/*
  * PNG image format

  * Copyright (c) 2003 Fabrice Bellard

  *
  * 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 "avcodec.h"

 #include "internal.h"

 #include "bytestream.h"

 #include "huffyuvencdsp.h"

 #include "png.h"
 

 #include "libavutil/avassert.h"

 #include "libavutil/opt.h"

 #include <zlib.h>
 

 #define IOBUF_SIZE 4096
 
 typedef struct PNGEncContext {

     AVClass *class;

     HuffYUVEncDSPContext hdsp;

     uint8_t *bytestream;
     uint8_t *bytestream_start;
     uint8_t *bytestream_end;
 

     int filter_type;
 

     z_stream zstream;
     uint8_t buf[IOBUF_SIZE];

     int dpi;                     ///< Physical pixel density, in dots per inch, if set
     int dpm;                     ///< Physical pixel density, in dots per meter, if set

 } PNGEncContext;
 

 static void png_get_interlaced_row(uint8_t *dst, int row_size,
                                    int bits_per_pixel, int pass,
                                    const uint8_t *src, int width)
 {
     int x, mask, dst_x, j, b, bpp;
     uint8_t *d;
     const uint8_t *s;

     static const int masks[] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};

     mask = masks[pass];

     switch (bits_per_pixel) {

     case 1:
         memset(dst, 0, row_size);
         dst_x = 0;

         for (x = 0; x < width; x++) {

             j = (x & 7);
             if ((mask << j) & 0x80) {
                 b = (src[x >> 3] >> (7 - j)) & 1;
                 dst[dst_x >> 3] |= b << (7 - (dst_x & 7));
                 dst_x++;
             }
         }
         break;
     default:
         bpp = bits_per_pixel >> 3;
         d = dst;
         s = src;

         for (x = 0; x < width; x++) {

             j = x & 7;
             if ((mask << j) & 0x80) {
                 memcpy(d, s, bpp);
                 d += bpp;
             }
             s += bpp;
         }
         break;
     }
 }
 

 static void sub_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top,
                                      int w, int bpp)

 {
     int i;

     for (i = 0; i < w; i++) {

         int a, b, c, p, pa, pb, pc;
 
         a = src[i - bpp];
         b = top[i];
         c = top[i - bpp];
 

         p  = b - c;

         pc = a - c;
 
         pa = abs(p);
         pb = abs(pc);
         pc = abs(p + pc);
 
         if (pa <= pb && pa <= pc)
             p = a;
         else if (pb <= pc)
             p = b;
         else
             p = c;
         dst[i] = src[i] - p;
     }
 }
 

 static void sub_left_prediction(PNGEncContext *c, uint8_t *dst, const uint8_t *src, int bpp, int size)

 {
     const uint8_t *src1 = src + bpp;
     const uint8_t *src2 = src;
     int x, unaligned_w;
 
     memcpy(dst, src, bpp);
     dst += bpp;
     size -= bpp;
     unaligned_w = FFMIN(32 - bpp, size);
     for (x = 0; x < unaligned_w; x++)
         *dst++ = *src1++ - *src2++;
     size -= unaligned_w;

     c->hdsp.diff_bytes(dst, src1, src2, size);

 }
 

 static void png_filter_row(PNGEncContext *c, uint8_t *dst, int filter_type,

                            uint8_t *src, uint8_t *top, int size, int bpp)
 {
     int i;
 

     switch (filter_type) {

     case PNG_FILTER_VALUE_NONE:
         memcpy(dst, src, size);
         break;
     case PNG_FILTER_VALUE_SUB:

         sub_left_prediction(c, dst, src, bpp, size);

         break;
     case PNG_FILTER_VALUE_UP:

         c->hdsp.diff_bytes(dst, src, top, size);

         break;
     case PNG_FILTER_VALUE_AVG:

         for (i = 0; i < bpp; i++)

             dst[i] = src[i] - (top[i] >> 1);

         for (; i < size; i++)
             dst[i] = src[i] - ((src[i - bpp] + top[i]) >> 1);

         break;
     case PNG_FILTER_VALUE_PAETH:

         for (i = 0; i < bpp; i++)

             dst[i] = src[i] - top[i];

         sub_png_paeth_prediction(dst + i, src + i, top + i, size - i, bpp);

         break;
     }
 }
 
 static uint8_t *png_choose_filter(PNGEncContext *s, uint8_t *dst,
                                   uint8_t *src, uint8_t *top, int size, int bpp)
 {
     int pred = s->filter_type;

     av_assert0(bpp || !pred);

     if (!top && pred)

         pred = PNG_FILTER_VALUE_SUB;

     if (pred == PNG_FILTER_VALUE_MIXED) {

         int i;
         int cost, bcost = INT_MAX;
         uint8_t *buf1 = dst, *buf2 = dst + size + 16;

         for (pred = 0; pred < 5; pred++) {

             png_filter_row(s, buf1 + 1, pred, src, top, size, bpp);

             buf1[0] = pred;
             cost = 0;

             for (i = 0; i <= size; i++)
                 cost += abs((int8_t) buf1[i]);
             if (cost < bcost) {

                 bcost = cost;

                 FFSWAP(uint8_t *, buf1, buf2);

             }
         }
         return buf2;
     } else {

         png_filter_row(s, dst + 1, pred, src, top, size, bpp);

         dst[0] = pred;
         return dst;
     }
 }
 

 static void png_write_chunk(uint8_t **f, uint32_t tag,
                             const uint8_t *buf, int length)
 {
     uint32_t crc;
     uint8_t tagbuf[4];
 
     bytestream_put_be32(f, length);
     crc = crc32(0, Z_NULL, 0);
     AV_WL32(tagbuf, tag);
     crc = crc32(crc, tagbuf, 4);

     bytestream_put_be32(f, av_bswap32(tag));

     if (length > 0) {
         crc = crc32(crc, buf, length);
         memcpy(*f, buf, length);
         *f += length;
     }
     bytestream_put_be32(f, crc);
 }
 
 /* XXX: do filtering */

 static int png_write_row(PNGEncContext *s, const uint8_t *data, int size)

 {
     int ret;
 
     s->zstream.avail_in = size;

     s->zstream.next_in  = (uint8_t *)data;

     while (s->zstream.avail_in > 0) {
         ret = deflate(&s->zstream, Z_NO_FLUSH);
         if (ret != Z_OK)
             return -1;
         if (s->zstream.avail_out == 0) {

             if (s->bytestream_end - s->bytestream > IOBUF_SIZE + 100)
                 png_write_chunk(&s->bytestream,
                                 MKTAG('I', 'D', 'A', 'T'), s->buf, IOBUF_SIZE);

             s->zstream.avail_out = IOBUF_SIZE;

             s->zstream.next_out  = s->buf;

         }
     }
     return 0;
 }
 

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

     PNGEncContext *s       = avctx->priv_data;
     const AVFrame *const p = pict;

     int bit_depth, color_type, y, len, row_size, ret, is_progressive;

     int bits_per_pixel, pass_row_size, enc_row_size;
     int64_t max_packet_size;

     int compression_level;

     uint8_t *ptr, *top, *crow_buf, *crow;
     uint8_t *crow_base       = NULL;

     uint8_t *progressive_buf = NULL;

     uint8_t *top_buf         = NULL;

 
     is_progressive = !!(avctx->flags & CODEC_FLAG_INTERLACED_DCT);

     switch (avctx->pix_fmt) {

     case AV_PIX_FMT_RGBA64BE:

         bit_depth = 16;

         color_type = PNG_COLOR_TYPE_RGB_ALPHA;
         break;

     case AV_PIX_FMT_RGB48BE:

         bit_depth = 16;

         color_type = PNG_COLOR_TYPE_RGB;
         break;

     case AV_PIX_FMT_RGBA:

         bit_depth  = 8;

         color_type = PNG_COLOR_TYPE_RGB_ALPHA;
         break;

     case AV_PIX_FMT_RGB24:

         bit_depth  = 8;

         color_type = PNG_COLOR_TYPE_RGB;
         break;

     case AV_PIX_FMT_GRAY16BE:

         bit_depth  = 16;

         color_type = PNG_COLOR_TYPE_GRAY;
         break;

     case AV_PIX_FMT_GRAY8:

         bit_depth  = 8;

         color_type = PNG_COLOR_TYPE_GRAY;
         break;

     case AV_PIX_FMT_GRAY8A:

         bit_depth = 8;
         color_type = PNG_COLOR_TYPE_GRAY_ALPHA;
         break;

     case AV_PIX_FMT_MONOBLACK:

         bit_depth  = 1;

         color_type = PNG_COLOR_TYPE_GRAY;
         break;

     case AV_PIX_FMT_PAL8:

         bit_depth  = 8;

         color_type = PNG_COLOR_TYPE_PALETTE;
         break;
     default:
         return -1;
     }
     bits_per_pixel = ff_png_get_nb_channels(color_type) * bit_depth;

     row_size       = (avctx->width * bits_per_pixel + 7) >> 3;

 
     s->zstream.zalloc = ff_png_zalloc;

     s->zstream.zfree  = ff_png_zfree;

     s->zstream.opaque = NULL;

     compression_level = avctx->compression_level == FF_COMPRESSION_DEFAULT
                       ? Z_DEFAULT_COMPRESSION
                       : av_clip(avctx->compression_level, 0, 9);

     ret = deflateInit2(&s->zstream, compression_level,

                        Z_DEFLATED, 15, 8, Z_DEFAULT_STRATEGY);
     if (ret != Z_OK)
         return -1;

 
     enc_row_size    = deflateBound(&s->zstream, row_size);

     max_packet_size = avctx->height * (int64_t)(enc_row_size +

                                        ((enc_row_size + IOBUF_SIZE - 1) / IOBUF_SIZE) * 12)
                       + FF_MIN_BUFFER_SIZE;

     if (max_packet_size > INT_MAX)
         return AVERROR(ENOMEM);

     if ((ret = ff_alloc_packet2(avctx, pkt, max_packet_size)) < 0)

         return ret;
 
     s->bytestream_start =
     s->bytestream       = pkt->data;
     s->bytestream_end   = pkt->data + pkt->size;
 

     crow_base = av_malloc((row_size + 32) << (s->filter_type == PNG_FILTER_VALUE_MIXED));
     if (!crow_base)

         goto fail;

     // pixel data should be aligned, but there's a control byte before it
     crow_buf = crow_base + 15;

     if (is_progressive) {

         progressive_buf = av_malloc(row_size + 1);
         if (!progressive_buf)
             goto fail;
     }

     if (is_progressive) {

         top_buf = av_malloc(row_size + 1);
         if (!top_buf)

             goto fail;
     }
 
     /* write png header */

     AV_WB64(s->bytestream, PNGSIG);

     s->bytestream += 8;
 
     AV_WB32(s->buf, avctx->width);
     AV_WB32(s->buf + 4, avctx->height);

     s->buf[8]  = bit_depth;
     s->buf[9]  = color_type;

     s->buf[10] = 0; /* compression type */
     s->buf[11] = 0; /* filter type */
     s->buf[12] = is_progressive; /* interlace type */
 
     png_write_chunk(&s->bytestream, MKTAG('I', 'H', 'D', 'R'), s->buf, 13);
 

     if (s->dpm) {
       AV_WB32(s->buf, s->dpm);
       AV_WB32(s->buf + 4, s->dpm);
       s->buf[8] = 1; /* unit specifier is meter */
     } else {
       AV_WB32(s->buf, avctx->sample_aspect_ratio.num);
       AV_WB32(s->buf + 4, avctx->sample_aspect_ratio.den);
       s->buf[8] = 0; /* unit specifier is unknown */
     }

     png_write_chunk(&s->bytestream, MKTAG('p', 'H', 'Y', 's'), s->buf, 9);
 

     /* put the palette if needed */
     if (color_type == PNG_COLOR_TYPE_PALETTE) {
         int has_alpha, alpha, i;
         unsigned int v;
         uint32_t *palette;
         uint8_t *alpha_ptr;
 

         palette   = (uint32_t *)p->data[1];
         ptr       = s->buf;

         alpha_ptr = s->buf + 256 * 3;
         has_alpha = 0;

         for (i = 0; i < 256; i++) {
             v     = palette[i];

             alpha = v >> 24;

             if (alpha != 0xff)

                 has_alpha = 1;
             *alpha_ptr++ = alpha;
             bytestream_put_be24(&ptr, v);
         }

         png_write_chunk(&s->bytestream,
                         MKTAG('P', 'L', 'T', 'E'), s->buf, 256 * 3);

         if (has_alpha) {

             png_write_chunk(&s->bytestream,
                             MKTAG('t', 'R', 'N', 'S'), s->buf + 256 * 3, 256);

         }
     }
 
     /* now put each row */
     s->zstream.avail_out = IOBUF_SIZE;

     s->zstream.next_out  = s->buf;

     if (is_progressive) {
         int pass;
 

         for (pass = 0; pass < NB_PASSES; pass++) {

             /* NOTE: a pass is completely omitted if no pixels would be

              * output */

             pass_row_size = ff_png_pass_row_size(pass, bits_per_pixel, avctx->width);
             if (pass_row_size > 0) {

                 top = NULL;

                 for (y = 0; y < avctx->height; y++)

                     if ((ff_png_pass_ymask[pass] << (y & 7)) & 0x80) {
                         ptr = p->data[0] + y * p->linesize[0];

                         FFSWAP(uint8_t *, progressive_buf, top_buf);

                         png_get_interlaced_row(progressive_buf, pass_row_size,

                                                bits_per_pixel, pass,

                                                ptr, avctx->width);

                         crow = png_choose_filter(s, crow_buf, progressive_buf,
                                                  top, pass_row_size, bits_per_pixel >> 3);

                         png_write_row(s, crow, pass_row_size + 1);
                         top = progressive_buf;

                     }
             }
         }
     } else {

         top = NULL;

         for (y = 0; y < avctx->height; y++) {

             ptr = p->data[0] + y * p->linesize[0];

             crow = png_choose_filter(s, crow_buf, ptr, top,
                                      row_size, bits_per_pixel >> 3);

             png_write_row(s, crow, row_size + 1);
             top = ptr;

         }
     }
     /* compress last bytes */

     for (;;) {

         ret = deflate(&s->zstream, Z_FINISH);
         if (ret == Z_OK || ret == Z_STREAM_END) {
             len = IOBUF_SIZE - s->zstream.avail_out;
             if (len > 0 && s->bytestream_end - s->bytestream > len + 100) {
                 png_write_chunk(&s->bytestream, MKTAG('I', 'D', 'A', 'T'), s->buf, len);
             }
             s->zstream.avail_out = IOBUF_SIZE;

             s->zstream.next_out  = s->buf;

             if (ret == Z_STREAM_END)
                 break;
         } else {
             goto fail;
         }
     }
     png_write_chunk(&s->bytestream, MKTAG('I', 'E', 'N', 'D'), NULL, 0);
 

     pkt->size   = s->bytestream - s->bytestream_start;
     pkt->flags |= AV_PKT_FLAG_KEY;
     *got_packet = 1;
     ret         = 0;
 

 the_end:

     av_free(crow_base);
     av_free(progressive_buf);
     av_free(top_buf);

     deflateEnd(&s->zstream);
     return ret;

 fail:

     ret = -1;
     goto the_end;
 }
 

 static av_cold int png_enc_init(AVCodecContext *avctx)
 {

     PNGEncContext *s = avctx->priv_data;
 

     switch (avctx->pix_fmt) {

     case AV_PIX_FMT_RGBA:
         avctx->bits_per_coded_sample = 32;
         break;
     case AV_PIX_FMT_RGB24:
         avctx->bits_per_coded_sample = 24;
         break;
     case AV_PIX_FMT_GRAY8:
         avctx->bits_per_coded_sample = 0x28;
         break;
     case AV_PIX_FMT_MONOBLACK:
         avctx->bits_per_coded_sample = 1;
         break;
     case AV_PIX_FMT_PAL8:
         avctx->bits_per_coded_sample = 8;
     }
 

     avctx->coded_frame = av_frame_alloc();
     if (!avctx->coded_frame)
         return AVERROR(ENOMEM);
 
     avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;
     avctx->coded_frame->key_frame = 1;
 

     ff_huffyuvencdsp_init(&s->hdsp);

     s->filter_type = av_clip(avctx->prediction_method,
                              PNG_FILTER_VALUE_NONE,
                              PNG_FILTER_VALUE_MIXED);
     if (avctx->pix_fmt == AV_PIX_FMT_MONOBLACK)

         s->filter_type = PNG_FILTER_VALUE_NONE;

     if (s->dpi && s->dpm) {
       av_log(avctx, AV_LOG_ERROR, "Only one of 'dpi' or 'dpm' options should be set\n");
       return AVERROR(EINVAL);
     } else if (s->dpi) {
       s->dpm = s->dpi * 10000 / 254;
     }
 

     return 0;
 }
 

 static av_cold int png_enc_close(AVCodecContext *avctx)
 {
     av_frame_free(&avctx->coded_frame);
     return 0;
 }
 

 #define OFFSET(x) offsetof(PNGEncContext, x)
 #define VE AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {
     {"dpi", "Set image resolution (in dots per inch)",  OFFSET(dpi), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 0x10000, VE},
     {"dpm", "Set image resolution (in dots per meter)", OFFSET(dpm), AV_OPT_TYPE_INT, {.i64 = 0}, 0, 0x10000, VE},
     { NULL }
 };
 
 static const AVClass pngenc_class = {
     .class_name = "PNG encoder",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 

 AVCodec ff_png_encoder = {

     .name           = "png",

     .long_name      = NULL_IF_CONFIG_SMALL("PNG (Portable Network Graphics) image"),

     .type           = AVMEDIA_TYPE_VIDEO,

     .id             = AV_CODEC_ID_PNG,

     .priv_data_size = sizeof(PNGEncContext),
     .init           = png_enc_init,

     .close          = png_enc_close,

     .encode2        = encode_frame,

     .capabilities   = CODEC_CAP_FRAME_THREADS | CODEC_CAP_INTRA_ONLY,

     .pix_fmts       = (const enum AVPixelFormat[]) {

         AV_PIX_FMT_RGB24, AV_PIX_FMT_RGBA,
         AV_PIX_FMT_RGB48BE, AV_PIX_FMT_RGBA64BE,
         AV_PIX_FMT_PAL8,
         AV_PIX_FMT_GRAY8, AV_PIX_FMT_GRAY8A,
         AV_PIX_FMT_GRAY16BE,

         AV_PIX_FMT_MONOBLACK, AV_PIX_FMT_NONE

     },

     .priv_class     = &pngenc_class,

 };