Moving graphics context creation around to hide actual creation.

Makes it easier to support APIs that don't have a concept of sharing.

src/xenia/ui/graphics_provider.h

@@ -0,0 +1,48 @@
+/**
+ ******************************************************************************
+ * Xenia : Xbox 360 Emulator Research Project                                 *
+ ******************************************************************************
+ * Copyright 2015 Ben Vanik. All rights reserved.                             *
+ * Released under the BSD license - see LICENSE in the root for more details. *
+ ******************************************************************************
+ */
+
+#ifndef XENIA_UI_GRAPHICS_PROVIDER_H_
+#define XENIA_UI_GRAPHICS_PROVIDER_H_
+
+#include <memory>
+
+namespace xe {
+namespace ui {
+
+class GraphicsContext;
+class Window;
+
+// Factory for graphics contexts.
+// All contexts created by the same provider will be able to share resources
+// according to the rules of the backing graphics API.
+class GraphicsProvider {
+ public:
+  virtual ~GraphicsProvider() = default;
+
+  // The 'main' window of an application, used to query provider information.
+  Window* main_window() const { return main_window_; }
+
+  // Creates a new graphics context and swapchain for presenting to a window.
+  virtual std::unique_ptr<GraphicsContext> CreateContext(
+      Window* target_window) = 0;
+
+  // Creates a new offscreen graphics context without a swapchain or immediate
+  // drawer.
+  virtual std::unique_ptr<GraphicsContext> CreateOffscreenContext() = 0;
+
+ protected:
+  explicit GraphicsProvider(Window* main_window) : main_window_(main_window) {}
+
+  Window* main_window_ = nullptr;
+};
+
+}  // namespace ui
+}  // namespace xe
+
+#endif  // XENIA_UI_GRAPHICS_PROVIDER_H_