Use mpadded for \raisebox MathML (#876)

* Use mpadded for \raisebox MathML

* Add MathML snapshot

src/buildHTML.js

@@ -1640,7 +1640,7 @@ groupTypes.raisebox = function(group, options) {
         value: [{
             type: "text",
             value: {
-                body: group.value.body,
+                body: group.value.value,
                 font: "mathrm", // simulate \textrm
             },
         }],

src/buildMathML.js

@@ -604,9 +604,13 @@ groupTypes.mclass = function(group, options) {
     return new mathMLTree.MathNode("mstyle", inner);
 };
 
-// Transforms (translation/rotation) don't seem to have a representation
-// in MathML, so just treat them like \text{...}
-groupTypes.raisebox = groupTypes.text;
+groupTypes.raisebox = function(group, options) {
+    const node = new mathMLTree.MathNode(
+        "mpadded", [buildGroup(group.value.body, options)]);
+    const dy = group.value.dy.value.number + group.value.dy.value.unit;
+    node.setAttribute("voffset", dy);
+    return node;
+};
 
 /**
  * Takes a list of nodes, builds them, and returns a list of the generated

src/functions.js

@@ -673,6 +673,7 @@ defineFunction(["\\raisebox"], {
     return {
         type: "raisebox",
         dy: amount,
-        body: ordargument(body),
+        body: body,
+        value: ordargument(body),
     };
 });

test/__snapshots__/mathml-spec.js.snap

@@ -74,6 +74,27 @@ exports[`A MathML builder should make prime operators into <mo> nodes 1`] = `
 
 `;
 
+exports[`A MathML builder should use <mpadded> for raisebox 1`] = `
+
+<math>
+  <semantics>
+    <mrow>
+      <mpadded voffset="0.25em">
+        <mrow>
+          <mtext>
+            b
+          </mtext>
+        </mrow>
+      </mpadded>
+    </mrow>
+    <annotation encoding="application/x-tex">
+      \\raisebox{0.25em}{b}
+    </annotation>
+  </semantics>
+</math>
+
+`;
+
 exports[`A MathML builder should use <msupsub> for regular operators 1`] = `
 
 <math>

test/mathml-spec.js

@@ -50,4 +50,8 @@ describe("A MathML builder", function() {
     it('should use <msupsub> for regular operators', () => {
         expect(getMathML("\\textstyle\\sum_a^b")).toMatchSnapshot();
     });
+
+    it('should use <mpadded> for raisebox', () => {
+        expect(getMathML("\\raisebox{0.25em}{b}")).toMatchSnapshot();
+    });
 });