leocad/common/im_png.cpp
2012-03-22 23:44:56 +00:00

374 lines
9.1 KiB
C++
Executable file

#include "lc_global.h"
#include <stdlib.h>
#include "image.h"
#include "lc_file.h"
#ifdef LC_HAVE_PNGLIB
#include <png.h>
#define alpha_composite(composite, fg, alpha, bg) { \
unsigned short temp = ((unsigned short)(fg)*(unsigned short)(alpha) + \
(unsigned short)(bg)*(unsigned short)(255 - (unsigned short)(alpha)) + (unsigned short)128); \
(composite) = (unsigned char)((temp + (temp >> 8)) >> 8); \
}
// =============================================================================
static void user_read_fn(png_structp png_ptr, png_bytep data, png_size_t length)
{
png_size_t check;
// Read() returns 0 on error, so it is OK to store this in a png_size_t
// instead of an int, which is what Read() actually returns.
check = (png_size_t)((lcFile*)png_get_io_ptr(png_ptr))->ReadBuffer(data, length);
if (check != length)
png_error(png_ptr, "Read Error");
}
bool Image::LoadPNG(lcFile& file)
{
unsigned char sig[8], red, green, blue;
unsigned char *image_data = NULL;
unsigned char *src, *dest;
unsigned char r, g, b, a;
unsigned long i, row;
unsigned long image_rowbytes;
png_color_16p pBackground;
png_structp png_ptr = NULL;
png_infop info_ptr = NULL;
png_uint_32 width, height;
png_bytepp row_pointers = NULL;
int bit_depth, color_type;
int image_channels;
double gamma;
FreeData();
file.ReadBuffer(sig, 8);
if (!png_check_sig(sig, 8))
return false; // bad signature
png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png_ptr)
return false; // out of memory
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_read_struct(&png_ptr, NULL, NULL);
return false; // out of memory
}
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
return false;
}
png_set_read_fn(png_ptr, (void*)&file, user_read_fn);
// png_init_io(png_ptr, f);
png_set_sig_bytes(png_ptr, 8); // we already read the 8 signature bytes
png_read_info(png_ptr, info_ptr); // read all PNG info up to image data
png_get_IHDR(png_ptr, info_ptr, &width, &height, &bit_depth, &color_type, NULL, NULL, NULL);
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
return false;
}
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_bKGD))
{
png_get_bKGD(png_ptr, info_ptr, &pBackground);
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
return false;
}
// however, it always returns the raw bKGD data, regardless of any
// bit-depth transformations, so check depth and adjust if necessary
if (bit_depth == 16)
{
red = pBackground->red >> 8;
green = pBackground->green >> 8;
blue = pBackground->blue >> 8;
}
else if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
{
if (bit_depth == 1)
red = green = blue = pBackground->gray? 255 : 0;
else if (bit_depth == 2)
red = green = blue = (255/3) * pBackground->gray;
else // bit_depth == 4
red = green = blue = (255/15) * pBackground->gray;
}
else
{
red = (unsigned char)pBackground->red;
green = (unsigned char)pBackground->green;
blue = (unsigned char)pBackground->blue;
}
}
else
{
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
return false;
}
red = green = blue = 0;
}
// expand palette images to RGB, low-bit-depth grayscale images to 8 bits,
// transparency chunks to full alpha channel; strip 16-bit-per-sample
// images to 8 bits per sample; and convert grayscale to RGB[A]
if (color_type == PNG_COLOR_TYPE_PALETTE)
png_set_expand(png_ptr);
if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
png_set_expand(png_ptr);
if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
png_set_expand(png_ptr);
if (bit_depth == 16)
png_set_strip_16(png_ptr);
if (color_type == PNG_COLOR_TYPE_GRAY ||
color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
png_set_gray_to_rgb(png_ptr);
if (png_get_gAMA(png_ptr, info_ptr, &gamma))
png_set_gamma(png_ptr, 2.2, gamma);
// all transformations have been registered; now update info_ptr data,
// get rowbytes and channels, and allocate image memory
png_read_update_info(png_ptr, info_ptr);
image_rowbytes = png_get_rowbytes(png_ptr, info_ptr);
image_channels = (int)png_get_channels(png_ptr, info_ptr);
if ((image_data = (unsigned char*)malloc(image_rowbytes*height)) == NULL)
{
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
return false;
}
if ((row_pointers = (png_bytepp)malloc(height*sizeof(png_bytep))) == NULL)
{
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
free(image_data);
return false;
}
// set the individual row_pointers to point at the correct offsets
for (i = 0; i < height; ++i)
row_pointers[i] = image_data + i*image_rowbytes;
// now we can go ahead and just read the whole image
png_read_image(png_ptr, row_pointers);
// and we're done! (png_read_end() can be omitted if no processing of
// post-IDAT text/time/etc. is desired)
free(row_pointers);
row_pointers = NULL;
png_read_end(png_ptr, NULL);
// done with PNG file, so clean up to minimize memory usage
png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
if (!image_data)
return false;
// get our buffer set to hold data
m_pData = (unsigned char*)malloc(width*height*image_channels);
if (m_pData == NULL)
{
free (image_data);
return false;
}
m_nWidth = width;
m_nHeight = height;
if (image_channels == 3)
m_bAlpha = false;
else
m_bAlpha = true;
for (row = 0; row < height; row++)
{
src = image_data + row*image_rowbytes;
dest = m_pData + row*image_channels*width;
if (image_channels == 3)
{
for (i = width; i > 0; i--)
{
r = *src++;
g = *src++;
b = *src++;
*dest++ = r;
*dest++ = g;
*dest++ = b;
}
}
else // if (image_channels == 4)
{
for (i = width; i > 0; i--)
{
r = *src++;
g = *src++;
b = *src++;
a = *src++;
if (a == 255)
{
*dest++ = r;
*dest++ = g;
*dest++ = b;
}
else if (a == 0)
{
*dest++ = red;
*dest++ = green;
*dest++ = blue;
}
else
{
// this macro (copied from png.h) composites the
// foreground and background values and puts the
// result into the first argument; there are no
// side effects with the first argument
alpha_composite(*dest++, r, a, red);
alpha_composite(*dest++, g, a, green);
alpha_composite(*dest++, b, a, blue);
}
*dest++ = a;
}
}
}
free(image_data);
return true;
}
// =============================================================================
static void user_write_fn(png_structp png_ptr, png_bytep data, png_size_t length)
{
png_uint_32 check;
check = ((lcFile*)png_get_io_ptr(png_ptr))->WriteBuffer(data, length);
if (check != length)
{
png_error(png_ptr, "Write Error");
}
}
static void user_flush_fn(png_structp png_ptr)
{
((lcFile*)png_get_io_ptr(png_ptr))->Flush();
}
bool Image::SavePNG(lcFile& file, bool transparent, bool interlaced, unsigned char* background) const
{
png_structp png_ptr;
png_infop info_ptr;
png_bytepp row_pointers = NULL;
png_color_8 sig_bit;
png_color_16 bg;
int i;
png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
if (!png_ptr)
return false;
info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr)
{
png_destroy_write_struct(&png_ptr, NULL);
return false;
}
if (setjmp(png_jmpbuf(png_ptr)))
{
png_destroy_write_struct(&png_ptr, (png_infopp)NULL);
return false;
}
// png_init_io(png_ptr, fp);
png_set_write_fn(png_ptr, &file, user_write_fn, user_flush_fn);
png_set_IHDR(png_ptr, info_ptr, m_nWidth, m_nHeight, 8,
transparent ? PNG_COLOR_TYPE_RGB_ALPHA : PNG_COLOR_TYPE_RGB,
interlaced ? PNG_INTERLACE_ADAM7 : PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT, PNG_FILTER_TYPE_DEFAULT);
bg.red = background[0];
bg.green = background[1];
bg.blue = background[2];
png_set_bKGD(png_ptr, info_ptr, &bg);
png_write_info(png_ptr, info_ptr);
// Set the true bit depth of the image data
sig_bit.red = 8;
sig_bit.green = 8;
sig_bit.blue = 8;
sig_bit.alpha = 8;
png_set_sBIT(png_ptr, info_ptr, &sig_bit);
if ((row_pointers = (png_bytepp)malloc(m_nHeight*sizeof(png_bytep))) == NULL)
{
png_destroy_write_struct(&png_ptr, (png_infopp)NULL);
return false;
}
// set the individual row_pointers to point at the correct offsets
if (transparent)
{
unsigned char *buf, *src, *dst, alpha;
dst = buf = (unsigned char*)malloc(m_nWidth*m_nHeight*4);
src = m_pData;
for (i = 0; i < m_nWidth*m_nHeight; i++)
{
if ((src[0] == background[0]) &&
(src[1] == background[1]) &&
(src[2] == background[2]))
alpha = 0;
else
alpha = 255;
*dst++ = *src++;
*dst++ = *src++;
*dst++ = *src++;
*dst++ = alpha;
}
for (i = 0; i < m_nHeight; i++)
row_pointers[i] = buf + i*m_nWidth*4;
png_write_image(png_ptr, row_pointers);
free(buf);
}
else
{
for (i = 0; i < m_nHeight; i++)
row_pointers[i] = m_pData + i*m_nWidth*3;
png_write_image(png_ptr, row_pointers);
}
free(row_pointers);
png_write_end(png_ptr, info_ptr);
png_destroy_write_struct(&png_ptr, &info_ptr);
return true;
}
#endif // LC_HAVE_PNGLIB