Issue 842 in moose-technology: ROTranslatingShape mouse hotspot mis-alignment
Labels: Type-Defect Priority-Medium
New issue 842 by google....(a)ben.coman.com.au: ROTranslatingShape mouse
Fix attached related to the following mail-posts
Also attached are before and after snapshots from
Ben Coman wrote:
> I was trying to apply ROTranslatingShape to produce a label sitting above
> children nodes. To understand it better how to get what I
> need, I made ROExample>>nestingTranslate to show a permutation of the
> the shapes can be applied. I have attached a screen snapshot and fileout
> this. The case I am particularly interested in is el3.
> The 'el0' case is the reference without any ROTranslatingShape.
> When running the example hover near and over the inner elements to view
> misalignment of the mouse hotspot. I have marked the approximate offset in
> green in the snapshot.
> I notice that the existing call chain goes...
> ROShape>>extentFor: (union of extent of each shape)
> It seems to me the hotspot misalignment is related to the translation
> applied at the shape draw level whereas the #contains: checking is done
> at the
> element level. This relies on the union of the shape extents to set the
> element bounds, but I can't see how that extent union could be modified to
> account for the translation - particular in the case of a negative
> since extents throw away information
> about any negative offset.
> So I thought perhaps that the element #contains: checking needs might be
> better chained through the shaped, so that the translation
> could be applied similar to ROTranslatingShape>>chainedDrawOn:for: and
> this would not cause any/much additional computation since all the shapes
> being cycled through anyway for #extentFor:
> Something like...
> ROShape>>chainedContains:For: (for each shape)
You can see in all case el1 to el8, the child elements have shifted in
However the hotspot remains aligned with the location in el0.
I think part of the problem is that ROChildrenShape is a
and is always at the end of the line - so the translation is applied to the
Whereas it might work better if the position of the child elements was not
affected by ROTranslatingShape, such that it becomes the reference for the
position of any other translated shapes.
This would require ROChildrenShape be always the first shape of an element,
rather than always be the last shape.
The following code snippet...
el := ROElement on: 1.
(el + ROBorder + ROTranslatingShape + ROLabel ) inspect.
produces shapes chained in order of:
which seems reversed from what I would intuitively expect reading the code
I think ideally the shape chain would be:
Otherwise as in el1 you can see the position of the label is the same as
since the label has actually been drawn first prior to the translation, and
instead the translation is applied to the border and child elements, the
of which affects the mouse hotspot.
Roassal-BenComan.310.mcz 242 KB
ROTranslatingShape-permutations-mouse-hotspot-broken.png 33.2 KB
ROTranslatingShape-permutations-mouse-hotspot-fixed.png 29.8 KB