OpenGL fix (missing macOS).

mrv2/lib/mrvGL/mrvGLOffscreenContext.cpp

@@ -141,7 +141,6 @@ namespace mrv
         TLRENDER_P();
 
 #if defined(_WIN32)
-        ///! Note:  Is this is not thread safe?  Not sure
         p.win->context(nullptr, true);
         p.win->make_current();
         if (!p.win->context())

mrv2/lib/mrvGL/mrvGLViewport.cpp

@@ -41,6 +41,18 @@
 
 #include "mrvApp/mrvSettingsObject.h"
 
+#include <FL/platform.H>
+#undef None
+
+#ifdef FLTK_USE_X11
+#    include <X11/Xlib.h>
+#    include <GL/glx.h>
+#endif
+
+#ifdef FLTK_USE_WAYLAND
+#    include <EGL/egl.h>
+#endif
+
 namespace
 {
     const char* kModule = "view";
@@ -179,11 +191,66 @@ namespace mrv
         return TimelineViewport::handle(event);
     }
 
+    void Viewport::make_current()
+    {
+        GLContext ctx = this->context();
+        if (!ctx)
+            return TimelineViewport::make_current();
+
+#ifdef _WIN32
+        HGLRC cur_hglrc = wglGetCurrentContext();
+        HGLRC hglrc = fl_win32_glcontext(ctx);
+        if (hglrc == cur_hglrc)
+            return;
+
+        HWND hwnd = fl_win32_xid(this);
+        assert(hwnd);
+        HDC hdc = fl_GetDC(hwnd);
+        assert(hdc);
+        assert(hglrc);
+        wglMakeCurrent(hdc, hglrc);
+#endif
+
+#ifdef __linux__
+#    ifdef FLTK_USE_X11
+        auto dpy = fl_x11_display();
+        if (dpy)
+        {
+            auto win = fl_x11_xid(this);
+            assert(win);
+            glXMakeCurrent(dpy, win, (GLXContext)ctx);
+        }
+#    endif
+#    ifdef FLTK_USE_WAYLAND
+        auto wldpy = fl_wl_display();
+        if (wldpy)
+        {
+            auto eglctx = fl_wl_glcontext(ctx);
+            EGLContext currentContext = eglGetCurrentContext();
+            if (currentContext == eglctx)
+                return;
+
+            auto win = fl_wl_xid(this);
+            assert(win);
+
+            auto surface = fl_wl_surface(win);
+            eglMakeCurrent(wldpy, surface, surface, eglctx);
+        }
+#    endif
+#endif
+
+#ifdef __APPLE__
+        // CGLSetCurrentContext(ctx);
+#endif
+    }
+
     void Viewport::draw()
     {
         TLRENDER_P();
         MRV2_GL();
 
+        make_current();
+
         if (!valid())
         {
             _initializeGL();

mrv2/lib/mrvGL/mrvGLViewport.h

@@ -37,6 +37,9 @@ namespace mrv
         //! Refresh window by clearing the associated resources.
         void refresh() override;
 
+        //! Force context to be made current, unlike FLTK's optimized approach.
+        void make_current();
+
     protected:
         void _initializeGL();
         void _initializeGLResources();