Alternative approach to initial window OpenGL context scope

Signed-off-by: falkTX <falktx@falktx.com>

dgl/Window.hpp

@@ -104,6 +104,43 @@ public:
     };
 #endif // DGL_FILE_BROWSER_DISABLED
 
+   /**
+      Window graphics context as a scoped struct.
+      This class gives graphics context drawing time to a window's widgets.
+      Typically used for allowing OpenGL drawing operations during a window + widget constructor.
+
+      Unless you are subclassing the Window or StandaloneWindow classes, you do not need to care.
+      In such cases you will need to use this struct as a way to get a valid OpenGL context.
+      For example in a standalone application:
+      ```
+      int main()
+      {
+          Application app;
+          Window win(app);
+          ScopedPointer<MyCustomTopLevelWidget> widget;
+          {
+              const ScopedGraphicsContext sgc(win);
+              widget = new MyCustomTopLevelWidget(win);
+          }
+          app.exec();
+          return 0;
+      }
+      ```
+
+      This struct is necessary because we cannot automatically make the window leave the OpenGL context in custom code.
+      We must always cleanly enter and leave the OpenGL context.
+      In order to avoid messing up the global host context, this class is used around widget creation.
+    */
+    class ScopedGraphicsContext
+    {
+        Window& window;
+    public:
+        explicit ScopedGraphicsContext(Window& window);
+        ~ScopedGraphicsContext();
+        DISTRHO_DECLARE_NON_COPYABLE(ScopedGraphicsContext)
+        DISTRHO_PREVENT_HEAP_ALLOCATION
+    };
+
    /**
       Constructor for a regular, standalone window.
     */
@@ -362,9 +399,6 @@ public:
     DISTRHO_DEPRECATED_BY("runAsModal(bool)")
     inline void exec(bool blockWait = false) { runAsModal(blockWait); }
 
-    // TESTING, DO NOT USE
-    void leaveContext();
-
 protected:
    /**
       A function called when the window is attempted to be closed.
@@ -414,6 +448,7 @@ private:
     struct PrivateData;
     PrivateData* const pData;
     friend class Application;
+    friend class PluginWindow;
     friend class TopLevelWidget;
 
     DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(Window);

dgl/src/Window.cpp

@@ -20,6 +20,20 @@
 
 START_NAMESPACE_DGL
 
+// -----------------------------------------------------------------------
+// ScopedGraphicsContext
+
+Window::ScopedGraphicsContext::ScopedGraphicsContext(Window& win)
+    : window(win)
+{
+    puglBackendEnter(window.pData->view);
+}
+
+Window::ScopedGraphicsContext::~ScopedGraphicsContext()
+{
+    puglBackendLeave(window.pData->view);
+}
+
 // -----------------------------------------------------------------------
 // Window
 
@@ -265,11 +279,6 @@ void Window::runAsModal(bool blockWait)
     pData->runAsModal(blockWait);
 }
 
-void Window::leaveContext()
-{
-    pData->leaveContext();
-}
-
 void Window::setGeometryConstraints(const uint minimumWidth,
                                     const uint minimumHeight,
                                     const bool keepAspectRatio,

dgl/src/WindowPrivateData.cpp

@@ -237,9 +237,6 @@ void Window::PrivateData::initPost()
     // create view now, as a few methods we allow devs to use require it
     puglRealize(view);
 
-    // FIXME this is bad, the enter/leave should be well scoped. try to find a better place for it..
-    puglBackendEnter(view);
-
     if (isEmbed)
     {
         appData->oneWindowShown();
@@ -630,14 +627,6 @@ void Window::PrivateData::runAsModal(const bool blockWait)
     }
 }
 
-// -----------------------------------------------------------------------
-// TESTING
-
-void Window::PrivateData::leaveContext()
-{
-    puglBackendLeave(view);
-}
-
 // -----------------------------------------------------------------------
 // pugl events
 

dgl/src/WindowPrivateData.hpp

@@ -161,9 +161,6 @@ struct Window::PrivateData : IdleCallback {
     void stopModal();
     void runAsModal(bool blockWait);
 
-    // TESTING
-    void leaveContext();
-
     // pugl events
     void onPuglConfigure(double width, double height);
     void onPuglExpose();

distrho/DistrhoUI.hpp

@@ -48,6 +48,10 @@ typedef DGL_NAMESPACE::NanoTopLevelWidget UIWidget;
 typedef DGL_NAMESPACE::TopLevelWidget UIWidget;
 #endif
 
+START_NAMESPACE_DGL
+class PluginWindow;
+END_NAMESPACE_DGL
+
 START_NAMESPACE_DISTRHO
 
 /* ------------------------------------------------------------------------------------------------------------
@@ -311,7 +315,7 @@ protected:
 private:
     struct PrivateData;
     PrivateData* const uiData;
-    friend class PluginWindow;
+    friend class DGL_NAMESPACE::PluginWindow;
     friend class UIExporter;
 
     DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(UI)

distrho/src/DistrhoUI.cpp

@@ -39,7 +39,7 @@ UI::PrivateData* UI::PrivateData::s_nextPrivateData = nullptr;
 PluginWindow& UI::PrivateData::createNextWindow(UI* const ui, const uint width, const uint height)
 {
     UI::PrivateData* const pData = s_nextPrivateData;
-    pData->window = new PluginWindow(ui, pData, width, height);
+    pData->window = new PluginWindow(ui, pData->app, pData->winId, width, height, pData->scaleFactor);
     return pData->window.getObject();
 }
 

distrho/src/DistrhoUIPrivateData.hpp

@@ -20,8 +20,9 @@
 #include "../DistrhoUI.hpp"
 #include "../../dgl/Application.hpp"
 
-#ifndef DISTRHO_PLUGIN_HAS_EXTERNAL_UI
-# include "../../dgl/Window.hpp"
+#if !DISTRHO_PLUGIN_HAS_EXTERNAL_UI
+# include "../../dgl/src/WindowPrivateData.hpp"
+# include "../../dgl/src/pugl.hpp"
 #endif
 
 #if defined(DISTRHO_PLUGIN_TARGET_JACK) || defined(DISTRHO_PLUGIN_TARGET_DSSI)
@@ -35,20 +36,9 @@
 # define DISTRHO_UI_USER_RESIZABLE 0
 #endif
 
-START_NAMESPACE_DISTRHO
-
-using DGL_NAMESPACE::Application;
-using DGL_NAMESPACE::Window;
-
 // -----------------------------------------------------------------------
-// UI callbacks
 
-typedef void (*editParamFunc)   (void* ptr, uint32_t rindex, bool started);
-typedef void (*setParamFunc)    (void* ptr, uint32_t rindex, float value);
-typedef void (*setStateFunc)    (void* ptr, const char* key, const char* value);
-typedef void (*sendNoteFunc)    (void* ptr, uint8_t channel, uint8_t note, uint8_t velo);
-typedef void (*setSizeFunc)     (void* ptr, uint width, uint height);
-typedef bool (*fileRequestFunc) (void* ptr, const char* key);
+START_NAMESPACE_DGL
 
 // -----------------------------------------------------------------------
 // Plugin Application, will set class name based on plugin details
@@ -73,7 +63,136 @@ public:
     DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(PluginApplication)
 };
 
-class PluginWindow;
+// -----------------------------------------------------------------------
+// Plugin Window, will pass some Window events to UI
+
+#if DISTRHO_PLUGIN_HAS_EXTERNAL_UI
+// TODO external ui stuff
+class PluginWindow
+{
+    UI* const ui;
+
+public:
+    explicit PluginWindow(UI* const uiPtr,
+                          PluginApplication& app,
+                          const uintptr_t parentWindowHandle,
+                          const uint width,
+                          const uint height,
+                          const double scaleFactor)
+        : Window(app, parentWindowHandle, width, height, scaleFactor, DISTRHO_UI_USER_RESIZABLE),
+          ui(uiPtr) {}
+
+    uint getWidth() const noexcept
+    {
+        return ui->getWidth();
+    }
+
+    uint getHeight() const noexcept
+    {
+        return ui->getHeight();
+    }
+
+    bool isVisible() const noexcept
+    {
+        return ui->isRunning();
+    }
+
+    uintptr_t getNativeWindowHandle() const noexcept
+    {
+        return 0;
+    }
+
+    DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(PluginWindow)
+};
+#else
+class PluginWindow : public Window
+{
+    UI* const ui;
+
+public:
+    explicit PluginWindow(UI* const uiPtr,
+                          PluginApplication& app,
+                          const uintptr_t parentWindowHandle,
+                          const uint width,
+                          const uint height,
+                          const double scaleFactor)
+        : Window(app, parentWindowHandle, width, height, scaleFactor, DISTRHO_UI_USER_RESIZABLE),
+          ui(uiPtr)
+    {
+        puglBackendEnter(pData->view);
+    }
+
+    void leaveContext()
+    {
+        puglBackendLeave(pData->view);
+    }
+
+protected:
+    void onFocus(const bool focus, const DGL_NAMESPACE::CrossingMode mode) override
+    {
+        DISTRHO_SAFE_ASSERT_RETURN(ui != nullptr,);
+
+        ui->uiFocus(focus, mode);
+    }
+
+    void onReshape(const uint width, const uint height) override
+    {
+        DISTRHO_SAFE_ASSERT_RETURN(ui != nullptr,);
+
+        ui->uiReshape(width, height);
+    }
+
+    void onScaleFactorChanged(const double scaleFactor) override
+    {
+        DISTRHO_SAFE_ASSERT_RETURN(ui != nullptr,);
+
+        ui->uiScaleFactorChanged(scaleFactor);
+    }
+
+# ifndef DGL_FILE_BROWSER_DISABLED
+    void onFileSelected(const char* const filename) override
+    {
+        DISTRHO_SAFE_ASSERT_RETURN(ui != nullptr,);
+
+#  if DISTRHO_PLUGIN_WANT_STATEFILES
+        if (char* const key = ui->uiData->uiStateFileKeyRequest)
+        {
+            ui->uiData->uiStateFileKeyRequest = nullptr;
+            // notify DSP
+            ui->setState(key, filename);
+            // notify UI
+            ui->stateChanged(key, filename);
+            std::free(key);
+            return;
+        }
+#  endif
+
+        ui->uiFileBrowserSelected(filename);
+    }
+# endif
+
+    DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(PluginWindow)
+};
+#endif // !DISTRHO_PLUGIN_HAS_EXTERNAL_UI
+
+END_NAMESPACE_DGL
+
+// -----------------------------------------------------------------------
+
+START_NAMESPACE_DISTRHO
+
+using DGL_NAMESPACE::PluginApplication;
+using DGL_NAMESPACE::PluginWindow;
+
+// -----------------------------------------------------------------------
+// UI callbacks
+
+typedef void (*editParamFunc)   (void* ptr, uint32_t rindex, bool started);
+typedef void (*setParamFunc)    (void* ptr, uint32_t rindex, float value);
+typedef void (*setStateFunc)    (void* ptr, const char* key, const char* value);
+typedef void (*sendNoteFunc)    (void* ptr, uint8_t channel, uint8_t note, uint8_t velo);
+typedef void (*setSizeFunc)     (void* ptr, uint width, uint height);
+typedef bool (*fileRequestFunc) (void* ptr, const char* key);
 
 // -----------------------------------------------------------------------
 // UI private data
@@ -194,100 +313,6 @@ struct UI::PrivateData {
     static PluginWindow& createNextWindow(UI* ui, uint width, uint height);
 };
 
-// -----------------------------------------------------------------------
-// Plugin Window, will pass some Window events to UI
-
-#if DISTRHO_PLUGIN_HAS_EXTERNAL_UI
-// TODO external ui stuff
-class PluginWindow
-{
-    UI* const ui;
-
-public:
-    explicit PluginWindow(UI* const uiPtr, UI::PrivateData* const pData, const uint width, const uint height)
-        : Window(pData->app, pData->winId, pData->scaleFactor, width, height, DISTRHO_UI_USER_RESIZABLE),
-          ui(uiPtr) {}
-
-    uint getWidth() const noexcept
-    {
-        return ui->getWidth();
-    }
-
-    uint getHeight() const noexcept
-    {
-        return ui->getHeight();
-    }
-
-    bool isVisible() const noexcept
-    {
-        return ui->isRunning();
-    }
-
-    uintptr_t getNativeWindowHandle() const noexcept
-    {
-        return 0;
-    }
-
-    DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(PluginWindow)
-};
-#else
-class PluginWindow : public Window
-{
-    UI* const ui;
-
-public:
-    explicit PluginWindow(UI* const uiPtr, UI::PrivateData* const pData, const uint width, const uint height)
-        : Window(pData->app, pData->winId, width, height, pData->scaleFactor, DISTRHO_UI_USER_RESIZABLE),
-          ui(uiPtr) {}
-
-protected:
-    void onFocus(const bool focus, const DGL_NAMESPACE::CrossingMode mode) override
-    {
-        DISTRHO_SAFE_ASSERT_RETURN(ui != nullptr,);
-
-        ui->uiFocus(focus, mode);
-    }
-
-    void onReshape(const uint width, const uint height) override
-    {
-        DISTRHO_SAFE_ASSERT_RETURN(ui != nullptr,);
-
-        ui->uiReshape(width, height);
-    }
-
-    void onScaleFactorChanged(const double scaleFactor) override
-    {
-        DISTRHO_SAFE_ASSERT_RETURN(ui != nullptr,);
-
-        ui->uiScaleFactorChanged(scaleFactor);
-    }
-
-# ifndef DGL_FILE_BROWSER_DISABLED
-    void onFileSelected(const char* const filename) override
-    {
-        DISTRHO_SAFE_ASSERT_RETURN(ui != nullptr,);
-
-#  if DISTRHO_PLUGIN_WANT_STATEFILES
-        if (char* const key = ui->uiData->uiStateFileKeyRequest)
-        {
-            ui->uiData->uiStateFileKeyRequest = nullptr;
-            // notify DSP
-            ui->setState(key, filename);
-            // notify UI
-            ui->stateChanged(key, filename);
-            std::free(key);
-            return;
-        }
-#  endif
-
-        ui->uiFileBrowserSelected(filename);
-    }
-# endif
-
-    DISTRHO_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR(PluginWindow)
-};
-#endif // !DISTRHO_PLUGIN_HAS_EXTERNAL_UI
-
 // -----------------------------------------------------------------------
 // UI private data fileRequestCallback, which requires PluginWindow definitions