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#include "fitz.h"
#include "muxps.h"
#include <zlib.h>
struct info
{
int width, height, depth, n;
int interlace, indexed;
int size;
unsigned char *samples;
unsigned char palette[256*4];
int transparency;
int trns[3];
int xres, yres;
};
static inline int getint(unsigned char *p)
{
return p[0] << 24 | p[1] << 16 | p[2] << 8 | p[3];
}
static inline int getcomp(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 void *zalloc(void *opaque, unsigned int items, unsigned int size)
{
return fz_calloc(items, size);
}
static void zfree(void *opaque, void *address)
{
fz_free(address);
}
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, int width, int height, int n, int depth)
{
int stride = (width * n * depth + 7) / 8;
int bpp = (n * depth + 7) / 8;
int i, row;
for (row = 0; row < height; row ++)
{
unsigned char *src = samples + (stride + 1) * row;
unsigned char *dst = samples + 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 int adam7_ix[7] = { 0, 4, 0, 2, 0, 1, 0 };
static const int adam7_dx[7] = { 8, 8, 4, 4, 2, 2, 1 };
static const int adam7_iy[7] = { 0, 0, 4, 0, 2, 0, 1 };
static const int adam7_dy[7] = { 8, 8, 8, 4, 4, 2, 2 };
static void
png_deinterlace_passes(struct info *info, int *w, int *h, 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(struct info *info, int *passw, int *passh, int *passofs)
{
int n = info->n;
int depth = info->depth;
int stride = (info->width * n * depth + 7) / 8;
unsigned char *output;
int p, x, y, k;
output = fz_calloc(info->height, stride);
for (p = 0; p < 7; p++)
{
unsigned char *sp = info->samples + passofs[p];
int w = passw[p];
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(info->samples);
info->samples = output;
}
static int
png_read_ihdr(struct info *info, unsigned char *p, int size)
{
int color, compression, filter;
if (size != 13)
return fz_throw("IHDR chunk is the wrong size");
info->width = getint(p + 0);
info->height = getint(p + 4);
info->depth = p[8];
color = p[9];
compression = p[10];
filter = p[11];
info->interlace = p[12];
if (info->width <= 0)
return fz_throw("image width must be > 0");
if (info->height <= 0)
return fz_throw("image height must be > 0");
if (info->depth != 1 && info->depth != 2 && info->depth != 4 &&
info->depth != 8 && info->depth != 16)
return fz_throw("image bit depth must be one of 1, 2, 4, 8, 16");
if (color == 2 && info->depth < 8)
return fz_throw("illegal bit depth for truecolor");
if (color == 3 && info->depth > 8)
return fz_throw("illegal bit depth for indexed");
if (color == 4 && info->depth < 8)
return fz_throw("illegal bit depth for grayscale with alpha");
if (color == 6 && info->depth < 8)
return fz_throw("illegal bit depth for truecolor with alpha");
info->indexed = 0;
if (color == 0) /* gray */
info->n = 1;
else if (color == 2) /* rgb */
info->n = 3;
else if (color == 4) /* gray alpha */
info->n = 2;
else if (color == 6) /* rgb alpha */
info->n = 4;
else if (color == 3) /* indexed */
{
info->indexed = 1;
info->n = 1;
}
else
return fz_throw("unknown color type");
if (compression != 0)
return fz_throw("unknown compression method");
if (filter != 0)
return fz_throw("unknown filter method");
if (info->interlace != 0 && info->interlace != 1)
return fz_throw("interlace method not supported");
return fz_okay;
}
static int
png_read_plte(struct info *info, unsigned char *p, int size)
{
int n = size / 3;
int i;
if (n > 256 || n > (1 << info->depth))
return fz_throw("too many samples in palette");
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];
}
return fz_okay;
}
static int
png_read_trns(struct info *info, unsigned char *p, int size)
{
int i;
info->transparency = 1;
if (info->indexed)
{
if (size > 256 || size > (1 << info->depth))
return fz_throw("too many samples in transparency table");
for (i = 0; i < size; i++)
info->palette[i * 4 + 3] = p[i];
}
else
{
if (size != info->n * 2)
return fz_throw("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);
}
return fz_okay;
}
static int
png_read_idat(struct info *info, unsigned char *p, int size, z_stream *stm)
{
int code;
stm->next_in = p;
stm->avail_in = size;
code = inflate(stm, Z_SYNC_FLUSH);
if (code != Z_OK && code != Z_STREAM_END)
return fz_throw("zlib error: %s", stm->msg);
if (stm->avail_in != 0)
{
if (stm->avail_out == 0)
return fz_throw("ran out of output before input");
return fz_throw("inflate did not consume buffer (%d remaining)", stm->avail_in);
}
return fz_okay;
}
static int
png_read_phys(struct info *info, unsigned char *p, int size)
{
if (size != 9)
return fz_throw("pHYs chunk is the wrong size");
if (p[8] == 1)
{
info->xres = getint(p) * 254 / 10000;
info->yres = getint(p + 4) * 254 / 10000;
}
return fz_okay;
}
static int
png_read_image(struct info *info, unsigned char *p, int total)
{
int passw[7], passh[7], passofs[8];
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))
return fz_throw("not a png image (wrong signature)");
p += 8;
total -= 8;
/* Read IHDR chunk (must come first) */
size = getint(p);
if (size + 12 > total)
return fz_throw("premature end of data in png image");
if (!memcmp(p + 4, "IHDR", 4))
{
code = png_read_ihdr(info, p + 8, size);
if (code)
return fz_rethrow(code, "cannot read png header");
}
else
return fz_throw("png file must start with IHDR chunk");
p += size + 12;
total -= size + 12;
/* Prepare output buffer */
if (!info->interlace)
{
info->size = info->height * (1 + (info->width * info->n * info->depth + 7) / 8);
}
else
{
png_deinterlace_passes(info, passw, passh, passofs);
info->size = passofs[7];
}
info->samples = fz_malloc(info->size);
stm.zalloc = zalloc;
stm.zfree = zfree;
stm.opaque = NULL;
stm.next_out = info->samples;
stm.avail_out = info->size;
code = inflateInit(&stm);
if (code != Z_OK)
return fz_throw("zlib error: %s", stm.msg);
/* Read remaining chunks until IEND */
while (total > 8)
{
size = getint(p);
if (size + 12 > total)
return fz_throw("premature end of data in png image");
if (!memcmp(p + 4, "PLTE", 4))
{
code = png_read_plte(info, p + 8, size);
if (code)
return fz_rethrow(code, "cannot read png palette");
}
if (!memcmp(p + 4, "tRNS", 4))
{
code = png_read_trns(info, p + 8, size);
if (code)
return fz_rethrow(code, "cannot read png transparency");
}
if (!memcmp(p + 4, "pHYs", 4))
{
code = png_read_phys(info, p + 8, size);
if (code)
return fz_rethrow(code, "cannot read png resolution");
}
if (!memcmp(p + 4, "IDAT", 4))
{
code = png_read_idat(info, p + 8, size, &stm);
if (code)
return fz_rethrow(code, "cannot read png image data");
}
if (!memcmp(p + 4, "IEND", 4))
break;
p += size + 12;
total -= size + 12;
}
code = inflateEnd(&stm);
if (code != Z_OK)
return fz_throw("zlib error: %s", stm.msg);
/* Apply prediction filter and deinterlacing */
if (!info->interlace)
png_predict(info->samples, info->width, info->height, info->n, info->depth);
else
png_deinterlace(info, passw, passh, passofs);
return fz_okay;
}
static fz_pixmap *
png_expand_palette(struct info *info, fz_pixmap *src)
{
fz_pixmap *dst = fz_new_pixmap(fz_device_rgb, 0, 0, src->w, src->h);
unsigned char *sp = src->samples;
unsigned char *dp = dst->samples;
int x, y;
dst->xres = src->xres;
dst->yres = src->yres;
for (y = 0; y < info->height; y++)
{
for (x = 0; x < info->width; x++)
{
int v = *sp << 2;
*dp++ = info->palette[v];
*dp++ = info->palette[v + 1];
*dp++ = info->palette[v + 2];
*dp++ = info->palette[v + 3];
sp += 2;
}
}
fz_drop_pixmap(src);
return dst;
}
static void
png_mask_transparency(struct info *info, fz_pixmap *dst)
{
int stride = (info->width * info->n * info->depth + 7) / 8;
int depth = info->depth;
int n = info->n;
int x, y, k, t;
for (y = 0; y < info->height; y++)
{
unsigned char *sp = info->samples + y * stride;
unsigned char *dp = dst->samples + y * dst->w * dst->n;
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;
}
}
}
int
xps_decode_png(fz_pixmap **imagep, byte *p, int total)
{
fz_pixmap *image;
fz_colorspace *colorspace;
struct info png;
int code;
int stride;
code = png_read_image(&png, p, total);
if (code)
return fz_rethrow(code, "cannot read png image");
if (png.n == 3 || png.n == 4)
colorspace = fz_device_rgb;
else
colorspace = fz_device_gray;
stride = (png.width * png.n * png.depth + 7) / 8;
image = fz_new_pixmap(colorspace, 0, 0, png.width, png.height);
image->xres = png.xres;
image->yres = png.yres;
fz_unpack_tile(image, png.samples, png.n, png.depth, stride, png.indexed);
if (png.indexed)
image = png_expand_palette(&png, image);
else if (png.transparency)
png_mask_transparency(&png, image);
if (png.transparency || png.n == 2 || png.n == 4)
fz_premultiply_pixmap(image);
fz_free(png.samples);
*imagep = image;
return fz_okay;
}
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