Balloon engine and bitmap fills: any clues why it ignores an alpha channel of bitmap?

 
I tried various paint rules
24, 34

nothing. A balloon engine seems like completely ignores an alpha channel,
so i could use it for filling shapes using bitmaps as long as these
bitmaps fully opaque.

I thought i could use a generic way to render bitmaps, instead of
using awkward warpBlt...
but it seems like something in plugin discards/ignores an alpha
channel of source bitmap.
I would be happy if this is not true.


--
Best regards,
Igor Stasenko AKA sig.

 
Hi -

[Apologies for being off-topic on vm-dev; I've set the reply-to to
squeak-dev]

On 4/21/2011 15:44, Igor Stasenko wrote:
It isn't true. Here is an example for transparent bitmap rendering with
the Balloon engine:

     "First we create a bitmap with a transparent pattern"
     f := Form extent: 100@100 depth: 32.
     f getCanvas asBalloonCanvas
         fillRectangle: f boundingBox
         fillStyle:
             ((GradientFillStyle colors: {Color transparent. Color white})
                 origin: 0@0; direction: 0@100).

     "Now we're displaying it"
     (Display getCanvas asBalloonCanvas)
         transformBy: ((MatrixTransform2x3 withAngle: 45));
         fillRectangle: (400@0 extent: 400@400)
         fillStyle: (BitmapFillStyle fromForm: f)

I'm not sure what you've been playing with but generally speaking you'll
be better off with BalloonCanvas instead of trying to manipulate the
Balloon engine directly.

Cheers,
   - Andreas