use RTL to shift \llap content and fix \llap, \rlap extreme wrapping

brucemiller · Jan 3, 2025 · 9704dbf · 9704dbf
1 parent f82b733
commit 9704dbf
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Showing 5 changed files with 21 additions and 8 deletions.
diff --git a/lib/LaTeXML/Engine/plain.pool.ltxml b/lib/LaTeXML/Engine/plain.pool.ltxml
@@ -536,9 +536,10 @@ DefConstructor('\ltx@centerline{}', sub {
   alias   => '\centerline',
   bounded => 1);
 
-# These should be 0 width, but perhaps also shifted?
-DefMacro('\llap{}', '\hbox to 0pt{\hss#1}');
-DefMacro('\rlap{}', '\hbox to 0pt{#1\hss}');
+# rely on RTL trickery to shift the \llap content over the previous text (see CSS)
+# the zero-width space prevents merging the two boxes in a single ltx:text
+DefMacro('\llap{}', '\hbox to 0pt{\@ADDCLASS{ltx_llap}' . "\x{200B}" . '\hbox{\@ADDCLASS{ltx_llap_content}#1}}');
+DefMacro('\rlap{}', '\hbox to 0pt{\@ADDCLASS{ltx_rlap}#1}');
 
 DefMacroI('\m@th', undef, '\mathsurround=0pt ');
 

diff --git a/lib/LaTeXML/resources/CSS/LaTeXML.css b/lib/LaTeXML/resources/CSS/LaTeXML.css
@@ -510,3 +510,15 @@ cite                 { font-style: normal; }
 
 .ltx_overlay {position:relative; }
 .ltx_overlay > span:nth-child(2) {position:absolute; left:0; }
+
+/* \llap, \rlap */
+.ltx_llap, .ltx_rlap {
+  white-space: nowrap; /* width 0pt causes extreme wrapping otherwise */ }
+
+/* shift \llap over the previous text by shifting text direction */
+.ltx_llap {
+  direction: rtl; }
+
+/* restore LTR inside \llap */
+.ltx_llap_content {
+  direction: ltr; }
diff --git a/t/alignment/halignatt.xml b/t/alignment/halignatt.xml
@@ -50,7 +50,7 @@
         <td border="l t" class="ltx_nopad_l ltx_nopad_r"/>
         <td align="right" border="r t">6</td>
         <td align="center" border="r t">51–59</td>
-        <td align="right" border="r t">.95<text width="0.0pt">*</text></td>
+        <td align="right" border="r t">.95<text class="ltx_rlap" width="0.0pt">*</text></td>
       </tr>
       <tr>
         <td align="left" border="t" class="ltx_nopad_l ltx_nopad_r" colspan="4">* (first quarter only)</td>

diff --git a/t/ams/mathtools.xml b/t/ams/mathtools.xml
@@ -7120,7 +7120,7 @@ Then a switch of tag forms.</p>
     <title><tag close=" ">11</tag>Stepped lines</title>
     <para xml:id="S11.p1">
       <equation xml:id="S11.Ex81">
-        <Math class="ltx_math_unparsed" mode="display" tex="\begin{gathered}x=1,\quad x+1=2\\&#10;y=2\end{gathered}" text="[1∗  ]@x@=@1@,@quad@x@+@1@=@2@[ over]@[2∗  ]@y@=@2@[ over]" xml:id="S11.Ex81.m1">
+        <Math class="ltx_math_unparsed" mode="display" tex="\begin{gathered}x=1,\quad x+1=2\\&#10;y=2\end{gathered}" text="[1∗  ]@x@=@1@,@quad@x@+@1@=@2@[ over]@[2∗  ]@y@=@2@[ over]" xml:id="S11.Ex81.m1">
           <XMath>
             <XMDual>
               <XMWrap rule="Anything,">
@@ -7150,7 +7150,7 @@ Then a switch of tag forms.</p>
                         <XMTok meaning="equals" role="RELOP" xml:id="S11.Ex81.m1.3">=</XMTok>
                         <XMApp>
                           <XMTok meaning="times" role="MULOP">⁢</XMTok>
-                          <XMText xml:id="S11.Ex81.m1.1"><text width="0.0pt">1</text><Math mode="inline" tex="*" text="*" xml:id="S11.Ex81.m1.m1">
+                          <XMText xml:id="S11.Ex81.m1.1"><text class="ltx_llap" width="0.0pt"><text class="ltx_llap_content">1</text></text><Math mode="inline" tex="*" text="*" xml:id="S11.Ex81.m1.m1">
                               <XMath>
                                 <XMTok meaning="times" role="MULOP">∗</XMTok>
                               </XMath>
@@ -7182,7 +7182,7 @@ Then a switch of tag forms.</p>
                       <XMTok meaning="equals" role="RELOP" xml:id="S11.Ex81.m1.14">=</XMTok>
                       <XMApp>
                         <XMTok meaning="times" role="MULOP">⁢</XMTok>
-                        <XMText xml:id="S11.Ex81.m1.12"><text width="0.0pt">2</text><Math mode="inline" tex="*" text="*" xml:id="S11.Ex81.m1.m2">
+                        <XMText xml:id="S11.Ex81.m1.12"><text class="ltx_llap" width="0.0pt"><text class="ltx_llap_content">2</text></text><Math mode="inline" tex="*" text="*" xml:id="S11.Ex81.m1.m2">
                             <XMath>
                               <XMTok meaning="times" role="MULOP">∗</XMTok>
                             </XMath>

diff --git a/t/structure/plainsample.xml b/t/structure/plainsample.xml
@@ -80,7 +80,7 @@ finish the remaining cases.</p>
                       <XMTok role="CLOSE" stretchy="false">)</XMTok>
                     </XMWrap>
                   </XMDual>
-                  <XMText width="0.0pt">Draft</XMText>
+                  <XMText class="ltx_rlap" width="0.0pt">Draft</XMText>
                 </XMApp>
               </XMath>
             </Math></tag>