Qt: Handle failed context creation better.

qt/src/EmuCanvas.hpp

@@ -14,7 +14,7 @@ class EmuCanvas : public QWidget
     virtual void deinit() = 0;
     virtual void draw() = 0;
     void paintEvent(QPaintEvent *) override = 0;
-    virtual void createContext() {}
+    virtual bool createContext() { return false; }
     virtual void recreateUIAssets() {}
     void output(uint8_t *buffer, int width, int height, QImage::Format format, int bytes_per_line, double frame_rate);
     void throttle();

qt/src/EmuCanvasOpenGL.cpp

@@ -122,10 +122,10 @@ void EmuCanvasOpenGL::customShaderDraw()
     shader->render(texture, output_data.width, output_data.height, viewport.x(), viewport.y(), viewport.width(), viewport.height(), S9xViewportCallback);
 }
 
-void EmuCanvasOpenGL::createContext()
+bool EmuCanvasOpenGL::createContext()
 {
     if (context)
-        return;
+        return true;
 
     auto platform = QGuiApplication::platformName();
     auto pni = QGuiApplication::platformNativeInterface();
@@ -139,7 +139,11 @@ void EmuCanvasOpenGL::createContext()
         int s = devicePixelRatio();
 
         if (!wayland_egl_context->attach(display, surface, { parent->x(), parent->y(), parent->width(), parent->height(), s }))
+        {
             printf("Couldn't attach context to wayland surface.\n");
+            context.reset();
+            return false;
+        }
 
         context.reset(wayland_egl_context);
     }
@@ -150,7 +154,11 @@ void EmuCanvasOpenGL::createContext()
 
         auto glx_context = new GTKGLXContext();
         if (!glx_context->attach(display, xid))
+        {
             printf("Couldn't attach to X11 window.\n");
+            context.reset();
+            return false;
+        }
 
         context.reset(glx_context);
     }
@@ -160,7 +168,8 @@ void EmuCanvasOpenGL::createContext()
     if (!wgl_context->attach((HWND)hwnd))
     {
         printf("Couldn't attach to context\n");
-        return;
+        context.reset();
+        return false;
     }
     context.reset(wgl_context);
 #endif
@@ -194,6 +203,8 @@ void EmuCanvasOpenGL::createContext()
     context->swap_interval(config->enable_vsync ? 1 : 0);
     QGuiApplication::sync();
     paintEvent(nullptr);
+
+    return true;
 }
 
 void EmuCanvasOpenGL::loadShaders()

qt/src/EmuCanvasOpenGL.hpp

@@ -14,7 +14,7 @@ class EmuCanvasOpenGL : public EmuCanvas
     EmuCanvasOpenGL(EmuConfig *config, QWidget *parent, QWidget *main_window);
     ~EmuCanvasOpenGL();
 
-    void createContext() override;
+    bool createContext() override;
     void deinit() override;
     void paintEvent(QPaintEvent *event) override;
     void resizeEvent(QResizeEvent *event) override;

qt/src/EmuCanvasVulkan.cpp

@@ -75,10 +75,10 @@ bool EmuCanvasVulkan::initImGui()
     return true;
 }
 
-void EmuCanvasVulkan::createContext()
+bool EmuCanvasVulkan::createContext()
 {
-    if (simple_output)
-        return;
+    if (context)
+        return true;
 
     platform = QGuiApplication::platformName();
     auto pni = QGuiApplication::platformNativeInterface();
@@ -89,7 +89,11 @@ void EmuCanvasVulkan::createContext()
 
 #ifdef _WIN32
     auto hwnd = (HWND)winId();
-    context->init_win32(nullptr, hwnd, config->display_device_index);
+    if (!context->init_win32(nullptr, hwnd, config->display_device_index))
+    {
+        context.reset();
+        return false;
+    }
 #else
     if (platform == "wayland")
     {
@@ -98,14 +102,21 @@ void EmuCanvasVulkan::createContext()
         auto surface = (wl_surface *)pni->nativeResourceForWindow("surface", main_window->windowHandle());
         wayland_surface->attach(display, surface, { parent->x(), parent->y(), width(), height(), static_cast<int>(devicePixelRatio()) });
         auto [scaled_width, scaled_height] = wayland_surface->get_size();
-        context->init_wayland(display, wayland_surface->child, scaled_width, scaled_height, config->display_device_index);
+        if (!context->init_wayland(display, wayland_surface->child, scaled_width, scaled_height, config->display_device_index))
+        {
+            context.reset();
+            return false;
+        }
     }
     else if (platform == "xcb")
     {
         auto display = (Display *)pni->nativeResourceForWindow("display", window);
         auto xid = (Window)winId();
-
-        context->init_Xlib(display, xid, config->display_device_index);
+        if (!context->init_Xlib(display, xid, config->display_device_index))
+        {
+            context.reset();
+            return false;
+        }
     }
 #endif
 
@@ -116,10 +127,15 @@ void EmuCanvasVulkan::createContext()
 
     QGuiApplication::sync();
     paintEvent(nullptr);
+
+    return true;
 }
 
 void EmuCanvasVulkan::tryLoadShader()
 {
+    if (!context)
+        return;
+
     simple_output.reset();
     shader_chain.reset();
     shader_parameters_dialog.reset();
@@ -143,6 +159,9 @@ void EmuCanvasVulkan::tryLoadShader()
 
 void EmuCanvasVulkan::shaderChanged()
 {
+    if (!context)
+        return;
+
     if (!config->use_shader)
         current_shader.clear();
 
@@ -248,7 +267,8 @@ void EmuCanvasVulkan::deinit()
 
     if (ImGui::GetCurrentContext())
     {
-        context->wait_idle();
+        if (context)
+            context->wait_idle();
         imgui_descriptor_pool.reset();
         imgui_render_pass.reset();
         ImGui_ImplVulkan_Shutdown();
@@ -305,6 +325,9 @@ void EmuCanvasVulkan::saveParameters(std::string filename)
 
 void EmuCanvasVulkan::recreateUIAssets()
 {
+    if (!context)
+        return;
+
     if (ImGui::GetCurrentContext())
     {
         context->wait_idle();

qt/src/EmuCanvasVulkan.hpp

@@ -16,7 +16,7 @@ class EmuCanvasVulkan : public EmuCanvas
     EmuCanvasVulkan(EmuConfig *config, QWidget *parent, QWidget *main_window);
     ~EmuCanvasVulkan();
 
-    void createContext() override;
+    bool createContext() override;
     void deinit() override;
     void paintEvent(QPaintEvent *event) override;
     void resizeEvent(QResizeEvent *event) override;

qt/src/EmuMainWindow.cpp

@@ -73,7 +73,7 @@ void EmuMainWindow::destroyCanvas()
     }
 }
 
-void EmuMainWindow::createCanvas()
+bool EmuMainWindow::createCanvas()
 {
     if (app->config->display_driver != "vulkan" &&
         app->config->display_driver != "opengl" &&
@@ -91,8 +91,12 @@ void EmuMainWindow::createCanvas()
         {
             canvas = new EmuCanvasVulkan(app->config.get(), central_widget, this);
             QGuiApplication::processEvents();
-            canvas->createContext();
-        }            
+            if (!canvas->createContext())
+            {
+                delete canvas;
+                return false;
+            }
+        }
         else if (app->config->display_driver == "opengl")
         {
             canvas = new EmuCanvasOpenGL(app->config.get(), central_widget, this);
@@ -106,7 +110,7 @@ void EmuMainWindow::createCanvas()
         using_stacked_widget = true;
         QGuiApplication::processEvents();
 
-        return;
+        return true;
     }
 #endif
 
@@ -114,26 +118,41 @@ void EmuMainWindow::createCanvas()
     {
         canvas = new EmuCanvasVulkan(app->config.get(), this, this);
         QGuiApplication::processEvents();
-        canvas->createContext();
+        if (!canvas->createContext())
+        {
+            delete canvas;
+            return false;
+        }
     }
     else if (app->config->display_driver == "opengl")
     {
         canvas = new EmuCanvasOpenGL(app->config.get(), this, this);
         QGuiApplication::processEvents();
         app->emu_thread->runOnThread([&] { canvas->createContext(); }, true);
-    } 
+    }
     else
         canvas = new EmuCanvasQt(app->config.get(), this, this);
 
     setCentralWidget(canvas);
     using_stacked_widget = false;
+
+    return true;
 }
 
 void EmuMainWindow::recreateCanvas()
 {
     app->suspendThread();
     destroyCanvas();
-    createCanvas();
+
+    if (!createCanvas())
+    {
+        QMessageBox::warning(this,
+            tr("Unable to Start Display Driver"),
+            tr("Unable to create a %1 context. Attempting to use qt.").arg(QString::fromUtf8(app->config->display_driver)));
+        app->config->display_driver = "qt";
+        createCanvas();
+    }
+
     app->unsuspendThread();
 }
 
@@ -526,7 +545,7 @@ bool EmuMainWindow::event(QEvent *event)
             minimized_pause = false;
             app->unpause();
         }
-        
+
         break;
     }
     case QEvent::MouseMove:
@@ -570,9 +589,9 @@ void EmuMainWindow::toggleFullscreen()
 
 bool EmuMainWindow::eventFilter(QObject *watched, QEvent *event)
 {
-    if (watched == canvas) 
+    if (watched == canvas)
     {
-        if (event->type() == QEvent::Resize) 
+        if (event->type() == QEvent::Resize)
         {
             app->emu_thread->runOnThread([&] {
                 canvas->resizeEvent((QResizeEvent *)event);

qt/src/EmuMainWindow.hpp

@@ -20,7 +20,7 @@ class EmuMainWindow : public QMainWindow
     ~EmuMainWindow();
 
     void toggleFullscreen();
-    void createCanvas();
+    bool createCanvas();
     void destroyCanvas();
     void recreateCanvas();
     void setBypassCompositor(bool);