From ad52fc9642ec24edb2526c58c46d4aa5ab925fb1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fr=C3=A9d=C3=A9ric=20Wang?= <fred.wang@free.fr>
Date: Sun, 27 Dec 2015 08:37:00 -0500
Subject: [PATCH] Bug 1231404 - SubscriptBaselineDropMin or
 SuperscriptBaselineDropMax are not read from the MATH table. r=jfkthame

---
 layout/mathml/nsMathMLmmultiscriptsFrame.cpp  |  21 +++++++++++---
 .../mathml/tests/test_opentype-scripts.html   |  26 +++++++++++++++++-
 layout/reftests/fonts/math/generate.py        |   5 ++++
 layout/reftests/fonts/math/mochitest.ini      |   1 +
 layout/reftests/fonts/math/scripts-9.otf      | Bin 0 -> 1864 bytes
 5 files changed, 48 insertions(+), 5 deletions(-)
 create mode 100644 layout/reftests/fonts/math/scripts-9.otf

diff --git a/layout/mathml/nsMathMLmmultiscriptsFrame.cpp b/layout/mathml/nsMathMLmmultiscriptsFrame.cpp
index e0c8700d835b..c1d9957a3c94 100644
--- a/layout/mathml/nsMathMLmmultiscriptsFrame.cpp
+++ b/layout/mathml/nsMathMLmmultiscriptsFrame.cpp
@@ -203,6 +203,14 @@ nsMathMLmmultiscriptsFrame::PlaceMultiScript(nsPresContext*  aPresContext,
     scriptSpace = nsPresContext::CSSPointsToAppUnits(0.5f);
   }
 
+  // Try and read sub and sup drops from the MATH table.
+  if (mathFont) {
+    subDrop = mathFont->
+      GetMathConstant(gfxFontEntry::SubscriptBaselineDropMin, oneDevPixel);
+    supDrop = mathFont->
+      GetMathConstant(gfxFontEntry::SuperscriptBaselineDropMax, oneDevPixel);
+  }
+
   // force the scriptSpace to be at least 1 pixel
   nscoord onePixel = nsPresContext::CSSPixelsToAppUnits(1);
   scriptSpace = std::max(onePixel, scriptSpace);
@@ -390,8 +398,11 @@ nsMathMLmmultiscriptsFrame::PlaceMultiScript(nsPresContext*  aPresContext,
         // subscript
         subScriptFrame = childFrame;
         GetReflowAndBoundingMetricsFor(subScriptFrame, subScriptSize, bmSubScript);
-        // get the subdrop from the subscript font
-        GetSubDropFromChild (subScriptFrame, subDrop, aFontSizeInflation);
+        if (!mathFont) {
+          // get the subdrop from the subscript font
+          GetSubDropFromChild (subScriptFrame, subDrop, aFontSizeInflation);
+        }
+
         // parameter v, Rule 18a, App. G, TeXbook
         minSubScriptShift = bmBase.descent + subDrop;
         trySubScriptShift = std::max(minSubScriptShift,subScriptShift);
@@ -431,8 +442,10 @@ nsMathMLmmultiscriptsFrame::PlaceMultiScript(nsPresContext*  aPresContext,
         // supscript
         supScriptFrame = childFrame;
         GetReflowAndBoundingMetricsFor(supScriptFrame, supScriptSize, bmSupScript);
-        // get the supdrop from the supscript font
-        GetSupDropFromChild (supScriptFrame, supDrop, aFontSizeInflation);
+        if (!mathFont) {
+          // get the supdrop from the supscript font
+          GetSupDropFromChild (supScriptFrame, supDrop, aFontSizeInflation);
+        }
         // parameter u, Rule 18a, App. G, TeXbook
         minSupScriptShift = bmBase.ascent - supDrop;
         nscoord superscriptBottomMin;
diff --git a/layout/mathml/tests/test_opentype-scripts.html b/layout/mathml/tests/test_opentype-scripts.html
index 584d3f1e7d21..7ad0e90ab03e 100644
--- a/layout/mathml/tests/test_opentype-scripts.html
+++ b/layout/mathml/tests/test_opentype-scripts.html
@@ -9,7 +9,7 @@
     <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
     <meta charset="utf-8"/>
     <style type="text/css">
-      math {
+      math, mspace {
         font-size: 10px;
       }
       @font-face {
@@ -44,6 +44,10 @@
         font-family: scripts-8;
         src: url(/tests/fonts/math/scripts-8.otf);
       }
+      @font-face {
+        font-family: scripts-9;
+        src: url(/tests/fonts/math/scripts-9.otf);
+      }
     </style>
     <script type="text/javascript">
       SimpleTest.waitForExplicitFinish();
@@ -107,6 +111,14 @@
         ok(almostEqual(getBox("ref10").bottom - getBox("sup10").bottom, 9 * 10),
            "Bad SuperscriptBottomMin");
 
+        ok(almostEqual(getBox("base11").bottom + 3 * 10,
+                       getBox("sub11").top),
+           "Bad SubscriptBaselineDrop");
+
+        ok(almostEqual(getBox("base11").top + 5 * 10,
+                       getBox("sup11").bottom),
+           "Bad SuperscriptBaselineDrop");
+
         SimpleTest.finish();
       }
     </script>
@@ -264,5 +276,17 @@
       </math>
     </p>
 
+    <p>
+      <math style="font-family: scripts-9;">
+        <msubsup>
+          <mspace id="base11" height="10em" depth="10em"
+                  width="1em" mathbackground="red"/>
+          <mspace id="sub11"
+                  height="0em" depth="1em" width="1em" mathbackground="green"/>
+          <mspace id="sup11"
+                  height="1em" depth="0em" width="1em" mathbackground="blue"/>
+        </msubsup>
+      </math>
+    </p>
   </body>
 </html>
diff --git a/layout/reftests/fonts/math/generate.py b/layout/reftests/fonts/math/generate.py
index 59d2a9cb4876..b42cd3e227c5 100644
--- a/layout/reftests/fonts/math/generate.py
+++ b/layout/reftests/fonts/math/generate.py
@@ -479,6 +479,11 @@ f = newMathFont("scripts-8")
 f.math.SuperscriptBottomMin = 9 * em
 saveMathFont(f)
 
+f = newMathFont("scripts-9")
+f.math.SubscriptBaselineDropMin = 3 * em
+f.math.SuperscriptBaselineDropMax = 5 * em
+saveMathFont(f)
+
 ################################################################################
 # Testing Limits Parameters
 f = newMathFont("limits-1")
diff --git a/layout/reftests/fonts/math/mochitest.ini b/layout/reftests/fonts/math/mochitest.ini
index 0aad9823750e..ff6ebcc04ceb 100644
--- a/layout/reftests/fonts/math/mochitest.ini
+++ b/layout/reftests/fonts/math/mochitest.ini
@@ -31,6 +31,7 @@ support-files =
   /tests/fonts/math/scripts-6.otf
   /tests/fonts/math/scripts-7.otf
   /tests/fonts/math/scripts-8.otf
+  /tests/fonts/math/scripts-9.otf
   /tests/fonts/math/stack-1.otf
   /tests/fonts/math/stack-2.otf
   /tests/fonts/math/stack-3.otf
diff --git a/layout/reftests/fonts/math/scripts-9.otf b/layout/reftests/fonts/math/scripts-9.otf
new file mode 100644
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