feat: conform to the Go color interface

implement RGBA with the default output

color.go

@@ -1,14 +1,15 @@
 package lipgloss
 
 import (
-	"fmt"
+	"strconv"
 
 	"github.com/muesli/termenv"
 )
 
 // TerminalColor is a color intended to be rendered in the terminal.
 type TerminalColor interface {
 	color(*Renderer) termenv.Color
+	RGBA() (r, g, b, a uint32)
 }
 
 var noColor = NoColor{}
@@ -26,6 +27,17 @@ func (NoColor) color(*Renderer) termenv.Color {
 	return termenv.NoColor{}
 }
 
+// RGBA returns the RGBA value of this color. Because we have to return
+// something, despite this color being the absence of color, we're returning
+// black with 100% opacity.
+//
+// Red: 0x0, Green: 0x0, Blue: 0x0, Alpha: 0xFFFF.
+//
+// Deprecated
+func (n NoColor) RGBA() (r, g, b, a uint32) {
+	return 0x0, 0x0, 0x0, 0xFFFF
+}
+
 // Color specifies a color by hex or ANSI value. For example:
 //
 //	ansiColor := lipgloss.Color("21")
@@ -36,6 +48,16 @@ func (c Color) color(r *Renderer) termenv.Color {
 	return r.ColorProfile().Color(string(c))
 }
 
+// RGBA returns the RGBA value of this color. This satisfies the Go Color
+// interface. Note that on error we return black with 100% opacity, or:
+//
+// Red: 0x0, Green: 0x0, Blue: 0x0, Alpha: 0xFFFF.
+//
+// Deprecated
+func (c Color) RGBA() (r, g, b, a uint32) {
+	return termenv.ConvertToRGB(c.color(renderer)).RGBA()
+}
+
 // ANSIColor is a color specified by an ANSI color value. It's merely syntactic
 // sugar for the more general Color function. Invalid colors will render as
 // black.
@@ -48,7 +70,18 @@ func (c Color) color(r *Renderer) termenv.Color {
 type ANSIColor uint
 
 func (ac ANSIColor) color(r *Renderer) termenv.Color {
-	return Color(fmt.Sprintf("%d", ac)).color(r)
+	return Color(strconv.FormatUint(uint64(ac), 10)).color(r)
+}
+
+// RGBA returns the RGBA value of this color. This satisfies the Go Color
+// interface. Note that on error we return black with 100% opacity, or:
+//
+// Red: 0x0, Green: 0x0, Blue: 0x0, Alpha: 0xFFFF.
+//
+// Deprecated
+func (ac ANSIColor) RGBA() (r, g, b, a uint32) {
+	cf := Color(strconv.FormatUint(uint64(ac), 10))
+	return cf.RGBA()
 }
 
 // AdaptiveColor provides color options for light and dark backgrounds. The
@@ -70,6 +103,16 @@ func (ac AdaptiveColor) color(r *Renderer) termenv.Color {
 	return Color(ac.Light).color(r)
 }
 
+// RGBA returns the RGBA value of this color. This satisfies the Go Color
+// interface. Note that on error we return black with 100% opacity, or:
+//
+// Red: 0x0, Green: 0x0, Blue: 0x0, Alpha: 0xFFFF.
+//
+// Deprecated
+func (ac AdaptiveColor) RGBA() (r, g, b, a uint32) {
+	return termenv.ConvertToRGB(ac.color(renderer)).RGBA()
+}
+
 // CompleteColor specifies exact values for truecolor, ANSI256, and ANSI color
 // profiles. Automatic color degradation will not be performed.
 type CompleteColor struct {
@@ -92,6 +135,16 @@ func (c CompleteColor) color(r *Renderer) termenv.Color {
 	}
 }
 
+// RGBA returns the RGBA value of this color. This satisfies the Go Color
+// interface. Note that on error we return black with 100% opacity, or:
+//
+// Red: 0x0, Green: 0x0, Blue: 0x0, Alpha: 0xFFFF.
+//
+// Deprecated
+func (c CompleteColor) RGBA() (r, g, b, a uint32) {
+	return termenv.ConvertToRGB(c.color(renderer)).RGBA()
+}
+
 // CompleteColor specifies exact values for truecolor, ANSI256, and ANSI color
 // profiles, with separate options for light and dark backgrounds. Automatic
 // color degradation will not be performed.
@@ -106,3 +159,13 @@ func (cac CompleteAdaptiveColor) color(r *Renderer) termenv.Color {
 	}
 	return cac.Light.color(r)
 }
+
+// RGBA returns the RGBA value of this color. This satisfies the Go Color
+// interface. Note that on error we return black with 100% opacity, or:
+//
+// Red: 0x0, Green: 0x0, Blue: 0x0, Alpha: 0xFFFF.
+//
+// Deprecated
+func (cac CompleteAdaptiveColor) RGBA() (r, g, b, a uint32) {
+	return termenv.ConvertToRGB(cac.color(renderer)).RGBA()
+}