gio/io/key/key.go

// SPDX-License-Identifier: Unlicense OR MIT

/*
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.
*/
package key

import (
	"strings"

	"gioui.org/f32"
	"gioui.org/internal/ops"
	"gioui.org/io/event"
	"gioui.org/op"
)

// Filter matches any [Event] that matches the parameters.
type Filter struct {
	Target event.Tag
	// Required is the set of modifiers that must be included in events matched.
	Required Modifiers
	// Optional is the set of modifiers that may be included in events matched.
	Optional Modifiers
	// Name of the key to be matched. As a special case, the empty
	// Name matches every key not matched by any other filter.
	Name Name
}

// InputHintOp describes the type of text expected by a tag.
type InputHintOp struct {
	Tag  event.Tag
	Hint InputHint
}

// SoftKeyboardCmd shows or hides the on-screen keyboard, if available.
type SoftKeyboardCmd struct {
	Show bool
}

// SelectionCmd updates the selection for an input handler.
type SelectionCmd struct {
	Tag event.Tag
	Range
	Caret
}

// SnippetCmd updates the content snippet for an input handler.
type SnippetCmd struct {
	Tag event.Tag
	Snippet
}

// Range represents a range of text, such as an editor's selection.
// Start and End are in runes.
type Range struct {
	Start int
	End   int
}

// Snippet represents a snippet of text content used for communicating between
// an editor and an input method.
type Snippet struct {
	Range
	Text string
}

// Caret represents the position of a 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
}

// SelectionEvent is generated when an input method changes the selection.
type SelectionEvent Range

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

// A FocusEvent is generated when a handler gains or loses
// focus.
type FocusEvent struct {
	Focus bool
}

// An Event is generated when a key is pressed. For text input
// use EditEvent.
type Event struct {
	// Name of the key.
	Name Name
	// 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 EditEvent requests an edit by an input method.
type EditEvent struct {
	// Range specifies the range to replace with Text.
	Range Range
	Text  string
}

// FocusFilter matches any [FocusEvent], [EditEvent], [SnippetEvent],
// or [SelectionEvent] with the specified target.
type FocusFilter struct {
	// Target is a tag specified in a previous event.Op.
	Target event.Tag
}

// InputHint changes the on-screen-keyboard type. That hints the
// type of data that might be entered by the user.
type InputHint uint8

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.
	HintText
	// HintNumeric hints that numeric input is expected. It may activate shortcuts for 0-9, "." and ",".
	HintNumeric
	// HintEmail hints that email input is expected. It may activate shortcuts for common email characters, such as "@" and ".com".
	HintEmail
	// HintURL hints that URL input is expected. It may activate shortcuts for common URL fragments such as "/" and ".com".
	HintURL
	// HintTelephone hints that telephone number input is expected. It may activate shortcuts for 0-9, "#" and "*".
	HintTelephone
	// HintPassword hints that password input is expected. It may disable autocorrection and enable password autofill.
	HintPassword
)

// State is the state of a key during an event.
type State uint8

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.
	Release
)

// 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.
	ModCommand
	// ModShift is the shift modifier key.
	ModShift
	// ModAlt is the alt modifier key, or the option
	// key on Apple keyboards.
	ModAlt
	// ModSuper is the "logo" modifier key, often
	// represented by a Windows logo.
	ModSuper
)

// Name is the identifier for a keyboard 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.
type Name string

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

type FocusDirection int

const (
	FocusRight FocusDirection = iota
	FocusLeft
	FocusUp
	FocusDown
	FocusForward
	FocusBackward
)

// Contain reports whether m contains all modifiers
// in m2.
func (m Modifiers) Contain(m2 Modifiers) bool {
	return m&m2 == m2
}

// FocusCmd requests to set or clear the keyboard focus.
type FocusCmd struct {
	// Tag is the new focus. The focus is cleared if Tag is nil, or if Tag
	// has no [event.Op] references.
	Tag event.Tag
}

func (h InputHintOp) Add(o *op.Ops) {
	if h.Tag == nil {
		panic("Tag must be non-nil")
	}
	data := ops.Write1(&o.Internal, ops.TypeKeyInputHintLen, h.Tag)
	data[0] = byte(ops.TypeKeyInputHint)
	data[1] = byte(h.Hint)
}

func (EditEvent) ImplementsEvent()      {}
func (Event) ImplementsEvent()          {}
func (FocusEvent) ImplementsEvent()     {}
func (SnippetEvent) ImplementsEvent()   {}
func (SelectionEvent) ImplementsEvent() {}

func (FocusCmd) ImplementsCommand()        {}
func (SoftKeyboardCmd) ImplementsCommand() {}
func (SelectionCmd) ImplementsCommand()    {}
func (SnippetCmd) ImplementsCommand()      {}

func (Filter) ImplementsFilter()      {}
func (FocusFilter) ImplementsFilter() {}

func (m Modifiers) String() string {
	var strs []string
	if m.Contain(ModCtrl) {
		strs = append(strs, string(NameCtrl))
	}
	if m.Contain(ModCommand) {
		strs = append(strs, string(NameCommand))
	}
	if m.Contain(ModShift) {
		strs = append(strs, string(NameShift))
	}
	if m.Contain(ModAlt) {
		strs = append(strs, string(NameAlt))
	}
	if m.Contain(ModSuper) {
		strs = append(strs, string(NameSuper))
	}
	return strings.Join(strs, "-")
}

func (s State) String() string {
	switch s {
	case Press:
		return "Press"
	case Release:
		return "Release"
	default:
		panic("invalid State")
	}
}