[OpenJDK 2D-Dev] freetypescaler fix for fonts that start with a control point

[Phil Race]

I've tested the fix (manually) and it looks good.

-phil.

On 09/09/2014 02:47 PM, Phil Race wrote:
> Martin,
>
> Although I have yet to test it, the fix looks reasonable to me.
> Probably this decompose outline function supporting
> the callbacks was overlooked when this code was written.
> A jtreg test is tricky as you need to have font data available that 
> exercises
> the buggy case and then use the resulting Path2D. But there is no way
> to rely on a particular font with a known property being available
> without creating one and checking it in .. that might be overkill.
>
> Plus how do you test this in an automated way ?
> You can't compare the freetype glyph rasterisation with the pisces 
> rasterisation (that done using fill(..))
> as they are highly likely to differ in some tiny ways and knowing how 
> much difference to
> allow is fraught too, leading to a fragile test.
>
> So noreg-hard and some alternative testing which likely involves a manual
> run through Font2DTest to make sure everything seems good.
> I think SQE have some image comparison testing but even if they cover much
> outline font rendering which I doubt, I don't think they run it on the 
> open builds very often
>
> FWIW the test code could have been simpler as in :-
>
>    public static void writeImage(File fontFile, File outputFile, 
> String value) throws Exception {
>         BufferedImage image = new BufferedImage(200, 200, 
> BufferedImage.TYPE_INT_RGB);
>         Graphics2D g = image.createGraphics();
>         g.setColor(Color.WHITE);
>         g.fillRect(0, 0, image.getWidth(), image.getHeight());
>         g.setColor(Color.BLACK);
>
>         Font font = Font.createFont(Font.TRUETYPE_FONT, fontFile);
>         font = font.deriveFont(Font.PLAIN, 72f);
>         FontRenderContext frc = new FontRenderContext(null, false, false);
>         GlyphVector gv = font.createGlyphVector(frc, value);
>         g.drawGlyphVector(gv, 10, 80);
>         g.fill(gv.getOutline(10, 180));
>         ImageIO.write(image, "png", outputFile);
>     }
>
> and then you don't need that G2D subclass.
>
> There should of course be a client-libs/2d bug on this.
> I submitted https://bugs.openjdk.java.net/browse/JDK-8057986
>
> Next thing to do is test the fix on an openjdk build using Font2DTest.
>
>
> -phil.
>
>
> On 9/5/2014 6:57 PM, Martin Buchholz wrote:
>> Hi font friends!
>>
>> I'm trying to share a font rendering bug fix contributed by my 
>> colleagues Behdad and Igor.
>>
>> http://cr.openjdk.java.net/~martin/webrevs/openjdk9/freetypeScaler-outline/ 
>> <http://cr.openjdk.java.net/%7Emartin/webrevs/openjdk9/freetypeScaler-outline/>
>>
>> Repro recipe:
>>
>> (cd test/java/awt/font/GlyphVector/ && javac GlyphVectorOutline.java 
>> && wget -q -O/tmp/msgothic.ttc 
>> https://browserlinux-jp.googlecode.com/files/msgothic.ttc && java 
>> GlyphVectorOutline /tmp/msgothic.ttc /tmp/katakana.png)
>>
>> After successfully running that, examine the two rendered Japanese 
>> characters.
>>
>> Without our fix, the lower one is misrendered.
>>
>> I don't know how the fix works, and whether/how the manual test case 
>> can be turned into a real jtreg test.
>>
>>
>

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