tcell_driver.go

// Copyright 2020 The gocui Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gocui

import (
	"github.com/gdamore/tcell/v2"
)

var screen tcell.Screen

// tcellInit initializes tcell screen for use.
func tcellInit() error {
	if s, e := tcell.NewScreen(); e != nil {
		return e
	} else if e = s.Init(); e != nil {
		return e
	} else {
		screen = s
		return nil
	}
}

// Suspend closes the tcell screen allowing other terminal apps to run
func Suspend() {
	screen.Fini()
}

// Resume re-initializes the tcell screen, intended to be used after "Suspend" has been called
func Resume() error {
	return tcellInit()
}

// tcellInitSimulation creates a tcell simulated screen for testing
func tcellInitSimulation() error {
	simScreen := tcell.NewSimulationScreen("UTF-8")
	if e := simScreen.Init(); e != nil {
		return e
	} else {
		screen = simScreen.(tcell.Screen)
		simulationScreen = simScreen
		return nil
	}
}

// tcellSetCell sets the character cell at a given location to the given
// content (rune) and attributes using provided OutputMode
func tcellSetCell(x, y int, ch rune, fg, bg Attribute, omode OutputMode) {
	st := getTcellStyle(fg, bg, omode)
	screen.SetContent(x, y, ch, nil, st)
}

// getTcellStyle creates tcell.Style from Attributes
func getTcellStyle(fg, bg Attribute, omode OutputMode) tcell.Style {
	st := tcell.StyleDefault

	// extract colors and attributes
	if fg != ColorDefault {
		st = st.Foreground(getTcellColor(fg, omode))
		st = setTcellFontEffectStyle(st, fg)
	}
	if bg != ColorDefault {
		st = st.Background(getTcellColor(bg, omode))
		st = setTcellFontEffectStyle(st, bg)
	}

	return st
}

// setTcellFontEffectStyle add additional attributes to tcell.Style
func setTcellFontEffectStyle(st tcell.Style, attr Attribute) tcell.Style {
	if attr&AttrBold != 0 {
		st = st.Bold(true)
	}
	if attr&AttrUnderline != 0 {
		st = st.Underline(true)
	}
	if attr&AttrReverse != 0 {
		st = st.Reverse(true)
	}
	if attr&AttrBlink != 0 {
		st = st.Blink(true)
	}
	if attr&AttrDim != 0 {
		st = st.Dim(true)
	}
	if attr&AttrItalic != 0 {
		st = st.Italic(true)
	}
	if attr&AttrStrikeThrough != 0 {
		st = st.StrikeThrough(true)
	}
	return st
}

// gocuiEventType represents the type of event.
type gocuiEventType uint8

// gocuiEvent represents events like a keys, mouse actions, or window resize.
//  The 'Mod', 'Key' and 'Ch' fields are valid if 'Type' is 'eventKey'.
//  The 'MouseX' and 'MouseY' fields are valid if 'Type' is 'eventMouse'.
//  The 'Width' and 'Height' fields are valid if 'Type' is 'eventResize'.
//  The 'Err' field is valid if 'Type' is 'eventError'.
type gocuiEvent struct {
	Type   gocuiEventType
	Mod    Modifier
	Key    Key
	Ch     rune
	Width  int
	Height int
	Err    error
	MouseX int
	MouseY int
	N      int
}

// Event types.
const (
	eventNone gocuiEventType = iota
	eventKey
	eventResize
	eventMouse
	eventInterrupt
	eventError
	eventRaw
	eventTime
)

var (
	lastMouseKey tcell.ButtonMask = tcell.ButtonNone
	lastMouseMod tcell.ModMask    = tcell.ModNone
)

// pollEvent get tcell.Event and transform it into gocuiEvent
func pollEvent() gocuiEvent {
	tev := screen.PollEvent()
	switch tev := tev.(type) {
	case *tcell.EventInterrupt:
		return gocuiEvent{Type: eventInterrupt}
	case *tcell.EventResize:
		w, h := tev.Size()
		return gocuiEvent{Type: eventResize, Width: w, Height: h}
	case *tcell.EventKey:
		k := tev.Key()
		ch := rune(0)
		if k == tcell.KeyRune {
			k = 0 // if rune remove key (so it can match rune instead of key)
			ch = tev.Rune()
			if ch == ' ' {
				// special handling for spacebar
				k = tcell.Key(KeySpace) // tcell keys ends at 31 or starts at 256
				ch = rune(0)
			}
		}
		mod := tev.Modifiers()
		// remove control modifier and setup special handling of ctrl+spacebar, etc.
		if mod == tcell.ModCtrl && k == tcell.Key(KeySpace) {
			mod = 0
			ch = rune(0)
			k = tcell.KeyCtrlSpace
		} else if mod == tcell.ModCtrl || mod == tcell.ModShift && (ch != 0 || k == tcell.Key(KeySpace)) {
			// remove Ctrl or Shift if specified
			// - shift - will be translated to the final code of rune
			// - ctrl  - is translated in the key
			mod = 0
		}
		return gocuiEvent{
			Type: eventKey,
			Key:  Key(k),
			Ch:   ch,
			Mod:  Modifier(mod),
		}
	case *tcell.EventMouse:
		x, y := tev.Position()
		button := tev.Buttons()
		mouseKey := Key(0)
		mouseMod := ModNone
		// process mouse wheel
		if button&tcell.WheelUp != 0 {
			mouseKey = MouseWheelUp
			mouseMod = Modifier(tev.Modifiers())
		}
		if button&tcell.WheelDown != 0 {
			mouseKey = MouseWheelDown
			mouseMod = Modifier(tev.Modifiers())
		}
		if button&tcell.WheelLeft != 0 {
			mouseKey = MouseWheelLeft
			mouseMod = Modifier(tev.Modifiers())
		}
		if button&tcell.WheelRight != 0 {
			mouseKey = MouseWheelRight
			mouseMod = Modifier(tev.Modifiers())
		}

		// process button events (not wheel events)
		button &= tcell.ButtonMask(0xff)
		if button != tcell.ButtonNone && lastMouseKey == tcell.ButtonNone {
			lastMouseKey = button
			lastMouseMod = tev.Modifiers()
			switch tev.Buttons() {
			case tcell.ButtonPrimary:
				mouseKey = MouseLeft
			case tcell.ButtonSecondary:
				mouseKey = MouseRight
			case tcell.ButtonMiddle:
				mouseKey = MouseMiddle
			}
			mouseMod = Modifier(lastMouseMod)
		}

		switch tev.Buttons() {
		case tcell.ButtonNone:
			if lastMouseKey != tcell.ButtonNone {
				mouseKey = MouseRelease
				mouseMod = Modifier(lastMouseMod)
				lastMouseMod = tcell.ModNone
				lastMouseKey = tcell.ButtonNone
			}
		}

		return gocuiEvent{
			Type:   eventMouse,
			MouseX: x,
			MouseY: y,
			Key:    mouseKey,
			Ch:     0,
			Mod:    mouseMod,
		}
	case *tcell.EventTime:
		return gocuiEvent{Type: eventTime}
	default:
		return gocuiEvent{Type: eventNone}
	}
}