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List: openjdk-2d-dev
Subject: Re: [OpenJDK 2D-Dev] [PATCH] Make automatic font substitution on macOS work for surrogate pairs
From: Dmitry Batrak <dmitry.batrak () jetbrains ! com>
Date: 2016-10-27 8:56:43
Message-ID: CAET5FPuJcKGY4XHQ_j=CUNyVVDwgbbDF14KoLxPmvAfmz0xMMQ () mail ! gmail ! com
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Sure, here's the simplest test, that can be used for visual inspection:
import javax.swing.*;
import java.awt.*;
public class SurrogatesFallbackTest {
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> {
JFrame frame = new JFrame();
JLabel label = new JLabel(new
String(Character.toChars(0x1d400))); // MATHEMATICAL BOLD CAPITAL A
label.setFont(new Font("Menlo", Font.PLAIN, 36)); // expected
to fallback to STIXGeneral
frame.add(label);
frame.pack();
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
});
}
}
I can convert it to an automatic test (rendering to a bitmap and comparing
the result to rendering of 'missing' glyph), and add it to the webrev, if
that makes sense.
Best regards,
Dmitry Batrak
On Thu, Oct 27, 2016 at 2:17 AM, Philip Race <philip.race@oracle.com> wrote:
> Hi,
>
> I can file a bug on this if I can't find one.
> If you can email me the test it will help even if it is not checked in.
>
> -phil.
>
> On 10/26/16, 6:28 AM, Dmitry Batrak wrote:
>
> Hello,
>
> I'd like to propose a patch to make automatic font substitution on macOS
> work for surrogate pairs.
> I have a Contributor status via agreement signed by JetBrains, hope
> someone can sponsor the patch.
>
> Currently, if requested font cannot render a Unicode character represented
> by a surrogate pair,
> no substitution is performed - Font.canDisplay will return false, and the
> character will be
> rendered as a 'missing' glyph. This behaviour doesn't violate any
> specification, but it looks like
> it can be easily improved, as underlying OS framework used under the hood
> does support surrogate pairs.
>
> The proposed change consists of two parts. First part is adjusting the
> code in CoreTextSupport.m
> to handle surrogate pairs while performing char-to-glyph mapping, by
> encoding non-displayable
> surrogate pairs using negative values of the codepoint, similar to how
> non-displayable BMP characters
> are encoded. Second part is fixing the rendering code (in
> CGGlyphImages.m), where wrong type was used
> to pass character values around, so that code for surrogate pairs
> handling, already present there,
> could work.
>
> I didn't include a test for this change, as it would depend on OS-specific
> font fallback mechanism
> and fonts installed, but I can create one that will work on a latest
> version of macOS with default
> fonts, if needed.
>
> Webrev for the fix is available at
> http://cr.openjdk.java.net/~avu/rfe_surrogates/webrev.00/
> (kindly posted by my colleague, having access to cr.openjdk.java.net).
>
> To my knowledge, there's no ticket in OpenJDK issue tracker for the
> proposed enhancement.
> I can submit it via http://bugs.java.com/, if that's an obstacle.
>
> Best regards,
> Dmitry Batrak
>
>
--
Dmitry Batrak
Senior Software Developer
JetBrains
http://www.jetbrains.com
The Drive to Develop
[Attachment #3 (text/html)]
<div dir="ltr">Sure, here's the simplest test, that can be used for visual \
inspection:<div><br></div><div><div>import javax.swing.*;</div><div>import \
java.awt.*;</div><div><br></div><div>public class SurrogatesFallbackTest {</div><div> \
public static void main(String[] args) {</div><div> \
SwingUtilities.invokeLater(() -> {</div><div> JFrame frame = new \
JFrame();</div><div> JLabel label = new JLabel(new \
String(Character.toChars(0x1d400))); // MATHEMATICAL BOLD CAPITAL A</div><div> \
label.setFont(new Font("Menlo", Font.PLAIN, 36)); // expected to fallback \
to STIXGeneral</div><div> frame.add(label);</div><div> \
frame.pack();</div><div> \
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);</div><div> \
frame.setLocationRelativeTo(null);</div><div> \
frame.setVisible(true);</div><div> });</div><div> \
}</div><div>}</div></div><div><br></div><div>I can convert it to an automatic test \
(rendering to a bitmap and comparing the result to rendering of 'missing' \
glyph), and add it to the webrev, if that makes sense.</div><div><br></div><div>Best \
regards,</div><div>Dmitry Batrak</div></div><div class="gmail_extra"><br><div \
class="gmail_quote">On Thu, Oct 27, 2016 at 2:17 AM, Philip Race <span \
dir="ltr"><<a href="mailto:philip.race@oracle.com" \
target="_blank">philip.race@oracle.com</a>></span> wrote:<br><blockquote \
class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc \
solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
Hi,<br>
<br>
I can file a bug on this if I can't find one.<br>
If you can email me the test it will help even if it is not checked
in.<br>
<br>
-phil.<br>
<br>
On 10/26/16, 6:28 AM, Dmitry Batrak wrote:
<blockquote type="cite">
<div dir="ltr">Hello,<br>
<br>
I'd like to propose a patch to make automatic font substitution
on macOS work for surrogate pairs.<br>
I have a Contributor status via agreement signed by JetBrains,
hope someone can sponsor the patch.<br>
<br>
Currently, if requested font cannot render a Unicode character
represented by a surrogate pair,<br>
no substitution is performed - Font.canDisplay will return
false, and the character will be<br>
rendered as a 'missing' glyph. This behaviour doesn't violate
any specification, but it looks like<br>
it can be easily improved, as underlying OS framework used under
the hood does support surrogate pairs.<br>
<br>
The proposed change consists of two parts. First part is
adjusting the code in CoreTextSupport.m <br>
to handle surrogate pairs while performing char-to-glyph
mapping, by encoding non-displayable <br>
surrogate pairs using negative values of the codepoint, similar
to how non-displayable BMP characters<br>
are encoded. Second part is fixing the rendering code (in
CGGlyphImages.m), where wrong type was used<br>
to pass character values around, so that code for surrogate
pairs handling, already present there, <br>
could work.<br>
<br>
I didn't include a test for this change, as it would depend on
OS-specific font fallback mechanism<br>
and fonts installed, but I can create one that will work on a
latest version of macOS with default<br>
fonts, if needed.<br>
<br>
Webrev for the fix is available at<br>
<a href="http://cr.openjdk.java.net/%7Eavu/rfe_surrogates/webrev.00/" \
target="_blank">http://cr.openjdk.java.net/~<wbr>avu/rfe_surrogates/webrev.00/</a><br>
(kindly posted by my colleague, having access to <a \
href="http://cr.openjdk.java.net" target="_blank">cr.openjdk.java.net</a>).<br> <br>
To my knowledge, there's no ticket in OpenJDK issue tracker for
the proposed enhancement. <br>
I can submit it via <a href="http://bugs.java.com/" \
target="_blank">http://bugs.java.com/</a>, if that's an obstacle.<br>
<br>
Best regards,<br>
Dmitry Batrak</div>
</blockquote>
</div>
</blockquote></div><br><br clear="all"><div><br></div>-- <br><div \
class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div \
dir="ltr">Dmitry Batrak<br>Senior Software Developer<br>JetBrains<br><a \
href="http://www.jetbrains.com" target="_blank">http://www.jetbrains.com</a><br>The \
Drive to Develop<br></div></div></div></div> </div>
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