Manual of Lua-OOCairo: fontopt

lua-oocairo-fontopt - options controlling text rendering

Introduction

A font options object contains options that tell Cairo how to render text on surfaces. They can be created with the font_options_create function in the main oocairo module (see lua-oocairo(3)), and retrieved from scaled fonts or context objects with get_font_options methods.

Font options objects can be compared with the == operator. Two different objects with the same options set will be considered equal.

Methods

The following methods are available on font options objects:

opt:copy ()

Returns a new font options object, with identical options to opt. The two objects will be completely independent, so you can set them to have different options.

opt:get_antialias ()

Get the current antialiasing mode, which will be one of the strings accepted by the opt:set_antialias() method.

opt:get_hint_metrics ()

Returns the current hint metrics option, which will be one of the same strings accepted by the opt:set_hint_metrics() method.

opt:get_hint_style ()

Get the kind of font hinting done when rendering text. Returns one of the strings accepted by the opt:set_hint_style() method.

opt:get_subpixel_order ()

Returns the current ordering of colour components in pixels used for subpixel rendering, which will be one of the same strings accepted by the opt:set_subpixel_order() method.

opt:hash ()

Return a number which can be used as a hash key identifying the particular options in opt. That is, if you wanted to cache fonts according to the options set on them, you could store them in a table with this hash value as the key. Two font options objects with the same options will have the same hash value.

opt:merge (srcopt)

Add any options which are set to a non-default value in srcopt to opt if that still has the default value from them. The options in srcopt will be unchanged. Nothing is returned.

opt:set_antialias (antialiastype)

Set the antialiasing mode used for drawing. The argument must be a string or boolean value accepted by the set_antialias method on context objects (see lua-oocairo-context(3)).

opt:set_hint_metrics (hintmetrics)

Set the kind of hinting to be applied to the metrics, as opposed to outlines, of the glyphs in a font. The hintmetrics value must be one of the following strings:

  • default

  • off

  • on

opt:set_hint_style (hintstyle)

Set the kind of font hinting done when rendering text. The hintstyle value must be one of the following strings:

  • default

  • none

  • slight

  • medium

  • full

opt:set_subpixel_order (order)

Used to inform Cairo of the arrangement of colour components in the pixels of a display device like a monitor. Only applies if subpixel antialiasing is used. The order value must be one of the following strings:

  • default

  • rgb

  • bgr

  • vrgb

  • vbgr

The last two options refer to vertical arrangements of colours.