Dec 1, 2009 · I think row_pointers = png_malloc(png_ptr, bitmap->height * sizeof(png_byte )); should be png_byte *row = (png_byte)png_malloc(png_ptr, sizeof(uint8_t) * bitmap …

Mar 29, 2012 · When the user assumes responsibility for libpng-allocated data, the application must use png_free() to free it, and when the user transfers responsibility to libpng for data that the user has allocated, the user must have used png_malloc() or png_zalloc() to allocate it.

Memory allocation is done through the functions png_malloc() and png_free(). These currently just call the standard C functions. If your pointers can't access more then 64K at a time, you will want to set MAXSEG_64K in zlib.h.

png_bytep buffer = png_malloc(png_ptr, height*width*pixel_size); for (int i = 0; i < height, i++) row_pointers[i] = buffer + i*width*pixel_size; png_set_rows(png_ptr, info_ptr, &row_pointers); If you use png_set_rows(), the application is responsible for freeing row_pointers (and row_pointers[i], if they were separately allocated).

*/ /* This is an example of how to use libpng to read and write PNG files. * The file libpng-manual.txt is much more verbose then this. If you have * not read it, do so first. This was designed to be a starting point of an * implementation.

Sep 1, 2009 · There is a fairly extensive man page on libpng and its usage. See: manpagez.com/man/3/libpng for an online version. Runnable example. This example reads and existing PNG, modifies it, and writes a modified version to disk. The modification part is done on raw bytes. Usage: Tested on Ubuntu 18.04, libpng 1.6.34, compile with:

Jul 31, 2022 · Hi all, the issue pnggroup/libpng#424 gave me the idea to improve png_malloc adding the steps required for initializing the memory if the malloc was successfull. I think it would really help to avoid a number of use-of-uninitialized-valu...

The interfaces defined on the following pages are included in libpng15 and are defined by this specification. Unless otherwise noted, these interfaces shall be included in the source standard. Other interfaces listed in Section 6.1 shall behave as described in the referenced base document.

Mar 30, 2022 · I am trying to write a monochrome image to PNG file using libpng library. PNG specification says that you can use grayscale type, since I do not need shades I want to use only grayscale, without alpha channel. So, the color_type parameter is PNG_COLOR_TYPE_GRAY.

Undocumented in source but is binding to C. You might be able to learn more by searching the web for its name.