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pngimage.c
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pngimage.c
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/* This is dvipdfmx, an eXtended version of dvipdfm by Mark A. Wicks.
Copyright (C) 2002-2014 by Jin-Hwan Cho and Shunsaku Hirata,
the dvipdfmx project team.
Copyright (C) 1998, 1999 by Mark A. Wicks <mwicks@kettering.edu>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
*/
#define XETEX 1 /* We are all xetex now */
#ifdef BUILDING_LIBTEXPDF
#include <config.h>
#endif
/*
* PNG SUPPORT
*
* All bitdepth less than 16 is supported.
* Supported color types are: PALETTE, RGB, GRAY, RGB_ALPHA, GRAY_ALPHA.
* Supported ancillary chunks: tRNS, cHRM, gAMA, (sRGB), (iCCP)
*
* cHRM support is not tested well. CalRGB/CalGray colorspace is used for
* PNG images that have cHRM chunk.
*
* LIMITATIONS
*
* Recent version of PDF (>= 1.5) support 16 bpc, but 16 bit bitdepth PNG
* images are automatically converted to 8 bit bitpedth image.
*
* TODO
* 16 bpc support for PDF-1.5. JBIG compression for monochrome image.
* Predictor for deflate ?
*/
#define PNG_DEBUG_STR "PNG"
#define PNG_DEBUG 3
/*
* Write, MNG, Progressive not required.
*/
#define PNG_NO_WRITE_SUPPORTED
#define PNG_NO_MNG_FEATURES
#define PNG_NO_PROGRESSIVE_READ
#if 0
/* 16_TO_8 required. */
#define PNG_NO_READ_TRANSFORMS
#endif
#include <png.h>
#include "pngimage.h"
#include "libtexpdf.h"
#include "pdfximage.h"
#define PDF_TRANS_TYPE_NONE 0
#define PDF_TRANS_TYPE_BINARY 1
#define PDF_TRANS_TYPE_ALPHA 2
/* ColorSpace */
static pdf_obj *create_cspace_Indexed (png_structp png_ptr, png_infop info_ptr);
/* CIE-Based: CalRGB/CalGray */
static pdf_obj *create_cspace_CalRGB (png_structp png_ptr, png_infop info_ptr);
static pdf_obj *create_cspace_CalGray (png_structp png_ptr, png_infop info_ptr);
static pdf_obj *make_param_Cal (png_byte color_type,
double G,
double xw, double yw,
double xr, double yr,
double xg, double yg,
double xb, double yb);
/* sRGB:
*
* We (and PDF) do not have direct sRGB support. The sRGB color space can be
* precisely represented by ICC profile, but we use approximate CalRGB color
* space.
*/
static pdf_obj *create_cspace_sRGB (png_structp png_ptr, png_infop info_ptr);
static pdf_obj *get_rendering_intent (png_structp png_ptr, png_infop info_ptr);
/* ICCBased:
*
* Not supported yet.
* Must check if ICC profile is valid and can be imported to PDF.
* There are few restrictions (should be applied to PNG too?) in ICC profile
* support in PDF. Some information should be obtained from profile.
*/
static pdf_obj *create_cspace_ICCBased (png_structp png_ptr, png_infop info_ptr);
/* Transparency */
static int check_transparency (png_structp png_ptr, png_infop info_ptr);
/* Color-Key Mask */
static pdf_obj *create_ckey_mask (png_structp png_ptr, png_infop info_ptr);
/* Soft Mask:
*
* create_soft_mask() is for PNG_COLOR_TYPE_PALLETE.
* Images with alpha chunnel use strip_soft_mask().
* An object representing mask itself is returned.
*/
static pdf_obj *create_soft_mask (png_structp png_ptr, png_infop info_ptr,
png_bytep image_data_ptr,
png_uint_32 width, png_uint_32 height);
static pdf_obj *strip_soft_mask (png_structp png_ptr, png_infop info_ptr,
png_bytep image_data_ptr,
png_uint_32p rowbytes_ptr,
png_uint_32 width, png_uint_32 height);
/* Read image body */
static void read_image_data (png_structp png_ptr,
png_bytep dest_ptr,
png_uint_32 height, png_uint_32 rowbytes);
int
texpdf_check_for_png (FILE *png_file)
{
unsigned char sigbytes[4];
rewind (png_file);
if (fread (sigbytes, 1, sizeof(sigbytes), png_file) !=
sizeof(sigbytes) ||
(png_sig_cmp (sigbytes, 0, sizeof(sigbytes))))
return 0;
else
return 1;
}
static void warn(png_structp png_ptr, png_const_charp msg)
{
(void)png_ptr; (void)msg; /* Make compiler happy */
}
int
png_include_image (pdf_ximage *ximage, FILE *png_file)
{
pdf_obj *stream;
pdf_obj *stream_dict;
pdf_obj *colorspace, *mask, *intent;
png_bytep stream_data_ptr;
int trans_type;
ximage_info info;
/* Libpng stuff */
png_structp png_ptr;
png_infop png_info_ptr;
png_byte bpc, color_type;
png_uint_32 width, height, rowbytes;
texpdf_ximage_init_image_info(&info);
stream = NULL;
stream_dict = NULL;
colorspace = mask = intent = NULL;
rewind (png_file);
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, warn);
if (png_ptr == NULL ||
(png_info_ptr = png_create_info_struct (png_ptr)) == NULL) {
WARN("%s: Creating Libpng read/info struct failed.", PNG_DEBUG_STR);
if (png_ptr)
png_destroy_read_struct(&png_ptr, NULL, NULL);
return -1;
}
#if PNG_LIBPNG_VER >= 10603
/* ignore possibly incorrect CMF bytes */
png_set_option(png_ptr, PNG_MAXIMUM_INFLATE_WINDOW, PNG_OPTION_ON);
#endif
/* Inititializing file IO. */
png_init_io (png_ptr, png_file);
/* Read PNG info-header and get some info. */
png_read_info(png_ptr, png_info_ptr);
color_type = png_get_color_type (png_ptr, png_info_ptr);
width = png_get_image_width (png_ptr, png_info_ptr);
height = png_get_image_height(png_ptr, png_info_ptr);
bpc = png_get_bit_depth (png_ptr, png_info_ptr);
/* We do not need 16-bpc color. Ask libpng to convert down to 8-bpc. */
if (bpc > 8) {
png_set_strip_16(png_ptr);
bpc = 8;
}
/* Ask libpng to gamma-correct.
* It is wrong to assume screen gamma value 2.2 but...
* We do gamma correction here only when uncalibrated color space is used.
*/
if (!png_get_valid(png_ptr, png_info_ptr, PNG_INFO_iCCP) &&
!png_get_valid(png_ptr, png_info_ptr, PNG_INFO_sRGB) &&
!png_get_valid(png_ptr, png_info_ptr, PNG_INFO_cHRM) &&
!png_get_valid(png_ptr, png_info_ptr, PNG_INFO_sRGB) &&
png_get_valid(png_ptr, png_info_ptr, PNG_INFO_gAMA)) {
double G = 1.0;
png_get_gAMA (png_ptr, png_info_ptr, &G);
png_set_gamma(png_ptr, 2.2, G);
}
trans_type = check_transparency(png_ptr, png_info_ptr);
/* check_transparency() does not do updata_info() */
png_read_update_info(png_ptr, png_info_ptr);
rowbytes = png_get_rowbytes(png_ptr, png_info_ptr);
/* Values listed below will not be modified in the remaining process. */
info.width = width;
info.height = height;
info.bits_per_component = bpc;
if (compat_mode)
info.xdensity = info.ydensity = 72.0 / 100.0;
else
{
png_uint_32 xppm = png_get_x_pixels_per_meter(png_ptr, png_info_ptr);
png_uint_32 yppm = png_get_y_pixels_per_meter(png_ptr, png_info_ptr);
if (xppm > 0)
info.xdensity = 72.0 / 0.0254 / xppm;
if (yppm > 0)
info.ydensity = 72.0 / 0.0254 / yppm;
}
stream = texpdf_new_stream (STREAM_COMPRESS);
stream_dict = texpdf_stream_dict(stream);
stream_data_ptr = (png_bytep) NEW(rowbytes*height, png_byte);
read_image_data(png_ptr, stream_data_ptr, height, rowbytes);
/* Non-NULL intent means there is valid sRGB chunk. */
intent = get_rendering_intent(png_ptr, png_info_ptr);
if (intent)
texpdf_add_dict(stream_dict, texpdf_new_name("Intent"), intent);
switch (color_type) {
case PNG_COLOR_TYPE_PALETTE:
colorspace = create_cspace_Indexed(png_ptr, png_info_ptr);
switch (trans_type) {
case PDF_TRANS_TYPE_BINARY:
/* Color-key masking */
mask = create_ckey_mask(png_ptr, png_info_ptr);
break;
case PDF_TRANS_TYPE_ALPHA:
/* Soft mask */
mask = create_soft_mask(png_ptr, png_info_ptr, stream_data_ptr, width, height);
break;
default:
/* Nothing to be done here.
* No tRNS chunk or image already composited with background color.
*/
break;
}
break;
case PNG_COLOR_TYPE_RGB:
case PNG_COLOR_TYPE_RGB_ALPHA:
if (png_get_valid(png_ptr, png_info_ptr, PNG_INFO_iCCP))
colorspace = create_cspace_ICCBased(png_ptr, png_info_ptr);
else if (intent) {
colorspace = create_cspace_sRGB(png_ptr, png_info_ptr);
} else {
colorspace = create_cspace_CalRGB(png_ptr, png_info_ptr);
}
if (!colorspace)
colorspace = texpdf_new_name("DeviceRGB");
switch (trans_type) {
case PDF_TRANS_TYPE_BINARY:
mask = create_ckey_mask(png_ptr, png_info_ptr);
break;
/* rowbytes changes 4 to 3 at here */
case PDF_TRANS_TYPE_ALPHA:
mask = strip_soft_mask(png_ptr, png_info_ptr,
stream_data_ptr, &rowbytes, width, height);
break;
default:
mask = NULL;
}
info.num_components = 3;
break;
case PNG_COLOR_TYPE_GRAY:
case PNG_COLOR_TYPE_GRAY_ALPHA:
if (png_get_valid(png_ptr, png_info_ptr, PNG_INFO_iCCP))
colorspace = create_cspace_ICCBased(png_ptr, png_info_ptr);
else if (intent) {
colorspace = create_cspace_sRGB(png_ptr, png_info_ptr);
} else {
colorspace = create_cspace_CalGray(png_ptr, png_info_ptr);
}
if (!colorspace)
colorspace = texpdf_new_name("DeviceGray");
switch (trans_type) {
case PDF_TRANS_TYPE_BINARY:
mask = create_ckey_mask(png_ptr, png_info_ptr);
break;
case PDF_TRANS_TYPE_ALPHA:
mask = strip_soft_mask(png_ptr, png_info_ptr,
stream_data_ptr, &rowbytes, width, height);
break;
default:
mask = NULL;
}
info.num_components = 1;
break;
default:
WARN("%s: Unknown PNG colortype %d.", PNG_DEBUG_STR, color_type);
}
texpdf_add_dict(stream_dict, texpdf_new_name("ColorSpace"), colorspace);
texpdf_add_stream(stream, stream_data_ptr, rowbytes*height);
RELEASE(stream_data_ptr);
if (mask) {
if (trans_type == PDF_TRANS_TYPE_BINARY)
texpdf_add_dict(stream_dict, texpdf_new_name("Mask"), mask);
else if (trans_type == PDF_TRANS_TYPE_ALPHA) {
texpdf_add_dict(stream_dict, texpdf_new_name("SMask"), texpdf_ref_obj(mask));
texpdf_release_obj(mask);
} else {
WARN("%s: Unknown transparency type...???", PNG_DEBUG_STR);
texpdf_release_obj(mask);
}
}
/* Finally read XMP Metadata
* See, XMP Specification Part 3, Storage in Files
* http://www.adobe.com/jp/devnet/xmp.html
*
* We require libpng version >= 1.6.14 since prior versions
* of libpng had a bug that incorrectly treat the compression
* flag of iTxt chunks.
*/
#if PNG_LIBPNG_VER >= 10614
if (texpdf_get_version() >= 4) {
png_textp text_ptr;
pdf_obj *XMP_stream, *XMP_stream_dict;
int i, num_text;
int have_XMP = 0;
num_text = png_get_text(png_ptr, png_info_ptr, &text_ptr, NULL);
for (i = 0; i < num_text; i++) {
if (!memcmp(text_ptr[i].key, "XML:com.adobe.xmp", 17)) {
/* XMP found */
if (text_ptr[i].compression != PNG_ITXT_COMPRESSION_NONE ||
text_ptr[i].itxt_length == 0)
WARN("%s: Invalid value(s) in iTXt chunk for XMP Metadata.", PNG_DEBUG_STR);
else if (have_XMP)
WARN("%s: Multiple XMP Metadata. Don't know how to treat it.", PNG_DEBUG_STR);
else {
/* We compress XMP metadata for included images here.
* It is not recommended to compress XMP metadata for PDF documents but
* we compress XMP metadata for included images here to avoid confusing
* application programs that only want PDF document global XMP metadata
* and scan for that.
*/
XMP_stream = texpdf_new_stream(STREAM_COMPRESS);
XMP_stream_dict = texpdf_stream_dict(XMP_stream);
texpdf_add_dict(XMP_stream_dict,
texpdf_new_name("Type"), texpdf_new_name("Metadata"));
texpdf_add_dict(XMP_stream_dict,
texpdf_new_name("Subtype"), texpdf_new_name("XML"));
texpdf_add_stream(XMP_stream, text_ptr[i].text, text_ptr[i].itxt_length);
texpdf_add_dict(stream_dict,
texpdf_new_name("Metadata"), texpdf_ref_obj(XMP_stream));
texpdf_release_obj(XMP_stream);
have_XMP = 1;
}
}
}
}
#endif /* PNG_LIBPNG_VER */
png_read_end(png_ptr, NULL);
/* Cleanup */
if (png_info_ptr)
png_destroy_info_struct(png_ptr, &png_info_ptr);
if (png_ptr)
png_destroy_read_struct(&png_ptr, NULL, NULL);
texpdf_ximage_set_image(ximage, &info, stream);
return 0;
}
/*
* The returned value trans_type is the type of transparency to be used for
* this image. Possible values are:
*
* PDF_TRANS_TYPE_NONE No Masking will be used/required.
* PDF_TRANS_TYPE_BINARY Pixels are either fully opaque/fully transparent.
* PDF_TRANS_TYPE_ALPHA Uses alpha channel, requies SMask.(PDF-1.4)
*
* check_transparency() must check the current setting of output PDF version
* and must choose appropriate trans_type value according to PDF version of
* current output PDF document.
*
* If the PDF version is less than 1.3, no transparency is supported for this
* version of PDF, hence PDF_TRANS_TYPE_NONE must be returned. And when the PDF
* version is equal to 1.3, possible retrun values are PDF_TRANS_TYPE_BINARY or
* PDF_TRANS_TYPE_NONE. The latter case arises when PNG file uses alpha channel
* explicitly (color type PNG_COLOR_TYPE_XXX_ALPHA), or the tRNS chunk for the
* PNG_COLOR_TYPE_PALETTE image contains intermediate values of opacity.
*
* Finally, in the case of PDF version 1.4, all kind of translucent pixels can
* be represented with Soft-Mask.
*/
static int
check_transparency (png_structp png_ptr, png_infop info_ptr)
{
int trans_type;
unsigned pdf_version;
png_byte color_type;
png_color_16p trans_values;
png_bytep trans;
int num_trans;
pdf_version = texpdf_get_version();
color_type = png_get_color_type(png_ptr, info_ptr);
/*
* First we set trans_type to appropriate value for PNG image.
*/
if (color_type == PNG_COLOR_TYPE_RGB_ALPHA ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
trans_type = PDF_TRANS_TYPE_ALPHA;
} else if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) &&
png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans, &trans_values)) {
/* Have valid tRNS chunk. */
switch (color_type) {
case PNG_COLOR_TYPE_PALETTE:
/* Use color-key mask if possible. */
trans_type = PDF_TRANS_TYPE_BINARY;
while (num_trans-- > 0) {
if (trans[num_trans] != 0x00 && trans[num_trans] != 0xff) {
/* This seems not binary transparency */
trans_type = PDF_TRANS_TYPE_ALPHA;
break;
}
}
break;
case PNG_COLOR_TYPE_GRAY:
case PNG_COLOR_TYPE_RGB:
/* RGB or GRAY, single color specified by trans_values is transparent. */
trans_type = PDF_TRANS_TYPE_BINARY;
break;
default:
/* Else tRNS silently ignored. */
trans_type = PDF_TRANS_TYPE_NONE;
}
} else { /* no transparency */
trans_type = PDF_TRANS_TYPE_NONE;
}
/*
* Now we check PDF version.
* We can convert alpha cahnnels to explicit mask via user supplied alpha-
* threshold value. But I will not do that.
*/
if (( pdf_version < 3 && trans_type != PDF_TRANS_TYPE_NONE ) ||
( pdf_version < 4 && trans_type == PDF_TRANS_TYPE_ALPHA )) {
/*
* No transparency supported but PNG uses transparency, or Soft-Mask
* required but no support for it is available in this version of PDF.
* We must do pre-composition of image with the background image here. But,
* we cannot do that in general since dvipdfmx is not a rasterizer. What we
* can do here is to composite image with a rectangle filled with the
* background color. However, images are stored as an Image XObject which
* can be referenced anywhere in the PDF document content. Hence, we cannot
* know the correct background color at this time. So we will choose white
* as background color, which is most probable color in our cases.
* We ignore bKGD chunk.
*/
png_color_16 bg;
bg.red = 255; bg.green = 255; bg.blue = 255; bg.gray = 255; bg.index = 0;
png_set_background(png_ptr, &bg, PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
WARN("%s: Transparency will be ignored. (no support in PDF ver. < 1.3)", PNG_DEBUG_STR);
if (pdf_version < 3)
WARN("%s: Please use -V 3 option to enable binary transparency support.", PNG_DEBUG_STR);
if (pdf_version < 4)
WARN("%s: Please use -V 4 option to enable full alpha channel support.", PNG_DEBUG_STR);
trans_type = PDF_TRANS_TYPE_NONE;
}
return trans_type;
}
/*
* sRGB:
*
* If sRGB chunk is present, cHRM and gAMA chunk must be ignored.
*
*/
static pdf_obj *
get_rendering_intent (png_structp png_ptr, png_infop info_ptr)
{
pdf_obj *intent;
int srgb_intent;
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sRGB) &&
png_get_sRGB (png_ptr, info_ptr, &srgb_intent)) {
switch (srgb_intent) {
case PNG_sRGB_INTENT_SATURATION:
intent = texpdf_new_name("Saturation");
break;
case PNG_sRGB_INTENT_PERCEPTUAL:
intent = texpdf_new_name("Perceptual");
break;
case PNG_sRGB_INTENT_ABSOLUTE:
intent = texpdf_new_name("AbsoluteColorimetric");
break;
case PNG_sRGB_INTENT_RELATIVE:
intent = texpdf_new_name("RelativeColorimetric");
break;
default:
WARN("%s: Invalid value in PNG sRGB chunk: %d", PNG_DEBUG_STR, srgb_intent);
intent = NULL;
}
} else
intent = NULL;
return intent;
}
/* Approximated sRGB */
static pdf_obj *
create_cspace_sRGB (png_structp png_ptr, png_infop info_ptr)
{
pdf_obj *colorspace;
pdf_obj *cal_param;
png_byte color_type;
color_type = png_get_color_type(png_ptr, info_ptr);
/* Parameters taken from PNG spec. section 4.2.2.3. */
cal_param = make_param_Cal(color_type,
2.2,
0.3127, 0.329,
0.64, 0.33, 0.3, 0.6, 0.15, 0.06);
if (!cal_param)
return NULL;
colorspace = texpdf_new_array();
switch (color_type) {
case PNG_COLOR_TYPE_RGB:
case PNG_COLOR_TYPE_RGB_ALPHA:
case PNG_COLOR_TYPE_PALETTE:
texpdf_add_array(colorspace, texpdf_new_name("CalRGB"));
break;
case PNG_COLOR_TYPE_GRAY:
case PNG_COLOR_TYPE_GRAY_ALPHA:
texpdf_add_array(colorspace, texpdf_new_name("CalGray"));
break;
}
texpdf_add_array(colorspace, cal_param);
return colorspace;
}
static pdf_obj *
create_cspace_ICCBased (png_structp png_ptr, png_infop info_ptr)
{
pdf_obj *colorspace;
int csp_id, colortype;
png_byte color_type;
png_charp name;
int compression_type; /* Manual page for libpng does not
* clarify whether profile data is inflated by libpng.
*/
#if PNG_LIBPNG_VER_MINOR < 5
png_charp profile;
#else
png_bytep profile;
#endif
png_uint_32 proflen;
if (!png_get_valid(png_ptr, info_ptr, PNG_INFO_iCCP) ||
!png_get_iCCP(png_ptr, info_ptr, &name, &compression_type, &profile, &proflen))
return NULL;
color_type = png_get_color_type(png_ptr, info_ptr);
if (color_type & PNG_COLOR_MASK_COLOR) {
colortype = PDF_COLORSPACE_TYPE_RGB;
#if 0
alternate = create_cspace_CalRGB(png_ptr, info_ptr);
#endif
} else {
colortype = PDF_COLORSPACE_TYPE_GRAY;
#if 0
alternate = create_cspace_CalGray(png_ptr, info_ptr);
#endif
}
#if 0
if (alternate)
texpdf_add_dict(dict, texpdf_new_name("Alternate"), alternate);
#endif
if (iccp_check_colorspace(colortype, profile, proflen) < 0)
colorspace = NULL;
else {
csp_id = iccp_load_profile(name, profile, proflen);
if (csp_id < 0) {
colorspace = NULL;
} else {
colorspace = texpdf_get_colorspace_reference(csp_id);
}
}
/* Rendering intent ... */
return colorspace;
}
/*
* gAMA, cHRM:
*
* If cHRM is present, we use CIE-Based color space. gAMA is also used here
* if available.
*/
#define INVALID_CHRM_VALUE(xw,yw,xr,yr,xg,yg,xb,yb) (\
(xw) <= 0.0 || (yw) < 1.0e-10 || \
(xr) < 0.0 || (yr) < 0.0 || (xg) < 0.0 || (yg) < 0.0 || \
(xb) < 0.0 || (yb) < 0.0)
static pdf_obj *
create_cspace_CalRGB (png_structp png_ptr, png_infop info_ptr)
{
pdf_obj *colorspace;
pdf_obj *cal_param;
double xw, yw, xr, yr, xg, yg, xb, yb;
double G;
if (!png_get_valid(png_ptr, info_ptr, PNG_INFO_cHRM) ||
!png_get_cHRM(png_ptr, info_ptr, &xw, &yw, &xr, &yr, &xg, &yg, &xb, &yb))
return NULL;
if (xw <= 0.0 || yw < 1.0e-10 ||
xr < 0.0 || yr < 0.0 || xg < 0.0 || yg < 0.0 || xb < 0.0 || yb < 0.0) {
WARN("%s: Invalid cHRM chunk parameters found.", PNG_DEBUG_STR);
return NULL;
}
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_gAMA) &&
png_get_gAMA (png_ptr, info_ptr, &G)) {
if (G < 1.0e-2) {
WARN("%s: Unusual Gamma value: 1.0 / %g", PNG_DEBUG_STR, G);
return NULL;
}
G = 1.0 / G; /* Gamma is inverted. */
} else {
G = 1.0;
}
cal_param = make_param_Cal(PNG_COLOR_TYPE_RGB, G, xw, yw, xr, yr, xg, yg, xb, yb);
if (!cal_param)
return NULL;
colorspace = texpdf_new_array();
texpdf_add_array(colorspace, texpdf_new_name("CalRGB"));
texpdf_add_array(colorspace, cal_param);
return colorspace;
}
static pdf_obj *
create_cspace_CalGray (png_structp png_ptr, png_infop info_ptr)
{
pdf_obj *colorspace;
pdf_obj *cal_param;
double xw, yw, xr, yr, xg, yg, xb, yb;
double G;
if (!png_get_valid(png_ptr, info_ptr, PNG_INFO_cHRM) ||
!png_get_cHRM(png_ptr, info_ptr, &xw, &yw, &xr, &yr, &xg, &yg, &xb, &yb))
return NULL;
if (xw <= 0.0 || yw < 1.0e-10 ||
xr < 0.0 || yr < 0.0 || xg < 0.0 || yg < 0.0 || xb < 0.0 || yb < 0.0) {
WARN("%s: Invalid cHRM chunk parameters found.", PNG_DEBUG_STR);
return NULL;
}
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_gAMA) &&
png_get_gAMA (png_ptr, info_ptr, &G)) {
if (G < 1.0e-2) {
WARN("%s: Unusual Gamma value: 1.0 / %g", PNG_DEBUG_STR, G);
return NULL;
}
G = 1.0 / G; /* Gamma is inverted. */
} else {
G = 1.0;
}
cal_param = make_param_Cal(PNG_COLOR_TYPE_GRAY, G, xw, yw, xr, yr, xg, yg, xb, yb);
if (!cal_param)
return NULL;
colorspace = texpdf_new_array();
texpdf_add_array(colorspace, texpdf_new_name("CalGray"));
texpdf_add_array(colorspace, cal_param);
return colorspace;
}
static pdf_obj *
make_param_Cal (png_byte color_type,
double G, /* Gamma */
double xw, double yw,
double xr, double yr, double xg, double yg, double xb, double yb)
{
pdf_obj *cal_param;
pdf_obj *white_point, *matrix, *dev_gamma;
double Xw, Yw, Zw; /* Yw = 1.0 */
double Xr, Xg, Xb, Yr, Yb, Yg, Zr, Zg, Zb;
#ifndef ABS
#define ABS(x) ((x) < 0 ? -(x) : (x))
#endif
/*
* TODO: Check validity
*
* Conversion found in
*
* com.sixlegs.image.png - Java package to read and display PNG images
* Copyright (C) 1998, 1999, 2001 Chris Nokleberg
*
* http://www.sixlegs.com/software/png/
*
*/
{
double zw, zr, zg, zb;
double fr, fg, fb;
double det;
/* WhitePoint */
zw = 1 - (xw + yw);
zr = 1 - (xr + yr); zg = 1 - (xg + yg); zb = 1 - (xb + yb);
Xw = xw / yw; Yw = 1.0; Zw = zw / yw;
/* Matrix */
det = xr * (yg * zb - zg * yb) - xg * (yr * zb - zr * yb) + xb * (yr * zg - zr * yg);
if (ABS(det) < 1.0e-10) {
WARN("Non invertible matrix: Maybe invalid value(s) specified in cHRM chunk.");
return NULL;
}
fr = (Xw * (yg * zb - zg * yb) - xg * (zb - Zw * yb) + xb * (zg - Zw * yg)) / det;
fg = (xr * (zb - Zw * yb) - Xw * (yr * zb - zr * yb) + xb * (yr * Zw - zr)) / det;
fb = (xr * (yg * Zw - zg) - xg * (yr * Zw - zr) + Xw * (yr * zg - zr * yg)) / det;
Xr = fr * xr; Yr = fr * yr; Zr = fr * zr;
Xg = fg * xg; Yg = fg * yg; Zg = fg * zg;
Xb = fb * xb; Yb = fb * yb; Zb = fb * zb;
}
if (G < 1.0e-2) {
WARN("Unusual Gamma specified: 1.0 / %g", G);
return NULL;
}
cal_param = texpdf_new_dict();
/* White point is always required. */
white_point = texpdf_new_array();
texpdf_add_array(white_point, texpdf_new_number(ROUND(Xw, 0.00001)));
texpdf_add_array(white_point, texpdf_new_number(ROUND(Yw, 0.00001)));
texpdf_add_array(white_point, texpdf_new_number(ROUND(Zw, 0.00001)));
texpdf_add_dict(cal_param, texpdf_new_name("WhitePoint"), white_point);
/* Matrix - default: Identity */
if (color_type & PNG_COLOR_MASK_COLOR) {
if (G != 1.0) {
dev_gamma = texpdf_new_array();
texpdf_add_array(dev_gamma, texpdf_new_number(ROUND(G, 0.00001)));
texpdf_add_array(dev_gamma, texpdf_new_number(ROUND(G, 0.00001)));
texpdf_add_array(dev_gamma, texpdf_new_number(ROUND(G, 0.00001)));
texpdf_add_dict(cal_param, texpdf_new_name("Gamma"), dev_gamma);
}
matrix = texpdf_new_array();
texpdf_add_array(matrix, texpdf_new_number(ROUND(Xr, 0.00001)));
texpdf_add_array(matrix, texpdf_new_number(ROUND(Yr, 0.00001)));
texpdf_add_array(matrix, texpdf_new_number(ROUND(Zr, 0.00001)));
texpdf_add_array(matrix, texpdf_new_number(ROUND(Xg, 0.00001)));
texpdf_add_array(matrix, texpdf_new_number(ROUND(Yg, 0.00001)));
texpdf_add_array(matrix, texpdf_new_number(ROUND(Zg, 0.00001)));
texpdf_add_array(matrix, texpdf_new_number(ROUND(Xb, 0.00001)));
texpdf_add_array(matrix, texpdf_new_number(ROUND(Yb, 0.00001)));
texpdf_add_array(matrix, texpdf_new_number(ROUND(Zb, 0.00001)));
texpdf_add_dict (cal_param, texpdf_new_name("Matrix"), matrix);
} else { /* Gray */
if (G != 1.0)
texpdf_add_dict(cal_param,
texpdf_new_name("Gamma"),
texpdf_new_number(ROUND(G, 0.00001)));
}
return cal_param;
}
/*
* Set up Indexed ColorSpace for color-type PALETTE:
*
* PNG allows only RGB color for base color space. If gAMA and/or cHRM
* chunk is available, we can use CalRGB color space instead of DeviceRGB
* for base color space.
*
*/
static pdf_obj *
create_cspace_Indexed (png_structp png_ptr, png_infop info_ptr)
{
pdf_obj *colorspace;
pdf_obj *base, *lookup;
png_byte *data_ptr;
png_colorp plte;
int num_plte, i;
if (!png_get_valid(png_ptr, info_ptr, PNG_INFO_PLTE) ||
!png_get_PLTE(png_ptr, info_ptr, &plte, &num_plte)) {
WARN("%s: PNG does not have valid PLTE chunk.", PNG_DEBUG_STR);
return NULL;
}
/* Order is important. */
colorspace = texpdf_new_array ();
texpdf_add_array(colorspace, texpdf_new_name("Indexed"));
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_iCCP))
base = create_cspace_ICCBased(png_ptr, info_ptr);
else {
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_sRGB))
base = create_cspace_sRGB(png_ptr, info_ptr);
else
base = create_cspace_CalRGB(png_ptr, info_ptr);
}
if (!base)
base = texpdf_new_name("DeviceRGB");
texpdf_add_array(colorspace, base);
texpdf_add_array(colorspace, texpdf_new_number(num_plte-1));
data_ptr = NEW(num_plte*3, png_byte);
for (i = 0; i < num_plte; i++) {
data_ptr[3*i] = plte[i].red;
data_ptr[3*i+1] = plte[i].green;
data_ptr[3*i+2] = plte[i].blue;
}
lookup = texpdf_new_string(data_ptr, num_plte*3);
RELEASE(data_ptr);
texpdf_add_array(colorspace, lookup);
return colorspace;
}
/*
* Colorkey Mask: array
*
* [component_0_min component_0_max ... component_n_min component_n_max]
*
*/
static pdf_obj *
create_ckey_mask (png_structp png_ptr, png_infop info_ptr)
{
pdf_obj *colorkeys;
png_byte color_type;
png_bytep trans;
int num_trans, i;
png_color_16p colors;
if (!png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) ||
!png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans, &colors)) {
WARN("%s: PNG does not have valid tRNS chunk!", PNG_DEBUG_STR);
return NULL;
}
colorkeys = texpdf_new_array();
color_type = png_get_color_type(png_ptr, info_ptr);
switch (color_type) {
case PNG_COLOR_TYPE_PALETTE:
for (i = 0; i < num_trans; i++) {
if (trans[i] == 0x00) {
texpdf_add_array(colorkeys, texpdf_new_number(i));
texpdf_add_array(colorkeys, texpdf_new_number(i));
} else if (trans[i] != 0xff) {
WARN("%s: You found a bug in pngimage.c.", PNG_DEBUG_STR);
}
}
break;
case PNG_COLOR_TYPE_RGB:
texpdf_add_array(colorkeys, texpdf_new_number(colors->red));
texpdf_add_array(colorkeys, texpdf_new_number(colors->red));
texpdf_add_array(colorkeys, texpdf_new_number(colors->green));
texpdf_add_array(colorkeys, texpdf_new_number(colors->green));
texpdf_add_array(colorkeys, texpdf_new_number(colors->blue));
texpdf_add_array(colorkeys, texpdf_new_number(colors->blue));
break;
case PNG_COLOR_TYPE_GRAY:
texpdf_add_array(colorkeys, texpdf_new_number(colors->gray));
texpdf_add_array(colorkeys, texpdf_new_number(colors->gray));
break;
default:
WARN("%s: You found a bug in pngimage.c.", PNG_DEBUG_STR);
texpdf_release_obj(colorkeys);
colorkeys = NULL;
}
return colorkeys;
}
/*
* Soft-Mask: stream
*
* <<
* /Type /XObject
* /Subtype /Image
* /Width -int-
* /Height -int-
* /BitsPerComponent bpc
* >>
* stream .... endstream
*
* ColorSpace, Mask, SMask must be absent. ImageMask must be false or absent.
*/
static pdf_obj *
create_soft_mask (png_structp png_ptr, png_infop info_ptr,
png_bytep image_data_ptr, png_uint_32 width, png_uint_32 height)
{
pdf_obj *smask, *dict;
png_bytep smask_data_ptr;
png_bytep trans;
int num_trans;
png_uint_32 i;
if (!png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS) ||
!png_get_tRNS(png_ptr, info_ptr, &trans, &num_trans, NULL)) {
WARN("%s: PNG does not have valid tRNS chunk but tRNS is requested.", PNG_DEBUG_STR);
return NULL;
}
smask = texpdf_new_stream(STREAM_COMPRESS);
dict = texpdf_stream_dict(smask);
smask_data_ptr = (png_bytep) NEW(width*height, png_byte);
texpdf_add_dict(dict, texpdf_new_name("Type"), texpdf_new_name("XObject"));
texpdf_add_dict(dict, texpdf_new_name("Subtype"), texpdf_new_name("Image"));
texpdf_add_dict(dict, texpdf_new_name("Width"), texpdf_new_number(width));
texpdf_add_dict(dict, texpdf_new_name("Height"), texpdf_new_number(height));
texpdf_add_dict(dict, texpdf_new_name("ColorSpace"), texpdf_new_name("DeviceGray"));
texpdf_add_dict(dict, texpdf_new_name("BitsPerComponent"), texpdf_new_number(8));
for (i = 0; i < width*height; i++) {
png_byte idx = image_data_ptr[i];
smask_data_ptr[i] = (idx < num_trans) ? trans[idx] : 0xff;
}
texpdf_add_stream(smask, (char *)smask_data_ptr, width*height);
RELEASE(smask_data_ptr);
return smask;
}
/* bitdepth is always 8 (16 is not supported) */
static pdf_obj *
strip_soft_mask (png_structp png_ptr, png_infop info_ptr,
/* next two values will be modified. */
png_bytep image_data_ptr, png_uint_32p rowbytes_ptr,
png_uint_32 width, png_uint_32 height)
{
pdf_obj *smask, *dict;
png_byte color_type;
png_bytep smask_data_ptr;
png_uint_32 i;
color_type = png_get_color_type(png_ptr, info_ptr);
if (color_type & PNG_COLOR_MASK_COLOR) {
if (*rowbytes_ptr != 4*width*sizeof(png_byte)) { /* Something wrong */
WARN("%s: Inconsistent rowbytes value.", PNG_DEBUG_STR);
return NULL;