/src/mupdf/source/fitz/image.c

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// Copyright (C) 2004-2023 Artifex Software, Inc.
//
// This file is part of MuPDF.
//
// MuPDF is free software: you can redistribute it and/or modify it under the
// terms of the GNU Affero General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// MuPDF 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 Affero General Public License for more
// details.
//
// You should have received a copy of the GNU Affero General Public License
// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
//
// Alternative licensing terms are available from the licensor.
// For commercial licensing, see <https://www.artifex.com/> or contact
// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
// CA 94129, USA, for further information.

#include "mupdf/fitz.h"

#include "context-imp.h"
#include "image-imp.h"
#include "pixmap-imp.h"

#include <string.h>
#include <math.h>
#include <assert.h>

/* TODO: here or public? */
static int
fz_key_storable_needs_reaping(fz_context *ctx, const fz_key_storable *ks)
{
  return ks == NULL ? 0 : (ks->store_key_refs == ks->storable.refs);
}

#define SANE_DPI 72.0f
#define INSANE_DPI 4800.0f

#define SCALABLE_IMAGE_DPI 96

struct fz_compressed_image
{
  fz_image super;
  fz_compressed_buffer *buffer;
};

struct fz_pixmap_image
{
  fz_image super;
  fz_pixmap *tile;
};

typedef struct
{
  int refs;
  fz_image *image;
  int l2factor;
  fz_irect rect;
} fz_image_key;

fz_image *
fz_keep_image(fz_context *ctx, fz_image *image)
{
  return fz_keep_key_storable(ctx, &image->key_storable);
}

fz_image *
fz_keep_image_store_key(fz_context *ctx, fz_image *image)
{
  return fz_keep_key_storable_key(ctx, &image->key_storable);
}

void
fz_drop_image_store_key(fz_context *ctx, fz_image *image)
{
  fz_drop_key_storable_key(ctx, &image->key_storable);
}

static int
fz_make_hash_image_key(fz_context *ctx, fz_store_hash *hash, void *key_)
{
  fz_image_key *key = (fz_image_key *)key_;
  hash->u.pir.ptr = key->image;
  hash->u.pir.i = key->l2factor;
  hash->u.pir.r = key->rect;
  return 1;
}

static void *
fz_keep_image_key(fz_context *ctx, void *key_)
{
  fz_image_key *key = (fz_image_key *)key_;
  return fz_keep_imp(ctx, key, &key->refs);
}

static void
fz_drop_image_key(fz_context *ctx, void *key_)
{
  fz_image_key *key = (fz_image_key *)key_;
  if (fz_drop_imp(ctx, key, &key->refs))
  {
    fz_drop_image_store_key(ctx, key->image);
    fz_free(ctx, key);
  }
}

static int
fz_cmp_image_key(fz_context *ctx, void *k0_, void *k1_)
{
  fz_image_key *k0 = (fz_image_key *)k0_;
  fz_image_key *k1 = (fz_image_key *)k1_;
  return k0->image == k1->image && k0->l2factor == k1->l2factor && k0->rect.x0 == k1->rect.x0 && k0->rect.y0 == k1->rect.y0 && k0->rect.x1 == k1->rect.x1 && k0->rect.y1 == k1->rect.y1;
}

static void
fz_format_image_key(fz_context *ctx, char *s, size_t n, void *key_)
{
  fz_image_key *key = (fz_image_key *)key_;
  fz_snprintf(s, n, "(image %d x %d sf=%d)", key->image->w, key->image->h, key->l2factor);
}

static int
fz_needs_reap_image_key(fz_context *ctx, void *key_)
{
  fz_image_key *key = (fz_image_key *)key_;

  return fz_key_storable_needs_reaping(ctx, &key->image->key_storable);
}

static const fz_store_type fz_image_store_type =
{
  "fz_image",
  fz_make_hash_image_key,
  fz_keep_image_key,
  fz_drop_image_key,
  fz_cmp_image_key,
  fz_format_image_key,
  fz_needs_reap_image_key
};

void
fz_drop_image(fz_context *ctx, fz_image *image)
{
  fz_drop_key_storable(ctx, &image->key_storable);
}

static void
fz_mask_color_key(fz_context *ctx, fz_pixmap *pix, int n, int bpc, const int *colorkey_in, int indexed)
{
  unsigned char *p = pix->samples;
  int w;
  int k, t;
  int h = pix->h;
  size_t stride = pix->stride - pix->w * (size_t)pix->n;
  int colorkey[FZ_MAX_COLORS * 2];
  int scale, shift, max;

  if (pix->w == 0)
    return;

  if (indexed)
  {
    /* no upscaling or downshifting needed for indexed images */
    scale = 1;
    shift = 0;
  }
  else
  {
    switch (bpc)
    {
    case 1: scale = 255; shift = 0; break;
    case 2: scale = 85; shift = 0; break;
    case 4: scale = 17; shift = 0; break;
    default:
    case 8: scale = 1; shift = 0; break;
    case 16: scale = 1; shift = 8; break;
    case 24: scale = 1; shift = 16; break;
    case 32: scale = 1; shift = 24; break;
    }
  }

  switch (bpc)
  {
  case 1: max = 1; break;
  case 2: max = 3; break;
  case 4: max = 15; break;
  default:
  case 8: max = 0xff; break;
  case 16: max = 0xffff; break;
  case 24: max = 0xffffff; break;
  case 32: max = 0xffffffff; break;
  }

  for (k = 0; k < 2 * n; k++)
  {
    colorkey[k] = colorkey_in[k];

    if (colorkey[k] > max)
    {
      if (indexed && bpc == 1)
      {
        if (k == 0)
        {
          fz_warn(ctx, "first color key masking value out of range in 1bpc indexed image, ignoring color key masking");
          return;
        }
        fz_warn(ctx, "later color key masking value out of range in 1bpc indexed image, assumed to be 1");
        colorkey[k] = 1;
      }
      else if (bpc != 1)
      {
        fz_warn(ctx, "color key masking value out of range, masking to valid range");
        colorkey[k] &= max;
      }
    }

    if (colorkey[k] < 0 || colorkey[k] > max)
    {
      fz_warn(ctx, "color key masking value out of range, clamping to valid range");
      colorkey[k] = fz_clampi(colorkey[k], 0, max);
    }

    if (scale > 1)
    {
      /* scale up color key masking value so it can be compared with samples. */
      colorkey[k] *= scale;
    }
    else if (shift > 0)
    {
      /* shifting down color key masking value so it can be compared with samples. */
      colorkey[k] >>= shift;
    }
  }

  while (h--)
  {
    w = pix->w;
    do
    {
      t = 1;
      for (k = 0; k < n; k++)
        if (p[k] < colorkey[k * 2] || p[k] > colorkey[k * 2 + 1])
          t = 0;
      if (t)
        for (k = 0; k < pix->n; k++)
          p[k] = 0;
      p += pix->n;
    }
    while (--w);
    p += stride;
  }
}

static void
fz_unblend_masked_tile(fz_context *ctx, fz_pixmap *tile, fz_image *image, const fz_irect *isa)
{
  fz_pixmap *mask;
  unsigned char *s, *d = tile->samples;
  int n = tile->n;
  int k;
  size_t sstride, dstride = tile->stride - tile->w * (size_t)tile->n;
  int h;
  fz_irect subarea;

  /* We need at least as much of the mask as there was of the tile. */
  if (isa)
    subarea = *isa;
  else
  {
    subarea.x0 = 0;
    subarea.y0 = 0;
    subarea.x1 = tile->w;
    subarea.y1 = tile->h;
  }

  mask = fz_get_pixmap_from_image(ctx, image->mask, &subarea, NULL, NULL, NULL);
  s = mask->samples;
  /* RJW: Urgh, bit of nastiness here. fz_pixmap_from_image will either return
   * an exact match for the subarea we asked for, or the full image, and the
   * normal way to know is that the matrix will be updated. That doesn't help
   * us here. */
  if (image->mask->w == mask->w && image->mask->h == mask->h) {
    subarea.x0 = 0;
    subarea.y0 = 0;
  }
  if (isa)
    s += (isa->x0 - subarea.x0) * (size_t)mask->n + (isa->y0 - subarea.y0) * (size_t)mask->stride;
  sstride = mask->stride - tile->w * (size_t)mask->n;
  h = tile->h;

  if (tile->w != 0)
  {
    while (h--)
    {
      int w = tile->w;
      do
      {
        if (*s == 0)
          for (k = 0; k < image->n; k++)
            d[k] = image->colorkey[k];
        else
          for (k = 0; k < image->n; k++)
            d[k] = fz_clampi(image->colorkey[k] + (d[k] - image->colorkey[k]) * 255 / *s, 0, 255);
        s++;
        d += n;
      }
      while (--w);
      s += sstride;
      d += dstride;
    }
  }

  fz_drop_pixmap(ctx, mask);
}

static void fz_adjust_image_subarea(fz_context *ctx, fz_image *image, fz_irect *subarea, int l2factor)
{
  int f = 1<<l2factor;
  int bpp = image->bpc * image->n;
  int mask;

  switch (bpp)
  {
  case 1: mask = 8*f; break;
  case 2: mask = 4*f; break;
  case 4: mask = 2*f; break;
  default: mask = (bpp & 7) == 0 ? f : 0; break;
  }

  if (mask != 0)
  {
    subarea->x0 &= ~(mask - 1);
    subarea->x1 = (subarea->x1 + mask - 1) & ~(mask - 1);
  }
  else
  {
    /* Awkward case - mask cannot be a power of 2. */
    mask = bpp*f;
    switch (bpp)
    {
    case 3:
    case 5:
    case 7:
    case 9:
    case 11:
    case 13:
    case 15:
    default:
      mask *= 8;
      break;
    case 6:
    case 10:
    case 14:
      mask *= 4;
      break;
    case 12:
      mask *= 2;
      break;
    }
    subarea->x0 = (subarea->x0 / mask) * mask;
    subarea->x1 = ((subarea->x1 + mask - 1) / mask) * mask;
  }

  subarea->y0 &= ~(f - 1);
  if (subarea->x1 > image->w)
    subarea->x1 = image->w;
  subarea->y1 = (subarea->y1 + f - 1) & ~(f - 1);
  if (subarea->y1 > image->h)
    subarea->y1 = image->h;
}

static void fz_compute_image_key(fz_context *ctx, fz_image *image, fz_matrix *ctm,
  fz_image_key *key, const fz_irect *subarea, int l2factor, int *w, int *h, int *dw, int *dh)
{
  key->refs = 1;
  key->image = image;
  key->l2factor = l2factor;

  if (subarea == NULL)
  {
    key->rect.x0 = 0;
    key->rect.y0 = 0;
    key->rect.x1 = image->w;
    key->rect.y1 = image->h;
  }
  else
  {
    key->rect = *subarea;
    ctx->tuning->image_decode(ctx->tuning->image_decode_arg, image->w, image->h, key->l2factor, &key->rect);
    fz_adjust_image_subarea(ctx, image, &key->rect, key->l2factor);
  }

  /* Based on that subarea, recalculate the extents */
  if (ctm)
  {
    float frac_w = (float) (key->rect.x1 - key->rect.x0) / image->w;
    float frac_h = (float) (key->rect.y1 - key->rect.y0) / image->h;
    float a = ctm->a * frac_w;
    float b = ctm->b * frac_w;
    float c = ctm->c * frac_h;
    float d = ctm->d * frac_h;
    *w = sqrtf(a * a + b * b);
    *h = sqrtf(c * c + d * d);
  }
  else
  {
    *w = image->w;
    *h = image->h;
  }

  /* Return the true sizes to the caller */
  if (dw)
    *dw = *w;
  if (dh)
    *dh = *h;
  if (*w > image->w)
    *w = image->w;
  if (*h > image->h)
    *h = image->h;

  if (*w == 0 || *h == 0)
    key->l2factor = 0;
}

typedef struct {
  fz_stream *src;
  size_t l_skip; /* Number of bytes to skip on the left. */
  size_t r_skip; /* Number of bytes to skip on the right. */
  size_t b_skip; /* Number of bytes to skip on the bottom. */
  int lines; /* Number of lines left to copy. */
  size_t stride; /* Number of bytes to read in the image. */
  size_t nskip; /* Number of bytes left to skip on this line. */
  size_t nread; /* Number of bytes left to read on this line. */
} subarea_state;

static int
subarea_next(fz_context *ctx, fz_stream *stm, size_t len)
{
  subarea_state *state = stm->state;
  size_t n;

  stm->wp = stm->rp = NULL;

  while (state->nskip > 0)
  {
    n = fz_skip(ctx, state->src, state->nskip);
    if (n == 0)
      return EOF;
    state->nskip -= n;
  }
  if (state->lines == 0)
    return EOF;
  n = fz_available(ctx, state->src, state->nread);
  if (n > state->nread)
    n = state->nread;
  if (n == 0)
    return EOF;
  stm->rp = state->src->rp;
  stm->wp = stm->rp + n;
  stm->pos += n;
  state->src->rp = stm->wp;
  state->nread -= n;
  if (state->nread == 0)
  {
    state->lines--;
    if (state->lines == 0)
      state->nskip = state->r_skip + state->b_skip;
    else
      state->nskip = state->l_skip + state->r_skip;
    state->nread = state->stride;
  }
  return *stm->rp++;
}

static void
subarea_drop(fz_context *ctx, void *state)
{
  fz_free(ctx, state);
}

static fz_stream *
subarea_stream(fz_context *ctx, fz_stream *stm, fz_image *image, const fz_irect *subarea, int l2factor)
{
  subarea_state *state;
  int f = 1<<l2factor;
  int stream_w = (image->w + f - 1)>>l2factor;
  size_t stream_stride = (stream_w * (size_t)image->n * image->bpc + 7) / 8;
  int l_margin = subarea->x0 >> l2factor;
  int t_margin = subarea->y0 >> l2factor;
  int r_margin = (image->w + f - 1 - subarea->x1) >> l2factor;
  int b_margin = (image->h + f - 1 - subarea->y1) >> l2factor;
  size_t l_skip = (l_margin * (size_t)image->n * image->bpc)/8;
  size_t r_skip = (r_margin * (size_t)image->n * image->bpc + 7)/8;
  size_t t_skip = t_margin * stream_stride;
  size_t b_skip = b_margin * stream_stride;
  int h = (subarea->y1 - subarea->y0 + f - 1) >> l2factor;
  int w = (subarea->x1 - subarea->x0 + f - 1) >> l2factor;
  size_t stride = (w * (size_t)image->n * image->bpc + 7) / 8;

  state = fz_malloc_struct(ctx, subarea_state);
  state->src = stm;
  state->l_skip = l_skip;
  state->r_skip = r_skip;
  state->b_skip = b_skip;
  state->lines = h;
  state->nskip = l_skip+t_skip;
  state->stride = stride;
  state->nread = stride;

  return fz_new_stream(ctx, state, subarea_next, subarea_drop);
}

typedef struct
{
  fz_stream *src;
  int w; /* Width in source pixels. */
  int h; /* Height (remaining) in scanlines. */
  int n; /* Number of components. */
  int f; /* Fill level (how many scanlines we've copied in). */
  size_t r; /* How many samples Remain to be filled in this line. */
  int l2; /* The amount of subsampling we're doing. */
  unsigned char data[1];
} l2sub_state;

static void
subsample_drop(fz_context *ctx, void *state)
{
  fz_free(ctx, state);
}

static int
subsample_next(fz_context *ctx, fz_stream *stm, size_t len)
{
  l2sub_state *state = (l2sub_state *)stm->state;
  size_t fill;

  stm->rp = stm->wp = &state->data[0];
  if (state->h == 0)
    return EOF;

  /* Copy in data */
  do
  {
    if (state->r == 0)
      state->r = state->w * (size_t)state->n;

    while (state->r > 0)
    {
      size_t a;
      a = fz_available(ctx, state->src, state->r);
      if (a == 0)
        return EOF;
      if (a > state->r)
        a = state->r;
      memcpy(&state->data[state->w * (size_t)state->n * (state->f+1) - state->r],
        state->src->rp, a);
      state->src->rp += a;
      state->r -= a;
    }
    state->f++;
    state->h--;
  }
  while (state->h > 0 && state->f != (1<<state->l2));

  /* Perform the subsample */
  fz_subsample_pixblock(state->data, state->w, state->f, state->n, state->l2, state->w * (size_t)state->n);
  state->f = 0;

  /* Update data pointers. */
  fill = ((state->w + (1<<state->l2) - 1)>>state->l2) * (size_t)state->n;
  stm->pos += fill;
  stm->rp = &state->data[0];
  stm->wp = &state->data[fill];

  return *stm->rp++;
}

static fz_stream *
subsample_stream(fz_context *ctx, fz_stream *src, int w, int h, int n, int l2extra)
{
  l2sub_state *state = fz_malloc(ctx, sizeof(l2sub_state) + w*(size_t)(n<<l2extra));

  state->src = src;
  state->w = w;
  state->h = h;
  state->n = n;
  state->f = 0;
  state->r = 0;
  state->l2 = l2extra;

  return fz_new_stream(ctx, state, subsample_next, subsample_drop);
}

/* l2factor is the amount of subsampling that the decoder is going to be
 * doing for us already. (So for JPEG 0,1,2,3 corresponding to 1, 2, 4,
 * 8. For other formats, probably 0.). l2extra is the additional amount
 * of subsampling we should perform here. */
fz_pixmap *
fz_decomp_image_from_stream(fz_context *ctx, fz_stream *stm, fz_compressed_image *cimg, fz_irect *subarea, int indexed, int l2factor, int *l2extra)
{
  fz_image *image = &cimg->super;
  fz_pixmap *tile = NULL;
  size_t stride, len, i;
  unsigned char *samples = NULL;
  int f = 1<<l2factor;
  int w = image->w;
  int h = image->h;
  int matte = image->use_colorkey && image->mask;
  fz_stream *read_stream = stm;
  fz_stream *sstream = NULL;
  fz_stream *l2stream = NULL;
  fz_stream *unpstream = NULL;

  if (matte)
  {
    /* Can't do l2factor decoding */
    if (image->w != image->mask->w || image->h != image->mask->h)
    {
      fz_warn(ctx, "mask must be of same size as image for /Matte");
      matte = 0;
    }
    assert(l2factor == 0);
  }
  if (subarea)
  {
    if (subarea->x0 == 0 && subarea->x1 == image->w &&
      subarea->y0 == 0 && subarea->y1 == image->h)
      subarea = NULL;
    else
    {
      fz_adjust_image_subarea(ctx, image, subarea, l2factor);
      w = (subarea->x1 - subarea->x0);
      h = (subarea->y1 - subarea->y0);
    }
  }
  w = (w + f - 1) >> l2factor;
  h = (h + f - 1) >> l2factor;

  fz_var(tile);
  fz_var(samples);
  fz_var(sstream);
  fz_var(unpstream);
  fz_var(l2stream);

  fz_try(ctx)
  {
    int alpha = (image->colorspace == NULL);
    if (image->use_colorkey)
      alpha = 1;

    if (subarea)
      read_stream = sstream = subarea_stream(ctx, stm, image, subarea, l2factor);
    if (image->bpc != 8 || image->use_colorkey)
      read_stream = unpstream = fz_unpack_stream(ctx, read_stream, image->bpc, w, h, image->n, indexed, image->use_colorkey, 0);
    if (l2extra && *l2extra && !indexed)
    {
      read_stream = l2stream = subsample_stream(ctx, read_stream, w, h, image->n + image->use_colorkey, *l2extra);
      w = (w + (1<<*l2extra) - 1)>>*l2extra;
      h = (h + (1<<*l2extra) - 1)>>*l2extra;
      *l2extra = 0;
    }

    tile = fz_new_pixmap(ctx, image->colorspace, w, h, NULL, alpha);
    if (image->interpolate & FZ_PIXMAP_FLAG_INTERPOLATE)
      tile->flags |= FZ_PIXMAP_FLAG_INTERPOLATE;
    else
      tile->flags &= ~FZ_PIXMAP_FLAG_INTERPOLATE;

    samples = tile->samples;
    stride = tile->stride;

    len = fz_read(ctx, read_stream, samples, h * stride);

    /* Pad truncated images */
    if (len < stride * h)
    {
      fz_warn(ctx, "padding truncated image");
      memset(samples + len, 0, stride * h - len);
    }

    /* Invert 1-bit image masks */
    if (image->imagemask)
    {
      /* 0=opaque and 1=transparent so we need to invert */
      unsigned char *p = samples;
      len = h * stride;
      for (i = 0; i < len; i++)
        p[i] = ~p[i];
    }

    /* color keyed transparency */
    if (image->use_colorkey && !image->mask)
      fz_mask_color_key(ctx, tile, image->n, image->bpc, image->colorkey, indexed);

    if (indexed)
    {
      fz_pixmap *conv;
      fz_decode_indexed_tile(ctx, tile, image->decode, (1 << image->bpc) - 1);
      conv = fz_convert_indexed_pixmap_to_base(ctx, tile);
      fz_drop_pixmap(ctx, tile);
      tile = conv;
    }
    else if (image->use_decode)
    {
      fz_decode_tile(ctx, tile, image->decode);
    }

    /* pre-blended matte color */
    if (matte)
      fz_unblend_masked_tile(ctx, tile, image, subarea);
  }
  fz_always(ctx)
  {
    fz_drop_stream(ctx, sstream);
    fz_drop_stream(ctx, unpstream);
    fz_drop_stream(ctx, l2stream);
  }
  fz_catch(ctx)
  {
    fz_drop_pixmap(ctx, tile);
    fz_rethrow(ctx);
  }

  return tile;
}

void
fz_drop_image_base(fz_context *ctx, fz_image *image)
{
  fz_drop_colorspace(ctx, image->colorspace);
  fz_drop_image(ctx, image->mask);
  fz_free(ctx, image);
}

void
fz_drop_image_imp(fz_context *ctx, fz_storable *image_)
{
  fz_image *image = (fz_image *)image_;

  image->drop_image(ctx, image);
  fz_drop_image_base(ctx, image);
}

static void
drop_compressed_image(fz_context *ctx, fz_image *image_)
{
  fz_compressed_image *image = (fz_compressed_image *)image_;

  fz_drop_compressed_buffer(ctx, image->buffer);
}

static void
drop_pixmap_image(fz_context *ctx, fz_image *image_)
{
  fz_pixmap_image *image = (fz_pixmap_image *)image_;

  fz_drop_pixmap(ctx, image->tile);
}

static fz_pixmap *
compressed_image_get_pixmap(fz_context *ctx, fz_image *image_, fz_irect *subarea, int w, int h, int *l2factor)
{
  fz_compressed_image *image = (fz_compressed_image *)image_;
  int native_l2factor;
  fz_stream *stm;
  int indexed;
  fz_pixmap *tile;
  int can_sub = 0;
  int local_l2factor;

  /* If we are using matte, then the decode code requires both image and tile sizes
   * to match. The simplest way to ensure this is to do no native l2factor decoding.
   */
  if (image->super.use_colorkey && image->super.mask)
  {
    local_l2factor = 0;
    l2factor = &local_l2factor;
  }

  /* We need to make a new one. */
  /* First check for ones that we can't decode using streams */
  switch (image->buffer->params.type)
  {
  case FZ_IMAGE_PNG:
    tile = fz_load_png(ctx, image->buffer->buffer->data, image->buffer->buffer->len);
    break;
  case FZ_IMAGE_GIF:
    tile = fz_load_gif(ctx, image->buffer->buffer->data, image->buffer->buffer->len);
    break;
  case FZ_IMAGE_BMP:
    tile = fz_load_bmp(ctx, image->buffer->buffer->data, image->buffer->buffer->len);
    break;
  case FZ_IMAGE_TIFF:
    tile = fz_load_tiff(ctx, image->buffer->buffer->data, image->buffer->buffer->len);
    break;
  case FZ_IMAGE_PNM:
    tile = fz_load_pnm(ctx, image->buffer->buffer->data, image->buffer->buffer->len);
    break;
  case FZ_IMAGE_JXR:
    tile = fz_load_jxr(ctx, image->buffer->buffer->data, image->buffer->buffer->len);
    break;
  case FZ_IMAGE_JPX:
    tile = fz_load_jpx(ctx, image->buffer->buffer->data, image->buffer->buffer->len, image->super.colorspace);
    break;
  case FZ_IMAGE_PSD:
    tile = fz_load_psd(ctx, image->buffer->buffer->data, image->buffer->buffer->len);
    break;
  case FZ_IMAGE_JPEG:
    /* Scan JPEG stream and patch missing height values in header */
    {
      unsigned char *s = image->buffer->buffer->data;
      unsigned char *e = s + image->buffer->buffer->len;
      unsigned char *d;
      for (d = s + 2; s < d && d + 9 < e && d[0] == 0xFF; d += (d[2] << 8 | d[3]) + 2)
      {
        if (d[1] < 0xC0 || (0xC3 < d[1] && d[1] < 0xC9) || 0xCB < d[1])
          continue;
        if ((d[5] == 0 && d[6] == 0) || ((d[5] << 8) | d[6]) > image->super.h)
        {
          d[5] = (image->super.h >> 8) & 0xFF;
          d[6] = image->super.h & 0xFF;
        }
      }
    }
    /* fall through */

  default:
    native_l2factor = l2factor ? *l2factor : 0;
    stm = fz_open_image_decomp_stream_from_buffer(ctx, image->buffer, l2factor);
    fz_try(ctx)
    {
      if (l2factor)
        native_l2factor -= *l2factor;
      indexed = fz_colorspace_is_indexed(ctx, image->super.colorspace);
      can_sub = 1;
      tile = fz_decomp_image_from_stream(ctx, stm, image, subarea, indexed, native_l2factor, l2factor);
    }
    fz_always(ctx)
      fz_drop_stream(ctx, stm);
    fz_catch(ctx)
      fz_rethrow(ctx);

    break;
  }

  if (can_sub == 0 && subarea != NULL)
  {
    subarea->x0 = 0;
    subarea->y0 = 0;
    subarea->x1 = image->super.w;
    subarea->y1 = image->super.h;
  }

  return tile;
}

static fz_pixmap *
pixmap_image_get_pixmap(fz_context *ctx, fz_image *image_, fz_irect *subarea, int w, int h, int *l2factor)
{
  fz_pixmap_image *image = (fz_pixmap_image *)image_;

  /* 'Simple' images created direct from pixmaps will have no buffer
   * of compressed data. We cannot do any better than just returning
   * a pointer to the original 'tile'.
   */
  return fz_keep_pixmap(ctx, image->tile); /* That's all we can give you! */
}

static void
update_ctm_for_subarea(fz_matrix *ctm, const fz_irect *subarea, int w, int h)
{
  fz_matrix m;

  if (ctm == NULL || (subarea->x0 == 0 && subarea->y0 == 0 && subarea->x1 == w && subarea->y1 == h))
    return;

  m.a = (float) (subarea->x1 - subarea->x0) / w;
  m.b = 0;
  m.c = 0;
  m.d = (float) (subarea->y1 - subarea->y0) / h;
  m.e = (float) subarea->x0 / w;
  m.f = (float) subarea->y0 / h;
  *ctm = fz_concat(m, *ctm);
}

void fz_default_image_decode(void *arg, int w, int h, int l2factor, fz_irect *subarea)
{
  (void)arg;

  if ((subarea->x1-subarea->x0)*(subarea->y1-subarea->y0) >= (w*h/10)*9)
  {
    /* Either no subarea specified, or a subarea 90% or more of the
     * whole area specified. Use the whole image. */
    subarea->x0 = 0;
    subarea->y0 = 0;
    subarea->x1 = w;
    subarea->y1 = h;
  }
  else
  {
    /* Clip to the edges if they are within 1% */
    if (subarea->x0 <= w/100)
      subarea->x0 = 0;
    if (subarea->y0 <= h/100)
      subarea->y0 = 0;
    if (subarea->x1 >= w*99/100)
      subarea->x1 = w;
    if (subarea->y1 >= h*99/100)
      subarea->y1 = h;
  }
}

static fz_pixmap *
fz_find_image_tile(fz_context *ctx, fz_image *image, fz_image_key *key, fz_matrix *ctm)
{
  fz_pixmap *tile;
  do
  {
    tile = fz_find_item(ctx, fz_drop_pixmap_imp, key, &fz_image_store_type);
    if (tile)
    {
      update_ctm_for_subarea(ctm, &key->rect, image->w, image->h);
      return tile;
    }
    key->l2factor--;
  }
  while (key->l2factor >= 0);
  return NULL;
}

fz_pixmap *
fz_get_pixmap_from_image(fz_context *ctx, fz_image *image, const fz_irect *subarea, fz_matrix *ctm, int *dw, int *dh)
{
  fz_pixmap *tile;
  int l2factor, l2factor_remaining;
  fz_image_key key;
  fz_image_key *keyp = NULL;
  int w;
  int h;

  fz_var(keyp);

  if (!image)
    return NULL;

  /* Figure out the extent. */
  if (ctm)
  {
    w = sqrtf(ctm->a * ctm->a + ctm->b * ctm->b);
    h = sqrtf(ctm->c * ctm->c + ctm->d * ctm->d);
  }
  else
  {
    w = image->w;
    h = image->h;
  }

  if (image->scalable)
  {
    /* If the image is scalable, we always want to re-render and never cache. */
    fz_irect subarea_copy;
    if (subarea)
      subarea_copy = *subarea;
    l2factor_remaining = 0;
    if (dw) *dw = w;
    if (dh) *dh = h;
    return image->get_pixmap(ctx, image, subarea ? &subarea_copy : NULL, image->w, image->h, &l2factor_remaining);
  }

  /* Clamp requested image size, since we never want to magnify images here. */
  if (w > image->w)
    w = image->w;
  if (h > image->h)
    h = image->h;

  if (image->decoded)
  {
    /* If the image is already decoded, then we can't offer a subarea,
     * or l2factor, and we don't want to cache. */
    l2factor_remaining = 0;
    if (dw) *dw = w;
    if (dh) *dh = h;
    return image->get_pixmap(ctx, image, NULL, image->w, image->h, &l2factor_remaining);
  }

  /* What is our ideal factor? We search for the largest factor where
   * we can subdivide and stay larger than the required size. We add
   * a fudge factor of +2 here to allow for the possibility of
   * expansion due to grid fitting. */
  l2factor = 0;
  if (w > 0 && h > 0)
  {
    while (image->w>>(l2factor+1) >= w+2 && image->h>>(l2factor+1) >= h+2 && l2factor < 6)
      l2factor++;
  }

  /* First, look through the store for existing tiles */
  if (subarea)
  {
    fz_compute_image_key(ctx, image, ctm, &key, subarea, l2factor, &w, &h, dw, dh);
    tile = fz_find_image_tile(ctx, image, &key, ctm);
    if (tile)
      return tile;
  }

  /* No subarea given, or no tile for subarea found; try entire image */
  fz_compute_image_key(ctx, image, ctm, &key, NULL, l2factor, &w, &h, dw, dh);
  tile = fz_find_image_tile(ctx, image, &key, ctm);
  if (tile)
    return tile;

  /* Neither subarea nor full image tile found; prepare the subarea key again */
  if (subarea)
    fz_compute_image_key(ctx, image, ctm, &key, subarea, l2factor, &w, &h, dw, dh);

  /* We'll have to decode the image; request the correct amount of downscaling. */
  l2factor_remaining = l2factor;
  tile = image->get_pixmap(ctx, image, &key.rect, w, h, &l2factor_remaining);

  /* Update the ctm to allow for subareas. */
  update_ctm_for_subarea(ctm, &key.rect, image->w, image->h);

  /* l2factor_remaining is updated to the amount of subscaling left to do */
  assert(l2factor_remaining >= 0 && l2factor_remaining <= 6);
  if (l2factor_remaining)
  {
    fz_try(ctx)
      fz_subsample_pixmap(ctx, tile, l2factor_remaining);
    fz_catch(ctx)
    {
      fz_drop_pixmap(ctx, tile);
      fz_rethrow(ctx);
    }
  }

  fz_try(ctx)
  {
    fz_pixmap *existing_tile;

    /* Now we try to cache the pixmap. Any failure here will just result
     * in us not caching. */
    keyp = fz_malloc_struct(ctx, fz_image_key);
    keyp->refs = 1;
    keyp->image = fz_keep_image_store_key(ctx, image);
    keyp->l2factor = l2factor;
    keyp->rect = key.rect;

    existing_tile = fz_store_item(ctx, keyp, tile, fz_pixmap_size(ctx, tile), &fz_image_store_type);
    if (existing_tile)
    {
      /* We already have a tile. This must have been produced by a
       * racing thread. We'll throw away ours and use that one. */
      fz_drop_pixmap(ctx, tile);
      tile = existing_tile;
    }
  }
  fz_always(ctx)
  {
    fz_drop_image_key(ctx, keyp);
  }
  fz_catch(ctx)
  {
    /* Do nothing */
    fz_rethrow_if(ctx, FZ_ERROR_SYSTEM);
    fz_report_error(ctx);
  }

  return tile;
}

fz_pixmap *
fz_get_unscaled_pixmap_from_image(fz_context *ctx, fz_image *image)
{
  return fz_get_pixmap_from_image(ctx, image, NULL /*subarea*/, NULL /*ctm*/, NULL /*dw*/, NULL /*dh*/);
}

static size_t
pixmap_image_get_size(fz_context *ctx, fz_image *image)
{
  fz_pixmap_image *im = (fz_pixmap_image *)image;

  if (image == NULL)
    return 0;

  return sizeof(fz_pixmap_image) + fz_pixmap_size(ctx, im->tile);
}

size_t fz_image_size(fz_context *ctx, fz_image *im)
{
  if (im == NULL)
    return 0;

  return im->get_size(ctx, im);
}

fz_image *
fz_new_image_from_pixmap(fz_context *ctx, fz_pixmap *pixmap, fz_image *mask)
{
  fz_pixmap_image *image;

  image = fz_new_derived_image(ctx, pixmap->w, pixmap->h, 8, pixmap->colorspace,
        pixmap->xres, pixmap->yres, 0, 0,
        NULL, NULL, mask, fz_pixmap_image,
        pixmap_image_get_pixmap,
        pixmap_image_get_size,
        drop_pixmap_image);
  image->tile = fz_keep_pixmap(ctx, pixmap);
  image->super.decoded = 1;

  return &image->super;
}

fz_image *
fz_new_image_of_size(fz_context *ctx, int w, int h, int bpc, fz_colorspace *colorspace,
    int xres, int yres, int interpolate, int imagemask, const float *decode,
    const int *colorkey, fz_image *mask, size_t size,
    fz_image_get_pixmap_fn *get_pixmap,
    fz_image_get_size_fn *get_size,
    fz_drop_image_fn *drop)
{
  fz_image *image;
  int i;

  assert(mask == NULL || mask->mask == NULL);
  assert(size >= sizeof(fz_image));

  image = Memento_label(fz_calloc(ctx, 1, size), "fz_image");
  FZ_INIT_KEY_STORABLE(image, 1, fz_drop_image_imp);
  image->drop_image = drop;
  image->get_pixmap = get_pixmap;
  image->get_size = get_size;
  image->w = w;
  image->h = h;
  image->xres = xres;
  image->yres = yres;
  image->bpc = bpc;
  image->n = (colorspace ? fz_colorspace_n(ctx, colorspace) : 1);
  image->colorspace = fz_keep_colorspace(ctx, colorspace);
  image->interpolate = interpolate;
  image->imagemask = imagemask;
  image->use_colorkey = (colorkey != NULL);
  if (colorkey)
    memcpy(image->colorkey, colorkey, sizeof(int)*image->n*2);
  image->use_decode = 0;
  if (decode)
  {
    memcpy(image->decode, decode, sizeof(float)*image->n*2);
  }
  else
  {
    float maxval = fz_colorspace_is_indexed(ctx, colorspace) ? (1 << bpc) - 1 : 1;
    for (i = 0; i < image->n; i++)
    {
      image->decode[2*i] = 0;
      image->decode[2*i+1] = maxval;
    }
  }
  /* ICC spaces have the default decode arrays pickled into them.
   * For most spaces this is fine, because [ 0 1 0 1 0 1 ] is
   * idempotent. For Lab, however, we need to adjust it. */
  if (fz_colorspace_is_lab_icc(ctx, colorspace))
  {
    /* Undo the default decode array of [0 100 -128 127 -128 127] */
    image->decode[0] = image->decode[0]/100.0f;
    image->decode[1] = image->decode[1]/100.0f;
    image->decode[2] = (image->decode[2]+128)/255.0f;
    image->decode[3] = (image->decode[3]+128)/255.0f;
    image->decode[4] = (image->decode[4]+128)/255.0f;
    image->decode[5] = (image->decode[5]+128)/255.0f;
  }
  for (i = 0; i < image->n; i++)
  {
    if (image->decode[i * 2] != 0 || image->decode[i * 2 + 1] != 1)
      break;
  }
  if (i != image->n)
    image->use_decode = 1;
  image->mask = fz_keep_image(ctx, mask);

  return image;
}

static size_t
compressed_image_get_size(fz_context *ctx, fz_image *image)
{
  fz_compressed_image *im = (fz_compressed_image *)image;

  if (image == NULL)
    return 0;

  return sizeof(fz_pixmap_image) + (im->buffer && im->buffer->buffer ? im->buffer->buffer->cap : 0);
}

fz_image *
fz_new_image_from_compressed_buffer(fz_context *ctx, int w, int h,
  int bpc, fz_colorspace *colorspace,
  int xres, int yres, int interpolate, int imagemask, const float *decode,
  const int *colorkey, fz_compressed_buffer *buffer, fz_image *mask)
{
  fz_compressed_image *image;

  fz_try(ctx)
  {
    image = fz_new_derived_image(ctx, w, h, bpc,
          colorspace, xres, yres,
          interpolate, imagemask, decode,
          colorkey, mask, fz_compressed_image,
          compressed_image_get_pixmap,
          compressed_image_get_size,
          drop_compressed_image);
    image->buffer = buffer;
  }
  fz_catch(ctx)
  {
    fz_drop_compressed_buffer(ctx, buffer);
    fz_rethrow(ctx);
  }

  return &image->super;
}

fz_compressed_buffer *fz_compressed_image_buffer(fz_context *ctx, fz_image *image)
{
  if (image == NULL || image->get_pixmap != compressed_image_get_pixmap)
    return NULL;
  return ((fz_compressed_image *)image)->buffer;
}

void fz_set_compressed_image_buffer(fz_context *ctx, fz_compressed_image *image, fz_compressed_buffer *buf)
{
  assert(image != NULL && image->super.get_pixmap == compressed_image_get_pixmap);
  ((fz_compressed_image *)image)->buffer = buf; /* Note: compressed buffers are not reference counted */
}

fz_pixmap *fz_pixmap_image_tile(fz_context *ctx, fz_pixmap_image *image)
{
  if (image == NULL || image->super.get_pixmap != pixmap_image_get_pixmap)
    return NULL;
  return ((fz_pixmap_image *)image)->tile;
}

void fz_set_pixmap_image_tile(fz_context *ctx, fz_pixmap_image *image, fz_pixmap *pix)
{
  assert(image != NULL && image->super.get_pixmap == pixmap_image_get_pixmap);
  ((fz_pixmap_image *)image)->tile = pix;
}

const char *
fz_image_type_name(int type)
{
  switch (type)
  {
  default:
  case FZ_IMAGE_UNKNOWN: return "unknown";
  case FZ_IMAGE_RAW: return "raw";
  case FZ_IMAGE_FAX: return "fax";
  case FZ_IMAGE_FLATE: return "flate";
  case FZ_IMAGE_LZW: return "lzw";
  case FZ_IMAGE_RLD: return "rld";
  case FZ_IMAGE_BMP: return "bmp";
  case FZ_IMAGE_GIF: return "gif";
  case FZ_IMAGE_JBIG2: return "jbig2";
  case FZ_IMAGE_JPEG: return "jpeg";
  case FZ_IMAGE_JPX: return "jpx";
  case FZ_IMAGE_JXR: return "jxr";
  case FZ_IMAGE_PNG: return "png";
  case FZ_IMAGE_PNM: return "pnm";
  case FZ_IMAGE_TIFF: return "tiff";
  }
}

int
fz_lookup_image_type(const char *type)
{
  if (type == NULL) return FZ_IMAGE_UNKNOWN;
  if (!strcmp(type, "raw")) return FZ_IMAGE_RAW;
  if (!strcmp(type, "fax")) return FZ_IMAGE_FAX;
  if (!strcmp(type, "flate")) return FZ_IMAGE_FLATE;
  if (!strcmp(type, "lzw")) return FZ_IMAGE_LZW;
  if (!strcmp(type, "rld")) return FZ_IMAGE_RLD;
  if (!strcmp(type, "bmp")) return FZ_IMAGE_BMP;
  if (!strcmp(type, "gif")) return FZ_IMAGE_GIF;
  if (!strcmp(type, "jbig2")) return FZ_IMAGE_JBIG2;
  if (!strcmp(type, "jpeg")) return FZ_IMAGE_JPEG;
  if (!strcmp(type, "jpx")) return FZ_IMAGE_JPX;
  if (!strcmp(type, "jxr")) return FZ_IMAGE_JXR;
  if (!strcmp(type, "png")) return FZ_IMAGE_PNG;
  if (!strcmp(type, "pnm")) return FZ_IMAGE_PNM;
  if (!strcmp(type, "tiff")) return FZ_IMAGE_TIFF;
  return FZ_IMAGE_UNKNOWN;
}

int
fz_recognize_image_format(fz_context *ctx, unsigned char p[8])
{
  if (p[0] == 'P' && p[1] >= '1' && p[1] <= '7')
    return FZ_IMAGE_PNM;
  if (p[0] == 'P' && (p[1] == 'F' || p[1] == 'f'))
    return FZ_IMAGE_PNM;
  if (p[0] == 0xff && p[1] == 0x4f)
    return FZ_IMAGE_JPX;
  if (p[0] == 0x00 && p[1] == 0x00 && p[2] == 0x00 && p[3] == 0x0c &&
      p[4] == 0x6a && p[5] == 0x50 && p[6] == 0x20 && p[7] == 0x20)
    return FZ_IMAGE_JPX;
  if (p[0] == 0xff && p[1] == 0xd8)
    return FZ_IMAGE_JPEG;
  if (p[0] == 137 && p[1] == 80 && p[2] == 78 && p[3] == 71 &&
      p[4] == 13 && p[5] == 10 && p[6] == 26 && p[7] == 10)
    return FZ_IMAGE_PNG;
  if (p[0] == 'I' && p[1] == 'I' && p[2] == 0xBC)
    return FZ_IMAGE_JXR;
  if (p[0] == 'I' && p[1] == 'I' && p[2] == 42 && p[3] == 0)
    return FZ_IMAGE_TIFF;
  if (p[0] == 'M' && p[1] == 'M' && p[2] == 0 && p[3] == 42)
    return FZ_IMAGE_TIFF;
  if (p[0] == 'G' && p[1] == 'I' && p[2] == 'F')
    return FZ_IMAGE_GIF;
  if (p[0] == 'B' && p[1] == 'M')
    return FZ_IMAGE_BMP;
  if (p[0] == 'B' && p[1] == 'A')
    return FZ_IMAGE_BMP;
  if (p[0] == 0x97 && p[1] == 'J' && p[2] == 'B' && p[3] == '2' &&
    p[4] == '\r' && p[5] == '\n'  && p[6] == 0x1a && p[7] == '\n')
    return FZ_IMAGE_JBIG2;
  if (p[0] == '8' && p[1] == 'B' && p[2] == 'P' && p[3] == 'S')
    return FZ_IMAGE_PSD;
  return FZ_IMAGE_UNKNOWN;
}

fz_image *
fz_new_image_from_buffer(fz_context *ctx, fz_buffer *buffer)
{
  fz_compressed_buffer *bc;
  int w, h, xres, yres;
  fz_colorspace *cspace;
  size_t len = buffer->len;
  unsigned char *buf = buffer->data;
  fz_image *image = NULL;
  int type;
  int bpc;
  uint8_t orientation = 0;

  if (len < 8)
    fz_throw(ctx, FZ_ERROR_FORMAT, "unknown image file format");

  type = fz_recognize_image_format(ctx, buf);
  bpc = 8;
  switch (type)
  {
  case FZ_IMAGE_PNM:
    fz_load_pnm_info(ctx, buf, len, &w, &h, &xres, &yres, &cspace);
    break;
  case FZ_IMAGE_JPX:
    fz_load_jpx_info(ctx, buf, len, &w, &h, &xres, &yres, &cspace);
    break;
  case FZ_IMAGE_JPEG:
    fz_load_jpeg_info(ctx, buf, len, &w, &h, &xres, &yres, &cspace, &orientation);
    break;
  case FZ_IMAGE_PNG:
    fz_load_png_info(ctx, buf, len, &w, &h, &xres, &yres, &cspace);
    break;
  case FZ_IMAGE_PSD:
    fz_load_psd_info(ctx, buf, len, &w, &h, &xres, &yres, &cspace);
    break;
  case FZ_IMAGE_JXR:
    fz_load_jxr_info(ctx, buf, len, &w, &h, &xres, &yres, &cspace);
    break;
  case FZ_IMAGE_TIFF:
    fz_load_tiff_info(ctx, buf, len, &w, &h, &xres, &yres, &cspace);
    break;
  case FZ_IMAGE_GIF:
    fz_load_gif_info(ctx, buf, len, &w, &h, &xres, &yres, &cspace);
    break;
  case FZ_IMAGE_BMP:
    fz_load_bmp_info(ctx, buf, len, &w, &h, &xres, &yres, &cspace);
    break;
  case FZ_IMAGE_JBIG2:
    fz_load_jbig2_info(ctx, buf, len, &w, &h, &xres, &yres, &cspace);
    bpc = 1;
    break;
  default:
    fz_throw(ctx, FZ_ERROR_FORMAT, "unknown image file format");
  }

  fz_try(ctx)
  {
    bc = fz_new_compressed_buffer(ctx);
    bc->buffer = fz_keep_buffer(ctx, buffer);
    bc->params.type = type;
    if (type == FZ_IMAGE_JPEG)
    {
      bc->params.u.jpeg.color_transform = -1;
      bc->params.u.jpeg.invert_cmyk = 1;
    }
    image = fz_new_image_from_compressed_buffer(ctx, w, h, bpc, cspace, xres, yres, 0, 0, NULL, NULL, bc, NULL);
    image->orientation = orientation;
  }
  fz_always(ctx)
    fz_drop_colorspace(ctx, cspace);
  fz_catch(ctx)
    fz_rethrow(ctx);

  return image;
}

int
fz_compressed_image_type(fz_context *ctx, fz_image *image)
{
  fz_compressed_image *cim;

  if (image == NULL || image->drop_image != drop_compressed_image)
    return FZ_IMAGE_UNKNOWN;

  cim = (fz_compressed_image *)image;

  return cim->buffer->params.type;
}

fz_image *
fz_new_image_from_file(fz_context *ctx, const char *path)
{
  fz_buffer *buffer;
  fz_image *image = NULL;

  buffer = fz_read_file(ctx, path);
  fz_try(ctx)
    image = fz_new_image_from_buffer(ctx, buffer);
  fz_always(ctx)
    fz_drop_buffer(ctx, buffer);
  fz_catch(ctx)
    fz_rethrow(ctx);

  return image;
}

void
fz_image_resolution(fz_image *image, int *xres, int *yres)
{
  *xres = image->xres;
  *yres = image->yres;
  if (*xres < 0 || *yres < 0 || (*xres == 0 && *yres == 0))
  {
    /* If neither xres or yres is sane, pick a sane value */
    *xres = SANE_DPI; *yres = SANE_DPI;
  }
  else if (*xres == 0)
  {
    *xres = *yres;
  }
  else if (*yres == 0)
  {
    *yres = *xres;
  }

  /* Scale xres and yres up until we get believable values */
  if (*xres < SANE_DPI || *yres < SANE_DPI || *xres > INSANE_DPI || *yres > INSANE_DPI)
  {
    if (*xres < *yres)
    {
      *yres = *yres * SANE_DPI / *xres;
      *xres = SANE_DPI;
    }
    else
    {
      *xres = *xres * SANE_DPI / *yres;
      *yres = SANE_DPI;
    }

    if (*xres == *yres || *xres < SANE_DPI || *yres < SANE_DPI || *xres > INSANE_DPI || *yres > INSANE_DPI)
    {
      *xres = SANE_DPI;
      *yres = SANE_DPI;
    }
  }
}

uint8_t fz_image_orientation(fz_context *ctx, fz_image *image)
{
  return image ? image->orientation : 0;
}

fz_matrix fz_image_orientation_matrix(fz_context *ctx, fz_image *image)
{
  fz_matrix m;

  switch (image ? image->orientation : 0)
  {
  case 0:
  case 1: /* 0 degree rotation */
    m.a =  1; m.b =  0;
    m.c =  0; m.d =  1;
    m.e =  0; m.f =  0;
    break;
  case 2: /* 90 degree ccw */
    m.a =  0; m.b = -1;
    m.c =  1; m.d =  0;
    m.e =  0; m.f =  1;
    break;
  case 3: /* 180 degree ccw */
    m.a = -1; m.b =  0;
    m.c =  0; m.d = -1;
    m.e =  1; m.f =  1;
    break;
  case 4: /* 270 degree ccw */
    m.a =  0; m.b =  1;
    m.c = -1; m.d =  0;
    m.e =  1; m.f =  0;
    break;
  case 5: /* flip on X */
    m.a = -1; m.b = 0;
    m.c =  0; m.d = 1;
    m.e =  1; m.f = 0;
    break;
  case 6: /* flip on X, then rotate ccw by 90 degrees */
    m.a =  0; m.b =  1;
    m.c =  1; m.d =  0;
    m.e =  0; m.f =  0;
    break;
  case 7: /* flip on X, then rotate ccw by 180 degrees */
    m.a =  1; m.b =  0;
    m.c =  0; m.d = -1;
    m.e =  0; m.f =  1;
    break;
  case 8: /* flip on X, then rotate ccw by 270 degrees */
    m.a =  0; m.b = -1;
    m.c = -1; m.d =  0;
    m.e =  1; m.f =  1;
    break;
  }

  return m;
}

typedef struct fz_display_list_image_s
{
  fz_image super;
  fz_matrix transform;
  fz_display_list *list;
} fz_display_list_image;

static fz_pixmap *
display_list_image_get_pixmap(fz_context *ctx, fz_image *image_, fz_irect *subarea, int w, int h, int *l2factor)
{
  fz_display_list_image *image = (fz_display_list_image *)image_;
  fz_matrix ctm;
  fz_device *dev;
  fz_pixmap *pix;

  fz_var(dev);

  if (subarea)
  {
    /* So, the whole image should be scaled to w * h, but we only want the
     * given subarea of it. */
    int l = (subarea->x0 * w) / image->super.w;
    int t = (subarea->y0 * h) / image->super.h;
    int r = (subarea->x1 * w + image->super.w - 1) / image->super.w;
    int b = (subarea->y1 * h + image->super.h - 1) / image->super.h;

    pix = fz_new_pixmap(ctx, image->super.colorspace, r-l, b-t, NULL, 0);
    pix->x = l;
    pix->y = t;
  }
  else
  {
    pix = fz_new_pixmap(ctx, image->super.colorspace, w, h, NULL, 0);
  }

  /* If we render the display list into pix with the image matrix, we'll get a unit
   * square result. Therefore scale by w, h. */
  ctm = fz_pre_scale(image->transform, w, h);

  fz_clear_pixmap(ctx, pix); /* clear to transparent */
  fz_try(ctx)
  {
    dev = fz_new_draw_device(ctx, ctm, pix);
    fz_run_display_list(ctx, image->list, dev, fz_identity, fz_infinite_rect, NULL);
    fz_close_device(ctx, dev);
  }
  fz_always(ctx)
    fz_drop_device(ctx, dev);
  fz_catch(ctx)
  {
    fz_drop_pixmap(ctx, pix);
    fz_rethrow(ctx);
  }

  /* Never do more subsampling, cos we've already given them the right size */
  if (l2factor)
    *l2factor = 0;

  return pix;
}

static void drop_display_list_image(fz_context *ctx, fz_image *image_)
{
  fz_display_list_image *image = (fz_display_list_image *)image_;

  if (image == NULL)
    return;
  fz_drop_display_list(ctx, image->list);
}

static size_t
display_list_image_get_size(fz_context *ctx, fz_image *image_)
{
  fz_display_list_image *image = (fz_display_list_image *)image_;

  if (image == NULL)
    return 0;

  return sizeof(fz_display_list_image) + 4096; /* FIXME */
}

fz_image *fz_new_image_from_display_list(fz_context *ctx, float w, float h, fz_display_list *list)
{
  fz_display_list_image *image;
  int iw, ih;

  iw = w * SCALABLE_IMAGE_DPI / 72;
  ih = h * SCALABLE_IMAGE_DPI / 72;

  image = fz_new_derived_image(ctx, iw, ih, 8, fz_device_rgb(ctx),
        SCALABLE_IMAGE_DPI, SCALABLE_IMAGE_DPI, 0, 0,
        NULL, NULL, NULL, fz_display_list_image,
        display_list_image_get_pixmap,
        display_list_image_get_size,
        drop_display_list_image);
  image->super.scalable = 1;
  image->transform = fz_scale(1 / w, 1 / h);
  image->list = fz_keep_display_list(ctx, list);

  return &image->super;
}

Coverage Report

Created: 2024-05-20 06:23