Tickit::Pen - store a collection of rendering attributes
A pen instance stores a collection of rendering attributes for text to display. It comes in two forms, mutable and immutable. Both types of pen are subclasses of the base Tickit::Pen class.
An immutable pen is an instance of Tickit::Pen::Immutable. Its attributes are set by the constructor and are fixed thereafter. Methods are provided to query the presence or value of attributes, and to fetch the entire set as a hash.
A mutable pen is an instance of Tickit::Pen::Mutable. Its attributes may be set by the constructor, and can be changed at any time. As well as supporting the same query methods as immutable pens, more methods are provided to change or remove them.
While mutable pens may initially seem more useful, they can complicate logic due to their shared referential nature. If the same mutable pen is shared across multiple places, care needs to be taken to redraw anything that depends on it if it is ever changed. If pens need sharing, especially if results are cached for performance, consider using immutable pens to simplify the logic.
The following named pen attributes are supported:
Foreground or background colour. COL may be an integer or one of the eight colour names. A colour name may optionally be prefixed by hi- for the high-intensity version (may not be supported by all terminals). Some terminals may support a palette of 256 colours instead, some 16, and some only 8. The pen object will not check this as it cannot be reliably detected in all cases.
Foreground or background colour secondary RGB8 specification. The value is a string encoding the three 8-bit values in hexadecimal notation, prefixed by a hash (#) symbol; for example
On input, either lower- or upper-case is accepted; on output the letters will be upper-case.
These attribute can only be set if the corresponding regular index attribute is also set. Changing or clearing the regular index will also clear the RGB8 version.
Applications wishing to use this attribute should be aware that the majority of terminal drivers will not be able to support it, and so should make sure to set an appropriate regular colour index as well. Some terminals using the xterm driver may make use of it, however, and therefore ignore the index version.
Bold, italics, reverse video, strikethrough, blink.
Underline. Should be one of the exported constants
PEN_UNDER_NONE PEN_UNDER_SINGLE PEN_UNDER_DOUBLE PEN_UNDER_WAVY
Size/positioning effects. Should be one of the exported constants
PEN_SIZEPOS_NORMAL PEN_SIZEPOS_SUPERSCRIPT PEN_SIZEPOS_SUBSCRIPT
Note that not all terminals can render the italics, strikethrough, or alternate font attributes.
$pen = Tickit::Pen->new( %attrs )
Returns a new pen, initialised from the given attributes.
Currently this method returns a Tickit::Pen::Mutable, though this may change in a future version. It is provided for backward-compatibility for code that expects to be able to construct a Tickit::Pen directly.
$pen = Tickit::Pen::Immutable->new( %attrs )
$pen = Tickit::Pen::Mutable->new( %attrs )
Return a new immutable, or mutable pen, initialised from the given attributes.
$pen = Tickit::Pen->new_from_attrs( $attrs )
Returns a new pen, initialised from keys in the given HASH reference. Used keys are deleted from the hash.
$pen = Tickit::Pen::Immutable->new_from_attrs( $attrs )
$pen = Tickit::Pen::Mutable->new_from_attrs( $attrs )
$pen = $orig->as_mutable
$pen = $orig->clone
Returns a new mutable pen, initialised by copying the attributes of the original.
clone is provided as a legacy alias, but may be removed in a future version.
$pen = $orig->as_immutable
Returns an immutable pen, initialised by copying the attributes of the original. When called on an immutable pen, this method just returns the same pen instance.
$is_mutable = $pen->mutable
Returns true on mutable pens and false on immutable ones.
The following query methods apply to both immutable and mutable pens.
$exists = $pen->hasattr( $attr )
Returns true if the given attribute exists on this object
$value = $pen->getattr( $attr )
Returns the current value of the given attribute
%values = $pen->getattrs
Returns a key/value list of all the attributes
$equiv = $pen->equiv_attr( $other, $attr )
Returns true if the two pens have the equivalent values for the given attribute; that is, either both define it to the same value, or neither defines it.
$equiv = $pen->equiv( $other )
Returns true if the two pens have equivalent values for all attributes.
The following mutation methods exist on mutable pens.
$pen->chattr( $attr, $value )
Change the value of an attribute. Setting undef deletes the attribute entirely. See also delattr.
$pen->chattrs( \%attrs )
Change the values of all the attributes given in the hash. Recgonised attributes will be deleted from the hash.
$pen->delattr( $attr )
Delete an attribute from this pen. This attribute will no longer be modified by this pen.
$pen->copy_from( $other )
$pen->default_from( $other )
Copy attributes from the given pen. copy_from will override attributes already defined by $pen; default_from will only copy attributes that are not yet defined by $pen.
As a convenience both methods return $pen.
Paul Evans <email@example.com>
To install Tickit, copy and paste the appropriate command in to your terminal.
perl -MCPAN -e shell
For more information on module installation, please visit the detailed CPAN module installation guide.