From ecc2d3ce359bf507b299cb3f52a44fcc1ae51260 Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Fri, 1 Jul 2016 19:21:02 -0400
Subject: [PATCH] add initial Window class

---
 src/gui/Window.cc | 166 ++++++++++++++++++++++++++++++++++++++++++++++
 src/gui/Window.h  |  21 ++++++
 2 files changed, 187 insertions(+)
 create mode 100644 src/gui/Window.cc
 create mode 100644 src/gui/Window.h

diff --git a/src/gui/Window.cc b/src/gui/Window.cc
new file mode 100644
index 0000000..eba7454
--- /dev/null
+++ b/src/gui/Window.cc
@@ -0,0 +1,166 @@
+#include "gl3w.h"
+#include "Window.h"
+
+#define INITIAL_WIDTH   500
+#define INITIAL_HEIGHT  500
+
+/**
+ * Initialize SDL.
+ *
+ * @retval true SDL was loaded successfully.
+ * @retval false Loading SDL failed.
+ */
+static bool Initialize_SDL()
+{
+    static bool initialized = false;
+
+    if (initialized)
+    {
+        return true;
+    }
+
+    if (SDL_Init(SDL_INIT_VIDEO) != 0)
+    {
+        return false;
+    }
+
+    atexit(SDL_Quit);
+
+    initialized = true;
+    return true;
+}
+
+/**
+ * Initialize OpenGL.
+ *
+ * @retval true OpenGL was loaded successfully.
+ * @retval false Loading OpenGL failed.
+ */
+static bool Initialize_OpenGL()
+{
+    if (gl3wInit() != 0)
+    {
+        /* Failed to gl3wInit() */
+        return false;
+    }
+
+    if (!gl3wIsSupported(3, 0))
+    {
+        /* OpenGL 3.0 is not supported */
+        return false;
+    }
+
+    glEnable(GL_SCISSOR_TEST);
+    glActiveTexture(GL_TEXTURE0);
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+    return true;
+}
+
+/**
+ * Create a Window.
+ *
+ * @retval true The Window was created successfully.
+ * @retval false There was an error while creating the Window.
+ */
+bool Window::create()
+{
+    if (!Initialize_SDL())
+    {
+        return false;
+    }
+
+    m_window = SDL_CreateWindow(
+            "jes",
+            SDL_WINDOWPOS_UNDEFINED,
+            SDL_WINDOWPOS_UNDEFINED,
+            INITIAL_WIDTH,
+            INITIAL_HEIGHT,
+            SDL_WINDOW_OPENGL | SDL_WINDOW_RESIZABLE);
+    if (m_window == NULL)
+    {
+        return false;
+    }
+
+    (void)SDL_GL_CreateContext(m_window);
+
+    if (!Initialize_OpenGL())
+    {
+        return false;
+    }
+
+    m_exit_requested = false;
+
+    resize();
+
+    return true;
+}
+
+/**
+ * Run the Window event loop.
+ *
+ * TODO: make this a static method to support multiple GUI windows.
+ */
+void Window::run_event_loop()
+{
+    SDL_Event event;
+
+    while ((!m_exit_requested) && SDL_WaitEvent(&event))
+    {
+        handle_event(event);
+    }
+}
+
+/**
+ * Handle a SDL event.
+ *
+ * @retval true E
+ */
+void Window::handle_event(SDL_Event & event)
+{
+    switch (event.type)
+    {
+    case SDL_QUIT:
+        m_exit_requested = true;
+        break;
+
+    case SDL_KEYDOWN:
+        switch (event.key.keysym.sym)
+        {
+        case SDLK_ESCAPE:
+            m_exit_requested = true;
+            break;
+        }
+        break;
+
+    case SDL_WINDOWEVENT:
+        switch (event.window.event)
+        {
+        case SDL_WINDOWEVENT_EXPOSED:
+            redraw();
+            break;
+        case SDL_WINDOWEVENT_RESIZED:
+            resize();
+            redraw();
+            break;
+        }
+        break;
+    }
+}
+
+void Window::resize()
+{
+    int width;
+    int height;
+    SDL_GetWindowSize(m_window, &width, &height);
+    glViewport(0, 0, width, height);
+}
+
+void Window::redraw()
+{
+    glClearColor (0.0, 0.0, 0.0, 0.0);
+    glClear(GL_COLOR_BUFFER_BIT);
+
+    SDL_GL_SwapWindow(m_window);
+}
diff --git a/src/gui/Window.h b/src/gui/Window.h
new file mode 100644
index 0000000..d79605b
--- /dev/null
+++ b/src/gui/Window.h
@@ -0,0 +1,21 @@
+#ifndef WINDOW_H
+#define WINDOW_H
+
+#include <SDL.h>
+
+class Window
+{
+public:
+    bool create();
+    void run_event_loop();
+
+protected:
+    void resize();
+    void redraw();
+    void handle_event(SDL_Event & event);
+
+    SDL_Window * m_window;
+    bool m_exit_requested;
+};
+
+#endif