Created attachment 728897 [details] testcase Using stretchy equal sign is used to implement the AMScd extension by LaTeXML and MathJax. I attach a testcase produced by MathJax. The idea would be to add a direction:horizontal to the equal sign here: http://mxr.mozilla.org/mozilla-central/source/layout/mathml/mathfont.properties#114 and to add a construction for the equal sign (for example by repeating U+2550 BOX DRAWINGS DOUBLE HORIZONTAL, which is in STIX fonts) in the Unicode table: http://mxr.mozilla.org/mozilla-central/source/layout/mathml/mathfontUnicode.properties Here is a minimal testcase <math> <mn>2</mn> <munder> <mi>BASE</mi> <mo stretchy="true">=</mo> </munder> </math> The "2" is to workaround bug 687807. Someone willing to work on this could also have a look at bug 687807 comment 4. Then I guess that should be enough to make the attached testcase render correctly.

I have read the above description, and I am interested in working on it.

(In reply to rushikesh from comment #1) > I have read the above description, and I am interested in working on it. Thanks, I guess you already read https://developer.mozilla.org/en-US/docs/Introduction but if you need more information, do not hesitate to ask. Regarding the syntax to use for mathfontUnicode see http://mxr.mozilla.org/mozilla-central/source/layout/mathml/mathfont.properties#1211 Here, I think you could just do as for the double vertical line: http://mxr.mozilla.org/mozilla-central/source/layout/mathml/mathfontUnicode.properties#27 that is only use U+2550 for both the "glue" and "size0" character.

And of course, you'll also need https://developer.mozilla.org/en-US/docs/Mozilla_MathML_Project/Fonts

(In reply to Frédéric Wang (:fredw) from comment #0) > The "2" is to workaround bug 687807. Someone willing to work on this could > also have a look at bug 687807 comment 4. Then I guess that should be enough > to make the attached testcase render correctly. I've uploaded a patch on bug 687807. With that new patch, a minimal test case for the present bug becomes: <math> <munder> <mi>BASE</mi> <mo stretchy="true">=</mo> </munder> </math>

Hi, I am still working ..I will need if any help is required

Rushikesh, could you confirm that you're still working on this?

Yes..but I am still finding it hard to get to the root of problem.. can you give me some hint?

Really the most difficult part is to understand the whole process to compile, create a patch, submit it etc: https://developer.mozilla.org/en-US/docs/Introduction You will probably find someone on IRC #introduction to help you. Have you been able to build the source? I also recommend to install the math fonts: https://developer.mozilla.org/en-US/docs/Mozilla_MathML_Project/Fonts/Test Then regarding the bug itself, consider <math> <munder> <mi>AVERYLONGBASE</mi> <mo stretchy="true">↔</mo> </munder> </math> you should see that the arrow stretches to cover AVERYLONGBASE. The construction is described at this line: http://mxr.mozilla.org/mozilla-central/source/layout/mathml/mathfontUnicode.properties#33 \u2194 = \u2190\uFFFD\u2192\u23AF\u2194\u27F7 where each \u**** is a Unicode code point that can be understood that way (from left to right): 1) \u2194: the character we want to stretch, "LEFT RIGHT ARROW U+2194" 2) The construction is described by various characters that we will put together to form the stretchy arrow: \u2190: the left piece "LEFTWARDS ARROW U+2190" \uFFFD: the middle piece. The character "REPLACEMENT CHARACTER U+FFFD" means that we don't actually use a middle piece (as opposed to e.g. horizontal braces) \u2192: the right piece "RIGHTWARDS ARROW U+2192" \u23AF: the glue "HORIZONTAL LINE EXTENSION U+23AF" that is we repeat several horizontal line characters between the left and right pieces. 3) Alternatively, for small sizes we can use a single character: \u2194: the smallest size "LEFT RIGHT ARROW U+2194" \u27F7: a larger size "LONG LEFT RIGHT ARROW U+27F7" Now, try instead with <math> <munder> <mi>AVERYLONGBASE</mi> <mo stretchy="true">=</mo> </munder> </math> At the moment, the equal sign does not stretch and this is the bug we want to fix. You need to modify http://mxr.mozilla.org/mozilla-central/source/layout/mathml/mathfontUnicode.properties to add a construction for the equal sign. Since its code point is EQUALS SIGN U+003D, that would be a new line \003D = ... I suggest considering U+2550 BOX DRAWINGS DOUBLE HORIZONTAL ═ for the pieces. Hope that helps.

Rushikesh, have you been able to build the source code since the last time? Have you tried asking help on #introduction?

Created attachment 756457 [details] [diff] [review] Patch https://tbpl.mozilla.org/?tree=Try&rev=89f9371c0b90 The test case from AMScd does not work because of other missing features / bugs with our stretchy support.

Comment on attachment 756457 [details] [diff] [review] Patch >+\u003D = \uFFFD\uFFFD\uFFFD\u2550\u003D # = equal sign Could we use U+003D EQUALS SIGN instead of U+2550 BOX DRAWINGS DOUBLE HORIZONTAL for the repeated glyph here? That should stretch fine I expect? And it would be more consistent with the unstretched glyph.

Created attachment 757813 [details] [diff] [review] Patch V2 Yes, that seems to work too.

https://hg.mozilla.org/integration/mozilla-inbound/rev/6a7dd82b2762

https://hg.mozilla.org/mozilla-central/rev/6a7dd82b2762

A note has been added to: https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/24#MathML