[squeak-dev] What it is the expected behavior of Rectangle (class) #intersect: if there is no interesection?

karl ramberg karlramberg at gmail.com
Tue Nov 29 05:50:18 UTC 2022


Hi,
I think you must use this method with a very similar name

intersects: aRectangle
"Answer whether aRectangle intersects the receiver anywhere."
"Optimized; old code answered:
(origin max: aRectangle origin) < (corner min: aRectangle corner)"

Best,
Karl

On Tue, Nov 29, 2022 at 1:50 AM LawsonEnglish <LEnglish5 at cox.net> wrote:

> I did this and created 2 small rectangles quite far from each other trying
> to figure out what the method returns when there is no intersection:
>
> r1 := Rectangle fromUser.
> r2 := Rectangle fromUser.
>
> r2 3072 at 993 corner: 3203 at 1136
> r1 2710 at 632 corner: 2835 at 752
>
> r2 intersect: r1 3072 at 993 corner: 2835 at 752
>
> r1 intersect: r2  3072 at 993 corner: 2835 at 752
>
> Could someone explain these results?
>
> Not in terms of the math involved (I assume that there’s no math bug as
> the routine was last edited 22 years ago and it is used everywhere in
> Morphic), but what the LOGIC is for returning what is returned and what it
> means in the context of the comments:
>
> intersect: aRectangle
>         "Answer a Rectangle that is the area in which the receiver
> overlaps with
>         aRectangle…. “
>
> I was trying to figure out how to look to identify when there is no
> intersection, and that isn’t at all obvious here.
>
> Thanks.
>
>
> L
>
>
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