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Code from charmbracelet/lipgloss#102
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package helpers | ||
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import ( | ||
"bytes" | ||
"strings" | ||
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"github.com/mattn/go-runewidth" | ||
"github.com/muesli/ansi" | ||
"github.com/muesli/reflow/truncate" | ||
"github.com/muesli/termenv" | ||
) | ||
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// Most of this code is borrowed from | ||
// https://github.com/charmbracelet/lipgloss/pull/102 | ||
// as well as the lipgloss library. | ||
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// Split a string into lines, additionally returning the size of the widest | ||
// line. | ||
func getLines(s string) (lines []string, widest int) { | ||
lines = strings.Split(s, "\n") | ||
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for _, l := range lines { | ||
w := ansi.PrintableRuneWidth(l) | ||
if widest < w { | ||
widest = w | ||
} | ||
} | ||
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return lines, widest | ||
} | ||
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// PlaceOverlay places fg on top of bg. | ||
func PlaceOverlay(x, y int, fg, bg string, opts ...WhitespaceOption) string { | ||
fgLines, fgWidth := getLines(fg) | ||
bgLines, bgWidth := getLines(bg) | ||
bgHeight := len(bgLines) | ||
fgHeight := len(fgLines) | ||
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if fgWidth >= bgWidth && fgHeight >= bgHeight { | ||
// FIXME: return fg or bg? | ||
return fg | ||
} | ||
// TODO: allow placement outside of the bg box? | ||
x = clamp(x, 0, bgWidth-fgWidth) | ||
y = clamp(y, 0, bgHeight-fgHeight) | ||
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ws := &whitespace{} | ||
for _, opt := range opts { | ||
opt(ws) | ||
} | ||
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var b strings.Builder | ||
for i, bgLine := range bgLines { | ||
if i > 0 { | ||
b.WriteByte('\n') | ||
} | ||
if i < y || i >= y+fgHeight { | ||
b.WriteString(bgLine) | ||
continue | ||
} | ||
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pos := 0 | ||
if x > 0 { | ||
left := truncate.String(bgLine, uint(x)) | ||
pos = ansi.PrintableRuneWidth(left) | ||
b.WriteString(left) | ||
if pos < x { | ||
b.WriteString(ws.render(x - pos)) | ||
pos = x | ||
} | ||
} | ||
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fgLine := fgLines[i-y] | ||
b.WriteString(fgLine) | ||
pos += ansi.PrintableRuneWidth(fgLine) | ||
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right := cutLeft(bgLine, pos) | ||
bgWidth := ansi.PrintableRuneWidth(bgLine) | ||
rightWidth := ansi.PrintableRuneWidth(right) | ||
if rightWidth <= bgWidth-pos { | ||
b.WriteString(ws.render(bgWidth - rightWidth - pos)) | ||
} | ||
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b.WriteString(right) | ||
} | ||
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return b.String() | ||
} | ||
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// cutLeft cuts printable characters from the left. | ||
// This function is heavily based on muesli's ansi and truncate packages. | ||
func cutLeft(s string, cutWidth int) string { | ||
var ( | ||
pos int | ||
isAnsi bool | ||
ab bytes.Buffer | ||
b bytes.Buffer | ||
) | ||
for _, c := range s { | ||
var w int | ||
if c == ansi.Marker || isAnsi { | ||
isAnsi = true | ||
ab.WriteRune(c) | ||
if ansi.IsTerminator(c) { | ||
isAnsi = false | ||
if bytes.HasSuffix(ab.Bytes(), []byte("[0m")) { | ||
ab.Reset() | ||
} | ||
} | ||
} else { | ||
w = runewidth.RuneWidth(c) | ||
} | ||
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if pos >= cutWidth { | ||
if b.Len() == 0 { | ||
if ab.Len() > 0 { | ||
b.Write(ab.Bytes()) | ||
} | ||
if pos-cutWidth > 1 { | ||
b.WriteByte(' ') | ||
continue | ||
} | ||
} | ||
b.WriteRune(c) | ||
} | ||
pos += w | ||
} | ||
return b.String() | ||
} | ||
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func clamp(v, lower, upper int) int { | ||
return min(max(v, lower), upper) | ||
} | ||
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func max(a, b int) int { | ||
if a > b { | ||
return a | ||
} | ||
return b | ||
} | ||
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func min(a, b int) int { | ||
if a < b { | ||
return a | ||
} | ||
return b | ||
} | ||
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type whitespace struct { | ||
style termenv.Style | ||
chars string | ||
} | ||
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// Render whitespaces. | ||
func (w whitespace) render(width int) string { | ||
if w.chars == "" { | ||
w.chars = " " | ||
} | ||
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r := []rune(w.chars) | ||
j := 0 | ||
b := strings.Builder{} | ||
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// Cycle through runes and print them into the whitespace. | ||
for i := 0; i < width; { | ||
b.WriteRune(r[j]) | ||
j++ | ||
if j >= len(r) { | ||
j = 0 | ||
} | ||
i += ansi.PrintableRuneWidth(string(r[j])) | ||
} | ||
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// Fill any extra gaps white spaces. This might be necessary if any runes | ||
// are more than one cell wide, which could leave a one-rune gap. | ||
short := width - ansi.PrintableRuneWidth(b.String()) | ||
if short > 0 { | ||
b.WriteString(strings.Repeat(" ", short)) | ||
} | ||
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return w.style.Styled(b.String()) | ||
} | ||
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// WhitespaceOption sets a styling rule for rendering whitespace. | ||
type WhitespaceOption func(*whitespace) |