Platform: unified and cleaned up context creation.

Added missing tryCreateContext() implementations. Error messages are
printed only by tryCreateContext(), createContext() is only a thin
wrapper which exits the application if tryCreateContext() fails and
doesn't print any additional information on the output.

Hopefully I didn't break anything :-)

src/Platform/AbstractXApplication.cpp

@@ -51,7 +51,11 @@ AbstractXApplication::AbstractXApplication(Implementation::AbstractContextHandle
 AbstractXApplication::AbstractXApplication(Implementation::AbstractContextHandler<Display*, VisualID, Window>* contextHandler, const Arguments&, std::nullptr_t): contextHandler(contextHandler), c(nullptr), flags(Flag::Redraw) {}
 
 void AbstractXApplication::createContext(const Configuration& configuration) {
-    CORRADE_ASSERT(!c, "AbstractXApplication::createContext(): context already created", );
+    if(!tryCreateContext(configuration)) std::exit(1);
+}
+
+bool AbstractXApplication::tryCreateContext(const Configuration& configuration) {
+    CORRADE_ASSERT(!c, "AbstractXApplication::tryCreateContext(): context already created", );
 
     viewportSize = configuration.size();
 
@@ -67,8 +71,8 @@ void AbstractXApplication::createContext(const Configuration& configuration) {
     visTemplate.visualid = visualId;
     visInfo = XGetVisualInfo(display, VisualIDMask, &visTemplate, &visualCount);
     if(!visInfo) {
-        Error() << "Cannot get X visual";
-        std::exit(1);
+        Error() << "Platform::WindowlessGlxApplication::tryCreateContext(): cannot get X visual";
+        return false;
     }
 
     /* Create X Window */
@@ -97,6 +101,7 @@ void AbstractXApplication::createContext(const Configuration& configuration) {
     contextHandler->makeCurrent();
 
     c = new Context;
+    return true;
 }
 
 AbstractXApplication::~AbstractXApplication() {

src/Platform/AbstractXApplication.h

@@ -90,6 +90,9 @@ class AbstractXApplication {
         /** @copydoc Sdl2Application::createContext() */
         void createContext(const Configuration& configuration);
 
+        /** @copydoc Sdl2Application::tryCreateContext() */
+        bool tryCreateContext(const Configuration& configuration);
+
         /** @{ @name Drawing functions */
 
         /** @copydoc Sdl2Application::viewportEvent() */

src/Platform/GlutApplication.cpp

@@ -60,10 +60,7 @@ void GlutApplication::initialize(int& argc, char** argv) {
 }
 
 void GlutApplication::createContext(const Configuration& configuration) {
-    if(!tryCreateContext(configuration)) {
-        Error() << "Platform::GlutApplication::createContext(): cannot create context";
-        std::exit(1);
-    }
+    if(!tryCreateContext(configuration)) std::exit(1);
 }
 
 bool GlutApplication::tryCreateContext(const Configuration& configuration) {
@@ -76,8 +73,10 @@ bool GlutApplication::tryCreateContext(const Configuration& configuration) {
 
     glutInitDisplayMode(flags);
     glutInitWindowSize(configuration.size().x(), configuration.size().y());
-    if(!glutCreateWindow(configuration.title().data()))
+    if(!glutCreateWindow(configuration.title().data())) {
+        Error() << "Platform::GlutApplication::tryCreateContext(): cannot create context";
         return false;
+    }
     glutReshapeFunc(staticViewportEvent);
     glutSpecialFunc(staticKeyEvent);
     glutMouseFunc(staticMouseEvent);

src/Platform/NaClApplication.cpp

@@ -69,10 +69,7 @@ NaClApplication::NaClApplication(const Arguments& arguments, std::nullptr_t): In
 }
 
 void NaClApplication::createContext(const Configuration& configuration) {
-    if(!tryCreateContext(configuration)) {
-        Error() << "Platform::NaClApplication::createContext(): cannot create context";
-        std::exit(1);
-    }
+    if(!tryCreateContext(configuration)) std::exit(1);
 }
 
 bool NaClApplication::tryCreateContext(const Configuration& configuration) {
@@ -93,13 +90,16 @@ bool NaClApplication::tryCreateContext(const Configuration& configuration) {
 
     graphics = new pp::Graphics3D(this, attributes);
     if(graphics->is_null()) {
+        Error() << "Platform::NaClApplication::tryCreateContext(): cannot create context";
         delete graphics;
         graphics = nullptr;
         return false;
     }
     if(!BindGraphics(*graphics)) {
         Error() << "Platform::NaClApplication::tryCreateContext(): cannot bind graphics";
-        std::exit(1);
+        delete graphics;
+        graphics = nullptr;
+        return false;
     }
 
     fullscreen = new pp::Fullscreen(this);

src/Platform/Sdl2Application.cpp

@@ -89,10 +89,7 @@ void Sdl2Application::initialize() {
 }
 
 void Sdl2Application::createContext(const Configuration& configuration) {
-    if(!tryCreateContext(configuration)) {
-        Error() << "Platform::Sdl2Application::createContext(): cannot create context:" << SDL_GetError();
-        std::exit(1);
-    }
+    if(!tryCreateContext(configuration)) std::exit(1);
 }
 
 bool Sdl2Application::tryCreateContext(const Configuration& configuration) {
@@ -115,10 +112,13 @@ bool Sdl2Application::tryCreateContext(const Configuration& configuration) {
     if(!(window = SDL_CreateWindow(configuration.title().data(),
             SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED,
             configuration.size().x(), configuration.size().y(),
-            SDL_WINDOW_OPENGL|flags)))
+            SDL_WINDOW_OPENGL|flags))) {
+        Error() << "Platform::Sdl2Application::tryCreateContext(): cannot create window:" << SDL_GetError();
         return false;
+    }
 
     if(!(context = SDL_GL_CreateContext(window))) {
+        Error() << "Platform::Sdl2Application::tryCreateContext(): cannot create context:" << SDL_GetError();
         SDL_DestroyWindow(window);
         window = nullptr;
         return false;

src/Platform/WindowlessGlxApplication.cpp

@@ -47,8 +47,12 @@ WindowlessGlxApplication::WindowlessGlxApplication(const Arguments&): c(nullptr)
 
 WindowlessGlxApplication::WindowlessGlxApplication(const Arguments&, std::nullptr_t): c(nullptr) {}
 
-void WindowlessGlxApplication::createContext(const Configuration&) {
-    CORRADE_ASSERT(!c, "WindowlessGlxApplication::createContext(): context already created", );
+void WindowlessGlxApplication::createContext(const Configuration& configuration) {
+    if(!tryCreateContext(configuration)) std::exit(1);
+}
+
+bool WindowlessGlxApplication::tryCreateContext(const Configuration&) {
+    CORRADE_ASSERT(!c, "Platform::WindowlessGlxApplication::tryCreateContext(): context already created", );
 
     display = XOpenDisplay(nullptr);
 
@@ -56,8 +60,8 @@ void WindowlessGlxApplication::createContext(const Configuration&) {
     int major, minor;
     glXQueryVersion(display, &major, &minor);
     if(major == 1 && minor < 4) {
-        Error() << "WindowlessGlxApplication: GLX version 1.4 or greater is required.";
-        std::exit(1);
+        Error() << "Platform::WindowlessGlxApplication::tryCreateContext(): GLX version 1.4 or greater is required";
+        return false;
     }
 
     /* Choose config */
@@ -65,8 +69,8 @@ void WindowlessGlxApplication::createContext(const Configuration&) {
     static const int fbAttributes[] = { None };
     GLXFBConfig* configs = glXChooseFBConfig(display, DefaultScreen(display), fbAttributes, &configCount);
     if(!configCount) {
-        Error() << "WindowlessGlxApplication: no supported framebuffer configuration found.";
-        std::exit(1);
+        Error() << "Platform::WindowlessGlxApplication::tryCreateContext(): no supported framebuffer configuration found";
+        return false;
     }
 
     GLint contextAttributes[] = {
@@ -82,8 +86,8 @@ void WindowlessGlxApplication::createContext(const Configuration&) {
     PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB = (PFNGLXCREATECONTEXTATTRIBSARBPROC) glXGetProcAddress((const GLubyte*)"glXCreateContextAttribsARB");
     context = glXCreateContextAttribsARB(display, configs[0], nullptr, True, contextAttributes);
     if(!context) {
-        Error() << "WindowlessGlxApplication: cannot create context.";
-        std::exit(1);
+        Error() << "Platform::WindowlessGlxApplication::tryCreateContext(): cannot create context";
+        return false;
     }
 
     /* Create pbuffer */
@@ -98,11 +102,12 @@ void WindowlessGlxApplication::createContext(const Configuration&) {
 
     /* Set OpenGL context as current */
     if(!glXMakeContextCurrent(display, pbuffer, pbuffer, context)) {
-        Error() << "WindowlessGlxApplication: cannot make context current";
-        std::exit(1);
+        Error() << "Platform::WindowlessGlxApplication::tryCreateContext(): cannot make context current";
+        return false;
     }
 
     c = new Context;
+    return true;
 }
 
 WindowlessGlxApplication::~WindowlessGlxApplication() {

src/Platform/WindowlessGlxApplication.h

@@ -109,6 +109,9 @@ class WindowlessGlxApplication {
         /** @copydoc Sdl2Application::createContext() */
         void createContext(const Configuration& configuration);
 
+        /** @copydoc Sdl2Application::tryCreateContext() */
+        bool tryCreateContext(const Configuration& configuration);
+
     private:
         Display* display;
         GLXContext context;

src/Platform/WindowlessNaClApplication.cpp

@@ -68,10 +68,7 @@ WindowlessNaClApplication::WindowlessNaClApplication(const Arguments& arguments,
 }
 
 void WindowlessNaClApplication::createContext(const Configuration& configuration) {
-    if(!tryCreateContext(configuration)) {
-        Error() << "Platform::WindowlessNaClApplication::createContext(): cannot create context";
-        std::exit(1);
-    }
+    if(!tryCreateContext(configuration)) std::exit(1);
 }
 
 bool WindowlessNaClApplication::tryCreateContext(const Configuration&) {
@@ -88,13 +85,16 @@ bool WindowlessNaClApplication::tryCreateContext(const Configuration&) {
 
     graphics = new pp::Graphics3D(this, attributes);
     if(graphics->is_null()) {
+        Error() << "Platform::WindowlessNaClApplication::tryCreateContext(): cannot create context";
         delete graphics;
         graphics = nullptr;
         return false;
     }
     if(!BindGraphics(*graphics)) {
         Error() << "Platform::WindowlessNaClApplication::tryCreateContext(): cannot bind graphics";
-        std::exit(1);
+        delete graphics;
+        graphics = nullptr;
+        return false;
     }
 
     glSetCurrentContextPPAPI(graphics->pp_resource());