Re: Any new comments on the non-uniform scaling patch?

["Marcel Toele" <dpy dia gmail com>]

2007/12/4, Lars Clausen <lars raeder dk>:

On Tue, 2007-12-04 at 12:28 +0100, Marcel Toele wrote:
> Lars/any dev with svn acces/anyone else,
>
> Can you please comment on the updated information about the
> non-uniform scaling patch
> (I've added extra information via Replies to that thread)

Sorry it took a bit, I've again been busier than I hoped for.  I got the
patch to work as intended, and can now start to look at problems with
it.

Cool.

A major but fixable problem is that the bounding box does not get
updated correctly when a sub-shape is large enough to be outside its
super-shape, leading to dirt on the diagram.  However, some of your
previous comments seem to indicate that you expect sub-shapes to always
be within the super-shape.  If that is the case, the super-shape should
limit its resize if it would put the sub-shape outside it.

That's a good idea, I'll look into it and fix it.

The sub-shape in the example that's anchored at the lower right doesn't
appear, but that's a bug in the SVG path for it.  Once I copied the
first star's paths, it turned out fine, and the bottom/left anchors work
fine.

Actually, it's not a bug in the SVG path code. The bottom-left sub-shape
does not have an outline, it consists of fill-only. But, as I have stated
previously, the default  value for "filling dia objects" has been changed
from true to false. This means that from now on, no shape will be filled
by default. As I also said before: this may be a big problem, because
many (if not all) custom shapes depend on this attribute to default to
true (if they are to appear according to their icon).

Anyway, if you simply turn on "draw background" (actually, "fill" comes
closer to its meaning) on the example shape the lower-left sub-shape
will appear.

To be honest, there should be a fix for this "draw background" default
attribute. It only appears in defaults.dia , cannot be changed in the GUI
(at least, I couldn't find the setting, so surprise me!), and as I said,
breaks most, if not all, custom shapes in the /shapes/ directory.

I'm not convinced that the default_scale attribute is the right way to
go about handling the scaling issues.  It means that whereas the
super-shape ignores the absolute scale and just uses the coordinates as
relative coordinates in a 2x2 cm space, the sub-shape actually uses the
units of the SVG, modified by the default_scale.  This is confusing: The
coordinates of the super-shape and the sub-shape are now interpreted in
different ways, one of which is controlled by a "default_scale"
attribute whose meaning is not clear from context.  If the default_scale
was on the main shape, it would be less confusing and at the same time
close a long-standing bug.

Another problem with the default_scale is that it's defined relative to
something that's not in the shape definition, namely the unit system.
mm might be default in many locals (I frankly don't know, and would
rather not have to remember), but how would the shape be rendered in the
US, where inches or suchlike are the default?  As I see it, the
coordinates for the super-shape and the sub-shape should have the same
meaning, or else editing the shape becomes a trap.  Rather than the
default_scale attribute we should, IMNSHO, have either a unit definition
or a bounding-box definition with units.

I'll look into it and will come back  to you on the default_scale issue, which
as you states, perhaps should be fixed outside the scope of sub-shapes,
or in combination with a default shape size of other shapes.

Can you point me to the bugreport you are referring to.
 

Am I right to think that there is no such thing as a sub-sub-shape?
When I try, the sub-sub-shape appears, but not different from when it's
a sub-shape.

Theoretically it should be possible to have sub-sub-shapes and recurse
to infinity, however, I have intentionally opted not to do this, as this will
be very confusing to end-users. It will also create a big user-interaction
problem: "How to resize the sub-sub-shapes or the sub-[sub]*-shapes?"

I'm not included to apply the patch until we have agreement on the
default_scale matter.

-Lars

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