Math: print 8-bit colors as hex in Debug.

So #ffffff00 instead of Vector(255, 255, 255, 0). Much shorter with the
same information value.

src/Magnum/CMakeLists.txt

@@ -229,6 +229,7 @@ endif()
 
 # Files shared between main library and math unit test library
 set(MagnumMath_SRCS
+    Math/Color.cpp
     Math/Functions.cpp
     Math/instantiation.cpp)
 

src/Magnum/Math/Color.cpp

@@ -0,0 +1,58 @@
+/*
+    This file is part of Magnum.
+
+    Copyright © 2010, 2011, 2012, 2013, 2014, 2015, 2016
+              Vladimír Vondruš <mosra@centrum.cz>
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included
+    in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+*/
+
+#include "Color.h"
+
+namespace Magnum { namespace Math {
+
+namespace {
+    constexpr const char Hex[]{"0123456789abcdef"};
+}
+
+Corrade::Utility::Debug& operator<<(Corrade::Utility::Debug& debug, const Color3<UnsignedByte>& value) {
+    char out[] = "#______";
+    out[1] = Hex[(value.r() >> 4) & 0xf];
+    out[2] = Hex[(value.r() >> 0) & 0xf];
+    out[3] = Hex[(value.g() >> 4) & 0xf];
+    out[4] = Hex[(value.g() >> 0) & 0xf];
+    out[5] = Hex[(value.b() >> 4) & 0xf];
+    out[6] = Hex[(value.b() >> 0) & 0xf];
+    return debug << out;
+}
+
+Corrade::Utility::Debug& operator<<(Corrade::Utility::Debug& debug, const Color4<UnsignedByte>& value) {
+    char out[] = "#________";
+    out[1] = Hex[(value.r() >> 4) & 0xf];
+    out[2] = Hex[(value.r() >> 0) & 0xf];
+    out[3] = Hex[(value.g() >> 4) & 0xf];
+    out[4] = Hex[(value.g() >> 0) & 0xf];
+    out[5] = Hex[(value.b() >> 4) & 0xf];
+    out[6] = Hex[(value.b() >> 0) & 0xf];
+    out[7] = Hex[(value.a() >> 4) & 0xf];
+    out[8] = Hex[(value.a() >> 0) & 0xf];
+    return debug << out;
+}
+
+}}

src/Magnum/Math/Color.h

@@ -615,11 +615,17 @@ template<class T> inline Corrade::Utility::Debug& operator<<(Corrade::Utility::D
     return debug << static_cast<const Vector3<T>&>(value);
 }
 
+/** @debugoperator{Magnum::Math::Color3} */
+MAGNUM_EXPORT Corrade::Utility::Debug& operator<<(Corrade::Utility::Debug& debug, const Color3<UnsignedByte>& value);
+
 /** @debugoperator{Magnum::Math::Color4} */
 template<class T> inline Corrade::Utility::Debug& operator<<(Corrade::Utility::Debug& debug, const Color4<T>& value) {
     return debug << static_cast<const Vector4<T>&>(value);
 }
 
+/** @debugoperator{Magnum::Math::Color4} */
+MAGNUM_EXPORT Corrade::Utility::Debug& operator<<(Corrade::Utility::Debug& debug, const Color4<UnsignedByte>& value);
+
 namespace Implementation {
     template<class T> struct TypeForSize<3, Color3<T>> { typedef Color3<T> Type; };
     template<class T> struct TypeForSize<3, Color4<T>> { typedef Color3<T> Type; };

src/Magnum/Math/Test/ColorTest.cpp

@@ -96,6 +96,7 @@ struct ColorTest: Corrade::TestSuite::Tester {
 
     void swizzleType();
     void debug();
+    void debugUb();
     void configuration();
 };
 
@@ -140,6 +141,7 @@ ColorTest::ColorTest() {
 
               &ColorTest::swizzleType,
               &ColorTest::debug,
+              &ColorTest::debugUb,
               &ColorTest::configuration});
 }
 
@@ -462,6 +464,18 @@ void ColorTest::debug() {
     CORRADE_COMPARE(o.str(), "Vector(0.5, 0.75, 0, 1)\n");
 }
 
+void ColorTest::debugUb() {
+    using namespace Magnum::Math::Literals;
+
+    std::ostringstream o;
+    Debug(&o) << 0x123456_rgb << 0x789abc_rgb;
+    CORRADE_COMPARE(o.str(), "#123456 #789abc\n");
+
+    o.str({});
+    Debug(&o) << 0x12345678_rgba << 0x90abcdef_rgba;
+    CORRADE_COMPARE(o.str(), "#12345678 #90abcdef\n");
+}
+
 void ColorTest::configuration() {
     Corrade::Utility::Configuration c;