Christoph Thiede uploaded a new version of Graphics to project The Inbox:
http://source.squeak.org/inbox/Graphicsct.437.mcz ==================== Summary ==================== Name: Graphicsct.437 Author: ct Time: 24 August 2020, 1:26:40.516818 pm UUID: 66c6c2fd69786d438edac22f0a5defca Ancestors: Graphicskfr.436 Proposal: Add Point >> #exactCenter:, complementing Graphicscbc.372. Refine relevant method comments in Point and Rectangle. Usage example: m := Morph new. m changeProportionalLayout. n := Morph new. n color: Color red. m addMorph: n fullFrame: (LayoutFrame fractions: ( 0.5 @ 0.25 exactCenter: 0.5 @ 0.5)). m openInHand. =============== Diff against Graphicskfr.436 =============== Item was changed:  Method: Point>>center: (in category 'converting to rectangle')  center: aPoint + "Answer a Rectangle whose extent is the receiver and whose center is approximately aPoint (after rounding to integers). This is one of the infix ways of expressing the creation of a rectangle."  "Answer a Rectangle whose extent is the receiver and whose center is  aPoint. This is one of the infix ways of expressing the creation of a  rectangle." + ^ Rectangle center: aPoint extent: self!  ^Rectangle center: aPoint extent: self! Item was added: +  Method: Point>>exactCenter: (in category 'converting to rectangle')  + exactCenter: aPoint + "Answer a Rectangle whose extent is the receiver and whose center is exactly aPoint. This is one of the infix ways of expressing the creation of a rectangle." + + ^ Rectangle exactCenter: aPoint extent: self! Item was changed:  Method: Rectangle class>>center:extent: (in category 'instance creation')  center: centerPoint extent: extentPoint + "Answer an instance of me whose center is approximately centerPoint (after rounding to integers) and whose extent is extentPoint."  "Answer an instance of me whose center is centerPoint and width  by height is extentPoint. " + ^ self origin: centerPoint  (extentPoint // 2) extent: extentPoint!  ^self origin: centerPoint  (extentPoint//2) extent: extentPoint! Item was changed:  Method: Rectangle class>>exactCenter:extent: (in category 'instance creation')  exactCenter: centerPoint extent: extentPoint + "Answer an instance of me whose center is exactly centerPoint and whose extent is extentPoint." +  "Answer an instance of me whose center is centerPoint and width  by height is extentPoint. " ^ self origin: centerPoint  (extentPoint / 2) extent: extentPoint ! 
In particular, when it comes to LayoutFrames, I have to say that I find the automatic rounding behaviors of Point/Rectangle quite confusing.
For instance, why does #scaleBy: allow producing float points/rectangles whereas #scaleFrom:to: applies rounding? In my opinion, the integer/float arithmetic of Point and Rectangle is not really clear. If these classes are intended containing integers only, the "truncation and round off" protocol would be redundant. If they are intended to contain floats as well, it is confusing that methods such as #center and #aboveCenter apply rounding. Would it be possible and wise to eliminate that automatic rounding behavior, or is too old and popular for such a breaking change?
See also this related discussion: http://forum.world.st/TheInboxGraphicscbc372mcztd4940274.html Best,
Christoph
Von: Squeakdev <[hidden email]> im Auftrag von [hidden email] <[hidden email]>
Gesendet: Montag, 24. August 2020 13:26:55 An: [hidden email] Betreff: [squeakdev] The Inbox: Graphicsct.437.mcz Christoph Thiede uploaded a new version of Graphics to project The Inbox:
http://source.squeak.org/inbox/Graphicsct.437.mcz ==================== Summary ==================== Name: Graphicsct.437 Author: ct Time: 24 August 2020, 1:26:40.516818 pm UUID: 66c6c2fd69786d438edac22f0a5defca Ancestors: Graphicskfr.436 Proposal: Add Point >> #exactCenter:, complementing Graphicscbc.372. Refine relevant method comments in Point and Rectangle. Usage example: m := Morph new. m changeProportionalLayout. n := Morph new. n color: Color red. m addMorph: n fullFrame: (LayoutFrame fractions: ( 0.5 @ 0.25 exactCenter: 0.5 @ 0.5)). m openInHand. =============== Diff against Graphicskfr.436 =============== Item was changed:  Method: Point>>center: (in category 'converting to rectangle')  center: aPoint + "Answer a Rectangle whose extent is the receiver and whose center is approximately aPoint (after rounding to integers). This is one of the infix ways of expressing the creation of a rectangle."  "Answer a Rectangle whose extent is the receiver and whose center is  aPoint. This is one of the infix ways of expressing the creation of a  rectangle." + ^ Rectangle center: aPoint extent: self!  ^Rectangle center: aPoint extent: self! Item was added: +  Method: Point>>exactCenter: (in category 'converting to rectangle')  + exactCenter: aPoint + "Answer a Rectangle whose extent is the receiver and whose center is exactly aPoint. This is one of the infix ways of expressing the creation of a rectangle." + + ^ Rectangle exactCenter: aPoint extent: self! Item was changed:  Method: Rectangle class>>center:extent: (in category 'instance creation')  center: centerPoint extent: extentPoint + "Answer an instance of me whose center is approximately centerPoint (after rounding to integers) and whose extent is extentPoint."  "Answer an instance of me whose center is centerPoint and width  by height is extentPoint. " + ^ self origin: centerPoint  (extentPoint // 2) extent: extentPoint!  ^self origin: centerPoint  (extentPoint//2) extent: extentPoint! Item was changed:  Method: Rectangle class>>exactCenter:extent: (in category 'instance creation')  exactCenter: centerPoint extent: extentPoint + "Answer an instance of me whose center is exactly centerPoint and whose extent is extentPoint." +  "Answer an instance of me whose center is centerPoint and width  by height is extentPoint. " ^ self origin: centerPoint  (extentPoint / 2) extent: extentPoint ! 
> In my opinion, the integer/float arithmetic of Point and Rectangle is
> not really clear Indeed. In my own images I have implemented #preciseCenter: and similar methods both in Pont and Rectangle to bypass rounding and work with floats. But I do not think that transitioning to an overall new convention (like getting rid of rounding altogether) is going to be safe. A lot of morphic code assumes that rectangles are always about pixels and expect their dimensions to be integers. Stef 
Scaling for morphs with TransformationMorph is a little weird. If you rotate a SystemWindow and use the scale handle, the window scales as a form Best, Karl On Mon, Aug 24, 2020 at 2:25 PM Stéphane Rollandin <[hidden email]> wrote: > In my opinion, the integer/float arithmetic of Point and Rectangle is 
Hmpf. Why can't we change Rectangle >> #center:extent: to use #/ instead of #//? What would break? I am surprised that my values get rounded at that location. They get rounded at a later anyway. At least in the graphics system and in Morphic. Best, Marcel

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