Make alpha optional when parsing a Color from an input stream

Changelog.md

@@ -2,6 +2,9 @@
 
 ## Ignition Math 6.x.x
 
+1. Make alpha optional when parsing a Color from an input stream.
+    * [Pull request 106](https://github.com/ignitionrobotics/ign-math/pull/106)
+
 1. Added a Gauss-Markov Process class.
     * [BitBucket pull request 342](https://osrf-migration.github.io/ignition-gh-pages/#!/ignitionrobotics/ign-math/pull-requests/342)
 

include/ignition/math/Color.hh

@@ -247,13 +247,27 @@ namespace ignition
       }
 
       /// \brief Stream insertion operator
-      /// \param[in] _in the input stream
+      /// \param[in] _in the input stream. If the input stream does not include
+      /// an alpha value, a default alpha value of 1.0 will be used.
       /// \param[in] _pt
       public: friend std::istream &operator>> (std::istream &_in, Color &_pt)
       {
         // Skip white spaces
         _in.setf(std::ios_base::skipws);
-        _in >> _pt.r >> _pt.g >> _pt.b >> _pt.a;
+        _in >> _pt.r >> _pt.g >> _pt.b;
+        // Since alpha is optional, check if it's there before parsing
+        while (!_in.eof() && std::isspace(_in.peek()))
+        {
+          _in.get();
+        }
+        if (!_in.eof())
+        {
+          _in >> _pt.a;
+        }
+        else
+        {
+          _pt.a = 1.0;
+        }
         return _in;
       }
 

src/Color_TEST.cc

@@ -336,6 +336,44 @@ TEST(Color, OperatorStreamOut)
   EXPECT_EQ(stream.str(), "0.1 0.2 0.3 0.5");
 }
 
+/////////////////////////////////////////////////
+TEST(Color, OperatorStreamIn)
+{
+  math::Color c(0.1f, 0.2f, 0.3f, 0.5f);
+  math::Color test;
+  std::stringstream ss("0.1 0.2 0.3 0.5");
+  ss >> test;
+  EXPECT_EQ(c, test);
+}
+
+/////////////////////////////////////////////////
+TEST(Color, OperatorStreamInWithoutAlpha)
+{
+  math::Color c(0.1f, 0.2f, 0.3f, 1.0f);
+  {
+    math::Color test;
+    std::stringstream ss("0.1 0.2 0.3");
+    ss.exceptions(std::stringstream::failbit);
+    EXPECT_NO_THROW(ss >> test);
+    EXPECT_EQ(c, test);
+  }
+  {
+    math::Color test;
+    std::stringstream ss("0.1  0.2 \t0.3   \t");
+    ss.exceptions(std::stringstream::failbit);
+    EXPECT_NO_THROW(ss >> test);
+    EXPECT_EQ(c, test);
+  }
+
+  {
+    math::Color test(0.5f, 0.6f, 0.7f, 0.8f);
+    std::stringstream ss("0.1  0.2 \t0.3   \t");
+    ss.exceptions(std::stringstream::failbit);
+    EXPECT_NO_THROW(ss >> test);
+    EXPECT_EQ(c, test);
+  }
+}
+
 /////////////////////////////////////////////////
 TEST(Color, HSV)
 {