Version 2.57.90
===============

librsvg crate version 2.58.0-beta.0

- Librsvg no longer uses gdk-pixbuf for loading raster images; all
  image loading uses Rust code now.  Older versions of librsvg would
  use the traditional libpng and libjpeg-turbo libraries, and
  gdk-pixbuf's own GIF decoder.  Starting with this version of
  librsvg, it only uses Rust crates for image codecs.

  In addition, librsvg will no longer accept any arbitrary image
  format that gdk-pixbuf happens to support: the only supported
  formats for the <image> element are PNG, JPEG, GIF, WEBP, and SVG.
  (The SVG2 specification only mandates PNG and JPEG.)

  The reasons for using Rust image loaders are as follows:

  - Reduce the attack surface from memory-unsafe libraries.  While
    libpng/libjpeg-turbo are very well tested and extensively fuzzed,
    other gdk-pixbuf loaders are not as well tested.  Switching to
    memory-safe code sounds like a better idea for the future.

  - Make using librsvg easier on Windows and MacOS, where installing
    gdk-pixbuf is somewhat tricky.

  - Give a chance to the Rust image codecs to improve by having more
    people test them from a widely-used code base like librsvg.  GNOME
    has already uses the Rust image crates in the Loupe image viewer,
    and this has led to fixes in the image crates.

  - Support SVG2 semantics for referencing other SVG documents in an
    <image> element.  For historical reasons, librsvg just used
    gdk-pixbuf to recurse into itself in that case.  Now it handles
    SVG sub-images directly.

  The normal SVG loader for gdk-pixbuf that librsvg installs is
  unchanged; you can still load SVG images with gdk-pixbuf as usual.

  The refactoring to load images directly in Rust is based on
  Emile Snyder's work from some months ago.

- #902 - Add basic support for "ch" length units in CSS (Mackenzie Morgan).