/*

  * Copyright (c) 2000 Fabrice Bellard
  * Copyright (c) 2002 Francois Revol
  * Copyright (c) 2006 Baptiste Coudurier

  *

  * first version by Francois Revol <revol@free.fr>
  *

  * 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
  */
 

 /**
  * @file
  * GIF encoder
  * @see http://www.w3.org/Graphics/GIF/spec-gif89a.txt

  */
 

 #define BITSTREAM_WRITER_LE

 #include "libavutil/opt.h"

 #include "libavutil/imgutils.h"

 #include "avcodec.h"
 #include "bytestream.h"

 #include "internal.h"

 #include "lzw.h"

 #include "gif.h"

 #include "put_bits.h"

 typedef struct GIFContext {

     const AVClass *class;

     LZWState *lzw;
     uint8_t *buf;

     int buf_size;

     AVFrame *last_frame;

     int flags;

     uint32_t palette[AVPALETTE_COUNT];  ///< local reference palette for !pal8

     int palette_loaded;
     int transparent_index;
     uint8_t *pal_exdata;

     uint8_t *tmpl;                      ///< temporary line buffer

 } GIFContext;
 

 enum {
     GF_OFFSETTING = 1<<0,

     GF_TRANSDIFF  = 1<<1,

 };
 

 static int pick_palette_entry(const uint8_t *buf, int linesize, int w, int h)
 {
     int histogram[AVPALETTE_COUNT] = {0};
     int x, y, i;
 
     for (y = 0; y < h; y++) {
         for (x = 0; x < w; x++)
             histogram[buf[x]]++;
         buf += linesize;
     }
     for (i = 0; i < FF_ARRAY_ELEMS(histogram); i++)
         if (!histogram[i])
             return i;
     return -1;
 }
 

 static int gif_image_write_image(AVCodecContext *avctx,
                                  uint8_t **bytestream, uint8_t *end,

                                  const uint32_t *palette,

                                  const uint8_t *buf, const int linesize,
                                  AVPacket *pkt)

 {

     GIFContext *s = avctx->priv_data;

     int len = 0, height = avctx->height, width = avctx->width, x, y;

     int x_start = 0, y_start = 0, trans = s->transparent_index;

     int honor_transparency = (s->flags & GF_TRANSDIFF) && s->last_frame && !palette;

     const uint8_t *ptr;
 

     /* Crop image */

     if ((s->flags & GF_OFFSETTING) && s->last_frame && !palette) {

         const uint8_t *ref = s->last_frame->data[0];
         const int ref_linesize = s->last_frame->linesize[0];
         int x_end = avctx->width  - 1,
             y_end = avctx->height - 1;
 
         /* skip common lines */

         while (y_start < y_end) {

             if (memcmp(ref + y_start*ref_linesize, buf + y_start*linesize, width))
                 break;
             y_start++;
         }
         while (y_end > y_start) {
             if (memcmp(ref + y_end*ref_linesize, buf + y_end*linesize, width))
                 break;
             y_end--;
         }
         height = y_end + 1 - y_start;
 
         /* skip common columns */

         while (x_start < x_end) {

             int same_column = 1;

             for (y = y_start; y <= y_end; y++) {

                 if (ref[y*ref_linesize + x_start] != buf[y*linesize + x_start]) {
                     same_column = 0;
                     break;
                 }
             }
             if (!same_column)
                 break;
             x_start++;
         }
         while (x_end > x_start) {
             int same_column = 1;

             for (y = y_start; y <= y_end; y++) {

                 if (ref[y*ref_linesize + x_end] != buf[y*linesize + x_end]) {
                     same_column = 0;
                     break;
                 }
             }
             if (!same_column)
                 break;
             x_end--;
         }
         width = x_end + 1 - x_start;
 
         av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n",
                width, height, x_start, y_start, avctx->width, avctx->height);
     }
 

     /* image block */

     bytestream_put_byte(bytestream, GIF_IMAGE_SEPARATOR);

     bytestream_put_le16(bytestream, x_start);
     bytestream_put_le16(bytestream, y_start);
     bytestream_put_le16(bytestream, width);
     bytestream_put_le16(bytestream, height);

 
     if (!palette) {

         bytestream_put_byte(bytestream, 0x00); /* flags */

     } else {
         unsigned i;
         bytestream_put_byte(bytestream, 1<<7 | 0x7); /* flags */
         for (i = 0; i < AVPALETTE_COUNT; i++) {
             const uint32_t v = palette[i];
             bytestream_put_be24(bytestream, v);
         }
     }

     if (honor_transparency && trans < 0) {

         trans = pick_palette_entry(buf + y_start*linesize + x_start,
                                    linesize, width, height);
         if (trans < 0) { // TODO, patch welcome
             av_log(avctx, AV_LOG_DEBUG, "No available color, can not use transparency\n");
         } else {

             uint8_t *pal_exdata = s->pal_exdata;
             if (!pal_exdata)
                 pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);

             if (!pal_exdata)
                 return AVERROR(ENOMEM);
             memcpy(pal_exdata, s->palette, AVPALETTE_SIZE);

             pal_exdata[trans*4 + 3*!HAVE_BIGENDIAN] = 0x00;

         }
     }

     if (trans < 0)
         honor_transparency = 0;

     bytestream_put_byte(bytestream, 0x08);
 

     ff_lzw_encode_init(s->lzw, s->buf, s->buf_size,

                        12, FF_LZW_GIF, put_bits);

     ptr = buf + y_start*linesize + x_start;

     if (honor_transparency) {

         const int ref_linesize = s->last_frame->linesize[0];
         const uint8_t *ref = s->last_frame->data[0] + y_start*ref_linesize + x_start;
 
         for (y = 0; y < height; y++) {
             memcpy(s->tmpl, ptr, width);
             for (x = 0; x < width; x++)
                 if (ref[x] == ptr[x])
                     s->tmpl[x] = trans;
             len += ff_lzw_encode(s->lzw, s->tmpl, width);
             ptr += linesize;
             ref += ref_linesize;
         }
     } else {

         for (y = 0; y < height; y++) {
             len += ff_lzw_encode(s->lzw, ptr, width);
             ptr += linesize;
         }

     }

     len += ff_lzw_encode_flush(s->lzw, flush_put_bits);
 
     ptr = s->buf;
     while (len > 0) {
         int size = FFMIN(255, len);
         bytestream_put_byte(bytestream, size);
         if (end - *bytestream < size)
             return -1;
         bytestream_put_buffer(bytestream, ptr, size);
         ptr += size;
         len -= size;

     }
     bytestream_put_byte(bytestream, 0x00); /* end of image block */
     return 0;
 }
 

 static av_cold int gif_encode_init(AVCodecContext *avctx)

 {
     GIFContext *s = avctx->priv_data;
 

     if (avctx->width > 65535 || avctx->height > 65535) {
         av_log(avctx, AV_LOG_ERROR, "GIF does not support resolutions above 65535x65535\n");

         return AVERROR(EINVAL);

     }

 #if FF_API_CODED_FRAME
 FF_DISABLE_DEPRECATION_WARNINGS

     avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
     avctx->coded_frame->key_frame = 1;

 FF_ENABLE_DEPRECATION_WARNINGS
 #endif

     s->transparent_index = -1;
 

     s->lzw = av_mallocz(ff_lzw_encode_state_size);

     s->buf_size = avctx->width*avctx->height*2 + 1000;
     s->buf = av_malloc(s->buf_size);

     s->tmpl = av_malloc(avctx->width);
     if (!s->tmpl || !s->buf || !s->lzw)

         return AVERROR(ENOMEM);

 
     if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0)
         av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8);
 

     return 0;
 }
 

 /* FIXME: duplicated with lavc */
 static int get_palette_transparency_index(const uint32_t *palette)
 {
     int transparent_color_index = -1;
     unsigned i, smallest_alpha = 0xff;
 
     if (!palette)
         return -1;
 
     for (i = 0; i < AVPALETTE_COUNT; i++) {
         const uint32_t v = palette[i];
         if (v >> 24 < smallest_alpha) {
             smallest_alpha = v >> 24;
             transparent_color_index = i;
         }
     }
     return smallest_alpha < 128 ? transparent_color_index : -1;
 }
 

 static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                             const AVFrame *pict, int *got_packet)

 {
     GIFContext *s = avctx->priv_data;

     uint8_t *outbuf_ptr, *end;

     const uint32_t *palette = NULL;

     int ret;
 

     if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + AV_INPUT_BUFFER_MIN_SIZE, 0)) < 0)

         return ret;
     outbuf_ptr = pkt->data;
     end        = pkt->data + pkt->size;

     if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {
         uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
         if (!pal_exdata)
             return AVERROR(ENOMEM);

         memcpy(pal_exdata, pict->data[1], AVPALETTE_SIZE);
         palette = (uint32_t*)pict->data[1];

 
         s->pal_exdata = pal_exdata;
 
         /* The first palette with PAL8 will be used as generic palette by the
          * muxer so we don't need to write it locally in the packet. We store
          * it as a reference here in case it changes later. */
         if (!s->palette_loaded) {
             memcpy(s->palette, palette, AVPALETTE_SIZE);
             s->transparent_index = get_palette_transparency_index(palette);
             s->palette_loaded = 1;
             palette = NULL;
         } else if (!memcmp(s->palette, palette, AVPALETTE_SIZE)) {
             palette = NULL;
         }

     }

     gif_image_write_image(avctx, &outbuf_ptr, end, palette,
                           pict->data[0], pict->linesize[0], pkt);

     if (!s->last_frame) {
         s->last_frame = av_frame_alloc();
         if (!s->last_frame)
             return AVERROR(ENOMEM);
     }
     av_frame_unref(s->last_frame);
     ret = av_frame_ref(s->last_frame, (AVFrame*)pict);
     if (ret < 0)
         return ret;

 
     pkt->size   = outbuf_ptr - pkt->data;
     pkt->flags |= AV_PKT_FLAG_KEY;
     *got_packet = 1;
 
     return 0;

 }
 

 static int gif_encode_close(AVCodecContext *avctx)
 {
     GIFContext *s = avctx->priv_data;
 
     av_freep(&s->lzw);
     av_freep(&s->buf);

     s->buf_size = 0;

     av_frame_free(&s->last_frame);

     av_freep(&s->tmpl);

     return 0;
 }
 

 #define OFFSET(x) offsetof(GIFContext, x)
 #define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption gif_options[] = {

     { "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" },

         { "offsetting", "enable picture offsetting", 0, AV_OPT_TYPE_CONST, {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" },

         { "transdiff", "enable transparency detection between frames", 0, AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS, "flags" },

     { NULL }
 };
 
 static const AVClass gif_class = {
     .class_name = "GIF encoder",
     .item_name  = av_default_item_name,
     .option     = gif_options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 

 AVCodec ff_gif_encoder = {

     .name           = "gif",

     .long_name      = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),

     .type           = AVMEDIA_TYPE_VIDEO,

     .id             = AV_CODEC_ID_GIF,

     .priv_data_size = sizeof(GIFContext),
     .init           = gif_encode_init,

     .encode2        = gif_encode_frame,

     .close          = gif_encode_close,

     .pix_fmts       = (const enum AVPixelFormat[]){
         AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE,
         AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE

     },

     .priv_class     = &gif_class,

 };