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eBookReaderSwitch/mupdf/source/fitz/load-png.c

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#include "mupdf/fitz.h"
#include <zlib.h>
#include <limits.h>
#include <string.h>
struct info
{
unsigned int width, height, depth, n;
enum fz_colorspace_type type;
int interlace, indexed;
unsigned int size;
unsigned char *samples;
unsigned char palette[256*4];
int transparency;
int trns[3];
int xres, yres;
fz_colorspace *cs;
};
static inline unsigned int getuint(const unsigned char *p)
{
return p[0] << 24 | p[1] << 16 | p[2] << 8 | p[3];
}
static inline int getcomp(const unsigned char *line, int x, int bpc)
{
switch (bpc)
{
case 1: return (line[x >> 3] >> ( 7 - (x & 7) ) ) & 1;
case 2: return (line[x >> 2] >> ( ( 3 - (x & 3) ) << 1 ) ) & 3;
case 4: return (line[x >> 1] >> ( ( 1 - (x & 1) ) << 2 ) ) & 15;
case 8: return line[x];
case 16: return line[x << 1] << 8 | line[(x << 1) + 1];
}
return 0;
}
static inline void putcomp(unsigned char *line, int x, int bpc, int value)
{
int maxval = (1 << bpc) - 1;
switch (bpc)
{
case 1: line[x >> 3] &= ~(maxval << (7 - (x & 7))); break;
case 2: line[x >> 2] &= ~(maxval << ((3 - (x & 3)) << 1)); break;
case 4: line[x >> 1] &= ~(maxval << ((1 - (x & 1)) << 2)); break;
}
switch (bpc)
{
case 1: line[x >> 3] |= value << (7 - (x & 7)); break;
case 2: line[x >> 2] |= value << ((3 - (x & 3)) << 1); break;
case 4: line[x >> 1] |= value << ((1 - (x & 1)) << 2); break;
case 8: line[x] = value; break;
case 16: line[x << 1] = value >> 8; line[(x << 1) + 1] = value & 0xFF; break;
}
}
static const unsigned char png_signature[8] =
{
137, 80, 78, 71, 13, 10, 26, 10
};
static inline int paeth(int a, int b, int c)
{
/* The definitions of ac and bc are correct, not a typo. */
int ac = b - c, bc = a - c, abcc = ac + bc;
int pa = (ac < 0 ? -ac : ac);
int pb = (bc < 0 ? -bc : bc);
int pc = (abcc < 0 ? -abcc : abcc);
return pa <= pb && pa <= pc ? a : pb <= pc ? b : c;
}
static void
png_predict(unsigned char *samples, unsigned int width, unsigned int height, unsigned int n, unsigned int depth)
{
unsigned int stride = (width * n * depth + 7) / 8;
unsigned int bpp = (n * depth + 7) / 8;
unsigned int i, row;
for (row = 0; row < height; row ++)
{
unsigned char *src = samples + (unsigned int)((stride + 1) * row);
unsigned char *dst = samples + (unsigned int)(stride * row);
unsigned char *a = dst;
unsigned char *b = dst - stride;
unsigned char *c = dst - stride;
switch (*src++)
{
default:
case 0: /* None */
for (i = 0; i < stride; i++)
*dst++ = *src++;
break;
case 1: /* Sub */
for (i = 0; i < bpp; i++)
*dst++ = *src++;
for (i = bpp; i < stride; i++)
*dst++ = *src++ + *a++;
break;
case 2: /* Up */
if (row == 0)
for (i = 0; i < stride; i++)
*dst++ = *src++;
else
for (i = 0; i < stride; i++)
*dst++ = *src++ + *b++;
break;
case 3: /* Average */
if (row == 0)
{
for (i = 0; i < bpp; i++)
*dst++ = *src++;
for (i = bpp; i < stride; i++)
*dst++ = *src++ + (*a++ >> 1);
}
else
{
for (i = 0; i < bpp; i++)
*dst++ = *src++ + (*b++ >> 1);
for (i = bpp; i < stride; i++)
*dst++ = *src++ + ((*b++ + *a++) >> 1);
}
break;
case 4: /* Paeth */
if (row == 0)
{
for (i = 0; i < bpp; i++)
*dst++ = *src++ + paeth(0, 0, 0);
for (i = bpp; i < stride; i++)
*dst++ = *src++ + paeth(*a++, 0, 0);
}
else
{
for (i = 0; i < bpp; i++)
*dst++ = *src++ + paeth(0, *b++, 0);
for (i = bpp; i < stride; i++)
*dst++ = *src++ + paeth(*a++, *b++, *c++);
}
break;
}
}
}
static const unsigned int adam7_ix[7] = { 0, 4, 0, 2, 0, 1, 0 };
static const unsigned int adam7_dx[7] = { 8, 8, 4, 4, 2, 2, 1 };
static const unsigned int adam7_iy[7] = { 0, 0, 4, 0, 2, 0, 1 };
static const unsigned int adam7_dy[7] = { 8, 8, 8, 4, 4, 2, 2 };
static void
png_deinterlace_passes(fz_context *ctx, struct info *info, unsigned int *w, unsigned int *h, unsigned int *ofs)
{
int p, bpp = info->depth * info->n;
ofs[0] = 0;
for (p = 0; p < 7; p++)
{
w[p] = (info->width + adam7_dx[p] - adam7_ix[p] - 1) / adam7_dx[p];
h[p] = (info->height + adam7_dy[p] - adam7_iy[p] - 1) / adam7_dy[p];
if (w[p] == 0) h[p] = 0;
if (h[p] == 0) w[p] = 0;
if (w[p] && h[p])
ofs[p + 1] = ofs[p] + h[p] * (1 + (w[p] * bpp + 7) / 8);
else
ofs[p + 1] = ofs[p];
}
}
static void
png_deinterlace(fz_context *ctx, struct info *info, unsigned int *passw, unsigned int *passh, unsigned int *passofs)
{
unsigned int n = info->n;
unsigned int depth = info->depth;
unsigned int stride = (info->width * n * depth + 7) / 8;
unsigned char *output;
unsigned int p, x, y, k;
if (info->height > UINT_MAX / stride)
fz_throw(ctx, FZ_ERROR_MEMORY, "image too large");
output = fz_malloc(ctx, info->height * stride);
for (p = 0; p < 7; p++)
{
unsigned char *sp = info->samples + (passofs[p]);
unsigned int w = passw[p];
unsigned int h = passh[p];
png_predict(sp, w, h, n, depth);
for (y = 0; y < h; y++)
{
for (x = 0; x < w; x++)
{
int outx = x * adam7_dx[p] + adam7_ix[p];
int outy = y * adam7_dy[p] + adam7_iy[p];
unsigned char *dp = output + outy * stride;
for (k = 0; k < n; k++)
{
int v = getcomp(sp, x * n + k, depth);
putcomp(dp, outx * n + k, depth, v);
}
}
sp += (w * depth * n + 7) / 8;
}
}
fz_free(ctx, info->samples);
info->samples = output;
}
static void
png_read_ihdr(fz_context *ctx, struct info *info, const unsigned char *p, unsigned int size)
{
int color, compression, filter;
if (size != 13)
fz_throw(ctx, FZ_ERROR_GENERIC, "IHDR chunk is the wrong size");
info->width = getuint(p + 0);
info->height = getuint(p + 4);
info->depth = p[8];
color = p[9];
compression = p[10];
filter = p[11];
info->interlace = p[12];
if (info->width <= 0)
fz_throw(ctx, FZ_ERROR_GENERIC, "image width must be > 0");
if (info->height <= 0)
fz_throw(ctx, FZ_ERROR_GENERIC, "image height must be > 0");
if (info->depth != 1 && info->depth != 2 && info->depth != 4 &&
info->depth != 8 && info->depth != 16)
fz_throw(ctx, FZ_ERROR_GENERIC, "image bit depth must be one of 1, 2, 4, 8, 16");
if (color == 2 && info->depth < 8)
fz_throw(ctx, FZ_ERROR_GENERIC, "illegal bit depth for truecolor");
if (color == 3 && info->depth > 8)
fz_throw(ctx, FZ_ERROR_GENERIC, "illegal bit depth for indexed");
if (color == 4 && info->depth < 8)
fz_throw(ctx, FZ_ERROR_GENERIC, "illegal bit depth for grayscale with alpha");
if (color == 6 && info->depth < 8)
fz_throw(ctx, FZ_ERROR_GENERIC, "illegal bit depth for truecolor with alpha");
info->indexed = 0;
if (color == 0) /* gray */
info->n = 1, info->type = FZ_COLORSPACE_GRAY;
else if (color == 2) /* rgb */
info->n = 3, info->type = FZ_COLORSPACE_RGB;
else if (color == 4) /* gray alpha */
info->n = 2, info->type = FZ_COLORSPACE_GRAY;
else if (color == 6) /* rgb alpha */
info->n = 4, info->type = FZ_COLORSPACE_RGB;
else if (color == 3) /* indexed */
{
info->type = FZ_COLORSPACE_RGB; /* after colorspace expansion it will be */
info->indexed = 1;
info->n = 1;
}
else
fz_throw(ctx, FZ_ERROR_GENERIC, "unknown color type");
if (compression != 0)
fz_throw(ctx, FZ_ERROR_GENERIC, "unknown compression method");
if (filter != 0)
fz_throw(ctx, FZ_ERROR_GENERIC, "unknown filter method");
if (info->interlace != 0 && info->interlace != 1)
fz_throw(ctx, FZ_ERROR_GENERIC, "interlace method not supported");
if (info->height > UINT_MAX / info->width / info->n / (info->depth / 8 + 1))
fz_throw(ctx, FZ_ERROR_GENERIC, "image dimensions might overflow");
}
static void
png_read_plte(fz_context *ctx, struct info *info, const unsigned char *p, unsigned int size)
{
int n = size / 3;
int i;
if (n > 256)
{
fz_warn(ctx, "too many samples in palette");
n = 256;
}
for (i = 0; i < n; i++)
{
info->palette[i * 4] = p[i * 3];
info->palette[i * 4 + 1] = p[i * 3 + 1];
info->palette[i * 4 + 2] = p[i * 3 + 2];
}
/* Fill in any missing palette entries */
for (; i < 256; i++)
{
info->palette[i * 4] = 0;
info->palette[i * 4 + 1] = 0;
info->palette[i * 4 + 2] = 0;
}
}
static void
png_read_trns(fz_context *ctx, struct info *info, const unsigned char *p, unsigned int size)
{
unsigned int i;
info->transparency = 1;
if (info->indexed)
{
if (size > 256)
{
fz_warn(ctx, "too many samples in transparency table");
size = 256;
}
for (i = 0; i < size; i++)
info->palette[i * 4 + 3] = p[i];
/* Fill in any missing entries */
for (; i < 256; i++)
info->palette[i * 4 + 3] = 255;
}
else
{
if (size != info->n * 2)
fz_throw(ctx, FZ_ERROR_GENERIC, "tRNS chunk is the wrong size");
for (i = 0; i < info->n; i++)
info->trns[i] = (p[i * 2] << 8 | p[i * 2 + 1]) & ((1 << info->depth) - 1);
}
}
static void
png_read_icc(fz_context *ctx, struct info *info, const unsigned char *p, unsigned int size)
{
#if FZ_ENABLE_ICC
fz_stream *mstm = NULL, *zstm = NULL;
fz_colorspace *cs = NULL;
fz_buffer *buf = NULL;
size_t m = fz_mini(80, size);
size_t n = fz_strnlen((const char *)p, m);
if (n + 2 > m)
{
fz_warn(ctx, "invalid ICC profile name");
return;
}
fz_var(mstm);
fz_var(zstm);
fz_var(buf);
fz_try(ctx)
{
mstm = fz_open_memory(ctx, p + n + 2, size - n - 2);
zstm = fz_open_flated(ctx, mstm, 15);
buf = fz_read_all(ctx, zstm, 0);
cs = fz_new_icc_colorspace(ctx, info->type, 0, NULL, buf);
fz_drop_colorspace(ctx, info->cs);
info->cs = cs;
}
fz_always(ctx)
{
fz_drop_buffer(ctx, buf);
fz_drop_stream(ctx, zstm);
fz_drop_stream(ctx, mstm);
}
fz_catch(ctx)
fz_warn(ctx, "ignoring embedded ICC profile in PNG");
#endif
}
static void
png_read_idat(fz_context *ctx, struct info *info, const unsigned char *p, unsigned int size, z_stream *stm)
{
int code;
stm->next_in = (Bytef*)p;
stm->avail_in = size;
code = inflate(stm, Z_SYNC_FLUSH);
if (code != Z_OK && code != Z_STREAM_END)
fz_throw(ctx, FZ_ERROR_GENERIC, "zlib error: %s", stm->msg);
if (stm->avail_in != 0)
{
if (stm->avail_out == 0)
fz_throw(ctx, FZ_ERROR_GENERIC, "ran out of output before input");
fz_throw(ctx, FZ_ERROR_GENERIC, "inflate did not consume buffer (%d remaining)", stm->avail_in);
}
}
static void
png_read_phys(fz_context *ctx, struct info *info, const unsigned char *p, unsigned int size)
{
if (size != 9)
fz_throw(ctx, FZ_ERROR_GENERIC, "pHYs chunk is the wrong size");
if (p[8] == 1)
{
info->xres = (getuint(p) * 254 + 5000) / 10000;
info->yres = (getuint(p + 4) * 254 + 5000) / 10000;
}
}
static void
png_read_image(fz_context *ctx, struct info *info, const unsigned char *p, size_t total, int only_metadata)
{
unsigned int passw[7], passh[7], passofs[8];
unsigned int code, size;
z_stream stm;
memset(info, 0, sizeof (struct info));
memset(info->palette, 255, sizeof(info->palette));
info->xres = 96;
info->yres = 96;
/* Read signature */
if (total < 8 + 12 || memcmp(p, png_signature, 8))
fz_throw(ctx, FZ_ERROR_GENERIC, "not a png image (wrong signature)");
p += 8;
total -= 8;
/* Read IHDR chunk (must come first) */
size = getuint(p);
if (total < 12 || size > total - 12)
fz_throw(ctx, FZ_ERROR_GENERIC, "premature end of data in png image");
if (!memcmp(p + 4, "IHDR", 4))
png_read_ihdr(ctx, info, p + 8, size);
else
fz_throw(ctx, FZ_ERROR_GENERIC, "png file must start with IHDR chunk");
p += size + 12;
total -= size + 12;
/* Prepare output buffer */
if (!only_metadata)
{
if (!info->interlace)
{
info->size = info->height * (1 + (info->width * info->n * info->depth + 7) / 8);
}
else
{
png_deinterlace_passes(ctx, info, passw, passh, passofs);
info->size = passofs[7];
}
info->samples = fz_malloc(ctx, info->size);
stm.zalloc = fz_zlib_alloc;
stm.zfree = fz_zlib_free;
stm.opaque = ctx;
stm.next_out = info->samples;
stm.avail_out = info->size;
code = inflateInit(&stm);
if (code != Z_OK)
fz_throw(ctx, FZ_ERROR_GENERIC, "zlib error: %s", stm.msg);
}
fz_try(ctx)
{
/* Read remaining chunks until IEND */
while (total > 8)
{
size = getuint(p);
if (total < 12 || size > total - 12)
fz_throw(ctx, FZ_ERROR_GENERIC, "premature end of data in png image");
if (!memcmp(p + 4, "PLTE", 4) && !only_metadata)
png_read_plte(ctx, info, p + 8, size);
if (!memcmp(p + 4, "tRNS", 4) && !only_metadata)
png_read_trns(ctx, info, p + 8, size);
if (!memcmp(p + 4, "pHYs", 4))
png_read_phys(ctx, info, p + 8, size);
if (!memcmp(p + 4, "IDAT", 4) && !only_metadata)
png_read_idat(ctx, info, p + 8, size, &stm);
if (!memcmp(p + 4, "iCCP", 4))
png_read_icc(ctx, info, p + 8, size);
if (!memcmp(p + 4, "IEND", 4))
break;
p += size + 12;
total -= size + 12;
}
if (!only_metadata && stm.avail_out != 0)
{
memset(stm.next_out, 0xff, stm.avail_out);
fz_warn(ctx, "missing pixel data in png image; possibly truncated");
}
else if (total <= 8)
fz_warn(ctx, "missing IEND chunk in png image; possibly truncated");
}
fz_catch(ctx)
{
if (!only_metadata)
{
inflateEnd(&stm);
fz_free(ctx, info->samples);
info->samples = NULL;
}
fz_rethrow(ctx);
}
if (!only_metadata)
{
code = inflateEnd(&stm);
if (code != Z_OK)
{
fz_free(ctx, info->samples);
info->samples = NULL;
fz_throw(ctx, FZ_ERROR_GENERIC, "zlib error: %s", stm.msg);
}
/* Apply prediction filter and deinterlacing */
fz_try(ctx)
{
if (!info->interlace)
png_predict(info->samples, info->width, info->height, info->n, info->depth);
else
png_deinterlace(ctx, info, passw, passh, passofs);
}
fz_catch(ctx)
{
fz_free(ctx, info->samples);
info->samples = NULL;
fz_rethrow(ctx);
}
}
if (info->cs && fz_colorspace_type(ctx, info->cs) != info->type)
{
fz_warn(ctx, "embedded ICC profile does not match PNG colorspace");
fz_drop_colorspace(ctx, info->cs);
info->cs = NULL;
}
if (info->cs == NULL)
{
if (info->n == 3 || info->n == 4 || info->indexed)
info->cs = fz_keep_colorspace(ctx, fz_device_rgb(ctx));
else
info->cs = fz_keep_colorspace(ctx, fz_device_gray(ctx));
}
}
static fz_pixmap *
png_expand_palette(fz_context *ctx, struct info *info, fz_pixmap *src)
{
fz_pixmap *dst = fz_new_pixmap(ctx, info->cs, src->w, src->h, NULL, info->transparency);
unsigned char *sp = src->samples;
unsigned char *dp = dst->samples;
unsigned int x, y;
int dstride = dst->stride - dst->w * dst->n;
int sstride = src->stride - src->w * src->n;
dst->xres = src->xres;
dst->yres = src->yres;
for (y = info->height; y > 0; y--)
{
for (x = info->width; x > 0; x--)
{
int v = *sp << 2;
*dp++ = info->palette[v];
*dp++ = info->palette[v + 1];
*dp++ = info->palette[v + 2];
if (info->transparency)
*dp++ = info->palette[v + 3];
++sp;
}
sp += sstride;
dp += dstride;
}
fz_drop_pixmap(ctx, src);
return dst;
}
static void
png_mask_transparency(struct info *info, fz_pixmap *dst)
{
unsigned int stride = (info->width * info->n * info->depth + 7) / 8;
unsigned int depth = info->depth;
unsigned int n = info->n;
unsigned int x, y, k, t;
for (y = 0; y < info->height; y++)
{
unsigned char *sp = info->samples + (unsigned int)(y * stride);
unsigned char *dp = dst->samples + (unsigned int)(y * dst->stride);
for (x = 0; x < info->width; x++)
{
t = 1;
for (k = 0; k < n; k++)
if (getcomp(sp, x * n + k, depth) != info->trns[k])
t = 0;
if (t)
dp[x * dst->n + dst->n - 1] = 0;
}
}
}
fz_pixmap *
fz_load_png(fz_context *ctx, const unsigned char *p, size_t total)
{
fz_pixmap *image = NULL;
struct info png;
int stride;
int alpha;
fz_var(image);
fz_try(ctx)
{
png_read_image(ctx, &png, p, total, 0);
stride = (png.width * png.n * png.depth + 7) / 8;
alpha = (png.n == 2 || png.n == 4 || png.transparency);
if (png.indexed)
{
image = fz_new_pixmap(ctx, NULL, png.width, png.height, NULL, 1);
fz_unpack_tile(ctx, image, png.samples, png.n, png.depth, stride, 1);
image = png_expand_palette(ctx, &png, image);
}
else
{
image = fz_new_pixmap(ctx, png.cs, png.width, png.height, NULL, alpha);
fz_unpack_tile(ctx, image, png.samples, png.n, png.depth, stride, 0);
if (png.transparency)
png_mask_transparency(&png, image);
}
if (alpha)
fz_premultiply_pixmap(ctx, image);
fz_set_pixmap_resolution(ctx, image, png.xres, png.yres);
}
fz_always(ctx)
{
fz_drop_colorspace(ctx, png.cs);
fz_free(ctx, png.samples);
}
fz_catch(ctx)
{
fz_drop_pixmap(ctx, image);
fz_rethrow(ctx);
}
return image;
}
void
fz_load_png_info(fz_context *ctx, const unsigned char *p, size_t total, int *wp, int *hp, int *xresp, int *yresp, fz_colorspace **cspacep)
{
struct info png;
fz_try(ctx)
png_read_image(ctx, &png, p, total, 1);
fz_catch(ctx)
{
fz_drop_colorspace(ctx, png.cs);
fz_rethrow(ctx);
}
*cspacep = png.cs;
*wp = png.width;
*hp = png.height;
*xresp = png.xres;
*yresp = png.xres;
}
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