[reportlab-users] RGBA Color support changed

Robin Becker robin at reportlab.com
Wed Dec 9 13:19:30 EST 2009

Following discussions with Andy I have committed a change to make alpha=1 the
default value for colour alpha values.

This should have no immediate effects on existing code (memory usage aside). It
fixes our graphics framework somewhat in that because colours should always have
an alpha the shapes hierarchies will normally work properly to set and unset
alpha as they are traversed. There is still a problem relative to recently added
shapes properties fill/strokeOpacity, but it's likely we will just ignore or
remove them.

The shapes/color changes allow us to make the renderPM opacity support come in
line with renderPDF.

With latest code the attached should work reasonably for both png and pdf. Note
that _renderPM.c (the C part of the renderPM extension) has had support for
opacity for some while so shouldn't need changing.

A separate issue is that using opacity settings <1 in Acrobat Reader seems to
change the colour model some how even when the states aren't used (evince
doesn't do this).
Robin Becker
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