Add support for \{,d,t}binom
Test Plan: `\binom xy^{\binom xy^{\binom xy}}` looks like something. `\dbinom` and `\tbinom` also seem to work.
Reviewers: emily
Reviewed By: emily
Subscribers: jessie
Differential Revision: http://phabricator.khanacademy.org/D13315
This commit is contained in:
Ben Alpert
parent
10e9b4ec12
commit
006a0a761c
138
src/buildTree.js
138
src/buildTree.js
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@ -364,14 +364,14 @@ var groupTypes = {
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[base, supsub]);
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},
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frac: function(group, options, prev) {
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genfrac: function(group, options, prev) {
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// Fractions are handled in the TeXbook on pages 444-445, rules 15(a-e).
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// Figure out what style this fraction should be in based on the
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// function used
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var fstyle = options.style;
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if (group.value.size === "dfrac") {
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if (group.value.size === "display") {
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fstyle = Style.DISPLAY;
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} else if (group.value.size === "tfrac") {
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} else if (group.value.size === "text") {
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fstyle = Style.TEXT;
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}
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@ -384,60 +384,118 @@ var groupTypes = {
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var denom = buildGroup(group.value.denom, options.withStyle(dstyle));
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var denomreset = makeSpan([fstyle.reset(), dstyle.cls()], [denom]);
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var ruleWidth = fontMetrics.metrics.defaultRuleThickness /
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options.style.sizeMultiplier;
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var ruleWidth;
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if (group.value.hasBarLine) {
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ruleWidth = fontMetrics.metrics.defaultRuleThickness /
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options.style.sizeMultiplier;
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} else {
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ruleWidth = 0;
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}
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var mid = makeSpan(
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[options.style.reset(), Style.TEXT.cls(), "frac-line"]);
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// Manually set the height of the line because its height is created in
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// CSS
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mid.height = ruleWidth;
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// Rule 15b, 15d
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var numShift, denomShift, clearance;
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// Rule 15b
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var numShift;
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var clearance;
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var denomShift;
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if (fstyle.size === Style.DISPLAY.size) {
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numShift = fontMetrics.metrics.num1;
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if (ruleWidth > 0) {
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clearance = 3 * ruleWidth;
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} else {
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clearance = 7 * fontMetrics.metrics.defaultRuleThickness;
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}
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denomShift = fontMetrics.metrics.denom1;
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clearance = 3 * ruleWidth;
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} else {
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numShift = fontMetrics.metrics.num2;
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if (ruleWidth > 0) {
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numShift = fontMetrics.metrics.num2;
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clearance = ruleWidth;
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} else {
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numShift = fontMetrics.metrics.num3;
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clearance = 3 * fontMetrics.metrics.defaultRuleThickness;
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}
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denomShift = fontMetrics.metrics.denom2;
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clearance = ruleWidth;
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}
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var axisHeight = fontMetrics.metrics.axisHeight;
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var frac;
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if (ruleWidth === 0) {
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// Rule 15c
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var candiateClearance =
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(numShift - numer.depth) - (denom.height - denomShift);
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if (candiateClearance < clearance) {
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numShift += 0.5 * (clearance - candiateClearance);
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denomShift += 0.5 * (clearance - candiateClearance);
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}
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// Rule 15d
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if ((numShift - numer.depth) - (axisHeight + 0.5 * ruleWidth)
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< clearance) {
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numShift +=
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clearance - ((numShift - numer.depth) -
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(axisHeight + 0.5 * ruleWidth));
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frac = buildCommon.makeVList([
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{type: "elem", elem: denomreset, shift: denomShift},
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{type: "elem", elem: numerreset, shift: -numShift}
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], "individualShift", null, options);
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} else {
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// Rule 15d
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var axisHeight = fontMetrics.metrics.axisHeight;
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if ((numShift - numer.depth) - (axisHeight + 0.5 * ruleWidth)
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< clearance) {
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numShift +=
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clearance - ((numShift - numer.depth) -
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(axisHeight + 0.5 * ruleWidth));
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}
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if ((axisHeight - 0.5 * ruleWidth) - (denom.height - denomShift)
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< clearance) {
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denomShift +=
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clearance - ((axisHeight - 0.5 * ruleWidth) -
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(denom.height - denomShift));
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}
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var mid = makeSpan(
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[options.style.reset(), Style.TEXT.cls(), "frac-line"]);
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// Manually set the height of the line because its height is
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// created in CSS
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mid.height = ruleWidth;
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var midShift = -(axisHeight - 0.5 * ruleWidth);
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frac = buildCommon.makeVList([
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{type: "elem", elem: denomreset, shift: denomShift},
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{type: "elem", elem: mid, shift: midShift},
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{type: "elem", elem: numerreset, shift: -numShift}
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], "individualShift", null, options);
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}
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if ((axisHeight - 0.5 * ruleWidth) - (denom.height - denomShift)
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< clearance) {
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denomShift +=
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clearance - ((axisHeight - 0.5 * ruleWidth) -
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(denom.height - denomShift));
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}
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var midShift = -(axisHeight - 0.5 * ruleWidth);
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var frac = buildCommon.makeVList([
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{type: "elem", elem: denomreset, shift: denomShift},
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{type: "elem", elem: mid, shift: midShift},
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{type: "elem", elem: numerreset, shift: -numShift}
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], "individualShift", null, options);
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// Since we manually change the style sometimes (with \dfrac or \tfrac),
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// account for the possible size change here.
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frac.height *= fstyle.sizeMultiplier / options.style.sizeMultiplier;
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frac.depth *= fstyle.sizeMultiplier / options.style.sizeMultiplier;
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// Rule 15e
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var innerChildren = [makeSpan(["mfrac"], [frac])];
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var delimSize;
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if (fstyle.size === Style.DISPLAY.size) {
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delimSize = fontMetrics.metrics.delim1;
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} else {
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delimSize = fontMetrics.metrics.getDelim2(fstyle);
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}
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if (group.value.leftDelim != null) {
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innerChildren.unshift(
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delimiter.customSizedDelim(
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group.value.leftDelim, delimSize, true,
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options.withStyle(fstyle), group.mode)
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);
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}
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if (group.value.rightDelim != null) {
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innerChildren.push(
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delimiter.customSizedDelim(
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group.value.rightDelim, delimSize, true,
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options.withStyle(fstyle), group.mode)
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);
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}
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return makeSpan(
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["minner", "mfrac", options.style.reset(), fstyle.cls()],
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[frac], options.getColor());
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["minner", options.style.reset(), fstyle.cls()],
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innerChildren,
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options.getColor());
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},
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spacing: function(group, options, prev) {
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@ -1,5 +1,7 @@
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/* jshint unused:false */
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var Style = require("./Style");
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/**
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* This file contains metrics regarding fonts and individual symbols. The sigma
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* and xi variables, as well as the metricMap map contain data extracted from
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@ -35,7 +37,9 @@ var sigma17 = 0.247;
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var sigma18 = 0.386;
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var sigma19 = 0.050;
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var sigma20 = 2.390;
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var sigma21 = 0.101;
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var sigma21 = 1.01;
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var sigma21Script = 0.81;
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var sigma21ScriptScript = 0.71;
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var sigma22 = 0.250;
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// These font metrics are extracted from TeX by using
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@ -81,8 +85,6 @@ var metrics = {
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sub2: sigma17,
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supDrop: sigma18,
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subDrop: sigma19,
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delim1: sigma20,
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delim2: sigma21,
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axisHeight: sigma22,
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defaultRuleThickness: xi8,
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bigOpSpacing1: xi9,
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@ -90,7 +92,21 @@ var metrics = {
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bigOpSpacing3: xi11,
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bigOpSpacing4: xi12,
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bigOpSpacing5: xi13,
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ptPerEm: ptPerEm
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ptPerEm: ptPerEm,
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// TODO(alpert): Missing parallel structure here. We should probably add
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// style-specific metrics for all of these.
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delim1: sigma20,
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getDelim2: function(style) {
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if (style.size === Style.TEXT.size) {
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return sigma21;
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} else if (style.size === Style.SCRIPT.size) {
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return sigma21Script;
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} else if (style.size === Style.SCRIPTSCRIPT.size) {
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return sigma21ScriptScript;
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}
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throw new Error("Unexpected style size: " + style.size);
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}
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};
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// This map contains a mapping from font name and character code to character
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@ -329,16 +329,55 @@ var duplicatedFunctions = [
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// Fractions
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{
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funcs: ["\\dfrac", "\\frac", "\\tfrac"],
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funcs: [
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"\\dfrac", "\\frac", "\\tfrac",
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"\\dbinom", "\\binom", "\\tbinom"
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],
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data: {
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numArgs: 2,
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greediness: 2,
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handler: function(func, numer, denom) {
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var hasBarLine;
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var leftDelim = null;
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var rightDelim = null;
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var size = "auto";
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switch (func) {
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case "\\dfrac":
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case "\\frac":
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case "\\tfrac":
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hasBarLine = true;
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break;
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case "\\dbinom":
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case "\\binom":
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case "\\tbinom":
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hasBarLine = false;
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leftDelim = "(";
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rightDelim = ")";
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break;
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default:
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throw new Error("Unrecognized genfrac command");
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}
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switch (func) {
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case "\\dfrac":
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case "\\dbinom":
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size = "display";
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break;
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case "\\tfrac":
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case "\\tbinom":
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size = "text";
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break;
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}
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return {
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type: "frac",
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type: "genfrac",
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numer: numer,
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denom: denom,
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size: func.slice(1)
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hasBarLine: hasBarLine,
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leftDelim: leftDelim,
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rightDelim: rightDelim,
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size: size
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};
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}
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}
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@ -11,6 +11,12 @@
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"url": "http://localhost:7936/test/huxley/test.html?m=\\dfrac{a}{b}\\frac{a}{b}\\tfrac{a}{b}"
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},
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{
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"name": "BinomTest",
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"screenSize": [1024, 768],
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"url": "http://localhost:7936/test/huxley/test.html?m=\\dbinom{a}{b}\\tbinom{a}{b}^{\\binom{a}{b}+17}"
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},
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{
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"name": "NestedFractions",
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"screenSize": [1024, 768],
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BIN
test/huxley/Huxleyfolder/BinomTest.hux/firefox-1.png
Normal file
BIN
test/huxley/Huxleyfolder/BinomTest.hux/firefox-1.png
Normal file
Binary file not shown.
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After Width: | Height: | Size: 24 KiB |
5
test/huxley/Huxleyfolder/BinomTest.record.json
Normal file
5
test/huxley/Huxleyfolder/BinomTest.record.json
Normal file
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@ -0,0 +1,5 @@
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[
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{
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"action": "screenshot"
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}
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]
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