Split BackendBinding from example/Utils into src/utils

This will make it possible to reuse the backend bindings for test suites

src/utils/OpenGLBinding.cpp

@@ -0,0 +1,56 @@
+// Copyright 2017 The NXT Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "BackendBinding.h"
+
+#include "GLFW/glfw3.h"
+
+namespace backend {
+    namespace opengl {
+        void Init(void* (*getProc)(const char*), nxtProcTable* procs, nxtDevice* device);
+        void HACKCLEAR();
+    }
+}
+
+namespace utils {
+    class OpenGLBinding : public BackendBinding {
+        public:
+            void SetupGLFWWindowHints() override {
+                #ifdef __APPLE__
+                    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
+                    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 1);
+                    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GLFW_TRUE);
+                    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+                #else
+                    glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 4);
+                    glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 5);
+                    glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GLFW_TRUE);
+                    glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
+                #endif
+            }
+            void GetProcAndDevice(nxtProcTable* procs, nxtDevice* device) override {
+                glfwMakeContextCurrent(window);
+                backend::opengl::Init(reinterpret_cast<void*(*)(const char*)>(glfwGetProcAddress), procs, device);
+            }
+            void SwapBuffers() override {
+                glfwSwapBuffers(window);
+                backend::opengl::HACKCLEAR();
+            }
+    };
+
+    BackendBinding* CreateOpenGLBinding() {
+        return new OpenGLBinding;
+    }
+
+}