn:
and calls its Canvas using asAlphaBlendingCanvas. That seems like a good
place to start.
I tried subclassing ImageMorph and adding this method:
drawOn: aCanvas
^ super drawOn: (aCanvas asAlphaBlendingCanvas: alphaValue).
Unfortunately, it didn't display anything at all. I tried alpha values of
0.5 and 1.0. If I remove the alpha blending stuff, and simply call:
^ super drawOn: aCanvas.
it works like a normal ImageMorph, so at least I know it isn't broken
someplace else.
Any suggestions on how to get asAlphaBlendingCanvas to blend some alphas?
On 4/23/07, Steven Greenberg <[EMAIL PROTECTED]> wrote:
Thanks for the pointer! I didn't try that code in the workspace, but if
you enable "haloTransitions" using the Preferences browser then the halos
fade in and out.
Thanks,
Steve
On 4/22/07, Bert Freudenberg <[EMAIL PROTECTED]> wrote:
>
>
> On Apr 23, 2007, at 0:44 , Steven Greenberg wrote:
>
> > I have a PNG image that I'd like to display fading out. I tried
> > the BitBlt method suggested by "Team RAR" to fade the image, but I
> > can't make it work.
> >
> > The image loads properly from a file and displays fine as an
> > ImageMorph. I have been able to use a TransformationMorph to
> > rotate and scale it, and PNG transparency is working properly.
> >
> > Is the "Team RAR" BitBlt method the only way, or are there
> > alternatives?
> >
> > I'm running a 3.9 image, and my display depth is set to 32 bits.
> >
>
> Normally you would just use an alpha-blending canvas. See HaloMorph
> fadeIn/fadeOut and draw methods. To try those halos, enable this:
>
> Preferences enable: #haloTransitions
>
> Now when I tried then the halo icons do not actually show until alpha
> is one. No idea why that is.
>
> - Bert -
>
>
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