[vwnc] Rectangle

Is it normal  that a rectangle with an origin left to its corner does
not contain a point like this:

(  (0@0) corner: (-1@-1) ) containsPoint: (-0.5@-0.5) -> false

Bernadette Queyras

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bernadette Queyras escreveu:
> Is it normal  that a rectangle with an origin left to its corner does
> not contain a point like this:
>
> (  (0@0) corner: (-1@-1) ) containsPoint: (-0.5@-0.5) -> false
>
Bernadette,

Inspect the rectangle you created and look at the method
Rectangle>>containsPoint: aPoint
        "Answer whether the argument aPoint is within the receiver."

        ^origin <= aPoint and: [aPoint < corner]

Notice that the logic checks if aPoint is greater than origin, but

(0@0) <= (-0.5@-0.5) "false"

also

(-0.5@-0.5) < (-1@-1)  "false"

If this "normal" (which I believe you meant "acceptable") is a thing to
check within the context of your application.

HTH

--
Cesar Rabak
GNU/Linux User 52247.
Get counted: http://counter.li.org/
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Maybe the thread 'Rectangle #contains: and #containsPoint' (25/04/07)
will answer your question.

HTH,
         Andrés


bernadette Queyras escribió: _______________________________________________
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Well, yes, I guess so. At least I get the same result in VA Smalltalk.
Looking at the implementiation it is at least explicable:

containsPoint: operand

    "Answer true if the receiver contains the point operand.  Otherwise
     answer false."

    ^operand >= origin and: [operand < corner]

Good luck

Joachim

bernadette Queyras <[hidden email]> hat am 6. November 2009 um
16:05 geschrieben:


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Yes.
If you're not sure when creating the rectangle which points x/y is  
topLeft, you should use the vertex:vertex: constructor.

Cheers,
Henry

On Nov 6, 2009, at 4:05 56PM, bernadette Queyras wrote:

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> Is it normal  that a rectangle with an origin left to its corner does
> not contain a point like this:
>
> (  (0@0) corner: (-1@-1) ) containsPoint: (-0.5@-0.5) -> false

Use the #vertex:vertex: message to create rectangles from arbitrary  
points. That sorts the points appropriately, i.e. in your case you get  
a rectangle (-1@-1) corner: 0@0.

Andre


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