1.101 class modifier

A modifier object describes a condition on the modifier keys (SHIFT, CONTROL and META). Modifier objects are used to describe the modifier condition of gestures or to validate the modifier condition for some event.

Modifiers are normally not specified as an object, but as a name that is automatically converted. In

?- new(X, move_gesture(middle, c)).

c is automatically modifier<-convert’ed into a modifier object.

See also

- gesture.modifier
- gesture-modifier
- class gesture
- event->has_modifier

1.101.1 Instance variables

modifier <-> control: [{up,down}]

Condition on the key:

up

Key may not be depressed

down

Key must be depressed

@(default)

State of key is ignored

modifier <-> meta: [{up,down}]

Inherits description from: modifier-control

modifier <-> shift: [{up,down}]

Inherits description from: modifier-control

1.101.2 Send methods

modifier ->initialise: shift=[{up,down}], control=[{up,down}], meta=[{up,down}], gui=[{up,down}]

Create from the constraints on the shift-, control- and meta-keys. Usually, modifiers are specified using a string consisting of the characters’s’,’c’and’m’. See modifier<-convert.

See also

modifier<-convert

1.101.3 Get methods

modifier <-convert: name -> modifier

Convert a name, consisting of the characters s (shift), c (control) and m (meta) to a modifier object that demands the specified keys to be depressed and the others not to be depressed.

The empty atom (” ), transforms into a modifier that demands all keys not to be depressed.

This is the normal way to specify modifiers. For example, the following defines a click_gesture for handling shift-click:

new(G, click_gesture(left, 's', single,
                                         message(@event?receiver,
                                                         selected, @on)).

Converted modifiers are stored in the hash-table @modifiers for better performance and to exploit reuse. As a consequence, modifiers created this way should by treated read-only.

See also

- event->has_modifier
- modifier->initialise
- gesture.modifier