Shape shadows

[Thorsten Zachmann]

On Wednesday, May 02, 2012 07:34:53 PM Inge Wallin wrote:
> On Wednesday, May 02, 2012 06:02:57 Thorsten Zachmann wrote:
> > On Wednesday, May 02, 2012 12:16:34 AM Inge Wallin wrote:
> > > https://bugs.kde.org/show_bug.cgi?id=260535 has the title:
> > > 
> > > kpresenter:openoffice:Shadow of the picture is not getting displayed.
> > > 
> > > I had a look at this, and the reason is the following code in void
> > > KoShapeShadow::Private::paintShadow() at line 86 in
> > > 
> > > libs/flake/KoShapeShadow.cpp:
> > >     if (shape->background()) {
> > >     
> > >         painter.save();
> > >         KoShape::applyConversion(painter, converter);
> > >         painter.setBrush(QBrush(color));
> > >         QPainterPath path(shape->outline());
> > >         KoPathShape * pathShape = dynamic_cast<KoPathShape*>(shape);
> > >         if (pathShape)
> > >         
> > >             path.setFillRule(pathShape->fillRule());
> > >         
> > >         painter.drawPath(path);
> > >         painter.restore();
> > >     
> > >     }
> > > 
> > > There is a similar test for stroke right behind it.
> > > 
> > > This means that only shapes with a defined background can ever get a
> > > shadow. I don't really see the reason for this.  Shouldn't it be enough
> > > to remove the test to make it work everywhere? What would be the
> > > drawbacks?
> > 
> > That means we only draw a shadow for the background if there is actually a
> > background. E.g. if there is a shape that only has a outline only a shadow
> > for the outline will be draw. This is done by the code in the test for the
> > stroke. So if that would be changed also e.g. a polygon would show a
> > background.
> 
> Yes, I know what it means.  My question was really why it is so from the
> beginning.  What is the thinking behind only drawing a shadow if there is a
> stroke and/or fill (a.k.a background)?  I think Yue should comment because
> he is the guy who wrote it.
> 
> > I see the problem is that the picture shape has no background and
> > therefore
> > this fails. One idea would be to add a method to test if there is a shadow
> > for the shape background the would in KoShape test if shape->background is
> > set and return true in case it is a picture shape. But maybe others have a
> > better idea. However that might fail in case the image has transparency at
> > the edges. Not sure if that is something we need to support.
> 
> We could have such a method but what I am not sure of the connection between
> the background and the shadow.  In my eyes, if a user wants a shadow he
> should have the shadow no matter what the shape contains.
> 
> Opinions?

I'm the one who wrote the orignal code of that. if you have a path with out 
filling you only want to draw the shadow of the path and not also a shadow for 
a background that is not visible right?
That is what the code does. As the picture shape does not use background this 
fails, while it works for most other shapes. Changing this would brake shadows 
for all object having no background.

Thorsten