On 21 November 2013 14:22, hilaire <hilaire.fernandes@gmail.com> wrote:

The problem is really not related to PNG bitmap as the same issue can be
exposed with simple, as in this example:

| morph rectangle |
rectangle := RectangleMorph new color: (Color red alpha: 0.5).
morph := TransformationMorph new asFlexOf: rectangle.
morph scale: 0.7.
morph openInWorld

In this example, the red appears darker once the rectangle is scaled.

Is it something related to the Blit ? I reallz don't know where to look.

no idea..

Except that while adopting cairo surfaces i also has odd transparency issues until i realized
that cairo surface stores pixel data using premultiplied alpha format,e.g.:

pixelColor = (R*A, G*A, B*A, A)

while bitblt assumes it is (R,G,B,A)

��

Hilaire

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Best regards,
Igor Stasenko.