cview/util.go

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package tview
import (
"math"
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"strings"
"github.com/gdamore/tcell"
)
// Text alignment within a box.
const (
AlignLeft = iota
AlignCenter
AlignRight
)
// Print prints text onto the screen at position (x,y). "align" is one of the
// Align constants and will affect the direction starting at (x,y) into which
// the text is printed. The screen's background color will be maintained. The
// number of runes printed will not exceed "maxWidth".
//
// Returns the number of 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
}
// Shorten text if it's too long.
if len(runes) > maxWidth {
switch align {
case AlignCenter:
trim := (len(runes) - maxWidth) / 2
runes = runes[trim : maxWidth+trim]
case AlignRight:
runes = runes[len(runes)-maxWidth:]
default: // AlignLeft.
runes = runes[:maxWidth]
}
}
// Adjust x-position.
if align == AlignCenter {
x -= len(runes) / 2
} else if align == AlignRight {
x -= len(runes) - 1
}
// Draw text.
for _, ch := range runes {
_, _, style, _ := screen.GetContent(x, y)
style = style.Foreground(color)
screen.SetContent(x, y, ch, nil, style)
x++
}
return len(runes)
}
// 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)
}
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// 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
}