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Published: Nov 30, 2023 License: MIT, Unlicense Imports: 8 Imported by: 174



Package key implements key and text events and operations.

The InputOp operations is used for declaring key input handlers. Use an implementation of the Queue interface from package ui to receive events.



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const (
	// Names for special keys.
	NameLeftArrow      = "←"
	NameRightArrow     = "→"
	NameUpArrow        = "↑"
	NameDownArrow      = "↓"
	NameReturn         = "⏎"
	NameEnter          = "⌤"
	NameEscape         = "⎋"
	NameHome           = "⇱"
	NameEnd            = "⇲"
	NameDeleteBackward = "⌫"
	NameDeleteForward  = "⌦"
	NamePageUp         = "⇞"
	NamePageDown       = "⇟"
	NameTab            = "Tab"
	NameSpace          = "Space"
	NameCtrl           = "Ctrl"
	NameShift          = "Shift"
	NameAlt            = "Alt"
	NameSuper          = "Super"
	NameCommand        = "⌘"
	NameF1             = "F1"
	NameF2             = "F2"
	NameF3             = "F3"
	NameF4             = "F4"
	NameF5             = "F5"
	NameF6             = "F6"
	NameF7             = "F7"
	NameF8             = "F8"
	NameF9             = "F9"
	NameF10            = "F10"
	NameF11            = "F11"
	NameF12            = "F12"
	NameBack           = "Back"
View Source
const ModShortcut = ModCtrl

ModShortcut is the platform's shortcut modifier, usually the ctrl modifier. On Apple platforms it is the cmd key.

View Source
const ModShortcutAlt = ModCtrl

ModShortcutAlt is the platform's alternative shortcut modifier, usually the ctrl modifier. On Apple platforms it is the alt modifier.


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type Caret

type Caret struct {
	// Pos is the intersection point of the caret and its baseline.
	Pos f32.Point
	// Ascent is the length of the caret above its baseline.
	Ascent float32
	// Descent is the length of the caret below its baseline.
	Descent float32

Caret represents the position of a caret.

type EditEvent

type EditEvent struct {
	// Range specifies the range to replace with Text.
	Range Range
	Text  string

An EditEvent requests an edit by an input method.

func (EditEvent) ImplementsEvent

func (EditEvent) ImplementsEvent()

type Event

type Event struct {
	// Name of the key. For letters, the upper case form is used, via
	// unicode.ToUpper. The shift modifier is taken into account, all other
	// modifiers are ignored. For example, the "shift-1" and "ctrl-shift-1"
	// combinations both give the Name "!" with the US keyboard layout.
	Name string
	// Modifiers is the set of active modifiers when the key was pressed.
	Modifiers Modifiers
	// State is the state of the key when the event was fired.
	State State

An Event is generated when a key is pressed. For text input use EditEvent.

func (Event) ImplementsEvent

func (Event) ImplementsEvent()

func (Event) String

func (e Event) String() string

type FocusEvent

type FocusEvent struct {
	Focus bool

A FocusEvent is generated when a handler gains or loses focus.

func (FocusEvent) ImplementsEvent

func (FocusEvent) ImplementsEvent()

type FocusOp

type FocusOp struct {
	// Tag is the new focus. The focus is cleared if Tag is nil, or if Tag
	// has no InputOp in the same frame.
	Tag event.Tag

FocusOp sets or clears the keyboard focus. It replaces any previous FocusOp in the same frame.

func (FocusOp) Add

func (h FocusOp) Add(o *op.Ops)

type InputHint

type InputHint uint8

InputHint changes the on-screen-keyboard type. That hints the type of data that might be entered by the user.

const (
	// HintAny hints that any input is expected.
	HintAny InputHint = iota
	// HintText hints that text input is expected. It may activate auto-correction and suggestions.
	// HintNumeric hints that numeric input is expected. It may activate shortcuts for 0-9, "." and ",".
	// HintEmail hints that email input is expected. It may activate shortcuts for common email characters, such as "@" and ".com".
	// HintURL hints that URL input is expected. It may activate shortcuts for common URL fragments such as "/" and ".com".
	// HintTelephone hints that telephone number input is expected. It may activate shortcuts for 0-9, "#" and "*".
	// HintPassword hints that password input is expected. It may disable autocorrection and enable password autofill.

type InputOp

type InputOp struct {
	Tag event.Tag
	// Hint describes the type of text expected by Tag.
	Hint InputHint
	// Keys is the set of keys Tag can handle. That is, Tag will only
	// receive an Event if its key and modifiers are accepted by Keys.Contains.
	// As a special case, the topmost (first added) InputOp handler receives all
	// unhandled events.
	Keys Set

InputOp declares a handler ready for key events. Key events are in general only delivered to the focused key handler.

func (InputOp) Add

func (h InputOp) Add(o *op.Ops)

type Modifiers

type Modifiers uint32


const (
	// ModCtrl is the ctrl modifier key.
	ModCtrl Modifiers = 1 << iota
	// ModCommand is the command modifier key
	// found on Apple keyboards.
	// ModShift is the shift modifier key.
	// ModAlt is the alt modifier key, or the option
	// key on Apple keyboards.
	// ModSuper is the "logo" modifier key, often
	// represented by a Windows logo.

func (Modifiers) Contain

func (m Modifiers) Contain(m2 Modifiers) bool

Contain reports whether m contains all modifiers in m2.

func (Modifiers) String

func (m Modifiers) String() string

type Range

type Range struct {
	Start int
	End   int

Range represents a range of text, such as an editor's selection. Start and End are in runes.

type SelectionEvent

type SelectionEvent Range

SelectionEvent is generated when an input method changes the selection.

func (SelectionEvent) ImplementsEvent

func (SelectionEvent) ImplementsEvent()

type SelectionOp

type SelectionOp struct {
	Tag event.Tag

SelectionOp updates the selection for an input handler.

func (SelectionOp) Add

func (s SelectionOp) Add(o *op.Ops)

type Set

type Set string

Set is an expression that describes a set of key combinations, in the form "<modifiers>-<keyset>|...". Modifiers are separated by dashes, optional modifiers are enclosed by parentheses. A key set is either a literal key name or a list of key names separated by commas and enclosed in brackets.

The "Short" modifier matches the shortcut modifier (ModShortcut) and "ShortAlt" matches the alternative modifier (ModShortcutAlt).


  • A|B matches the A and B keys
  • [A,B] also matches the A and B keys
  • Shift-A matches A key if shift is pressed, and no other modifier.
  • Shift-(Ctrl)-A matches A if shift is pressed, and optionally ctrl.

func (Set) Contains

func (k Set) Contains(name string, mods Modifiers) bool

type Snippet

type Snippet struct {
	Text string

Snippet represents a snippet of text content used for communicating between an editor and an input method.

type SnippetEvent

type SnippetEvent Range

SnippetEvent is generated when the snippet range is updated by an input method.

func (SnippetEvent) ImplementsEvent

func (SnippetEvent) ImplementsEvent()

type SnippetOp

type SnippetOp struct {
	Tag event.Tag

SnippetOp updates the content snippet for an input handler.

func (SnippetOp) Add

func (s SnippetOp) Add(o *op.Ops)

type SoftKeyboardOp

type SoftKeyboardOp struct {
	Show bool

SoftKeyboardOp shows or hide the on-screen keyboard, if available. It replaces any previous SoftKeyboardOp.

func (SoftKeyboardOp) Add

func (h SoftKeyboardOp) Add(o *op.Ops)

type State

type State uint8

State is the state of a key during an event.

const (
	// Press is the state of a pressed key.
	Press State = iota
	// Release is the state of a key that has been released.
	// Note: release events are only implemented on the following platforms:
	// macOS, Linux, Windows, WebAssembly.

func (State) String

func (s State) String() string

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