gilo/editor/draw.go

// Editor methods involved in drawing to the console
package editor

import (
	"fmt"
	"strings"
	"timshome.page/gilo/terminal"
)

// ----------------------------------------------------------------------------
// !Editor Methods
// ----------------------------------------------------------------------------

func (e *editor) RefreshScreen() {
	ab := newBuffer()

	ab.append(terminal.HideCursor)
	ab.append(terminal.ResetCursor)

	e.drawRows(ab)
	ab.append(terminal.MoveCursor(e.cursor.x, e.cursor.y))

	ab.append(terminal.ShowCursor)

	terminal.Write(ab.toString())
}

func (e *editor) drawRows(ab *buffer) {
	for y :=0; y < e.screen.Rows; y++ {
		if y >= len(e.rows) {
			if len(e.rows) == 0 && y == e.screen.Rows / 3 {
				welcome := fmt.Sprintf("Gilo editor -- version %s", KiloVersion)
				if len(welcome) > e.screen.Cols {
					welcome = truncateString(welcome, e.screen.Cols)
				}

				padding := (e.screen.Cols - len(welcome)) / 2
				if padding > 0 {
					ab.appendRune('~')
					padding--
				}

				for padding > 0 {
					padding--
					ab.appendRune(' ')
				}

				ab.append(welcome)
			} else {
				ab.appendRune('~')
			}
		} else {
			row := truncateString(string(e.rows[y].chars), e.screen.Cols)
			ab.append(row)
		}

		ab.append(terminal.ClearLine)

		if y < (e.screen.Rows - 1) {
			ab.append("\r\n")
		}
	}
}

// ----------------------------------------------------------------------------
// !Output Buffer
// ----------------------------------------------------------------------------

type buffer struct {
	buf *strings.Builder
}

func newBuffer() *buffer {
	var buf strings.Builder

	b := new(buffer)
	b.buf = &buf

	return b
}

func (b *buffer) appendRune(r rune) int {
	size, _ := b.buf.WriteRune(r)

	return size
}

func (b *buffer) append(s string) int {
	size, _ := b.buf.WriteString(s)

	return size
}

func (b *buffer) appendLn(s string) int {
	str := fmt.Sprintf("%s\r\n", s)
	size, _ := b.buf.WriteString(str)

	return size
}

func (b *buffer) toString() string {
	return b.buf.String()
}