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/* light.c
此程序利用GLUT绘制一个OpenGL窗口，并显示一个加以光照的球。
*/
/* 由于头文件glut.h中已经包含了头文件gl.h和glu.h，所以只需要include 此文件*/
# include <GL/glut.h>
# include <stdlib.h>
    
/* 初始化材料属性、光源属性、光照模型，打开深度缓冲区 */
void init ( void )
{
    GLfloat mat_specular [ ] = { 1.0, 1.0, 1.0, 1.0 };
    GLfloat mat_shininess [ ] = { 50.0 };
    GLfloat light_position [ ] = { 1.0, 1.0, 1.0, 0.0 };
    glClearColor ( 0.0, 0.0, 0.0, 0.0 );
    glShadeModel ( GL_SMOOTH );
    glMaterialfv ( GL_FRONT, GL_SPECULAR, mat_specular);
    glMaterialfv ( GL_FRONT, GL_SHININESS, mat_shininess);
    glLightfv ( GL_LIGHT0, GL_POSITION, light_position);
    glEnable (GL_LIGHTING);
    glEnable (GL_LIGHT0);
    glEnable (GL_DEPTH_TEST);
}
/*调用GLUT函数，绘制一个球*/
void display ( void )
{
    glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
    glutSolidSphere (1.0, 40, 50);
    glFlush ();
}
    
int main(int argc, char** argv)
{
    /* GLUT环境初始化*/
    glutInit (&argc, argv);
    /* 显示模式初始化 */
    glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH);
    /* 定义窗口大小 */
    glutInitWindowSize (300, 300);
    /* 定义窗口位置 */
    glutInitWindowPosition (100, 100);
    /* 显示窗口，窗口标题为执行函数名 */
    glutCreateWindow ( argv [ 0 ] );
    /* 调用OpenGL初始化函数 */
    init ( );
    /* 注册OpenGL绘图函数 */
    glutDisplayFunc ( display );
    // /* 进入GLUT消息循环，开始执行程序 */
    glutMainLoop( );
    return 0;
} 

#include <X11/Xlib.h>
#include <X11/Xatom.h>
#include <X11/Xutil.h>
#include <cairo.h>
#include <cairo-xlib.h>

#include <stdio.h>
#include <stdlib.h>

/*! Simple Cairo/Xlib example.
 * @author Bernhard R. Fischer, 2048R/5C5FFD47 <bf@abenteuerland.at>.
 * @version 2014110801
 * Compile with
 * gcc -Wall $(pkg-config --libs --cflags cairo x11) -o cairo_xlib_simple cairo_xlib_simple.c
 */

/*! Check for Xlib Mouse/Keypress events. All other events are discarded. 
 * @param sfc Pointer to Xlib surface.
 * @param block If block is set to 0, this function always returns immediately
 * and does not block. if set to a non-zero value, the function will block
 * until the next event is received.
 * @return The function returns 0 if no event occured (and block is set). A
 * positive value indicates that a key was pressed and the X11 key symbol as
 * defined in <X11/keysymdef.h> is returned. A negative value indicates a mouse
 * button event. -1 is button 1 (left button), -2 is the middle button, and -3
 * the right button.
 */
int cairo_check_event(cairo_surface_t *sfc, int block)
{
   char keybuf[8];
   KeySym key;
   XEvent e;

   for (;;)
   {
      if (block || XPending(cairo_xlib_surface_get_display(sfc)))
         XNextEvent(cairo_xlib_surface_get_display(sfc), &e);
      else 
         return 0;

      switch (e.type)
      {
         case ButtonPress:
            return -e.xbutton.button;
         case KeyPress:
            XLookupString(&e.xkey, keybuf, sizeof(keybuf), &key, NULL);
            return key;
         default:
            fprintf(stderr, "Dropping unhandled XEevent.type = %d.\n", e.type);
      }
   }
}


/*! Open an X11 window and create a cairo surface base on that window.
 * @param x Width of window.
 * @param y Height of window.
 * @return Returns a pointer to a valid Xlib cairo surface. The function does
 * not return on error (exit(3)).
 */
cairo_surface_t *cairo_create_x11_surface0(int x, int y)
{
   Display *dsp;
   Drawable da;
   int screen;
   cairo_surface_t *sfc;

   if ((dsp = XOpenDisplay(NULL)) == NULL)
      exit(1);
   screen = DefaultScreen(dsp);
   da = XCreateSimpleWindow(dsp, DefaultRootWindow(dsp), 0, 0, x, y, 0, 0, 0);
   XSelectInput(dsp, da, ButtonPressMask | KeyPressMask);
   XMapWindow(dsp, da);

   sfc = cairo_xlib_surface_create(dsp, da, DefaultVisual(dsp, screen), x, y);
   cairo_xlib_surface_set_size(sfc, x, y);

   return sfc;
}


/*! Destroy cairo Xlib surface and close X connection.
 */
void cairo_close_x11_surface(cairo_surface_t *sfc)
{
   Display *dsp = cairo_xlib_surface_get_display(sfc);

   cairo_surface_destroy(sfc);
   XCloseDisplay(dsp);
}


int main(int argc, char **argv)
{
   cairo_surface_t *sfc;
   cairo_t *ctx;

   sfc = cairo_create_x11_surface0(500, 500);

   ctx = cairo_create(sfc);
   cairo_set_source_rgb(ctx, 1, 1, 1);
   cairo_paint(ctx);
   cairo_move_to(ctx, 20, 20);
   cairo_line_to(ctx, 200, 400);
   cairo_line_to(ctx, 450, 100);
   cairo_line_to(ctx, 20, 20);
   cairo_set_source_rgb(ctx, 0, 0, 1);
   cairo_fill_preserve(ctx);
   cairo_set_line_width(ctx, 5);
   cairo_set_source_rgb(ctx, 1, 1, 0);
   cairo_stroke(ctx);
   cairo_destroy(ctx);

   cairo_check_event(sfc, 1);

   cairo_close_x11_surface(sfc);

   return 0;
}