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stb_image_write.h: Set PNG compress lvl via stbi_write_png_level

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This allows the user to change the deflate/zlib compress level used for
PNG compression by changing a global variable.
This commit is contained in:
Daniel Gibson 2017-07-04 18:07:33 +02:00
parent c7110588a4
commit e6bbecd3a9
1 changed files with 11 additions and 1 deletions
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12
stb_image_write.h
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@ -73,6 +73,9 @@ USAGE:
writer, both because it is in BGR order and because it may have padding writer, both because it is in BGR order and because it may have padding
at the end of the line.) at the end of the line.)
PNG allows you to set the deflate compression level by setting the global
variable 'stbi_write_png_level' (it defaults to 8).
HDR expects linear float data. Since the format is always 32-bit rgb(e) HDR expects linear float data. Since the format is always 32-bit rgb(e)
data, alpha (if provided) is discarded, and for monochrome data it is data, alpha (if provided) is discarded, and for monochrome data it is
replicated across all three channels. replicated across all three channels.
@ -124,6 +127,7 @@ extern "C" {
#else #else
#define STBIWDEF extern #define STBIWDEF extern
extern int stbi_write_tga_with_rle; extern int stbi_write_tga_with_rle;
extern int stbi_write_png_level;
#endif #endif
#ifndef STBI_WRITE_NO_STDIO #ifndef STBI_WRITE_NO_STDIO
@ -894,6 +898,12 @@ static unsigned char stbiw__paeth(int a, int b, int c)
return STBIW_UCHAR(c); return STBIW_UCHAR(c);
} }
#ifdef STB_IMAGE_WRITE_STATIC
static int stbi_write_png_level = 8;
#else
int stbi_write_png_level = 8;
#endif
// @OPTIMIZE: provide an option that always forces left-predict or paeth predict // @OPTIMIZE: provide an option that always forces left-predict or paeth predict
unsigned char *stbi_write_png_to_mem(unsigned char *pixels, int stride_bytes, int x, int y, int n, int *out_len) unsigned char *stbi_write_png_to_mem(unsigned char *pixels, int stride_bytes, int x, int y, int n, int *out_len)
{ {
@ -949,7 +959,7 @@ unsigned char *stbi_write_png_to_mem(unsigned char *pixels, int stride_bytes, in
STBIW_MEMMOVE(filt+j*(x*n+1)+1, line_buffer, x*n); STBIW_MEMMOVE(filt+j*(x*n+1)+1, line_buffer, x*n);
} }
STBIW_FREE(line_buffer); STBIW_FREE(line_buffer);
zlib = stbi_zlib_compress(filt, y*( x*n+1), &zlen, 8); // increase 8 to get smaller but use more memory zlib = stbi_zlib_compress(filt, y*( x*n+1), &zlen, stbi_write_png_level);
STBIW_FREE(filt); STBIW_FREE(filt);
if (!zlib) return 0; if (!zlib) return 0;