Platform: ability to specify context flags in Sdl2Application.

Finally proper support for debug contexts :-)

src/Magnum/Context.h

@@ -103,7 +103,7 @@ class MAGNUM_EXPORT Context {
         /**
          * @brief Context flag
          *
-         * @see @ref Flags, @ref flags()
+         * @see @ref Flags, @ref flags(), @ref Platform::Sdl2Application::Configuration::setFlags() "Platform::*Application::Configuration::setFlags()"
          */
         enum class Flag: GLint {
             /**

src/Magnum/Platform/Sdl2Application.cpp

@@ -109,6 +109,9 @@ bool Sdl2Application::tryCreateContext(const Configuration& configuration) {
     SDL_GL_SetAttribute(SDL_GL_MULTISAMPLEBUFFERS, configuration.sampleCount() > 1 ? 1 : 0);
     SDL_GL_SetAttribute(SDL_GL_MULTISAMPLESAMPLES, configuration.sampleCount());
 
+    /* Context flags */
+    SDL_GL_SetAttribute(SDL_GL_CONTEXT_FLAGS, int(configuration.flags()));
+
     /* Flags: if not hidden, set as shown */
     Uint32 windowFlags(configuration.windowFlags());
     if(!(configuration.windowFlags() & Configuration::WindowFlag::Hidden)) windowFlags |= SDL_WINDOW_SHOWN;

src/Magnum/Platform/Sdl2Application.h

@@ -423,6 +423,30 @@ depth buffer.
 */
 class Sdl2Application::Configuration {
     public:
+        /**
+         * @brief Context flag
+         *
+         * @see @ref Flags @ref setFlags()
+         */
+        enum class Flag: int {
+            Debug = SDL_GL_CONTEXT_DEBUG_FLAG,  /**< Create debug context */
+
+            /** Create context with robust access */
+            RobustAccess = SDL_GL_CONTEXT_ROBUST_ACCESS_FLAG
+        };
+
+        /**
+         * @brief Context flags
+         *
+         * @see @ref setFlags()
+         */
+        #ifndef DOXYGEN_GENERATING_OUTPUT
+        typedef Containers::EnumSet<Flag, int, SDL_GL_CONTEXT_DEBUG_FLAG|
+            SDL_GL_CONTEXT_ROBUST_ACCESS_FLAG> Flags;
+        #else
+        typedef Containers::EnumSet<Flag, int> Flags;
+        #endif
+
         /**
          * @brief Window flag
          *
@@ -508,6 +532,20 @@ class Sdl2Application::Configuration {
             return *this;
         }
 
+        /** @brief Context flags */
+        Flags flags() const { return _flags; }
+
+        /**
+         * @brief Set context flags
+         * @return Reference to self (for method chaining)
+         *
+         * Default is no flag.
+         */
+        Configuration& setFlags(Flags flags) {
+            _flags = flags;
+            return *this;
+        }
+
         #ifndef CORRADE_TARGET_EMSCRIPTEN
         /**
          * @brief Context version
@@ -561,8 +599,10 @@ class Sdl2Application::Configuration {
         #ifndef CORRADE_TARGET_EMSCRIPTEN
         Version _version;
         #endif
+        Flags _flags;
 };
 
+CORRADE_ENUMSET_OPERATORS(Sdl2Application::Configuration::Flags)
 CORRADE_ENUMSET_OPERATORS(Sdl2Application::Configuration::WindowFlags)
 
 /**