This function is called whenever there is a non-fatal error. This function * should not be changed. If there is a need to handle warnings different

Free a pointer allocated by png_malloc(). If ptr is NULL, return * without taking any action. */

Optionally skip data and then check the CRC. Depending on whether we * are reading an ancillary or critical chunk, and how the program has set * th

returns 1 if success, 0 if failure ==> nothing done*/

* Prints a printf-formatted informational message (level = OPNG_MSG_INFO) * to the logger. */

muldiv functions */ This API takes signed arguments and rounds the result to the nearest * integer (or, for a fixed point number - the standard argum

Place a 16-bit number into a buffer in PNG byte order. * The parameter is declared unsigned int, not png_uint_16, * just to avoid potential problems

Read data, and (optionally) run it through the CRC. */

* Prints an error message (level = OPNG_MSG_ERROR), optionally accompanied * by a submessage, to the logger. */

NOTE: P_LINEAR values to this routine must be 16-bit, but P_FILE values must * be 8-bit. */

========================================================================= */

Create an error message in allocated memory and set state->err and state->msg accordingly. Free any previous error message already there. Do n

Write the data of a PNG chunk started with png_write_chunk_header(). * Note that multiple calls to this function are allowed, and that the * sum of

* Forumla to calculate signed area<br> * Positive if CCW<br> * Negative if CW<br> * 0 if collinear<br> * <pre> * A[P1,P2,P3] = (x1*y2 - y1*x2)

Write a PNG chunk all at once. The type is an array of ASCII characters * representing the chunk name. The array must be at least 4 bytes in * len

returns 1 if success, 0 if failure ==> nothing done*/

This is the shared test on whether a gamma value is 'significant' - whether * it is worth doing gamma correction. */

Utility to safely appends strings to a buffer. This never errors out so * error checking is not required in the caller. */

more fixed point functions for gamma */ Calculate a reciprocal, return 0 on div-by-zero or overflow. */

Is it OK to set a transformation now? Only if png_start_read_image or * png_read_update_info have not been called. It is not necessary for the IHDR

Free all memory used by the read */

Place a 32-bit number into a buffer in PNG byte order. We work * with unsigned numbers for convenience, although one supported * ancillary chunk us

This function returns a pointer to the io_ptr associated with the user * functions. The application should free any memory associated with this * p

The png_save_int_32 function assumes integers are stored in two's * complement format. If this isn't the case, then this routine needs to * be modi

chunkName must be string of 4 characters*/

* This is a helper used by opng_transform_set_object. */

Combines the row recently read in with the existing pixels in the row. This * routine takes care of alpha and transparency if requested. This routi

Free all memory used by the write. * In libpng 1.6.0 this API changed quietly to no longer accept a NULL value for * *png_ptr_ptr. Prior to 1.6.0 i

returns 1 if success, 0 if failure ==> nothing done*/

========================================================================= */

Compress whatever is at avail_in and next_in and write to the output file. Return -1 if there is an error writing to the output file, otherwise 0.

Build a set of tables to decode the provided canonical Huffman code. The code lengths are lens[0..codes-1]. The result starts at *table, whose

Write the start of a PNG chunk. The type is the chunk type. * The total_length is the sum of the lengths of all the data you will be * passing in p

Ensure that png_ptr->zstream.msg holds some appropriate error message string. * If it doesn't 'ret' is used to set it to something appropriate, even

Finish a chunk started with png_write_chunk_header(). */

Internal use only. Called when finished processing a row of data. */

Update neighbor pointers