add Widget module

runtime/lib/widget.rb

@@ -0,0 +1,33 @@
+module Widget
+  def initialize
+    @x = 0
+    @y = 0
+    @width = 0
+    @height = 0
+  end
+
+  def children
+    []
+  end
+
+  def resize(x, y, width, height)
+    @x = x
+    @y = y
+    @width = width
+    @height = height
+  end
+
+  def draw
+    if @x > 0 and @y > 0
+      render_begin
+      render
+      children.each do |child|
+        child.draw
+      end
+      render_end
+    end
+  end
+
+  def render_end
+  end
+end

runtime/lib/window.rb

@@ -1,6 +1,8 @@
 require "set"
 
 class Window
+  include Widget
+
   @windows = Set.new
 
   class << self

runtime/main.rb

@@ -5,6 +5,7 @@ end
 def load_lib_files
   require "gl_program"
   require "runtime"
+  require "widget"
   require "window"
 end
 

src/Widget.cc

@@ -0,0 +1,23 @@
+#include "Widget.h"
+#include "ruby.h"
+#include "gl3w.h"
+
+static VALUE ruby_class;
+
+static VALUE Widget_render_begin(VALUE self)
+{
+    int x = FIX2INT(rb_iv_get(self, "@x"));
+    int y = FIX2INT(rb_iv_get(self, "@y"));
+    int width = FIX2INT(rb_iv_get(self, "@width"));
+    int height = FIX2INT(rb_iv_get(self, "@height"));
+
+    glViewport(x, y, width, height);
+
+    return Qnil;
+}
+
+void Widget_Init()
+{
+    ruby_class = rb_define_module("Widget");
+    rb_define_method(ruby_class, "render_begin", (VALUE(*)(...))Widget_render_begin, 0);
+}

src/Widget.h

@@ -0,0 +1,6 @@
+#ifndef WIDGET_H
+#define WIDGET_H
+
+void Widget_Init();
+
+#endif

src/main.cc

@@ -4,6 +4,7 @@
 #include "Font.h"
 #include "GLProgram.h"
 #include "GLShader.h"
+#include "Widget.h"
 #include "Window.h"
 
 using namespace std;
@@ -55,6 +56,7 @@ static int bootstrap()
     Font_Init();
     GLProgram_Init();
     GLShader_Init();
+    Widget_Init();
     Window_Init();
 
     rb_eval_string_protect(