t/gui: Add scene manager

src/xrt/targets/gui/CMakeLists.txt

@@ -18,6 +18,7 @@ set(SOURCE_FILES
 	gui_main.c
 	gui_ogl.c
 	gui_prober.c
+	gui_scene.cpp
 	gui_sdl2.c
 	../../../external/glad/gl.h
 	../../../external/glad/gl.c

src/xrt/targets/gui/gui_common.h

@@ -28,6 +28,7 @@ extern "C" {
 struct xrt_device;
 struct xrt_prober;
 struct time_state;
+struct gui_scene_manager;
 
 /*!
  * Common struct holding state for the GUI interface.
@@ -42,6 +43,8 @@ struct program
 	bool stopped;
 	bool initialized;
 
+	struct gui_scene_manager *gsm;
+
 	struct
 	{
 		SDL_Surface *sf;
@@ -59,6 +62,15 @@ struct program
 	struct gui_ogl_texture *texs[256];
 };
 
+/*!
+ * A single currently running scene.
+ */
+struct gui_scene
+{
+	void (*render)(struct gui_scene *, struct program *);
+	void (*destroy)(struct gui_scene *);
+};
+
 /*!
  * A OpenGL texture.
  *
@@ -156,6 +168,46 @@ gui_ogl_sink_create(const char *name,
 void
 gui_ogl_sink_update(struct gui_ogl_texture *);
 
+/*!
+ * Push the scene to the top of the lists.
+ *
+ * @ingroup gui
+ */
+void
+gui_scene_push_front(struct program *p, struct gui_scene *me);
+
+/*!
+ * Put a scene on the delete list, also removes it from any other list.
+ *
+ * @ingroup gui
+ */
+void
+gui_scene_delete_me(struct program *p, struct gui_scene *me);
+
+/*!
+ * Render the scenes.
+ *
+ * @ingroup gui
+ */
+void
+gui_scene_manager_render(struct program *p);
+
+/*!
+ * Initialize the scene manager.
+ *
+ * @ingroup gui
+ */
+void
+gui_scene_manager_init(struct program *p);
+
+/*!
+ * Destroy the scene manager.
+ *
+ * @ingroup gui
+ */
+void
+gui_scene_manager_destroy(struct program *p);
+
 
 #ifdef __cplusplus
 }

src/xrt/targets/gui/gui_scene.cpp

@@ -0,0 +1,96 @@
+// Copyright 2019, Collabora, Ltd.
+// SPDX-License-Identifier: BSL-1.0
+/*!
+ * @file
+ * @brief  SDL2 functions to drive the GUI.
+ * @author Jakob Bornecrantz <jakob@collabora.com>
+ * @ingroup gui
+ */
+
+
+#include "gui_common.h"
+
+#include <vector>
+
+
+struct gui_scene_manager
+{
+public:
+	std::vector<gui_scene *> scenes = {};
+	std::vector<gui_scene *> del = {};
+};
+
+extern "C" void
+gui_scene_push_front(struct program *p, struct gui_scene *me)
+{
+	auto &gsm = *p->gsm;
+
+	// Need to remove the scene if it is already on the list.
+	auto index = gsm.scenes.begin();
+	for (auto scene : gsm.scenes) {
+		if (scene != me) {
+			index++;
+			continue;
+		}
+
+		gsm.scenes.erase(index);
+		break;
+	}
+
+	// Now push it to the front.
+	gsm.scenes.push_back(me);
+}
+
+extern "C" void
+gui_scene_delete_me(struct program *p, struct gui_scene *me)
+{
+	auto &gsm = *p->gsm;
+
+	auto index = gsm.scenes.begin();
+	for (auto scene : gsm.scenes) {
+		if (scene != me) {
+			index++;
+			continue;
+		}
+
+		gsm.scenes.erase(index);
+		break;
+	}
+
+	gsm.del.push_back(me);
+}
+
+extern "C" void
+gui_scene_manager_render(struct program *p)
+{
+	auto &gsm = *p->gsm;
+	auto copy = gsm.scenes;
+
+	for (auto scene : copy) {
+		scene->render(scene, p);
+	}
+
+	copy = gsm.del;
+	gsm.del.clear();
+	for (auto scene : copy) {
+		scene->destroy(scene);
+	}
+
+	// If there are no scenes left stop the program.
+	if (gsm.scenes.size() == 0) {
+		p->stopped = true;
+	}
+}
+
+extern "C" void
+gui_scene_manager_init(struct program *p)
+{
+	p->gsm = new gui_scene_manager;
+}
+
+extern "C" void
+gui_scene_manager_destroy(struct program *p)
+{
+	delete p->gsm;
+	p->gsm = NULL;
+}