## Why does the API change?

From time to time, during development, it becomes clear that the public API needs to change; either because the existing API has flaws in it, or to accommodate new functionality. Such changes are not undertaken lightly, and they are kept as minimal as possible.

The alternative would be to freeze the API and to introduce more and more compatibility veneers, ultimately leading to a bloated API and additional complexity. We have done this in the past, and will do it again in future if circumstances demand it, but we consider small changes in the API to be a price worth paying for clarity and simplicity.

To minimise the impact of such changes, we undertake to list the API changes between different versions of the library here, to make it as simple as possible for integrators to make the small changes that may be require to update between versions.

Note, that we only list changes in existing APIs here, not all additions to the API.

## Changes from 1.18 to 1.19

We were inconsistent with the behaviour of fz_create_ and pdf_create_ functions, in that sometimes they returned a borrowed reference, rather than a reference that the caller had to drop. We now always return a reference that the caller owns and must drop.

## Changes from 1.17 to 1.18

None worth mentioning.

## Changes from 1.16 to 1.17

The accessors for reading and creating QuadPoints, InkList and Vertices data for Highlight, Underline, StrikeOut, Squiggle, Ink, Polygon, and PolyLine annotation types have been simplified. They now take and return fz_quad and fz_point structs instead of float arrays. We have also added functions to construct the datastructures one piece at a time, removing the need to allocate a temporary array to pass.

- typedef struct fz_quad { fz_point ul, ur, ll, lr; };

To facilitate loading EPUB documents without laying out the entire document at once, we have introduced chapters into the document structure. Each document instead of having just a plain list of pages, now has a list of chapters, and each chapter has a list of pages. Most of the old functions have the same functionality, but we have added several new functions, which if used, will provide significant speedups when jumping to a random page in large EPUB documents.

- int fz_count_chapters(ctx, doc)
- int fz_count_chapter_pages(ctx, doc, chapter)
- fz_page *fz_load_chapter_page(ctx, doc, chapter, page)
- int fz_search_chapter_page_number(ctx, doc, chapter, page, needle, hit_quads, hit_size)

However, in order to support bookmarks and links using chapters we have had to introduce a new struct "fz_location", and the functions to resolve links have changed to use this new struct.

- typedef struct { int chapter, page; } fz_location;
- fz_location fz_resolve_link(ctx, doc, uri, x, y);

Functions to map between a fixed page number and a fz_location have been added to help facilitate migration to the new API.

- int fz_page_number_from_location(ctx, doc, location);
- fz_location fz_location_from_page_number(ctx, doc, number);
- fz_location fz_next_page(ctx, doc, location);
- fz_location fz_previous_page(ctx, doc, location);
- fz_location fz_last_page(ctx, doc);

The layout information for each chapter can at your option be cached in an "accelerator" file for even faster loading. This will help performance when using the old page number based rather than location based functions.

- fz_document fz_open_accelerated_document(ctx, filename, accelerator_filename);
- void fz_save_accelerator(ctx, document, accelerator_filename);

## Changes from 1.15 to 1.16

There has been a major overhaul of the color management architecture. Unless you're implementing custom devices or interpreters, this should only have a minor impact.

- Argument order when passing color and colorspace to functions regularized: sourceColorspace, sourceColorArray, destinationColorspace, destinationColorArray, proofColorspace, colorParams.
- Pass fz_color_params argument by value.
- Changed fz_default_parameters from a function to a global constant.
- Replaced fz_set_icc_engine with fz_enable_icc and fz_disable_icc to toggle color management at runtime.
- Replaced pixmap color converter struct with a single fz_convert_pixmap function call.
- Replaced fz_cal_colorspace struct with constructor to create an ICC-backed calibrated colorspace directly.
- Passing NULL is not a shortcut for DeviceGray any more!
- Added public definitions for Indexed and Separation colorspaces.
- Changed colorspace constructors.

The fz_set_stdout and fz_set_stderr functions have been removed. If you were using these to capture warning and error messages, use the new user callbacks for warning and error logging instead: fz_set_warning_callback and fz_set_error_callback.

The structured text html and xhtml output formats take an additional argument: the page number. This number is used to create an id attribute for each page to use as a hyperlink target.

## Changes from 1.14 to 1.15

PDF Portfolios
  This functionality has been removed. We do not believe anyone was using this. If you were, please contact us for assistance. This functionality can be achieved using "mutool run" and docs/examples/pdf-portfolio.js.
FZ_ERROR_TRYLATER
  This functionality has been removed. We do not believe anyone was using this. If you were, please contact us for assistance.
Annotations/Forms
  We are undertaking a significant rework of this functionality at the moment. We do not believe anyone is using this at the moment, and would therefore encourage anyone who is to contact us for help in upgrading.
Various functions involving fz_colorspace have lost consts.
  fz_colorspaces are immutable once created, other than changes due to reference counting. Passing a const fz_colorspace to a function that might keep a reference to it either has to take a non const fz_colorspace pointer, or take a const one, and 'break' the const. Having some functions take const fz_colorspace and some not is confusing, so therefore, for simplicity, all fz_colorspaces are now passed as non const. This should not affect any user code.
fz_process_shade()
  This now takes an extra 'scissor' argument. To upgrade old code, if you don't have an appropriate scissor rect available, it is safe (but unwise) to pass fz_infinite_rect.
fz_tint_pixmap()
  Rather than taking r, g and b, values to tint with, the function now takes 8 bit hex rgb values for black and white, enabling greater control, allowing "low contrast" and "night view" effects.
pdf_add_image()
  This no longer requires a mask flag. The image already knows if it is a mask.
pdf_processor.op_BI()
  The op_BI callback is now passed an additional colorspace resource name.