Merge branch 'connagh-opteran-feature/lockable-contexts'

morph/Visual.h

@@ -81,6 +81,9 @@
 #include <cstddef>
 
 #include <morph/VisualDefaultShaders.h>
+#ifndef OWNED_MODE
+#include <mutex>
+#endif
 
 // Use Lode Vandevenne's PNG encoder
 #define LODEPNG_NO_COMPILE_DECODER 1
@@ -261,6 +264,33 @@ namespace morph {
         // A callback friendly wrapper
         static void set_context (morph::Visual<glver>* _v) { _v->setContext(); };
 
+        //! Lock the context  to prevent accessing the OpenGL context from multiple threads
+        //! then obtain the context.
+        void lockContext()
+        {
+            this->context_.lock();
+            this->setContext();
+        }
+
+        //! Attempt to lock the context . If the lock is obtained, set the OpenGL context
+        //! and return true. If the lock is not obtained, return false.
+        bool tryLockContext()
+        {
+            if (this->context_.try_lock()) {
+                this->setContext();
+                return true;
+            } else {
+                return false;
+            }
+        }
+
+        //! Release the OpenGL context and unlock the context .
+        void unlockContext()
+        {
+            this->releaseContext();
+            this->context_mutex.unlock();
+        }
+
         //! Release the OpenGL context
         void releaseContext() { glfwMakeContextCurrent (nullptr); }
         // A callback friendly wrapper
@@ -1070,6 +1100,11 @@ namespace morph {
         //! The window (and OpenGL context) for this Visual
         morph::win_t* window = nullptr;
 
+#ifndef OWNED_MODE
+        //! Context mutex to prevent contexts being acquired in a non-threadsafe manner.
+        std::mutex context_mutex;
+#endif
+
         //! Current window width
         int window_w = 640;
         //! Current window height
@@ -1256,6 +1291,7 @@ namespace morph {
                 std::cout << "Shift-Down: Halve cyl proj radius\n";
                 std::cout << "Ctrl-Up: Double cyl proj height\n";
                 std::cout << "Ctrl-Down: Halve cyl proj height\n";
+                std::cout << std::flush;
             }
 
             if (_key == key::l && (mods & keymod::control) && action == keyaction::press) {