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Johann Hibschman | 8 Feb 14:51
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Centering text in morphic

How can I center text in morphic? I have a RectangleMorph subclass
representing a "tile." I'd like to display a centered string label
within the morph.

My current approach is to just override #drawOn: with:

    TileMorph>>drawOn: aCanvas
        super drawOn: aCanvas.
        aCanvas drawString: 'hi' on: self innerBounds

However, that just always puts the text in the upper-left corner.
(Code is from memory, so I may have got something wrong.)

By "center", I want the baseline-to-max-ascent for the font to be
centered vertically (not the actual height of whatever characters I
have), while the actual width is centered vertically.

Would it be better to use a StringMorph for placing text like this?
I'm afraid I don't yet understand what layout options I'd need to use
to make it work.

Thanks,
- Johann
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Lawson English | 8 Feb 19:44
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Re: Centering text in morphic

Hi Johann, just after you left IRC, I figured out an easy (though 
perhaps not the best) way to do what you want:

a := SimpleButtonMorph new openInWorld.
a actWhen: #buttonDown.   "turns off visible button behavior"
a label: 'new label'.              "lets you change the label to a 
different string of text"
a clipSubmorphs: true.        "true means that your text doesn't extend 
beyond the border of the button"

Hope this helps.

Lawson (saijanai_ on irc)

On 2/8/12 6:51 AM, Johann Hibschman wrote:
> How can I center text in morphic? I have a RectangleMorph subclass
> representing a "tile." I'd like to display a centered string label
> within the morph.
>
> My current approach is to just override #drawOn: with:
>
>      TileMorph>>drawOn: aCanvas
>          super drawOn: aCanvas.
>          aCanvas drawString: 'hi' on: self innerBounds
>
> However, that just always puts the text in the upper-left corner.
> (Code is from memory, so I may have got something wrong.)
>
> By "center", I want the baseline-to-max-ascent for the font to be
> centered vertically (not the actual height of whatever characters I
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Johann Hibschman | 9 Feb 14:40
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Re: Centering text in morphic

On Wed, Feb 8, 2012 at 12:44 PM, Lawson English <lenglish5 <at> cox.net> wrote:
> Hi Johann, just after you left IRC, I figured out an easy (though perhaps
> not the best) way to do what you want:
>
> a := SimpleButtonMorph new openInWorld.
> a actWhen: #buttonDown.   "turns off visible button behavior"
> a label: 'new label'.              "lets you change the label to a different
> string of text"
> a clipSubmorphs: true.        "true means that your text doesn't extend
> beyond the border of the button"

Thanks, that's helpful. I don't think I'm going to use
SimpleButtonMorph, since it builds in a fixed margin, but reading its
implementation was useful. It makes a StringMorph and uses its #extent
to do the centering, and I can just do the same thing. (And I can just
look at StringMorph's #extent if I need to.)

If SimpleButtonMorph works by embedding a StringMorph, I think that's
a sign that I should do that rather than override #drawOn.

Johann
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Lawson English | 9 Feb 17:29
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Re: Centering text in morphic

Sure. My first pass at writing code using Morphic is to see if an 
existing class does what I want and then deciding if it is worth the 
time to "roll my own" using whatever insight I got from seeing how the 
existing code works.

#drawOn should only be used if you need to do things which don't use 
exisint morphs and/or need a great deal of speed. The built-in 
composition capabilities of Morphic are usually powerful enough to 
accomplish any kind of  behavior using compositions of simpler morphs. 
Obviously, you don't create high-level paint programs using morphs as 
the pixels, but anything higher level than that is probably a good 
candidate for composition.

OTOH, if I was to write an educational program showing how line-drawing 
algorithms work, I probably WOULD use morphs as pixels. YMMV.

L

On 2/9/12 6:40 AM, Johann Hibschman wrote:
> Thanks, that's helpful. I don't think I'm going to use 
> SimpleButtonMorph, since it builds in a fixed margin, but reading its 
> implementation was useful. It makes a StringMorph and uses its #extent 
> to do the centering, and I can just do the same thing. (And I can just 
> look at StringMorph's #extent if I need to.) If SimpleButtonMorph 
> works by embedding a StringMorph, I think that's a sign that I should 
> do that rather than override #drawOn. Johann 
> _______________________________________________ Beginners mailing list 
> Beginners <at> lists.squeakfoundation.org 
> http://lists.squeakfoundation.org/mailman/listinfo/beginners
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