Initial import of vendor/pnglite

LICENSE

+pnglite.h - Interface for pnglite library
+
+Copyright (c) 2007 Daniel Karling
+
+This software is provided 'as-is', without any express or implied
+warranty. In no event will the authors be held liable for any damages
+arising from the use of this software.
+
+Permission is granted to anyone to use this software for any purpose,
+including commercial applications, and to alter it and redistribute it
+freely, subject to the following restrictions:
+
+1. The origin of this software must not be misrepresented; you must not
+   claim that you wrote the original software. If you use this software
+   in a product, an acknowledgment in the product documentation would be
+   appreciated but is not required.
+
+2. Altered source versions must be plainly marked as such, and must not be
+   misrepresented as being the original software.
+
+3. This notice may not be removed or altered from any source
+   distribution.
+
+Daniel Karling
+daniel.karling@gmail.com

README.md

+pnglite
+====
+#### A pretty small png library
+
+Currently all documentation resides in pnglite.h. 

pnglite.c

+/*  pnglite.c - pnglite library
+    For conditions of distribution and use, see copyright notice in pnglite.h
+*/
+#define DO_CRC_CHECKS 1
+#define USE_ZLIB 1
+
+#if USE_ZLIB
+#include <zlib.h>
+#else
+#include "zlite.h"
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "pnglite.h"
+
+static png_alloc_t png_alloc;
+static png_free_t png_free;
+
+static size_t file_read(png_t* png, void* out, size_t size, size_t numel)
+{
+	size_t result;
+	if(png->read_fun)
+	{
+		result = png->read_fun(out, size, numel, png->user_pointer);
+	}
+	else
+	{
+		if(!out)
+		{
+			result = fseek(png->user_pointer, (long)(size*numel), SEEK_CUR);
+		}
+		else
+		{
+			result = fread(out, size, numel, png->user_pointer);
+		}
+	}
+
+	return result;
+}
+
+static size_t file_write(png_t* png, void* p, size_t size, size_t numel)
+{
+	size_t result;
+
+	if(png->write_fun)
+	{
+		result = png->write_fun(p, size, numel, png->user_pointer);
+	}
+	else
+	{
+		result = fwrite(p, size, numel, png->user_pointer);
+	}
+
+	return result;
+}
+
+static int file_read_ul(png_t* png, unsigned *out)
+{
+	unsigned char buf[4];
+
+	if(file_read(png, buf, 1, 4) != 4)
+		return PNG_FILE_ERROR;
+
+	*out = (buf[0]<<24) | (buf[1]<<16) | (buf[2]<<8) | buf[3];
+
+	return PNG_NO_ERROR;
+}
+
+static int file_write_ul(png_t* png, unsigned in)
+{
+	unsigned char buf[4];
+
+	buf[0] = (in>>24) & 0xff;
+	buf[1] = (in>>16) & 0xff;
+	buf[2] = (in>>8) & 0xff;
+	buf[3] = (in) & 0xff;
+
+	if(file_write(png, buf, 1, 4) != 4)
+		return PNG_FILE_ERROR;
+
+	return PNG_NO_ERROR;
+}
+
+static unsigned get_ul(unsigned char* buf)
+{
+	unsigned result;
+	unsigned char foo[4];
+
+	memcpy(foo, buf, 4);
+
+	result = (foo[0]<<24) | (foo[1]<<16) | (foo[2]<<8) | foo[3];
+
+	return result;
+}
+
+static unsigned set_ul(unsigned char* buf, unsigned in)
+{
+	buf[0] = (in>>24) & 0xff;
+	buf[1] = (in>>16) & 0xff;
+	buf[2] = (in>>8) & 0xff;
+	buf[3] = (in) & 0xff;
+
+	return PNG_NO_ERROR;
+}
+
+int png_init(png_alloc_t pngalloc, png_free_t pngfree)
+{
+	if(pngalloc)
+		png_alloc = pngalloc;
+	else
+		png_alloc = &malloc;
+
+	if(pngfree)
+		png_free = pngfree;
+	else
+		png_free = &free;
+
+	return PNG_NO_ERROR;
+}
+
+static int png_get_bpp(png_t* png)
+{
+	int bpp;
+
+	switch(png->color_type)
+	{
+	case PNG_GREYSCALE:
+		bpp = 1; break;
+	case PNG_TRUECOLOR:
+		bpp = 3; break;
+	case PNG_INDEXED:
+		bpp = 1; break;
+	case PNG_GREYSCALE_ALPHA:
+		bpp = 2; break;
+	case PNG_TRUECOLOR_ALPHA:
+		bpp = 4; break;
+	default:
+		return PNG_FILE_ERROR;
+	}
+
+	bpp *= png->depth/8;
+
+	return bpp;
+}
+
+static int png_read_ihdr(png_t* png)
+{
+	unsigned length;
+#if DO_CRC_CHECKS
+	unsigned orig_crc;
+	unsigned calc_crc;
+#endif
+	unsigned char ihdr[13+4];		 /* length should be 13, make room for type (IHDR) */
+
+	file_read_ul(png, &length);
+
+	if(length != 13)
+	{
+		printf("%d\n", length);
+		return PNG_CRC_ERROR;
+	}
+
+	if(file_read(png, ihdr, 1, 13+4) != 13+4)
+		return PNG_EOF_ERROR;
+#if DO_CRC_CHECKS
+	file_read_ul(png, &orig_crc);
+
+	calc_crc = crc32(0L, 0, 0);
+	calc_crc = crc32(calc_crc, ihdr, 13+4);
+
+	if(orig_crc != calc_crc)
+		return PNG_CRC_ERROR;
+#else
+	file_read_ul(png);
+#endif
+
+	png->width = get_ul(ihdr+4);
+	png->height = get_ul(ihdr+8);
+	png->depth = ihdr[12];
+	png->color_type = ihdr[13];
+	png->compression_method = ihdr[14];
+	png->filter_method = ihdr[15];
+	png->interlace_method = ihdr[16];
+
+	if(png->color_type == PNG_INDEXED)
+		return PNG_NOT_SUPPORTED;
+
+	if(png->depth != 8 && png->depth != 16)
+		return PNG_NOT_SUPPORTED;
+
+	if(png->interlace_method)
+		return PNG_NOT_SUPPORTED;
+
+	return PNG_NO_ERROR;
+}
+
+static int png_write_ihdr(png_t* png)
+{
+	unsigned char ihdr[13+4];
+	unsigned char *p = ihdr;
+	unsigned crc;
+
+	file_write(png, "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A", 1, 8);
+
+	file_write_ul(png, 13);
+
+	*p = 'I';			p++;
+	*p = 'H';			p++;
+	*p = 'D';			p++;
+	*p = 'R';			p++;
+	set_ul(p, png->width);		p+=4;
+	set_ul(p, png->height);		p+=4;
+	*p = png->depth;		p++;
+	*p = png->color_type;		p++;
+	*p = 0;				p++;
+	*p = 0;				p++;
+	*p = 0;				p++;
+
+	file_write(png, ihdr, 1, 13+4);
+
+	crc = crc32(0L, 0, 0);
+	crc = crc32(crc, ihdr, 13+4);
+
+	file_write_ul(png, crc);
+
+	return PNG_NO_ERROR;
+}
+
+void png_print_info(png_t* png)
+{
+	printf("PNG INFO:\n");
+	printf("\twidth:\t\t%d\n", png->width);
+	printf("\theight:\t\t%d\n", png->height);
+	printf("\tdepth:\t\t%d\n", png->depth);
+	printf("\tcolor:\t\t");
+
+	switch(png->color_type)
+	{
+	case PNG_GREYSCALE:		printf("greyscale\n"); break;
+	case PNG_TRUECOLOR:		printf("truecolor\n"); break;
+	case PNG_INDEXED:		printf("palette\n"); break;
+	case PNG_GREYSCALE_ALPHA:	printf("greyscale with alpha\n"); break;
+	case PNG_TRUECOLOR_ALPHA:	printf("truecolor with alpha\n"); break;
+	default:			printf("unknown, this is not good\n"); break;
+	}
+
+	printf("\tcompression:\t%s\n",	png->compression_method?"unknown, this is not good":"inflate/deflate");
+	printf("\tfilter:\t\t%s\n",	png->filter_method?"unknown, this is not good":"adaptive");
+	printf("\tinterlace:\t%s\n",	png->interlace_method?"interlace":"no interlace");
+}
+
+int png_open_read(png_t* png, png_read_callback_t read_fun, void* user_pointer)
+{
+	char header[8];
+	int result;
+
+	png->read_fun = read_fun;
+	png->write_fun = 0;
+	png->user_pointer = user_pointer;
+
+	if(!read_fun && !user_pointer)
+		return PNG_WRONG_ARGUMENTS;
+
+	if(file_read(png, header, 1, 8) != 8)
+		return PNG_EOF_ERROR;
+
+	if(memcmp(header, "\x89\x50\x4E\x47\x0D\x0A\x1A\x0A", 8) != 0)
+		return PNG_HEADER_ERROR;
+
+	result = png_read_ihdr(png);
+
+	png->bpp = (unsigned char)png_get_bpp(png);
+
+	return result;
+}
+
+int png_open_write(png_t* png, png_write_callback_t write_fun, void* user_pointer)
+{
+	png->write_fun = write_fun;
+	png->read_fun = 0;
+	png->user_pointer = user_pointer;
+
+	if(!write_fun && !user_pointer)
+		return PNG_WRONG_ARGUMENTS;
+
+	return PNG_NO_ERROR;
+}
+
+int png_open(png_t* png, png_read_callback_t read_fun, void* user_pointer)
+{
+	return png_open_read(png, read_fun, user_pointer);
+}
+
+int png_open_file_read(png_t *png, const char* filename)
+{
+	FILE* fp = fopen(filename, "rb");
+
+	if(!fp)
+		return PNG_FILE_ERROR;
+
+	return png_open_read(png, 0, fp);
+}
+
+int png_open_file_write(png_t *png, const char* filename)
+{
+	FILE* fp = fopen(filename, "wb");
+
+	if(!fp)
+		return PNG_FILE_ERROR;
+
+	return png_open_write(png, 0, fp);
+}
+
+int png_open_file(png_t *png, const char* filename)
+{
+	return png_open_file_read(png, filename);
+}
+
+int png_close_file(png_t* png)
+{
+	fclose(png->user_pointer);
+
+	return PNG_NO_ERROR;
+}
+
+static int png_init_deflate(png_t* png, unsigned char* data, int datalen)
+{
+	z_stream *stream;
+	png->zs = png_alloc(sizeof(z_stream));
+
+	stream = png->zs;
+
+	if(!stream)
+		return PNG_MEMORY_ERROR;
+
+	memset(stream, 0, sizeof(z_stream));
+
+	if(deflateInit(stream, Z_DEFAULT_COMPRESSION) != Z_OK)
+		return PNG_ZLIB_ERROR;
+
+	stream->next_in = data;
+	stream->avail_in = datalen;
+
+	return PNG_NO_ERROR;
+}
+
+static int png_init_inflate(png_t* png)
+{
+#if USE_ZLIB
+	z_stream *stream;
+	png->zs = png_alloc(sizeof(z_stream));
+#else
+	zl_stream *stream;
+	png->zs = png_alloc(sizeof(zl_stream));
+#endif
+
+	stream = png->zs;
+
+	if(!stream)
+		return PNG_MEMORY_ERROR;
+
+#if USE_ZLIB
+	memset(stream, 0, sizeof(z_stream));
+	if(inflateInit(stream) != Z_OK)
+		return PNG_ZLIB_ERROR;
+#else
+	memset(stream, 0, sizeof(zl_stream));
+	if(z_inflateInit(stream) != Z_OK)
+		return PNG_ZLIB_ERROR;
+#endif
+
+	stream->next_out = png->png_data;
+	stream->avail_out = png->png_datalen;
+
+	return PNG_NO_ERROR;
+}
+
+static int png_end_deflate(png_t* png)
+{
+	z_stream *stream = png->zs;
+
+	if(!stream)
+		return PNG_MEMORY_ERROR;
+
+	deflateEnd(stream);
+
+	png_free(png->zs);
+
+	return PNG_NO_ERROR;
+}
+
+static int png_end_inflate(png_t* png)
+{
+#if USE_ZLIB
+	z_stream *stream = png->zs;
+#else
+	zl_stream *stream = png->zs;
+#endif
+
+	if(!stream)
+		return PNG_MEMORY_ERROR;
+
+#if USE_ZLIB
+	if(inflateEnd(stream) != Z_OK)
+#else
+	if(z_inflateEnd(stream) != Z_OK)
+#endif
+	{
+		printf("ZLIB says: %s\n", stream->msg);
+		return PNG_ZLIB_ERROR;
+	}
+
+	png_free(png->zs);
+
+	return PNG_NO_ERROR;
+}
+
+static int png_inflate(png_t* png, unsigned char* data, int len)
+{
+	int result;
+#if USE_ZLIB
+	z_stream *stream = png->zs;
+#else
+	zl_stream *stream = png->zs;
+#endif
+
+	if(!stream)
+		return PNG_MEMORY_ERROR;
+
+	stream->next_in = data;
+	stream->avail_in = len;
+
+#if USE_ZLIB
+	result = inflate(stream, Z_SYNC_FLUSH);
+#else
+	result = z_inflate(stream);
+#endif
+
+	if(result != Z_STREAM_END && result != Z_OK)
+	{
+		printf("%s\n", stream->msg);
+		return PNG_ZLIB_ERROR;
+	}
+
+	if(stream->avail_in != 0)
+		return PNG_ZLIB_ERROR;
+
+	return PNG_NO_ERROR;
+}
+
+static int png_deflate(png_t* png, char* outdata, int outlen, int *outwritten)
+{
+	int result;
+
+	z_stream *stream = png->zs;
+
+	if(!stream)
+		return PNG_MEMORY_ERROR;
+
+	stream->next_out = (unsigned char*)outdata;
+	stream->avail_out = outlen;
+
+	result = deflate(stream, Z_SYNC_FLUSH);
+
+	*outwritten = outlen - stream->avail_out;
+
+	if(result != Z_STREAM_END && result != Z_OK)
+	{
+		printf("%s\n", stream->msg);
+		return PNG_ZLIB_ERROR;
+	}
+
+	return result;
+}
+
+static int png_write_idats(png_t* png, unsigned char* data)
+{
+	unsigned char *chunk;
+	unsigned long written;
+	unsigned long crc;
+	unsigned size = png->width * png->height * png->bpp + png->height;
+	unsigned chunk_size = compressBound(size);
+
+	(void)png_init_deflate;
+	(void)png_end_deflate;
+	(void)png_deflate;
+
+	chunk = png_alloc(chunk_size + 4);
+	memcpy(chunk, "IDAT", 4);
+
+	written = chunk_size;
+	compress(chunk+4, &written, data, size);
+
+	crc = crc32(0L, Z_NULL, 0);
+	crc = crc32(crc, chunk, written+4);
+	set_ul(chunk+written+4, crc);
+	file_write_ul(png, written);
+	file_write(png, chunk, 1, written+8);
+	png_free(chunk);
+
+	file_write_ul(png, 0);
+	file_write(png, "IEND", 1, 4);
+	crc = crc32(0L, (const unsigned char *)"IEND", 4);
+	file_write_ul(png, crc);
+
+	return PNG_NO_ERROR;
+}
+
+static int png_read_idat(png_t* png, unsigned length)
+{
+#if DO_CRC_CHECKS
+	unsigned orig_crc;
+	unsigned calc_crc;
+#endif
+
+	if(!png->readbuf || png->readbuflen < length)
+	{
+		if (png->readbuf)
+		{
+			png_free(png->readbuf);
+		}
+		png->readbuf = png_alloc(length);
+		png->readbuflen = length;
+	}
+
+	if(!png->readbuf)
+	{
+		return PNG_MEMORY_ERROR;
+	}
+
+	if(file_read(png, png->readbuf, 1, length) != length)
+	{
+		return PNG_FILE_ERROR;
+	}
+
+#if DO_CRC_CHECKS
+	calc_crc = crc32(0L, Z_NULL, 0);
+	calc_crc = crc32(calc_crc, (unsigned char*)"IDAT", 4);
+	calc_crc = crc32(calc_crc, (unsigned char*)png->readbuf, length);
+
+	file_read_ul(png, &orig_crc);
+
+	if(orig_crc != calc_crc)
+	{
+		return PNG_CRC_ERROR;
+	}
+#else
+	file_read_ul(png);
+#endif
+
+	return png_inflate(png, png->readbuf, length);
+}
+
+static int png_process_chunk(png_t* png)
+{
+	int result = PNG_NO_ERROR;
+	unsigned type;
+	unsigned length;
+
+	file_read_ul(png, &length);
+
+	if(file_read(png, &type, 1, 4) != 4)
+		return PNG_FILE_ERROR;
+
+	if(type == *(unsigned int*)"IDAT")	/* if we found an idat, all other idats should be followed with no other chunks in between */
+	{
+		if(!png->png_data) /* first IDAT */
+		{
+			png->png_datalen = png->width * png->height * png->bpp + png->height;
+			png->png_data = png_alloc(png->png_datalen);
+		}
+
+		if(!png->png_data)
+			return PNG_MEMORY_ERROR;
+
+		if(!png->zs)
+		{
+			result = png_init_inflate(png);
+			if(result != PNG_NO_ERROR)
+				return result;
+		}
+
+		return png_read_idat(png, length);
+	}
+	else if(type == *(unsigned int*)"IEND")
+	{
+		return PNG_DONE;
+	}
+	else
+	{
+		file_read(png, 0, 1, length + 4); /* unknown chunk */
+	}
+
+	return result;
+}
+
+static void png_filter_sub(int stride, unsigned char* in, unsigned char* out, int len)
+{
+	int i;
+	unsigned char a = 0;
+