[Pharo-dev] float printing glitch?

Stéphane Ducasse stephane.ducasse at inria.fr
Thu Dec 26 10:45:35 EST 2013


On 25 Dec 2013, at 23:39, Nicolas Cellier <nicolas.cellier.aka.nice at gmail.com> wrote:

> 
> 2013/12/25 Stéphane Ducasse <stephane.ducasse at inria.fr>
> thanks nicolas.
> I will give a try.
> 
> 
> I just made a quick pass in Squeak, analyzed senders of roundTo: and modified a few whose sole intention was printing.
> This need to be redone in Pharo.

If you do it and publish the code we will happily integrate that in Pharo because
so far we do not have much expertise in this domain.

Stef


> 
> On 24 Dec 2013, at 18:15, Nicolas Cellier <nicolas.cellier.aka.nice at gmail.com> wrote:
> 
>> Yes, you should change the tickPrintBlock because it probably incorrectly use (aFloat roundTo: 0.1) printString.
>> There is no guaranty that this return the nearest Float to the aimed decimal fraction.
>> Since this is not the nearest Float, you have additional digits displayed.
>> The print block should use a selector like printShowingDecimalPlaces: (Squeak) or something equivalent in Pharo (can't remember if the selectors are 100% compatible).
>> 
>> For completeness, do test these expressions:
>> (0 to: 10) collect: [:i | (i/10) asFloat].
>> versus
>> (0 to: 10) collect: [:i | i*0.1].
>> versus
>> (0 to: 10) collect: [:i | (i/10) roundTo: 0.1].
>> 
>> Only the first one is correct. Trying to roundTo: 0.1 spoils thing because 0.1 is not exactly 1/10 and thus introduce small errors...
>> 
>> 
>> 2013/12/24 Stéphane Ducasse <stephane.ducasse at inria.fr>
>> Hi (nicolas :))
>> 
>> I was fixing the sound package and the EnvelopeEditorMorph shows a strange glitch
>> 
>> EnvelopeEditorMorph openOn: (FMSound brass1) copy title: 'brass1'
>> 
>> See ^^^^^^^^^^^^^^^^ below
>> 
>> I have the impression that this related to float printString. Any idea how to fix it?
>> 
>> 
>> 
>> 
>> 
>> buildLabels
>>         | scale x1 y1 y2 captionMorph loopStart offset |
>>         majorTickLength * minorTickLength < 0
>>                 ifTrue: [ minorTickLength := 0 - minorTickLength ].
>>         self removeAllMorphs.
>>         caption ifNotNil:
>>                 [ captionMorph := StringMorph contents: caption.
>>                 offset := captionAbove
>>                         ifTrue: [majorTickLength abs + captionMorph height + 7]
>>                         ifFalse: [2].
>>                 captionMorph
>>                         align: captionMorph bounds bottomCenter
>>                         with: self bounds bottomCenter - (0 @ offset).
>>                 self addMorph: captionMorph].
>>         tickPrintBlock ifNotNil:
>>                         ["Calculate the offset for the labels, depending on whether or not
>>                           1) there's a caption
>>                         below, 2) the labels are above or below the ticks, and 3) the
>>                         ticks go up or down"
>>                         offset := labelsAbove
>>                                         ifTrue: [majorTickLength abs + minorTickLength abs + 2]
>>                                         ifFalse: [2].
>>                         caption
>>                                 ifNotNil: [captionAbove ifFalse: [offset := offset + captionMorph height + 2]].
>>                         scale := (self innerBounds width - 1) / (stop - start) asFloat.
>>                         x1 := self innerBounds left.
>>                         y1 := self innerBounds bottom.
>>                         y2 := y1 - offset.
>>                         "Start loop on multiple of majorTick"
>>                         loopStart := (start / majorTick) ceiling * majorTick.
>>                         loopStart to: stop
>>                                 by: majorTick
>>                                 do:
>>                                         [ :v | | x tickMorph |
>>                                         x := x1 + (scale * (v - start)).
>>                                         tickMorph := StringMorph contents: (tickPrintBlock value: v).
>>                                                                                                  ^^^^^^^^^^^^^^^^ printString?
>> 
>>                                         tickMorph align: tickMorph bounds bottomCenter with: x @ y2.
>>                                         tickMorph left < self left
>>                                                 ifTrue: [ tickMorph position: self left @ tickMorph top ].
>>                                         tickMorph right > self right
>>                                                 ifTrue: [ tickMorph position: (self right - tickMorph width) @ tickMorph top].
>>                                         self addMorph: tickMorph ]]
>> 
> 
> 

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