text: /*
   * Copyright (c) 2015 Paul B. Mahol
   *
   * 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 "libavutil/avstring.h"
  #include "libavutil/eval.h"
  #include "libavutil/imgutils.h"
  #include "libavutil/opt.h"
  
  #include "avfilter.h"
  #include "formats.h"
  #include "internal.h"
  #include "video.h"
  
  typedef struct SwapRectContext {
      const AVClass *class;
      char *w, *h;
      char *x1, *y1;
      char *x2, *y2;
  
      int nb_planes;
      int pixsteps[4];
  
      const AVPixFmtDescriptor *desc;
      uint8_t *temp;
  } SwapRectContext;
  
  #define OFFSET(x) offsetof(SwapRectContext, x)
  #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_RUNTIME_PARAM
  static const AVOption swaprect_options[] = {
      { "w",  "set rect width",                     OFFSET(w),  AV_OPT_TYPE_STRING, {.str="w/2"}, 0, 0, .flags = FLAGS },
      { "h",  "set rect height",                    OFFSET(h),  AV_OPT_TYPE_STRING, {.str="h/2"}, 0, 0, .flags = FLAGS },
      { "x1", "set 1st rect x top left coordinate", OFFSET(x1), AV_OPT_TYPE_STRING, {.str="w/2"}, 0, 0, .flags = FLAGS },
      { "y1", "set 1st rect y top left coordinate", OFFSET(y1), AV_OPT_TYPE_STRING, {.str="h/2"}, 0, 0, .flags = FLAGS },
      { "x2", "set 2nd rect x top left coordinate", OFFSET(x2), AV_OPT_TYPE_STRING, {.str="0"},   0, 0, .flags = FLAGS },
      { "y2", "set 2nd rect y top left coordinate", OFFSET(y2), AV_OPT_TYPE_STRING, {.str="0"},   0, 0, .flags = FLAGS },
      { NULL },
  };
  
  AVFILTER_DEFINE_CLASS(swaprect);
  
  static int query_formats(AVFilterContext *ctx)
  {
      int reject_flags = AV_PIX_FMT_FLAG_PAL     |
                         AV_PIX_FMT_FLAG_HWACCEL |
                         AV_PIX_FMT_FLAG_BITSTREAM;
  
      return ff_set_common_formats(ctx, ff_formats_pixdesc_filter(0, reject_flags));
  }
  
  static const char *const var_names[] = {   "w",   "h",   "a",   "n",   "t",   "pos",   "sar",   "dar",        NULL };
  enum                                   { VAR_W, VAR_H, VAR_A, VAR_N, VAR_T, VAR_POS, VAR_SAR, VAR_DAR, VAR_VARS_NB };
  
  static int filter_frame(AVFilterLink *inlink, AVFrame *in)
  {
      AVFilterContext *ctx = inlink->dst;
      AVFilterLink *outlink = ctx->outputs[0];
      SwapRectContext *s = ctx->priv;
      double var_values[VAR_VARS_NB];
      int x1[4], y1[4];
      int x2[4], y2[4];
      int aw[4], ah[4];
      int lw[4], lh[4];
      int pw[4], ph[4];
      double dw,  dh;
      double dx1, dy1;
      double dx2, dy2;
      int y, p, w, h, ret;
  
      var_values[VAR_W]   = inlink->w;
      var_values[VAR_H]   = inlink->h;
      var_values[VAR_A]   = (float) inlink->w / inlink->h;
      var_values[VAR_SAR] = inlink->sample_aspect_ratio.num ? av_q2d(inlink->sample_aspect_ratio) : 1;
      var_values[VAR_DAR] = var_values[VAR_A] * var_values[VAR_SAR];
      var_values[VAR_N]   = inlink->frame_count_out;
      var_values[VAR_T]   = in->pts == AV_NOPTS_VALUE ? NAN : in->pts * av_q2d(inlink->time_base);
      var_values[VAR_POS] = in->pkt_pos == -1 ? NAN : in->pkt_pos;
  
      ret = av_expr_parse_and_eval(&dw, s->w,
                                   var_names, &var_values[0],
                                   NULL, NULL, NULL, NULL,
                                   0, 0, ctx);
      if (ret < 0)
          return ret;
  
      ret = av_expr_parse_and_eval(&dh, s->h,
                                   var_names, &var_values[0],
                                   NULL, NULL, NULL, NULL,
                                   0, 0, ctx);
      if (ret < 0)
          return ret;
  
      ret = av_expr_parse_and_eval(&dx1, s->x1,
                                   var_names, &var_values[0],
                                   NULL, NULL, NULL, NULL,
                                   0, 0, ctx);
      if (ret < 0)
          return ret;
  
      ret = av_expr_parse_and_eval(&dy1, s->y1,
                                   var_names, &var_values[0],
                                   NULL, NULL, NULL, NULL,
                                   0, 0, ctx);
      if (ret < 0)
          return ret;
  
      ret = av_expr_parse_and_eval(&dx2, s->x2,
                                   var_names, &var_values[0],
                                   NULL, NULL, NULL, NULL,
                                   0, 0, ctx);
      if (ret < 0)
          return ret;
  
      ret = av_expr_parse_and_eval(&dy2, s->y2,
                                   var_names, &var_values[0],
                                   NULL, NULL, NULL, NULL,
                                   0, 0, ctx);
      if (ret < 0)
          return ret;
  
      w = dw; h = dh; x1[0] = dx1; y1[0] = dy1; x2[0] = dx2; y2[0] = dy2;
  
      x1[0] = av_clip(x1[0], 0, inlink->w - 1);
      y1[0] = av_clip(y1[0], 0, inlink->w - 1);
  
      x2[0] = av_clip(x2[0], 0, inlink->w - 1);
      y2[0] = av_clip(y2[0], 0, inlink->w - 1);
  
      ah[1] = ah[2] = AV_CEIL_RSHIFT(h, s->desc->log2_chroma_h);
      ah[0] = ah[3] = h;
      aw[1] = aw[2] = AV_CEIL_RSHIFT(w, s->desc->log2_chroma_w);
      aw[0] = aw[3] = w;
  
      w = FFMIN3(w, inlink->w - x1[0], inlink->w - x2[0]);
      h = FFMIN3(h, inlink->h - y1[0], inlink->h - y2[0]);
  
      ph[1] = ph[2] = AV_CEIL_RSHIFT(h, s->desc->log2_chroma_h);
      ph[0] = ph[3] = h;
      pw[1] = pw[2] = AV_CEIL_RSHIFT(w, s->desc->log2_chroma_w);
      pw[0] = pw[3] = w;
  
      lh[1] = lh[2] = AV_CEIL_RSHIFT(inlink->h, s->desc->log2_chroma_h);
      lh[0] = lh[3] = inlink->h;
      lw[1] = lw[2] = AV_CEIL_RSHIFT(inlink->w, s->desc->log2_chroma_w);
      lw[0] = lw[3] = inlink->w;
  
      x1[1] = x1[2] = AV_CEIL_RSHIFT(x1[0], s->desc->log2_chroma_w);
      x1[0] = x1[3] = x1[0];
      y1[1] = y1[2] = AV_CEIL_RSHIFT(y1[0], s->desc->log2_chroma_h);
      y1[0] = y1[3] = y1[0];
  
      x2[1] = x2[2] = AV_CEIL_RSHIFT(x2[0], s->desc->log2_chroma_w);
      x2[0] = x2[3] = x2[0];
      y2[1] = y2[2] = AV_CEIL_RSHIFT(y2[0], s->desc->log2_chroma_h);
      y2[0] = y2[3] = y2[0];
  
      for (p = 0; p < s->nb_planes; p++) {
          if (ph[p] == ah[p] && pw[p] == aw[p]) {
              uint8_t *src = in->data[p] + y1[p] * in->linesize[p] + x1[p] * s->pixsteps[p];
              uint8_t *dst = in->data[p] + y2[p] * in->linesize[p] + x2[p] * s->pixsteps[p];
  
              for (y = 0; y < ph[p]; y++) {
                  memcpy(s->temp, src, pw[p] * s->pixsteps[p]);
                  memmove(src, dst, pw[p] * s->pixsteps[p]);
                  memcpy(dst, s->temp, pw[p] * s->pixsteps[p]);
                  src += in->linesize[p];
                  dst += in->linesize[p];
              }
          }
      }
  
      return ff_filter_frame(outlink, in);
  }
  
  static int config_input(AVFilterLink *inlink)
  {
      AVFilterContext *ctx = inlink->dst;
      SwapRectContext *s = ctx->priv;
  
      if (!s->w  || !s->h  ||
          !s->x1 || !s->y1 ||
          !s->x2 || !s->y2)
          return AVERROR(EINVAL);
  
      s->desc = av_pix_fmt_desc_get(inlink->format);
      av_image_fill_max_pixsteps(s->pixsteps, NULL, s->desc);
      s->nb_planes = av_pix_fmt_count_planes(inlink->format);
  
      s->temp = av_malloc_array(inlink->w, s->pixsteps[0]);
      if (!s->temp)
          return AVERROR(ENOMEM);
  
      return 0;
  }
  
  static av_cold void uninit(AVFilterContext *ctx)
  {
      SwapRectContext *s = ctx->priv;
      av_freep(&s->temp);
  }
  
  static const AVFilterPad inputs[] = {
      {
          .name           = "default",
          .type           = AVMEDIA_TYPE_VIDEO,
          .flags          = AVFILTERPAD_FLAG_NEEDS_WRITABLE,
          .filter_frame   = filter_frame,
          .config_props   = config_input,
      },
  };
  
  static const AVFilterPad outputs[] = {
      {
          .name = "default",
          .type = AVMEDIA_TYPE_VIDEO,
      },
  };
  
  const AVFilter ff_vf_swaprect = {
      .name          = "swaprect",
      .description   = NULL_IF_CONFIG_SMALL("Swap 2 rectangular objects in video."),
      .priv_size     = sizeof(SwapRectContext),
      .priv_class    = &swaprect_class,
      .uninit        = uninit,
      FILTER_INPUTS(inputs),
      FILTER_OUTPUTS(outputs),
      FILTER_QUERY_FUNC(query_formats),
      .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC,
      .process_command = ff_filter_process_command,
  };
  