xcb：画直线，曲线，矩形

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

#include <xcb/xcb.h>

int
main ()
{
  xcb_connection_t    *c;
  xcb_screen_t        *screen;
  xcb_drawable_t       win;
  xcb_gcontext_t       foreground;
  xcb_generic_event_t *e;
  uint32_t             mask = 0;
  uint32_t             values[2];

  /* geometric objects */
  xcb_point_t          points[] = {
    {10, 10},
    {10, 20},
    {20, 10},
    {20, 20}};

  xcb_point_t          polyline[] = {
    {50, 10},
    { 5, 20},     /* rest of points are relative */
    {25,-20},
    {10, 10}};

  xcb_segment_t        segments[] = {
    {100, 10, 140, 30},
    {110, 25, 130, 60}};

  xcb_rectangle_t      rectangles[] = {
    { 10, 50, 40, 20},
    { 80, 50, 10, 40}};

  xcb_arc_t            arcs[] = {
    {10, 100, 60, 40, 0, 90 << 6},
    {90, 100, 55, 40, 0, 270 << 6}};

  /* Open the connection to the X server */
  c = xcb_connect (NULL, NULL);

  /* Get the first screen */
  screen = xcb_setup_roots_iterator (xcb_get_setup (c)).data;

  /* Create black (foreground) graphic context */
  win = screen->root;

  foreground = xcb_generate_id (c);
  mask = XCB_GC_FOREGROUND | XCB_GC_GRAPHICS_EXPOSURES;
  values[0] = screen->black_pixel;
  values[1] = 0;
  xcb_create_gc (c, foreground, win, mask, values);

  /* Ask for our window's Id */
  win = xcb_generate_id(c);

  /* Create the window */
  mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
  values[0] = screen->white_pixel;
  values[1] = XCB_EVENT_MASK_EXPOSURE;
  xcb_create_window (c,                             /* Connection          */
                     XCB_COPY_FROM_PARENT,          /* depth               */
                     win,                           /* window Id           */
                     screen->root,                  /* parent window       */
                     0, 0,                          /* x, y                */
                     150, 150,                      /* width, height       */
                     10,                            /* border_width        */
                     XCB_WINDOW_CLASS_INPUT_OUTPUT, /* class               */
                     screen->root_visual,           /* visual              */
                     mask, values);                 /* masks */

  /* Map the window on the screen */
  xcb_map_window (c, win);


  /* We flush the request */
  xcb_flush (c);

  while ((e = xcb_wait_for_event (c))) {
    switch (e->response_type & ~0x80) {
    case XCB_EXPOSE: {
      /* We draw the points */
      xcb_poly_point (c, XCB_COORD_MODE_ORIGIN, win, foreground, 4, points);

      /* We draw the polygonal line */
      xcb_poly_line (c, XCB_COORD_MODE_PREVIOUS, win, foreground, 4, polyline);

      /* We draw the segements */
      xcb_poly_segment (c, win, foreground, 2, segments);

      /* We draw the rectangles */
      xcb_poly_rectangle (c, win, foreground, 2, rectangles);

      /* We draw the arcs */
      xcb_poly_arc (c, win, foreground, 2, arcs);

      /* We flush the request */
      xcb_flush (c);

      break;
    }
    default: {
      /* Unknown event type, ignore it */
      break;
    }
    }
    /* Free the Generic Event */
    free (e);
  }

  return 0;
}

编译

$ gcc main.c -lxcb