Groups > comp.lang.java.programmer > #36085

Re: When resizing text to fill a JLabel the text sometimes "jiggles", how do I fix this?

From	Arne Vajhøj <arne@vajhoej.dk>
Newsgroups	comp.lang.java.programmer
Subject	Re: When resizing text to fill a JLabel the text sometimes "jiggles", how do I fix this?
Date	2016-12-11 20:48 -0500
Organization	Aioe.org NNTP Server
Message-ID	<o2kvkk$1i8r$1@gioia.aioe.org> (permalink)
References	<75624c6e-6a78-4e8a-82a4-4ff2556cc241@googlegroups.com> <5bda0936-09ee-4eea-8001-e0ad17f31b0b@googlegroups.com>

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On 12/9/2016 2:35 PM, The Kreepy Gamer wrote:
> public class Fonts {

>    public Fonts() {
>       JFrame window = new JFrame("Test");
>       window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
>       window.setSize(300,300);
>
>       label.setHorizontalAlignment(JLabel.CENTER);
>
>       window.add(label);
>       window.setVisible(true);
>    }
>
>    public static void main(String[] args) {
>       new Fonts();

See Eric Sosman's comments about EDT.

And fix it.

The behavior of the code is unpredictable.

I don't think it impact this problem though.

>       Font compFont = comp.getFont();
>       String compText = text;
>       int stringWidth = comp.getFontMetrics(compFont)
>                         .stringWidth(compText);
>       int compWidth = comp.getWidth()-75;
>
>       if (stringWidth == 0) {
>          stringWidth++;
>       }
>
>       while (compWidth < 0) {
>     	  compWidth++;
>       }
>
>       double widthRatio = (double)compWidth / (double)stringWidth;
>
>       int newFontSize = (int)(compFont.getSize() * widthRatio);
>       int compHeight = comp.getHeight();
>
>       int fontSizeToUse = Math.min(newFontSize, compHeight);
>       if (fontSizeToUse < 1) {
>          return new Font(compFont.getName(), Font.PLAIN, 1);
>       }
>       return new Font(compFont.getName(), Font.PLAIN, fontSizeToUse);

There is any guarantee that this algorithm will be stable.

And in fact it keeps jumping (between 17 and 18 on my PC).

There are a couple of possible fixes:

1)

replace:

int newFontSize = (int)(compFont.getSize() * widthRatio);

with:

int newFontSize = (int)(compFont.getSize() * widthRatio + 0.5);

(or use Math.round)

It solves the problem on my PC. But I don't think it guarantees
stability either.

2)

replace:

int newFontSize = (int)(compFont.getSize() * widthRatio);

with:

int newFontSize = (int)(compFont.getSize() * (widthRatio/2 + 0.5));

I think this is a good change as I believe it in general should make
it more stable, but I still don't think it guarantees.

3)

But maybe with an extra check.

replace:

int newFontSize = (int)(compFont.getSize() * widthRatio);

with:

int newFontSize = (int)(compFont.getSize() * (widthRatio/2 + 0.5));
if(newFontSize == oldFontSize) newFontSize = compFont.getSize();
oldFontSize = compFont.getSize();

I don't know if it is guaranteed to be stable, but I am rather
confident that it will be in practice.

Arne

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