2014-03-22 16:59 GMT+01:00 Pharo4Stef <pharo4s...@free.fr>:
>
> From the st80 ages, rectangle have allways been oriented.
> You have an origin and a corner inst var, not 2 corners or vertices.
> And you have creation messages Rectangle class>>origin:corner:
> The conventions are that of latin scribes, the orientation of rectangle
> should be (left->right , top->down)
>
> There is an assumption that a rectangle with negative width (right->left)
> or height (bottom->top) should be treated as empty.
>
>
>
> And this was globally well maintained except a few breakages introduced in
> Squeak along the years (but I hope I corrected most of the slips since
> then).
>
> Now Igor and Stephane had another view more geometric and un-oriented, and
> wanted to change conventions/handling of empty rectangles in Pharo.
> I don't know how far they went, or even if it is feasible at all... IMO,
> it's a recipe for maximizing breakage/gain ratio.
>
>
> It is clearly not. :)
> We removed bugs in the invalid rectangle areas and others.
> And we fixed all the places that were created negative dimensions (like in
> framelayout) because rectangle where hijack to represent two points that
> were not
> a rectangle.
> We also introduce margin which is really nice to represent 1,2, or 4
> digits and avoid to overuse again a rectangle.
>
>
You did not fix everything that was fixed in Squeak.
Example:
rect1 := 10@10 corner: 40@40.
empty2 := 30@30 corner: 20@20.
(rect1 intersects: empty2) - > true
What I see is that you provided intersect:ifNone: to avoid producing empty
rectangle in the first place - or to produce explicitely empty 0@0 extent:
0@0.
But
- not all intersect: senders have been changed,
- some senders have been changed questionably (allowedArea in
IdentifierChooserMorph is re-implementing RealEstateAgent class
maximumUsableArea differently)
- I don't know if intersect: was the sole source of empty rectangles...
Until all producers have been eradicated, the empty invariant still exists,
and Rectangle methods must still be guarded against empty rectangle edge
cases.
Right now, it is not enforced everywhere (see intersects: case above).
Right now you're in the middle of the bridge, but that's OK if the
emptiness invariant eradication is still planned, it's just a temporary
transition..
Note that VW has Rectangle class>>vertex:vertex:, and we probably should
> add such message...
>
>
>
>
> 2014-03-21 15:15 GMT+01:00 Noury Bouraqadi <bouraq...@gmail.com>:
>
>> Inverting the origin and the corner of a rectangle changes the result of
>> intersection.
>> I guess it's a bug, though I imagine that changing the code of Rectangle
>> is likely to have deep/undesired consequences..
>>
>> (0@0 corner: 100@100) intersects: (-50@ -50 corner: 80@80) ==> true
>> (100@100 corner: 0@0) intersects: (-50@ -50 corner: 80@80) ==> false
>> !!!!
>>
>> Noury
>>
>>
>>
>>
>>
>
>
