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

[Phil Race]

On 9/10/2014 2:31 PM, Martin Buchholz wrote:
> I have tried to cross all the t's left here.  I took your suggestion 
> and minimized the test greatly.  I've taken ownership of the bug and 
> it's now marked noreg-hard.
>
> I'm inclined to check in the test case as is, even though it's manual. 
>  But I leave that to you, the 2d maintainers.
>
> The only testing I've done is to run the one manual test.  Hope that's OK.
>
> OK to commit this fix?

Do we yet have a 2nd reviewer on the change ?
Other than that its fine by me.

-phil.

>
> On Tue, Sep 9, 2014 at 2:47 PM, Phil Race <philip.race at oracle.com 
> <mailto:philip.race at oracle.com>> 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.
>>
>>
>
>