Split the OpenGL layer out, pt 14: Platform::{Context => GLContext}.

Compatibility header and alias in the next commit so Git is able to
recognize the file move.

doc/platform.dox

@@ -164,10 +164,10 @@ back to no-AA rendering:
 In case you want to use some not-yet-supported toolkit or you don't want to use
 the application wrappers in @ref Platform namespace, you can initialize Magnum
 manually. First create OpenGL context and then create instance of
-@ref Platform::Context class, which will take care of proper initialization and
+@ref Platform::GLContext class, which will take care of proper initialization
-feature detection. The instance must be alive for whole application lifetime.
+and feature detection. The instance must be alive for whole application
-Example @cpp main() @ce function with manual initialization is in the following
+lifetime. Example @cpp main() @ce function with manual initialization is in the
-code listing.
+following code listing.
 
 @note Fully contained application using with manual Magnum initialization on
     top of Qt toolkit is available in `base-qt` branch of
@@ -178,11 +178,11 @@ code listing.
 
 @snippet MagnumPlatform-custom.cpp custom
 
-@attention The @ref Platform::Context instance is bound to a single OpenGL
+@attention The @ref Platform::GLContext instance is bound to a single OpenGL
     context, which must be always set as current when calling any Magnum APIs
     touching OpenGL state.
 
-On majority of platforms the @ref Platform::Context class does GL function
+On majority of platforms the @ref Platform::GLContext class does GL function
 pointer loading using platform-specific APIs. In that case you also need to
 find particular `*Context` library, add its include dir and then link to it.
 These platform-specific libraries are available:
@@ -220,7 +220,7 @@ is accompanied by a @ref Platform::WindowlessEglContext "Platform::Windowless*Co
 class that manages just GL context creation, making it current and destruction.
 Similarly to using custom platform toolkits above, the workflow is to first
 create a GL context instance, then making it current and finally instantiating
-the @ref Platform::Context instance to initialize Magnum.
+the @ref Platform::GLContext instance to initialize Magnum.
 
 Similarly as with the applications, to simplify the porting, the library
 provides @cpp Platform::WindowlessGLContext @ce typedef, but only if just one

modules/FindMagnum.cmake

@@ -625,7 +625,7 @@ foreach(_component ${Magnum_FIND_COMPONENTS})
         # Context libraries
         elseif(_component MATCHES ".+Context")
             set(_MAGNUM_${_COMPONENT}_INCLUDE_PATH_SUFFIX Magnum/Platform)
-            set(_MAGNUM_${_COMPONENT}_INCLUDE_PATH_NAMES Context.h)
+            set(_MAGNUM_${_COMPONENT}_INCLUDE_PATH_NAMES GLContext.h)
 
             # GLX context dependencies
             if(_component STREQUAL GlxContext)

src/Magnum/GL/Context.h

@@ -45,7 +45,7 @@
 
 namespace Magnum {
 
-namespace Platform { class Context; }
+namespace Platform { class GLContext; }
 
 namespace GL {
 
@@ -109,14 +109,14 @@ through @ref Context::current() is automatically created during construction of
 `*Application` classes in @ref Platform namespace. You can safely assume that
 the instance is available during whole lifetime of `*Application` object. It's
 also possible to create the context without using any `*Application` class
-using @ref Platform::Context subclass, see @ref platform documentation for more
+using @ref Platform::GLContext subclass, see @ref platform documentation for
-information.
+more information.
 
 @section GL-Context-command-line Command-line options
 
 The context is configurable through command-line options, that are passed
-either from the `Platform::*Application` classes or from the @ref Platform::Context
+either from the `Platform::*Application` classes or from the
-class. Usage:
+@ref Platform::GLContext class. Usage:
 
 @code{.sh}
 <application> [--magnum-help] [--magnum-disable-workarounds LIST]
@@ -634,7 +634,7 @@ class MAGNUM_GL_EXPORT Context {
     private:
         #ifndef DOXYGEN_GENERATING_OUTPUT /* https://bugzilla.gnome.org/show_bug.cgi?id=776986 */
         friend Implementation::ContextState;
-        friend Platform::Context;
+        friend Platform::GLContext;
         #endif
 
         explicit Context(NoCreateT, Int argc, const char** argv, void functionLoader());

src/Magnum/Platform/CMakeLists.txt

@@ -25,7 +25,7 @@
 
 # Headers
 set(MagnumPlatform_HEADERS
-    Context.h
+    GLContext.h
     Platform.h
     Screen.h
     ScreenedApplication.h

src/Magnum/Platform/GLContext.h

@@ -1,5 +1,5 @@
-#ifndef Magnum_Platform_Context_h
+#ifndef Magnum_Platform_GLContext_h
-#define Magnum_Platform_Context_h
+#define Magnum_Platform_GLContext_h
 /*
     This file is part of Magnum.
 
@@ -25,21 +25,34 @@
     DEALINGS IN THE SOFTWARE.
 */
 
+#ifdef MAGNUM_TARGET_GL
+/** @file
+ * @brief Class @ref Magnum::Platform::GLContext
+ */
+#endif
+
 #include <Corrade/Utility/Debug.h>
 
-#include "Magnum/Context.h"
+#include "Magnum/configure.h"
-#include "Magnum/OpenGL.h"
+
+#ifdef MAGNUM_TARGET_GL
+#include "Magnum/GL/Context.h"
+#include "Magnum/GL/OpenGL.h"
 
 namespace Magnum { namespace Platform {
 
 /**
-@brief Platform-specific context
+@brief Platform-specific OpenGL context
 
 In most cases not needed to be used directly as the initialization is done
 automatically in `*Application` classes. See @ref platform for more
 information.
+
+@note This class is available only if Magnum is compiled with
+    @ref MAGNUM_TARGET_GL enabled (done by default). See @ref building-features
+    for more information.
 */
-class Context: public Magnum::Context {
+class GLContext: public GL::Context {
     public:
         /**
          * @brief Constructor
@@ -54,24 +67,24 @@ class Context: public Magnum::Context {
          *      @def_gl{MINOR_VERSION}, @def_gl{CONTEXT_FLAGS},
          *      @def_gl{NUM_EXTENSIONS}, @fn_gl{GetString} with @def_gl{EXTENSIONS}
          */
-        explicit Context(Int argc, const char** argv): Context{NoCreate, argc, argv} { create(); }
+        explicit GLContext(Int argc, const char** argv): GLContext{NoCreate, argc, argv} { create(); }
 
         /** @overload */
-        explicit Context(Int argc, char** argv): Context{argc, const_cast<const char**>(argv)} {}
+        explicit GLContext(Int argc, char** argv): GLContext{argc, const_cast<const char**>(argv)} {}
 
         /** @overload */
-        explicit Context(Int argc, std::nullptr_t argv): Context{argc, static_cast<const char**>(argv)} {}
+        explicit GLContext(Int argc, std::nullptr_t argv): GLContext{argc, static_cast<const char**>(argv)} {}
 
         /**
          * @brief Default constructor
          *
          * Equivalent to passing @cpp {0, nullptr} @ce to
-         * @ref Context(Int, const char**). Even if the command-line options
+         * @ref GLContext(Int, const char**). Even if the command-line options
          * are not propagated, it's still possible to affect the renderer
          * behavior from the environment. See @ref Context-command-line for
          * more information.
          */
-        explicit Context(): Context{0, nullptr} {}
+        explicit GLContext(): GLContext{0, nullptr} {}
 
         /**
          * @brief Construct the class without doing complete setup
@@ -81,18 +94,18 @@ class Context: public Magnum::Context {
          * left in empty state. Use @ref create() or @ref tryCreate() to
          * complete the setup.
          */
-        explicit Context(NoCreateT, Int argc, const char** argv):
+        explicit GLContext(NoCreateT, Int argc, const char** argv):
             #ifndef CORRADE_TARGET_EMSCRIPTEN
-            Magnum::Context{NoCreate, argc, argv, flextGLInit} {}
+            GL::Context{NoCreate, argc, argv, flextGLInit} {}
             #else
-            Magnum::Context{NoCreate, argc, argv, nullptr} {}
+            GL::Context{NoCreate, argc, argv, nullptr} {}
             #endif
 
         /** @overload */
-        explicit Context(NoCreateT, Int argc, char** argv): Context{NoCreate, argc, const_cast<const char**>(argv)} {}
+        explicit GLContext(NoCreateT, Int argc, char** argv): GLContext{NoCreate, argc, const_cast<const char**>(argv)} {}
 
         /** @overload */
-        explicit Context(NoCreateT, Int argc, std::nullptr_t argv): Context{NoCreate, argc, static_cast<const char**>(argv)} {}
+        explicit GLContext(NoCreateT, Int argc, std::nullptr_t argv): GLContext{NoCreate, argc, static_cast<const char**>(argv)} {}
 
         /**
          * @brief Construct the class without doing complete setup
@@ -103,7 +116,7 @@ class Context: public Magnum::Context {
          * renderer behavior from the environment. See @ref Context-command-line
          * for more information.
          */
-        explicit Context(NoCreateT): Context{NoCreate, 0, nullptr} {}
+        explicit GLContext(NoCreateT): GLContext{NoCreate, 0, nullptr} {}
 
         /**
          * @brief Complete the context setup and exit on failure
@@ -114,7 +127,7 @@ class Context: public Magnum::Context {
          * output and the application exits. See @ref Context(Int, char**) for
          * more information and @ref tryCreate() for an alternative.
          */
-        void create() { return Magnum::Context::create(); }
+        void create() { return GL::Context::create(); }
 
         /**
          * @brief Complete the context setup
@@ -122,10 +135,12 @@ class Context: public Magnum::Context {
          * Unlike @ref create() just prints a message to error output and
          * returns `false` on error.
          */
-        bool tryCreate() { return Magnum::Context::tryCreate(); }
+        bool tryCreate() { return GL::Context::tryCreate(); }
-
 };
 
 }}
+#else
+#error this header is available only in the OpenGL build
+#endif
 
 #endif

src/Magnum/Platform/Platform.h

@@ -34,7 +34,10 @@ namespace Magnum { namespace Platform {
 #ifndef DOXYGEN_GENERATING_OUTPUT
 template<class> class BasicScreen;
 template<class> class BasicScreenedApplication;
-class Context;
+
+#ifdef MAGNUM_TARGET_GL
+class GLContext;
+#endif
 #endif
 
 }}