[cairo] Solid stroke of lines with thickness less than 1 pixel broken…

… after r191658 https://bugs.webkit.org/show_bug.cgi?id=151947 Reviewed by Martin Robinson. Source/WebCore: Test: mathml/presentation/radical-bar-visibility.html * platform/graphics/cairo/GraphicsContextCairo.cpp: (WebCore::GraphicsContext::drawLine): Force a minimal thickness of 1px LayoutTests: Add a test to check that the radical overbar appears on the screen when it has thickness less than 1px. * mathml/presentation/radical-bar-visibility-expected-mismatch.html: Added. * mathml/presentation/radical-bar-visibility.html: Added. Canonical link: https://commits.webkit.org/170130@main git-svn-id: https://svn.webkit.org/repository/webkit/trunk@193743 268f45cc-cd09-0410-ab3c-d52691b4dbfc
WebKit · Dec 8, 2015 · 0572f6c269dd5f1153254babaf9289e2fa4a4b20 · 0572f6c
1 parent a12785e
commit 0572f6c269dd5f1153254babaf9289e2fa4a4b20
diff --git a/LayoutTests/ChangeLog b/LayoutTests/ChangeLog
@@ -1,3 +1,15 @@
+2015-12-08  Frederic Wang  <fred.wang@free.fr>
+
+        [cairo] Solid stroke of lines with thickness less than 1 pixel broken after r191658
+        https://bugs.webkit.org/show_bug.cgi?id=151947
+
+        Reviewed by Martin Robinson.
+
+        Add a test to check that the radical overbar appears on the screen when it has thickness less than 1px.
+
+        * mathml/presentation/radical-bar-visibility-expected-mismatch.html: Added.
+        * mathml/presentation/radical-bar-visibility.html: Added.
+
 2015-12-07  Brady Eidson  <beidson@apple.com>
 
         Move an IDB test from the "generic failure" section to the "fails because no workers" section.

diff --git a/LayoutTests/mathml/presentation/radical-bar-visibility-expected-mismatch.html b/LayoutTests/mathml/presentation/radical-bar-visibility-expected-mismatch.html
@@ -0,0 +1,17 @@
+<!doctype html>
+<html>
+  <head>
+    <title>Radical bar visibility</title>
+    <meta charset="utf-8"/>
+  </head>
+  <body>
+
+    <p>This test passes if you see the radical bar.</p>
+
+    <div>
+      <!-- blue square to hide the radical symbol -->
+      <div style="position: absolute; background: blue; width: 100px; height: 100px;"></div>
+    </div>
+
+  </body>
+</html>
diff --git a/LayoutTests/mathml/presentation/radical-bar-visibility.html b/LayoutTests/mathml/presentation/radical-bar-visibility.html
@@ -0,0 +1,34 @@
+<!doctype html>
+<html>
+  <head>
+    <title>Radical bar visibility</title>
+    <meta charset="utf-8"/>
+    <style>
+      math, msqrt {
+        /* Latin Modern Math has
+           RadicalRuleThickess = 40
+           em = 1000
+           So the actual rule thickness is 24 * 40 / 1000 = 0.96 < 1 pixel */
+        font-family: Latin Modern Math;
+        font-size: 24px;
+      }
+    </style>
+  </head>
+  <body>
+
+    <p>This test passes if you see the radical bar.</p>
+
+    <div>
+      <div style="position: absolute">
+        <math>
+          <msqrt>
+            <mspace width="500px"/>
+          </msqrt>
+        </math>
+      </div>
+      <!-- blue square to hide the radical symbol -->
+      <div style="position: absolute; background: blue; width: 100px; height: 100px;"></div>
+    </div>
+
+  </body>
+</html>
diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
@@ -1,3 +1,15 @@
+2015-12-08  Frederic Wang  <fred.wang@free.fr>
+
+        [cairo] Solid stroke of lines with thickness less than 1 pixel broken after r191658
+        https://bugs.webkit.org/show_bug.cgi?id=151947
+
+        Reviewed by Martin Robinson.
+
+        Test: mathml/presentation/radical-bar-visibility.html
+
+        * platform/graphics/cairo/GraphicsContextCairo.cpp:
+        (WebCore::GraphicsContext::drawLine): Force a minimal thickness of 1px
+
 2015-12-08  Gwang Yoon Hwang  <yoon@igalia.com>
 
         [ThreadedCompositor] Support WebGL for OpenGL.

diff --git a/Source/WebCore/platform/graphics/cairo/GraphicsContextCairo.cpp b/Source/WebCore/platform/graphics/cairo/GraphicsContextCairo.cpp
@@ -311,8 +311,12 @@ void GraphicsContext::drawLine(const FloatPoint& point1, const FloatPoint& point
         }
         const double dashedLine[2] = { static_cast<double>(patternWidth), static_cast<double>(patternWidth) };
         cairo_set_dash(cairoContext, dashedLine, 2, patternOffset);
-    } else
+    } else {
         setSourceRGBAFromColor(cairoContext, strokeColor);
+        if (thickness < 1)
+            cairo_set_line_width(cairoContext, 1);
+    }
+
 
     FloatPoint p1 = point1;
     FloatPoint p2 = point2;