text: /*
   * XCB input grabber
   * Copyright (C) 2014 Luca Barbato <lu_zero@gentoo.org>
   *
   * This file is part of FFmpeg.
   *
   * FFmpeg is free software; you can redistribute it and/or
   * modify it under the terms of the GNU Lesser General Public
   * License as published by the Free Software Foundation; either
   * version 2.1 of the License, or (at your option) any later version.
   *
   * FFmpeg is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public
   * License along with FFmpeg; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
   */
  
  #include "config.h"
  
  #include <stdlib.h>
  #include <xcb/xcb.h>
  
  #if CONFIG_LIBXCB_XFIXES
  #include <xcb/xfixes.h>
  #endif
  
  #if CONFIG_LIBXCB_SHM
  #include <sys/shm.h>
  #include <xcb/shm.h>
  #endif
  
  #if CONFIG_LIBXCB_SHAPE
  #include <xcb/shape.h>
  #endif
  
  #include "libavutil/internal.h"
  #include "libavutil/mathematics.h"
  #include "libavutil/opt.h"
  #include "libavutil/parseutils.h"
  #include "libavutil/time.h"
  
  #include "libavformat/avformat.h"
  #include "libavformat/internal.h"
  
  typedef struct XCBGrabContext {
      const AVClass *class;
  
      uint8_t *buffer;
  
      xcb_connection_t *conn;
      xcb_screen_t *screen;
      xcb_window_t window;
  #if CONFIG_LIBXCB_SHM
      xcb_shm_seg_t segment;
  #endif
      int64_t time_frame;
      AVRational time_base;
  
      int x, y;
      int width, height;
      int frame_size;
      int bpp;
  
      int draw_mouse;
      int follow_mouse;
      int show_region;
      int region_border;
      int centered;
  
      const char *video_size;
      const char *framerate;
  
      int has_shm;
  } XCBGrabContext;
  
  #define FOLLOW_CENTER -1
  
  #define OFFSET(x) offsetof(XCBGrabContext, x)
  #define D AV_OPT_FLAG_DECODING_PARAM
  static const AVOption options[] = {
      { "x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
      { "y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
      { "grab_x", "Initial x coordinate.", OFFSET(x), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
      { "grab_y", "Initial y coordinate.", OFFSET(y), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, INT_MAX, D },
      { "video_size", "A string describing frame size, such as 640x480 or hd720.", OFFSET(video_size), AV_OPT_TYPE_STRING, {.str = "vga" }, 0, 0, D },
      { "framerate", "", OFFSET(framerate), AV_OPT_TYPE_STRING, {.str = "ntsc" }, 0, 0, D },
      { "draw_mouse", "Draw the mouse pointer.", OFFSET(draw_mouse), AV_OPT_TYPE_INT, { .i64 = 1 }, 0, 1, D },
      { "follow_mouse", "Move the grabbing region when the mouse pointer reaches within specified amount of pixels to the edge of region.",
        OFFSET(follow_mouse), AV_OPT_TYPE_INT, { .i64 = 0 },  FOLLOW_CENTER, INT_MAX, D, "follow_mouse" },
      { "centered", "Keep the mouse pointer at the center of grabbing region when following.", 0, AV_OPT_TYPE_CONST, { .i64 = -1 }, INT_MIN, INT_MAX, D, "follow_mouse" },
      { "show_region", "Show the grabbing region.", OFFSET(show_region), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, D },
      { "region_border", "Set the region border thickness.", OFFSET(region_border), AV_OPT_TYPE_INT, { .i64 = 3 }, 1, 128, D },
      { NULL },
  };
  
  static const AVClass xcbgrab_class = {
      .class_name = "xcbgrab indev",
      .item_name  = av_default_item_name,
      .option     = options,
      .version    = LIBAVUTIL_VERSION_INT,
      .category   = AV_CLASS_CATEGORY_DEVICE_VIDEO_INPUT,
  };
  
  static int xcbgrab_reposition(AVFormatContext *s,
                                xcb_query_pointer_reply_t *p,
                                xcb_get_geometry_reply_t *geo)
  {
      XCBGrabContext *c = s->priv_data;
      int x = c->x, y = c->y;
      int w = c->width, h = c->height, f = c->follow_mouse;
      int p_x, p_y;
  
      if (!p || !geo)
          return AVERROR(EIO);
  
      p_x = p->win_x;
      p_y = p->win_y;
  
      if (f == FOLLOW_CENTER) {
          x = p_x - w / 2;
          y = p_y - h / 2;
      } else {
          int left   = x + f;
          int right  = x + w - f;
          int top    = y + f;
          int bottom = y + h - f;
          if (p_x > right) {
              x += p_x - right;
          } else if (p_x < left) {
              x -= left - p_x;
          }
          if (p_y > bottom) {
              y += p_y - bottom;
          } else if (p_y < top) {
              y -= top - p_y;
          }
      }
  
      c->x = FFMIN(FFMAX(0, x), geo->width  - w);
      c->y = FFMIN(FFMAX(0, y), geo->height - h);
  
      return 0;
  }
  
  static int xcbgrab_frame(AVFormatContext *s, AVPacket *pkt)
  {
      XCBGrabContext *c = s->priv_data;
      xcb_get_image_cookie_t iq;
      xcb_get_image_reply_t *img;
      xcb_drawable_t drawable = c->screen->root;
      xcb_generic_error_t *e = NULL;
      uint8_t *data;
      int length, ret;
  
      iq  = xcb_get_image(c->conn, XCB_IMAGE_FORMAT_Z_PIXMAP, drawable,
                          c->x, c->y, c->width, c->height, ~0);
  
      img = xcb_get_image_reply(c->conn, iq, &e);
  
      if (e) {
          av_log(s, AV_LOG_ERROR,
                 "Cannot get the image data "
                 "event_error: response_type:%u error_code:%u "
                 "sequence:%u resource_id:%u minor_code:%u major_code:%u.\n",
                 e->response_type, e->error_code,
                 e->sequence, e->resource_id, e->minor_code, e->major_code);
          return AVERROR(EACCES);
      }
  
      if (!img)
          return AVERROR(EAGAIN);
  
      data   = xcb_get_image_data(img);
      length = xcb_get_image_data_length(img);
  
      ret = av_new_packet(pkt, length);
  
      if (!ret)
          memcpy(pkt->data, data, length);
  
      free(img);
  
      return ret;
  }
  
  static void wait_frame(AVFormatContext *s, AVPacket *pkt)
  {
      XCBGrabContext *c = s->priv_data;
      int64_t curtime, delay;
      int64_t frame_time = av_rescale_q(1, c->time_base, AV_TIME_BASE_Q);
  
      c->time_frame += frame_time;
  
      for (;;) {
          curtime = av_gettime();
          delay   = c->time_frame - curtime;
          if (delay <= 0)
              break;
          av_usleep(delay);
      }
  
      pkt->pts = curtime;
  }
  
  #if CONFIG_LIBXCB_SHM
  static int check_shm(xcb_connection_t *conn)
  {
      xcb_shm_query_version_cookie_t cookie = xcb_shm_query_version(conn);
      xcb_shm_query_version_reply_t *reply;
  
      reply = xcb_shm_query_version_reply(conn, cookie, NULL);
      if (reply) {
          free(reply);
          return 1;
      }
  
      return 0;
  }
  
  static int allocate_shm(AVFormatContext *s)
  {
      XCBGrabContext *c = s->priv_data;
      int size = c->frame_size + AV_INPUT_BUFFER_PADDING_SIZE;
      uint8_t *data;
      int id;
  
      if (c->buffer)
          return 0;
      id = shmget(IPC_PRIVATE, size, IPC_CREAT | 0777);
      if (id == -1) {
          char errbuf[1024];
          int err = AVERROR(errno);
          av_strerror(err, errbuf, sizeof(errbuf));
          av_log(s, AV_LOG_ERROR, "Cannot get %d bytes of shared memory: %s.\n",
                 size, errbuf);
          return err;
      }
      xcb_shm_attach(c->conn, c->segment, id, 0);
      data = shmat(id, NULL, 0);
      shmctl(id, IPC_RMID, 0);
      if ((intptr_t)data == -1 || !data)
          return AVERROR(errno);
      c->buffer = data;
      return 0;
  }
  
  static int xcbgrab_frame_shm(AVFormatContext *s, AVPacket *pkt)
  {
      XCBGrabContext *c = s->priv_data;
      xcb_shm_get_image_cookie_t iq;
      xcb_shm_get_image_reply_t *img;
      xcb_drawable_t drawable = c->screen->root;
      xcb_generic_error_t *e = NULL;
      int ret;
  
      ret = allocate_shm(s);
      if (ret < 0)
          return ret;
  
      iq = xcb_shm_get_image(c->conn, drawable,
                             c->x, c->y, c->width, c->height, ~0,
                             XCB_IMAGE_FORMAT_Z_PIXMAP, c->segment, 0);
      img = xcb_shm_get_image_reply(c->conn, iq, &e);
  
      xcb_flush(c->conn);
  
      if (e) {
          av_log(s, AV_LOG_ERROR,
                 "Cannot get the image data "
                 "event_error: response_type:%u error_code:%u "
                 "sequence:%u resource_id:%u minor_code:%u major_code:%u.\n",
                 e->response_type, e->error_code,
                 e->sequence, e->resource_id, e->minor_code, e->major_code);
  
          return AVERROR(EACCES);
      }
  
      free(img);
  
      pkt->data = c->buffer;
      pkt->size = c->frame_size;
  
      return 0;
  }
  #endif /* CONFIG_LIBXCB_SHM */
  
  #if CONFIG_LIBXCB_XFIXES
  static int check_xfixes(xcb_connection_t *conn)
  {
      xcb_xfixes_query_version_cookie_t cookie;
      xcb_xfixes_query_version_reply_t *reply;
  
      cookie = xcb_xfixes_query_version(conn, XCB_XFIXES_MAJOR_VERSION,
                                        XCB_XFIXES_MINOR_VERSION);
      reply  = xcb_xfixes_query_version_reply(conn, cookie, NULL);
  
      if (reply) {
          free(reply);
          return 1;
      }
      return 0;
  }
  
  #define BLEND(target, source, alpha) \
      (target) + ((source) * (255 - (alpha)) + 255 / 2) / 255
  
  static void xcbgrab_draw_mouse(AVFormatContext *s, AVPacket *pkt,
                                 xcb_query_pointer_reply_t *p,
                                 xcb_get_geometry_reply_t *geo)
  {
      XCBGrabContext *gr = s->priv_data;
      uint32_t *cursor;
      uint8_t *image = pkt->data;
      int stride     = gr->bpp / 8;
      xcb_xfixes_get_cursor_image_cookie_t cc;
      xcb_xfixes_get_cursor_image_reply_t *ci;
      int cx, cy, x, y, w, h, c_off, i_off;
  
      cc = xcb_xfixes_get_cursor_image(gr->conn);
      ci = xcb_xfixes_get_cursor_image_reply(gr->conn, cc, NULL);
      if (!ci)
          return;
  
      cursor = xcb_xfixes_get_cursor_image_cursor_image(ci);
      if (!cursor)
          return;
  
      cx = ci->x - ci->xhot;
      cy = ci->y - ci->yhot;
  
      x = FFMAX(cx, gr->x);
      y = FFMAX(cy, gr->y);
  
      w = FFMIN(cx + ci->width,  gr->x + gr->width)  - x;
      h = FFMIN(cy + ci->height, gr->y + gr->height) - y;
  
      c_off = x - cx;
      i_off = x - gr->x;
  
      cursor += (y - cy) * ci->width;
      image  += (y - gr->y) * gr->width * stride;
  
      for (y = 0; y < h; y++) {
          cursor += c_off;
          image  += i_off * stride;
          for (x = 0; x < w; x++, cursor++, image += stride) {
              int r, g, b, a;
  
              r =  *cursor        & 0xff;
              g = (*cursor >>  8) & 0xff;
              b = (*cursor >> 16) & 0xff;
              a = (*cursor >> 24) & 0xff;
  
              if (!a)
                  continue;
  
              if (a == 255) {
                  image[0] = r;
                  image[1] = g;
                  image[2] = b;
              } else {
                  image[0] = BLEND(r, image[0], a);
                  image[1] = BLEND(g, image[1], a);
                  image[2] = BLEND(b, image[2], a);
              }
  
          }
          cursor +=  ci->width - w - c_off;
          image  += (gr->width - w - i_off) * stride;
      }
  
      free(ci);
  }
  #endif /* CONFIG_LIBXCB_XFIXES */
  
  static void xcbgrab_update_region(AVFormatContext *s)
  {
      XCBGrabContext *c     = s->priv_data;
      const uint32_t args[] = { c->x - c->region_border,
                                c->y - c->region_border };
  
      xcb_configure_window(c->conn,
                           c->window,
                           XCB_CONFIG_WINDOW_X | XCB_CONFIG_WINDOW_Y,
                           args);
  }
  
  static int xcbgrab_read_packet(AVFormatContext *s, AVPacket *pkt)
  {
      XCBGrabContext *c = s->priv_data;
      xcb_query_pointer_cookie_t pc;
      xcb_get_geometry_cookie_t gc;
      xcb_query_pointer_reply_t *p  = NULL;
      xcb_get_geometry_reply_t *geo = NULL;
      int ret = 0;
  
      wait_frame(s, pkt);
  
      if (c->follow_mouse || c->draw_mouse) {
          pc  = xcb_query_pointer(c->conn, c->screen->root);
          gc  = xcb_get_geometry(c->conn, c->screen->root);
          p   = xcb_query_pointer_reply(c->conn, pc, NULL);
          geo = xcb_get_geometry_reply(c->conn, gc, NULL);
      }
  
      if (c->follow_mouse && p->same_screen)
          xcbgrab_reposition(s, p, geo);
  
      if (c->show_region)
          xcbgrab_update_region(s);
  
  #if CONFIG_LIBXCB_SHM
      if (c->has_shm && xcbgrab_frame_shm(s, pkt) < 0)
          c->has_shm = 0;
  #endif
      if (!c->has_shm)
          ret = xcbgrab_frame(s, pkt);
  
  #if CONFIG_LIBXCB_XFIXES
      if (ret >= 0 && c->draw_mouse && p->same_screen)
          xcbgrab_draw_mouse(s, pkt, p, geo);
  #endif
  
      free(p);
      free(geo);
  
      return ret;
  }
  
  static av_cold int xcbgrab_read_close(AVFormatContext *s)
  {
      XCBGrabContext *ctx = s->priv_data;
  
  #if CONFIG_LIBXCB_SHM
      if (ctx->buffer) {
          shmdt(ctx->buffer);
      }
  #endif
  
      xcb_disconnect(ctx->conn);
  
      return 0;
  }
  
  static xcb_screen_t *get_screen(const xcb_setup_t *setup, int screen_num)
  {
      xcb_screen_iterator_t it = xcb_setup_roots_iterator(setup);
      xcb_screen_t *screen     = NULL;
  
      for (; it.rem > 0; xcb_screen_next (&it)) {
          if (!screen_num) {
              screen = it.data;
              break;
          }
  
          screen_num--;
      }
  
      return screen;
  }
  
  static int pixfmt_from_pixmap_format(AVFormatContext *s, int depth,
                                       int *pix_fmt)
  {
      XCBGrabContext *c        = s->priv_data;
      const xcb_setup_t *setup = xcb_get_setup(c->conn);
      const xcb_format_t *fmt  = xcb_setup_pixmap_formats(setup);
      int length               = xcb_setup_pixmap_formats_length(setup);
  
      *pix_fmt = 0;
  
      while (length--) {
          if (fmt->depth == depth) {
              switch (depth) {
              case 32:
                  if (fmt->bits_per_pixel == 32)
                      *pix_fmt = AV_PIX_FMT_0RGB;
                  break;
              case 24:
                  if (fmt->bits_per_pixel == 32)
                      *pix_fmt = AV_PIX_FMT_0RGB32;
                  else if (fmt->bits_per_pixel == 24)
                      *pix_fmt = AV_PIX_FMT_RGB24;
                  break;
              case 16:
                  if (fmt->bits_per_pixel == 16)
                      *pix_fmt = AV_PIX_FMT_RGB565;
                  break;
              case 15:
                  if (fmt->bits_per_pixel == 16)
                      *pix_fmt = AV_PIX_FMT_RGB555;
                  break;
              case 8:
                  if (fmt->bits_per_pixel == 8)
                      *pix_fmt = AV_PIX_FMT_RGB8;
                  break;
              }
          }
  
          if (*pix_fmt) {
              c->bpp        = fmt->bits_per_pixel;
              c->frame_size = c->width * c->height * fmt->bits_per_pixel / 8;
              return 0;
          }
  
          fmt++;
      }
      avpriv_report_missing_feature(s, "Mapping this pixmap format");
  
      return AVERROR_PATCHWELCOME;
  }
  
  static int create_stream(AVFormatContext *s)
  {
      XCBGrabContext *c = s->priv_data;
      AVStream *st      = avformat_new_stream(s, NULL);
      xcb_get_geometry_cookie_t gc;
      xcb_get_geometry_reply_t *geo;
      int ret;
  
      if (!st)
          return AVERROR(ENOMEM);
  
      ret = av_parse_video_size(&c->width, &c->height, c->video_size);
      if (ret < 0)
          return ret;
  
      ret = av_parse_video_rate(&st->avg_frame_rate, c->framerate);
      if (ret < 0)
          return ret;
  
      avpriv_set_pts_info(st, 64, 1, 1000000);
  
      gc  = xcb_get_geometry(c->conn, c->screen->root);
      geo = xcb_get_geometry_reply(c->conn, gc, NULL);
  
      if (c->x + c->width > geo->width ||
          c->y + c->height > geo->height) {
          av_log(s, AV_LOG_ERROR,
                 "Capture area %dx%d at position %d.%d "
                 "outside the screen size %dx%d\n",
                 c->width, c->height,
                 c->x, c->y,
                 geo->width, geo->height);
          return AVERROR(EINVAL);
      }
  
      c->time_base  = (AVRational){ st->avg_frame_rate.den,
                                    st->avg_frame_rate.num };
      c->time_frame = av_gettime();
  
      st->codecpar->codec_type = AVMEDIA_TYPE_VIDEO;
      st->codecpar->codec_id   = AV_CODEC_ID_RAWVIDEO;
      st->codecpar->width      = c->width;
      st->codecpar->height     = c->height;
  
      ret = pixfmt_from_pixmap_format(s, geo->depth, &st->codecpar->format);
  
      free(geo);
  
      return ret;
  }
  
  static void draw_rectangle(AVFormatContext *s)
  {
      XCBGrabContext *c = s->priv_data;
      xcb_gcontext_t gc = xcb_generate_id(c->conn);
      uint32_t mask     = XCB_GC_FOREGROUND |
                          XCB_GC_BACKGROUND |
                          XCB_GC_LINE_WIDTH |
                          XCB_GC_LINE_STYLE |
                          XCB_GC_FILL_STYLE;
      uint32_t values[] = { c->screen->black_pixel,
                            c->screen->white_pixel,
                            c->region_border,
                            XCB_LINE_STYLE_DOUBLE_DASH,
                            XCB_FILL_STYLE_SOLID };
      xcb_rectangle_t r = { 1, 1,
                            c->width  + c->region_border * 2 - 3,
                            c->height + c->region_border * 2 - 3 };
  
      xcb_create_gc(c->conn, gc, c->window, mask, values);
  
      xcb_poly_rectangle(c->conn, c->window, gc, 1, &r);
  }
  
  static void setup_window(AVFormatContext *s)
  {
      XCBGrabContext *c = s->priv_data;
      uint32_t mask     = XCB_CW_OVERRIDE_REDIRECT | XCB_CW_EVENT_MASK;
      uint32_t values[] = { 1,
                            XCB_EVENT_MASK_EXPOSURE |
                            XCB_EVENT_MASK_STRUCTURE_NOTIFY };
      av_unused xcb_rectangle_t rect = { 0, 0, c->width, c->height };
  
      c->window = xcb_generate_id(c->conn);
  
      xcb_create_window(c->conn, XCB_COPY_FROM_PARENT,
                        c->window,
                        c->screen->root,
                        c->x - c->region_border,
                        c->y - c->region_border,
                        c->width + c->region_border * 2,
                        c->height + c->region_border * 2,
                        0,
                        XCB_WINDOW_CLASS_INPUT_OUTPUT,
                        XCB_COPY_FROM_PARENT,
                        mask, values);
  
  #if CONFIG_LIBXCB_SHAPE
      xcb_shape_rectangles(c->conn, XCB_SHAPE_SO_SUBTRACT,
                           XCB_SHAPE_SK_BOUNDING, XCB_CLIP_ORDERING_UNSORTED,
                           c->window,
                           c->region_border, c->region_border,
                           1, &rect);
  #endif
  
      xcb_map_window(c->conn, c->window);
  
      draw_rectangle(s);
  }
  
  static av_cold int xcbgrab_read_header(AVFormatContext *s)
  {
      XCBGrabContext *c = s->priv_data;
      int screen_num, ret;
      const xcb_setup_t *setup;
      char *display_name = av_strdup(s->url);
  
      if (!display_name)
          return AVERROR(ENOMEM);
  
      if (!sscanf(s->url, "%[^+]+%d,%d", display_name, &c->x, &c->y)) {
          *display_name = 0;
          sscanf(s->url, "+%d,%d", &c->x, &c->y);
      }
  
      c->conn = xcb_connect(display_name[0] ? display_name : NULL, &screen_num);
      av_freep(&display_name);
  
      if ((ret = xcb_connection_has_error(c->conn))) {
          av_log(s, AV_LOG_ERROR, "Cannot open display %s, error %d.\n",
                 s->url[0] ? s->url : "default", ret);
          return AVERROR(EIO);
      }
  
      setup = xcb_get_setup(c->conn);
  
      c->screen = get_screen(setup, screen_num);
      if (!c->screen) {
          av_log(s, AV_LOG_ERROR, "The screen %d does not exist.\n",
                 screen_num);
          xcbgrab_read_close(s);
          return AVERROR(EIO);
      }
  
      ret = create_stream(s);
  
      if (ret < 0) {
          xcbgrab_read_close(s);
          return ret;
      }
  
  #if CONFIG_LIBXCB_SHM
      if ((c->has_shm = check_shm(c->conn)))
          c->segment = xcb_generate_id(c->conn);
  #endif
  
  #if CONFIG_LIBXCB_XFIXES
      if (c->draw_mouse) {
          if (!(c->draw_mouse = check_xfixes(c->conn))) {
              av_log(s, AV_LOG_WARNING,
                     "XFixes not available, cannot draw the mouse.\n");
          }
          if (c->bpp < 24) {
              avpriv_report_missing_feature(s, "%d bits per pixel screen",
                                            c->bpp);
              c->draw_mouse = 0;
          }
      }
  #endif
  
      if (c->show_region)
          setup_window(s);
  
      return 0;
  }
  
  AVInputFormat ff_xcbgrab_demuxer = {
      .name           = "x11grab",
      .long_name      = NULL_IF_CONFIG_SMALL("X11 screen capture, using XCB"),
      .priv_data_size = sizeof(XCBGrabContext),
      .read_header    = xcbgrab_read_header,
      .read_packet    = xcbgrab_read_packet,
      .read_close     = xcbgrab_read_close,
      .flags          = AVFMT_NOFILE,
      .priv_class     = &xcbgrab_class,
  };
  