Add rendering implementation for LWJGL

imgui-lwjgl3/src/main/java/InputHandler.java

@@ -0,0 +1,125 @@
+import org.lwjgl.glfw.GLFWKeyCallback;
+import org.lwjgl.glfw.GLFWMouseButtonCallback;
+
+import static org.lwjgl.glfw.GLFW.*;
+
+public class InputHandler {
+    private static long window;
+    private static final int KEYBOARD_SIZE = 512;
+    private static final int MOUSE_SIZE = 16;
+
+    private static int[] keyStates = new int[KEYBOARD_SIZE];
+    private static boolean[] activeKeys = new boolean[KEYBOARD_SIZE];
+
+    private static int[] mouseButtonStates = new int[MOUSE_SIZE];
+    private static boolean[] activeMouseButtons = new boolean[MOUSE_SIZE];
+    private static long lastMouseNS = 0;
+    private static long mouseDoubleClickPeriodNS = 1000000000 / 5; //5th of a second for double click.
+
+    private static int NO_STATE = -1;
+
+    protected static GLFWKeyCallback keyboard = new GLFWKeyCallback()
+    {
+        @Override
+        public void invoke(long window, int key, int scancode, int action, int mods)
+        {
+            activeKeys[key] = action != GLFW_RELEASE;
+            keyStates[key] = action;
+        }
+    };
+
+    protected static GLFWMouseButtonCallback mouse = new GLFWMouseButtonCallback()
+    {
+        @Override
+        public void invoke(long window, int button, int action, int mods)
+        {
+            activeMouseButtons[button] = action != GLFW_RELEASE;
+            mouseButtonStates[button] = action;
+        }
+    };
+
+    protected static void init(long window)
+    {
+        InputHandler.window = window;
+        resetKeyboard();
+        resetMouse();
+    }
+
+    protected static void update()
+    {
+        resetKeyboard();
+        resetMouse();
+    }
+
+    private static void resetKeyboard()
+    {
+        for (int i = 0; i < keyStates.length; i++)
+        {
+            keyStates[i] = NO_STATE;
+        }
+    }
+
+    private static void resetMouse()
+    {
+        for (int i = 0; i < mouseButtonStates.length; i++)
+        {
+            mouseButtonStates[i] = NO_STATE;
+        }
+
+        long now = System.nanoTime();
+
+        if (now - lastMouseNS > mouseDoubleClickPeriodNS)
+            lastMouseNS = 0;
+    }
+
+    public static boolean keyDown(int key)
+    {
+        return activeKeys[key];
+    }
+
+    public static boolean keyPressed(int key)
+    {
+        return keyStates[key] == GLFW_PRESS;
+    }
+
+    public static boolean keyReleased(int key)
+    {
+        return keyStates[key] == GLFW_RELEASE;
+    }
+
+    public static boolean mouseButtonDown(int button)
+    {
+        return activeMouseButtons[button];
+    }
+
+    public static boolean mouseButtonPressed(int button)
+    {
+        return mouseButtonStates[button] == GLFW_RELEASE;
+    }
+
+    public static boolean mouseButtonReleased(int button)
+    {
+        boolean flag = mouseButtonStates[button] == GLFW_RELEASE;
+
+        if (flag)
+            lastMouseNS = System.nanoTime();
+
+        return flag;
+    }
+
+    public static boolean mouseButtonDoubleClicked(int button)
+    {
+        long last = lastMouseNS;
+        boolean flag = mouseButtonReleased(button);
+
+        long now = System.nanoTime();
+
+        if (flag && now - last < mouseDoubleClickPeriodNS)
+        {
+            lastMouseNS = 0;
+            return true;
+        }
+
+        return false;
+    }
+}