util.go

package main

import (
	"unicode/utf8"

	"github.com/nsf/termbox-go"
)

func fill(x, y, w, h int, cell termbox.Cell) {
	for ly := 0; ly < h; ly++ {
		for lx := 0; lx < w; lx++ {
			termbox.SetCell(x+lx, y+ly, cell.Ch, cell.Fg, cell.Bg)
		}
	}
}

func tclear(x, y, w, h int) {
	fill(x, y, w, h, termbox.Cell{Ch: ' '})
}

func tclearcolor(x, y, w, h int, color termbox.Attribute) {
	fill(x, y, w, h, termbox.Cell{Ch: ' ', Bg: color})
}

func voffset_coffset(text []byte, boffset int) (voffset, coffset int) {
	text = text[:boffset]
	for len(text) > 0 {
		_, size := utf8.DecodeRune(text)
		text = text[size:]
		coffset += 1
		voffset += 1
	}
	return
}

func byte_slice_grow(s []byte, desired_cap int) []byte {
	if cap(s) < desired_cap {
		ns := make([]byte, len(s), desired_cap)
		copy(ns, s)
		return ns
	}
	return s
}

func byte_slice_remove(text []byte, from, to int) []byte {
	size := to - from
	copy(text[from:], text[to:])
	text = text[:len(text)-size]
	return text
}

func byte_slice_insert(text []byte, offset int, what []byte) []byte {
	n := len(text) + len(what)
	text = byte_slice_grow(text, n)
	text = text[:n]
	copy(text[offset+len(what):], text[offset:])
	copy(text[offset:], what)
	return text
}