feat: lipgloss writer

Instead of using fmt.Printf to write out rendered styles, we supply our
own writer and implementation that parses the rendered ansi and degrades
colors as needed.

examples/writer/main.go

@@ -0,0 +1,12 @@
+package main
+
+import (
+	"github.com/charmbracelet/lipgloss"
+)
+
+func main() {
+	// w := lipgloss.Writer{Forward: os.Stdout, Profile: lipgloss.ANSI}
+	style := lipgloss.NewStyle().Bold(true).Foreground(lipgloss.Color("#FF88CC"))
+
+	lipgloss.Println(style.Render("Hello, ANSI!"))
+}

style.go

@@ -98,7 +98,6 @@ func (p props) has(k propKey) bool {
 // Style{} primitive, it's recommended to use this function for creating styles
 // in case the underlying implementation changes.
 func NewStyle() Style {
-	onceStdDefaults.Do(UseStdDefaults)
 	return Style{
 		profile:            ColorProfile,
 		hasLightBackground: HasLightBackground,

writer.go

@@ -0,0 +1,284 @@
+package lipgloss
+
+import (
+	"bytes"
+	"fmt"
+	"image/color"
+	"io"
+	"os"
+	"sync"
+
+	"github.com/charmbracelet/x/ansi"
+	"github.com/charmbracelet/x/ansi/parser"
+)
+
+var (
+	output = NewWriter(os.Stdout, os.Environ())
+	mtx    sync.Mutex
+)
+
+// Default returns the default Lip Gloss writer that uses the standard output
+// and environment variables.
+func Default() *Writer {
+	return output
+}
+
+// SetOutput sets the default Lip Gloss writer to the given writer.
+func SetOutput(w io.Writer) {
+	mtx.Lock()
+	output.Forward = w
+	mtx.Unlock()
+}
+
+// SetProfile sets the default Lip Gloss writer's color profile to the given
+// profile.
+func SetProfile(p Profile) {
+	mtx.Lock()
+	output.Profile = p
+	mtx.Unlock()
+}
+
+// Print writes the given text to the default Lip Gloss writer.
+func Print(text string) (n int, err error) {
+	return output.Print(text)
+}
+
+// Println writes the given text to the default Lip Gloss writer followed by a
+// newline.
+func Println(text string) (n int, err error) {
+	return output.Println(text)
+}
+
+// Printf writes the given text to the default Lip Gloss writer with the given
+// format.
+func Printf(format string, a ...interface{}) (n int, err error) {
+	return output.Printf(format, a...)
+}
+
+// NewWriter creates a new Lip Gloss writer that writes text to the given writer.
+//
+// It queries the given writer to determine if it supports ANSI escape codes.
+// If it does, along with the given environment variables, it will determine
+// the appropriate color profile to use for color formatting.
+//
+// This respects the NO_COLOR, CLICOLOR, and CLICOLOR_FORCE environment variables.
+func NewWriter(w io.Writer, environ []string) *Writer {
+	return &Writer{
+		Forward: w,
+		Profile: DetectColorProfile(w, environ),
+		parser:  ansi.NewParser(parser.MaxParamsSize, 0),
+	}
+}
+
+// When a Lip Gloss writer is created, it queries the given writer to determine
+// if it supports ANSI escape codes. If it does, the Lip Gloss writer will
+// write text with ANSI escape codes. If it does not, the Lip Gloss writer will
+// write text without ANSI escape codes.
+// It also determines the appropriate color profile to use based on the
+// capabilities of the underlying writer and environment.
+
+// Writer represents a Lip Gloss writer that writes text to the underlying
+// writer.
+type Writer struct {
+	parser *ansi.Parser
+
+	Forward io.Writer
+	Profile Profile
+}
+
+// Print writes the given text to the underlying writer.
+func (w *Writer) Print(text string) (n int, err error) {
+	return fmt.Fprint(w, text)
+}
+
+// Println writes the given text to the underlying writer followed by a newline.
+func (w *Writer) Println(text string) (n int, err error) {
+	return fmt.Fprintln(w, text)
+}
+
+// Printf writes the given text to the underlying writer with the given format.
+func (w *Writer) Printf(format string, a ...interface{}) (n int, err error) {
+	return fmt.Fprintf(w, format, a...)
+}
+
+// Write writes the given text to the underlying writer.
+func (w *Writer) Write(p []byte) (int, error) {
+	if w.Profile == TrueColor {
+		return w.Forward.Write(p)
+	} else if w.Profile == NoTTY {
+		return io.WriteString(w.Forward, ansi.Strip(string(p)))
+	}
+
+	if w.parser == nil {
+		w.parser = ansi.NewParser(parser.MaxParamsSize, 0)
+	}
+
+	convertColorAppend := func(c ansi.Color, sel colorSelector, pen *ansi.CsiSequence) {
+		if c := w.Profile.Convert(c); c != nil && c != noColor {
+			pen.Params = append(pen.Params, ansiColorToParams(c, sel)...)
+		}
+	}
+
+	var buf bytes.Buffer
+	for i, b := range p {
+		w.parser.Advance(func(s ansi.Sequence) {
+			pen := ansi.CsiSequence{Cmd: 'm'}
+			switch s := s.(type) {
+			case ansi.CsiSequence:
+				switch s.Cmd {
+				case 'm':
+					if w.Profile > Ascii {
+						return
+					}
+					for j := 0; j < len(s.Params); j++ {
+						param := s.Param(j)
+						switch param {
+						case 30, 31, 32, 33, 34, 35, 36, 37: // 8-bit foreground color
+							if w.Profile > ANSI {
+								convertColorAppend(ansi.BasicColor(param-30), foreground, &pen)
+								continue
+							}
+						case 39: // default foreground color
+							if w.Profile > ANSI {
+								continue
+							}
+						case 40, 41, 42, 43, 44, 45, 46, 47: // 8-bit background color
+							if w.Profile > ANSI {
+								convertColorAppend(ansi.BasicColor(param-40), background, &pen)
+								continue
+							}
+						case 49: // default background color
+							if w.Profile > ANSI {
+								continue
+							}
+						case 90, 91, 92, 93, 94, 95, 96, 97: // 8-bit bright foreground color
+							if w.Profile > ANSI {
+								convertColorAppend(ansi.BasicColor(param-90+8), foreground, &pen)
+								continue
+							}
+						case 100, 101, 102, 103, 104, 105, 106, 107: // 8-bit bright background color
+							if w.Profile > ANSI {
+								convertColorAppend(ansi.BasicColor(param-100+8), background, &pen)
+								continue
+							}
+						case 59: // default underline color
+							if w.Profile > ANSI {
+								continue
+							}
+						case 38: // 16 or 24-bit foreground color
+							fallthrough
+						case 48: // 16 or 24-bit background color
+							fallthrough
+						case 58: // 16 or 24-bit underline color
+							var sel colorSelector
+							switch param {
+							case 38:
+								sel = foreground
+							case 48:
+								sel = background
+							case 58:
+								sel = underline
+							}
+							if c := readColor(&j, &s); c != nil {
+								switch c.(type) {
+								case ansi.ExtendedColor:
+									if w.Profile > ANSI256 {
+										convertColorAppend(c, sel, &pen)
+										continue
+									}
+								default:
+									if w.Profile > TrueColor {
+										convertColorAppend(c, sel, &pen)
+										continue
+									}
+								}
+							}
+						}
+						pen.Params = append(pen.Params, param)
+					}
+					buf.Write(pen.Bytes())
+					return
+				}
+			}
+			buf.Write(s.Bytes())
+		}, b, i < len(p)-1)
+	}
+
+	n, err := buf.WriteTo(w.Forward)
+	return int(n), err
+}
+
+func readColor(idxp *int, seq *ansi.CsiSequence) (c ansi.Color) {
+	i := *idxp
+	paramsLen := len(seq.Params)
+	// Note: we accept both main and subparams here
+	switch seq.Param(i + 1) {
+	case 2: // RGB
+		if i+2 < paramsLen && i+3 < paramsLen && i+4 < paramsLen {
+			c = color.RGBA{
+				R: uint8(seq.Param(i + 2)),
+				G: uint8(seq.Param(i + 3)),
+				B: uint8(seq.Param(i + 4)),
+				A: 0xff,
+			}
+			*idxp += 4
+		}
+	case 5: // 256 colors
+		if i+2 < paramsLen {
+			c = ansi.ExtendedColor(seq.Param(i + 2))
+			*idxp += 2
+		}
+	}
+	return
+}
+
+type colorSelector uint8
+
+const (
+	foreground colorSelector = iota
+	background
+	underline
+)
+
+func ansiColorToParams(c ansi.Color, sel colorSelector) []int {
+	switch c := c.(type) {
+	case ansi.BasicColor:
+		offset := 30
+		if c >= ansi.BrightBlack {
+			offset = 90
+			c -= ansi.BrightBlack
+		}
+		switch sel {
+		case foreground:
+			return []int{offset + int(c)}
+		case background:
+			return []int{offset + 10 + int(c)}
+		case underline:
+			// XXX: ANSI doesn't have underline colors, use ANSI256.
+			return []int{58, 5, int(c)}
+		}
+	case ansi.ExtendedColor:
+		switch sel {
+		case foreground:
+			return []int{38, 5, int(c)}
+		case background:
+			return []int{48, 5, int(c)}
+		case underline:
+			return []int{58, 5, int(c)}
+		}
+	default:
+		r, g, b, _ := c.RGBA()
+		r = r >> 8
+		g = g >> 8
+		b = b >> 8
+		switch sel {
+		case foreground:
+			return []int{38, 2, int(r), int(g), int(b)}
+		case background:
+			return []int{48, 2, int(r), int(g), int(b)}
+		case underline:
+			return []int{58, 2, int(r), int(g), int(b)}
+		}
+	}
+	return nil
+}