gridpattern v1.5.1

Breaking Changes

• Custom patterns are no longer given generic default values for the pattern_amplitude parameter
  nor for the {ambient} noise parameters (pattern_fractal, pattern_octaves, etc.).
  These are now pattern-specific defaults of the builtin "wave" and "ambient" patterns.
  A custom pattern that reads them should now set its own defaults
  with register_pattern()'s defaults argument.
  The generic defaults for pattern_frequency and pattern_gravity are now the constants
  0.1 and "center" (matching {ggpattern}) instead of 1 / pattern_spacing and
  a function of pattern_type; the "wave", "ambient", and "image" patterns override them.
  pattern_subtype now has a generic default of NA (matching {ggpattern}) and like
  pattern_type and pattern_gravity an NA value is treated as unset so pattern-specific defaults apply.
  An NA pattern_res is also treated as unset (previously an obscure error).

New Features

• register_pattern() is now the recommended way for packages to register patterns
  (in their .onLoad() function, ideally wrapped in rlang::on_package_load())
  instead of setting the ggpattern_geometry_funcs / ggpattern_array_funcs global options
  which may clobber other registrations (#108).

  • Patterns are owned by either the package that registered them or the user.
  • register_pattern()'s defaults argument sets pattern-specific default parameter values
    (constants or functions of the other parameters, named e.g. pattern_spacing or fill;
    unprefixed names are an error unless declared in the unprefixed argument).
    The builtin patterns now use this to register their pattern-specific defaults.
  • patternGrob() caches the pattern resolved when the grob is created so redraws
    (e.g. resizing an interactive device) still work if the pattern is later unregistered or masked.
  • Package patterns (including builtins) may be referred to by their qualified name
    e.g. "gridpattern::stripe" or "pkg::name".

• unregister_pattern() can be used to unregister a pattern.

• prefer_pattern("owner::name") sets preferences and unprefer_pattern(name) removes them
  (both are vectorized and return the previous preferences so they can be restored).
  Bare pattern names resolve to the pattern preferred by prefer_pattern() (if any) and otherwise to the pattern of the only owner (the user, {gridpattern}, or a package) with that name.
  If more than one owner has a pattern with that name there is a conflict and an error asks for either a qualified name or a prefer_pattern() preference (similar to the {conflicted} package).

• conflicting_patterns() lists patterns whose bare names are shared by more than one pattern

• has_pattern() returns whether a pattern name resolves to a pattern.

• local_pattern() registers a pattern until the current function (or test) exits and then restores any previous registration (useful in tests and examples).

Bug fixes and minor improvements

• Fixes a bug where the "hatch" pattern failed when pattern_subtype was NA
  (the {ggpattern} default) instead of NULL (#106).
• Patterns set via the global options may now share a name with a builtin pattern
  (resolved with prefer_pattern()) instead of always throwing an error.
• Name clashes between patterns now only throw an error when the conflicted
  pattern name is used rather than for every pattern.