screen.go

/*
The MIT License (MIT)

Copyright (c) 2013 Marin Staykov

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/


package termboxutil

import (
	"errors"
	termbox "github.com/nsf/termbox-go"
	"sync"
)

var screenMutex sync.Mutex

type Screen []*Window

var curWindow *Window

type Window struct {
	sync.Mutex

	xpos, ypos int
	selected   int // selected row
	scrollable bool
	scrollPos  int
	closing    bool
	autoResize bool
	screen     *Screen

	Fg, Bg       termbox.Attribute
	RowFg, RowBg termbox.Attribute // selected row colors
	Rows         []Row
	CatchEvent   func(termbox.Event)
}

type Row struct {
	Text   string
	Fg, Bg termbox.Attribute
}

func (s *Screen) Focus(w *Window) {

	screenMutex.Lock()
	curWindow = w
	screenMutex.Unlock()
}

func (s *Screen) NewWindow(fg, bg, rowFg, rowBg termbox.Attribute) Window {

	screenMutex.Lock()
	defer screenMutex.Unlock()

	window := Window{sync.Mutex{}, 0, 0, 0, false, 0, false, true, s, fg, bg, rowFg, rowBg, nil, nil}

	*s = append(*s, &window)
	curWindow = &window

	return window
}

func (s *Screen) Loop() {
	for {
		e := termbox.PollEvent()

		// handle error
		if e.Type == termbox.EventError {
			panic(e.Err)
		}

		w := curWindow // TODO rename w to curWindow

		// handle resize
		if w.autoResize && e.Type == termbox.EventResize {
			err := w.Redraw()
			if err != nil {
				panic(err) // TODO dont panic here
			}

			termbox.Flush()
			continue
		}

		if w.CatchEvent != nil {
			w.CatchEvent(e)
		}
	}
}

func (w *Window) Draw(data []string) error {

	w.Lock()
	w.selected = 0
	w.scrollPos = 0
	w.Rows = make([]Row, len(data))

	for i, str := range data {
		w.Rows[i] = Row{str, w.RowFg, w.RowBg}
	}

	w.Unlock()
	return w.Redraw()
}

func (w *Window) Redraw() error {

	w.Lock()

	err := termbox.Clear(w.Fg, w.Bg)
	maxx, maxy := termbox.Size()

	if err != nil {
		return err
	}

	for i, row := range w.Rows[w.scrollPos:] {
		for _, c := range row.Text {

			if i == w.selected {
				termbox.SetCell(w.xpos, w.ypos, rune(c), row.Fg, row.Bg)
			} else {
				termbox.SetCell(w.xpos, w.ypos, rune(c), w.Fg, w.Bg)
			}

			if w.xpos += 1; w.xpos > maxx {
				break
			}
		}
		w.xpos = 0

		if w.ypos += 1; w.ypos > maxy {
			break
		}
	}
	w.ypos = 0
	w.xpos = 0 // redundant but lets avoid problems later

	w.Unlock()
	return nil
}

func (w *Window) CurrentRow() *Row {
	return &w.Rows[w.selected+w.scrollPos]
}

// selects the next row
func (w *Window) NextRow() {

	_, maxy := termbox.Size()
	if w.scrollable == true {
		if w.selected+w.scrollPos == len(w.Rows)-1 {
			return // bottom of the visible output
		} else if w.selected == maxy-1 {
			w.ScrollDown()
		} else {
			w.selected += 1
		}
	} else {
		w.selected += 1
	}
}

// selects the prev row
func (w *Window) PrevRow() {

	if w.scrollable == false {
		w.selected -= 1
	} else {
		if w.selected == 0 {
			w.ScrollUp()
		} else {
			w.selected -= 1
		}
	}
}

func (w *Window) ScrollUp() {
	if w.scrollPos > 0 {
		w.scrollPos -= 1
	}
}

func (w *Window) ScrollDown() {
	w.scrollPos += 1
}

// toggle if NextRow() and PrevRow will scroll the window
func (w *Window) Scrollable(togl bool) {
	w.scrollable = togl
}

func (w *Window) MarkRow(i int, fg, bg termbox.Attribute) error {
	if i < 0 || i > len(w.Rows)-1 {
		return errors.New("termbox: unknown row")
	}

	row := &w.Rows[i]
	row.Fg = fg
	row.Bg = bg

	return nil
}

func (w *Window) UnmarkRow(i int) error {
	return w.MarkRow(i, w.Fg, w.Bg)
}