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moar/twin/colors.go
Johan Walles 44a064c024 Write tcell replacement
Fixes #37 and fixes #34.
2021-04-17 22:24:40 +02:00

151 lines
3.6 KiB
Go

package twin
import "fmt"
// Create using NewColor16(), NewColor256 or NewColor24Bit(), or use
// ColorDefault.
type Color uint32
type ColorType uint8
const (
// Default foreground / background color
colorTypeDefault ColorType = iota
// https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-bit
colorType16
// https://en.wikipedia.org/wiki/ANSI_escape_code#8-bit
colorType256
// RGB: https://en.wikipedia.org/wiki/ANSI_escape_code#24-bit
colorType24bit
)
// Reset to default foreground / background color
var ColorDefault = newColor(colorTypeDefault, 0)
// From: https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-bit
var colorNames16 = map[int]string{
0: "0 black",
1: "1 red",
2: "2 green",
3: "3 yellow (orange)",
4: "4 blue",
5: "5 magenta",
6: "6 cyan",
7: "7 white (light gray)",
8: "8 bright black (dark gray)",
9: "9 bright red",
10: "10 bright green",
11: "11 bright yellow",
12: "12 bright blue",
13: "13 bright magenta",
14: "14 bright cyan",
15: "15 bright white",
}
func newColor(colorType ColorType, value uint32) Color {
return Color(value | (uint32(colorType) << 24))
}
// Four bit colors as defined here:
// https://en.wikipedia.org/wiki/ANSI_escape_code#3-bit_and_4-bit
func NewColor16(colorNumber0to15 int) Color {
return newColor(colorType16, uint32(colorNumber0to15))
}
func NewColor256(colorNumber uint8) Color {
return newColor(colorType256, uint32(colorNumber))
}
func NewColor24Bit(red uint8, green uint8, blue uint8) Color {
return newColor(colorType24bit, (uint32(red)<<16)+(uint32(green)<<8)+(uint32(blue)<<0))
}
func NewColorHex(rgb uint32) Color {
return newColor(colorType24bit, rgb)
}
func (color Color) colorType() ColorType {
return ColorType(color >> 24)
}
func (color Color) colorValue() uint32 {
return uint32(color & 0xff_ff_ff)
}
// Render color into an ANSI string.
//
// Ref: https://en.wikipedia.org/wiki/ANSI_escape_code#SGR_(Select_Graphic_Rendition)_parameters
func (color Color) ansiString(foreground bool) string {
value := color.colorValue()
fgBgMarker := "3"
if !foreground {
fgBgMarker = "4"
}
if color.colorType() == colorType16 {
if value < 8 {
return fmt.Sprint("\x1b[", fgBgMarker, value, "m")
} else if value <= 15 {
fgBgMarker := "9"
if !foreground {
fgBgMarker = "10"
}
return fmt.Sprint("\x1b[", fgBgMarker, value-8, "m")
}
}
if color.colorType() == colorType256 {
if value <= 255 {
return fmt.Sprint("\x1b[", fgBgMarker, "8;5;", value, "m")
}
}
if color.colorType() == colorType24bit {
red := (value & 0xff0000) >> 16
green := (value & 0xff00) >> 8
blue := value & 0xff
return fmt.Sprint("\x1b[", fgBgMarker, "8;2;", red, ";", green, ";", blue, "m")
}
if color.colorType() == colorTypeDefault {
return fmt.Sprint("\x1b[", fgBgMarker, "9m")
}
panic(fmt.Errorf("unhandled color type=%d value=%#x", color.colorType(), value))
}
func (color Color) ForegroundAnsiString() string {
// FIXME: Test this function with all different color types.
return color.ansiString(true)
}
func (color Color) BackgroundAnsiString() string {
// FIXME: Test this function with all different color types.
return color.ansiString(false)
}
func (color Color) String() string {
switch color.colorType() {
case colorTypeDefault:
return "Default color"
case colorType16:
return colorNames16[int(color.colorValue())]
case colorType256:
if color.colorValue() < 16 {
return colorNames16[int(color.colorValue())]
}
return fmt.Sprintf("#%02x", color.colorValue())
case colorType24bit:
return fmt.Sprintf("#%06x", color.colorValue())
}
panic(fmt.Errorf("unhandled color type %d", color.colorType()))
}