/*
  * 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,
 };