Fix correct repainting of OpenGLContexts if a non-compositing window manager is used on linux

modules/juce_gui_basics/native/juce_linux_Windowing.cpp

@@ -2320,6 +2320,10 @@ public:
         XEvent nextEvent;
         ScopedXLock xlock;
 
+        // if we have opengl contexts then just repaint them all
+        // regardless if this is really necessary
+        repaintOpenGLContexts ();
+
         if (exposeEvent.window != windowH)
         {
             Window child;
@@ -2509,6 +2513,28 @@ public:
         return currentScaleFactor;
     }
 
+    //===============================================================================
+    void addOpenGLRepaintListener (Component* dummy)
+    {
+        if (dummy != nullptr)
+            glRepaintListeners.addIfNotAlreadyThere (dummy);
+    }
+
+    void removeOpenGLRepaintListener (Component* dummy)
+    {
+        if (dummy != nullptr)
+            glRepaintListeners.removeAllInstancesOf (dummy);
+    }
+
+    void repaintOpenGLContexts()
+    {
+        for (int i = 0; i < glRepaintListeners.size(); ++i)
+        {
+            if (Component* c = glRepaintListeners [i])
+                c->handleCommandMessage (0);
+        }
+    }
+
     //==============================================================================
     bool dontRepaint;
 
@@ -2668,6 +2694,7 @@ private:
     BorderSize<int> windowBorder;
     bool isAlwaysOnTop;
     double currentScaleFactor;
+    Array<Component*> glRepaintListeners;
     enum { KeyPressEventType = 2 };
 
     struct MotifWmHints
@@ -4124,6 +4151,18 @@ Rectangle<int> juce_LinuxScaledToPhysicalBounds(ComponentPeer* peer, const Recta
     return retval;
 }
 
+void juce_LinuxAddRepaintListener (ComponentPeer* peer, Component* dummy)
+{
+    if (LinuxComponentPeer* linuxPeer = dynamic_cast<LinuxComponentPeer*> (peer))
+        linuxPeer->addOpenGLRepaintListener (dummy);
+}
+
+void juce_LinuxRemoveRepaintListener (ComponentPeer* peer, Component* dummy)
+{
+    if (LinuxComponentPeer* linuxPeer = dynamic_cast<LinuxComponentPeer*> (peer))
+        linuxPeer->removeOpenGLRepaintListener (dummy);
+}
+
 //==============================================================================
 #if JUCE_MODAL_LOOPS_PERMITTED
 void JUCE_CALLTYPE NativeMessageBox::showMessageBox (AlertWindow::AlertIconType iconType,

modules/juce_opengl/native/juce_OpenGL_linux.h

@@ -28,11 +28,31 @@ extern XContext windowHandleXContext;
 
 //==============================================================================
 // Defined juce_linux_Windowing.cpp
-Rectangle<int> juce_LinuxScaledToPhysicalBounds(ComponentPeer* peer, const Rectangle<int>& bounds);
+Rectangle<int> juce_LinuxScaledToPhysicalBounds (ComponentPeer* peer, const Rectangle<int>& bounds);
+void juce_LinuxAddRepaintListener (ComponentPeer* peer, Component* dummy);
+void juce_LinuxRemoveRepaintListener (ComponentPeer* peer, Component* dummy);
 
 //==============================================================================
 class OpenGLContext::NativeContext
 {
+private:
+    class DummyComponent : public Component
+    {
+    public:
+        DummyComponent (OpenGLContext::NativeContext& nativeParentContext)
+            : native (nativeParentContext)
+        {
+        }
+
+        void handleCommandMessage (int commandId) override
+        {
+            if (commandId == 0)
+                native.triggerRepaint();
+        }
+    private:
+        OpenGLContext::NativeContext& native;
+    };
+
 public:
     NativeContext (Component& comp,
                    const OpenGLPixelFormat& cPixelFormat,
@@ -40,7 +60,7 @@ public:
                    bool /*useMultisampling*/,
                    OpenGLVersion)
         : component (comp), renderContext (0), embeddedWindow (0), swapFrames (0), bestVisual (0),
-          contextToShareWith (shareContext)
+          contextToShareWith (shareContext), context (nullptr), dummy (*this)
     {
         ScopedXLock xlock;
         XSync (display, False);
@@ -96,10 +116,14 @@ public:
         XFreeColormap (display, colourMap);
 
         XSync (display, False);
+
+        juce_LinuxAddRepaintListener (peer, &dummy);
     }
 
     ~NativeContext()
     {
+        juce_LinuxRemoveRepaintListener (component.getPeer(), &dummy);
+
         if (embeddedWindow != 0)
         {
             ScopedXLock xlock;
@@ -111,15 +135,17 @@ public:
             XFree (bestVisual);
     }
 
-    void initialiseOnRenderThread (OpenGLContext& context)
+    void initialiseOnRenderThread (OpenGLContext& c)
     {
         ScopedXLock xlock;
         renderContext = glXCreateContext (display, bestVisual, (GLXContext) contextToShareWith, GL_TRUE);
-        context.makeActive();
+        c.makeActive();
+        context = &c;
     }
 
     void shutdownOnRenderThread()
     {
+        context = nullptr;
         deactivateCurrentContext();
         glXDestroyContext (display, renderContext);
         renderContext = nullptr;
@@ -183,6 +209,12 @@ public:
     void* getRawContext() const noexcept        { return renderContext; }
     GLuint getFrameBufferID() const noexcept    { return 0; }
 
+    void triggerRepaint()
+    {
+        if (context != nullptr)
+            context->triggerRepaint();
+    }
+
     struct Locker { Locker (NativeContext&) {} };
 
 private:
@@ -195,6 +227,9 @@ private:
     XVisualInfo* bestVisual;
     void* contextToShareWith;
 
+    OpenGLContext* context;
+    DummyComponent dummy;
+
     JUCE_DECLARE_NON_COPYABLE_WITH_LEAK_DETECTOR (NativeContext)
 };