Terminal-based user interface toolkit
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package tview
import (
"math"
"strings"
"github.com/gdamore/tcell"
)
// Text alignment within a box.
const (
AlignLeft = iota
AlignCenter
AlignRight
)
// Semigraphical runes.
const (
GraphicsHoriBar = '\u2500'
GraphicsVertBar = '\u2502'
GraphicsTopLeftCorner = '\u250c'
GraphicsTopRightCorner = '\u2510'
GraphicsBottomRightCorner = '\u2518'
GraphicsBottomLeftCorner = '\u2514'
GraphicsDbVertBar = '\u2550'
GraphicsDbHorBar = '\u2551'
GraphicsDbTopLeftCorner = '\u2554'
GraphicsDbTopRightCorner = '\u2557'
GraphicsDbBottomRightCorner = '\u255d'
GraphicsDbBottomLeftCorner = '\u255a'
GraphicsRightT = '\u2524'
GraphicsLeftT = '\u251c'
GraphicsTopT = '\u252c'
GraphicsBottomT = '\u2534'
GraphicsCross = '\u253c'
GraphicsEllipsis = '\u2026'
)
// Print prints text onto the screen into the given box at (x,y,maxWidth,1),
// no exceeding that box. "align" is one of AlignLeft, AlignCenter, or
// AlignRight. The screen's background color will be maintained.
//
// Returns the number of actual runes printed.
func Print(screen tcell.Screen, text string, x, y, maxWidth, align int, color tcell.Color) int {
// We deal with runes, not with bytes.
runes := []rune(text)
if maxWidth < 0 {
return 0
}
// AlignCenter is split into two parts.
if align == AlignCenter {
half := len(runes) / 2
halfWidth := maxWidth / 2
return Print(screen, string(runes[:half]), x, y, halfWidth, AlignRight, color) +
Print(screen, string(runes[half:]), x+halfWidth, y, maxWidth-halfWidth, AlignLeft, color)
}
// Draw text.
drawn := 0
for pos, ch := range runes {
if pos >= maxWidth {
break
}
finalX := x + pos
if align == AlignRight {
ch = runes[len(runes)-1-pos]
finalX = x + maxWidth - 1 - pos
}
_, _, style, _ := screen.GetContent(finalX, y)
style = style.Foreground(color)
screen.SetContent(finalX, y, ch, nil, style)
drawn++
}
return drawn
}
// PrintSimple prints white text to the screen at the given position.
func PrintSimple(screen tcell.Screen, text string, x, y int) {
Print(screen, text, x, y, math.MaxInt64, AlignLeft, tcell.ColorWhite)
}
// WordWrap splits a text such that each resulting line does not exceed the
// given width. Possible split points are after commas, dots, dashes, and any
// whitespace. Whitespace at split points will be dropped.
//
// Text is always split at newline characters ('\n').
func WordWrap(text string, width int) (lines []string) {
x := 0
start := 0
candidate := -1 // -1 = no candidate yet.
startAfterCandidate := 0
countAfterCandidate := 0
var evaluatingCandidate bool
text = strings.TrimSpace(text)
for pos, ch := range text {
if !evaluatingCandidate && x >= width {
// We've exceeded the width, we must split.
if candidate >= 0 {
lines = append(lines, text[start:candidate])
start = startAfterCandidate
x = countAfterCandidate
} else {
lines = append(lines, text[start:pos])
start = pos
x = 0
}
candidate = -1
evaluatingCandidate = false
}
switch ch {
// We have a candidate.
case ',', '.', '-':
if x > 0 {
candidate = pos + 1
evaluatingCandidate = true
}
// If we've had a candidate, skip whitespace. If not, we have a candidate.
case ' ', '\t':
if x > 0 && !evaluatingCandidate {
candidate = pos
evaluatingCandidate = true
}
// Split in any case.
case '\n':
lines = append(lines, text[start:pos])
start = pos + 1
evaluatingCandidate = false
countAfterCandidate = 0
x = 0
continue
// If we've had a candidate, we have a new start.
default:
if evaluatingCandidate {
startAfterCandidate = pos
evaluatingCandidate = false
countAfterCandidate = 0
}
}
x++
countAfterCandidate++
}
// Process remaining text.
text = strings.TrimSpace(text[start:])
if len(text) > 0 {
lines = append(lines, text)
}
return
}