Better palette support

1 files changed, 45 insertions, 70 deletions

diff --git a/thumbnailer.go b/thumbnailer.go
index 89f9fed..6c69fc1 100644
--- a/thumbnailer.go
+++ b/thumbnailer.go
@@ -126,66 +126,51 @@ func load(filename string) (image.Image, error) {
 	return img, nil
 }
 
-var (
-	xtermBlack         = color.RGBA{R: 0x00, G: 0x00, B: 0x00, A: 0xff}
-	xtermRed           = color.RGBA{R: 0xcd, G: 0x00, B: 0x00, A: 0xff}
-	xtermGreen         = color.RGBA{R: 0x00, G: 0xcd, B: 0x00, A: 0xff}
-	xtermYellow        = color.RGBA{R: 0xcd, G: 0xcd, B: 0x00, A: 0xff}
-	xtermBlue          = color.RGBA{R: 0x00, G: 0x00, B: 0xee, A: 0xff}
-	xtermMagenta       = color.RGBA{R: 0xcd, G: 0x00, B: 0xcd, A: 0xff}
-	xtermCyan          = color.RGBA{R: 0x00, G: 0xcd, B: 0xcd, A: 0xff}
-	xtermWhite         = color.RGBA{R: 0xe5, G: 0xe5, B: 0xe5, A: 0xff}
-	xtermGray          = color.RGBA{R: 0x7f, G: 0x7f, B: 0x7f, A: 0xff}
-	xtermBrightRed     = color.RGBA{R: 0xff, G: 0x00, B: 0x00, A: 0xff}
-	xtermBrightGreen   = color.RGBA{R: 0x00, G: 0xff, B: 0x00, A: 0xff}
-	xtermBrightYellow  = color.RGBA{R: 0xff, G: 0xff, B: 0x00, A: 0xff}
-	xtermBrightBlue    = color.RGBA{R: 0x5c, G: 0x5c, B: 0xff, A: 0xff}
-	xtermBrightMagenta = color.RGBA{R: 0xff, G: 0x00, B: 0xff, A: 0xff}
-	xtermBrightCyan    = color.RGBA{R: 0x00, G: 0xff, B: 0xff, A: 0xff}
-	xtermBrightWhite   = color.RGBA{R: 0xff, G: 0xff, B: 0xff, A: 0xff}
-)
+type xtermColor int8
 
-var xtermPalette = color.Palette{xtermBlack, xtermRed, xtermGreen, xtermYellow, xtermBlue, xtermMagenta, xtermCyan, xtermWhite, xtermGray, xtermBrightRed, xtermBrightGreen, xtermBrightYellow, xtermBrightBlue, xtermBrightMagenta, xtermBrightCyan, xtermBrightWhite}
-
-func xtermColorCode(c color.Color) int {
+func (c xtermColor) RGBA() (r, g, b, a uint32) {
+	var col color.RGBA
 	switch c {
-	case xtermBlack:
-		return 0
-	case xtermRed:
-		return 1
-	case xtermGreen:
-		return 2
-	case xtermYellow:
-		return 3
-	case xtermBlue:
-		return 4
-	case xtermMagenta:
-		return 5
-	case xtermCyan:
-		return 6
-	case xtermWhite:
-		return 7
-	case xtermGray:
-		return 60
-	case xtermBrightRed:
-		return 61
-	case xtermBrightGreen:
-		return 62
-	case xtermBrightYellow:
-		return 63
-	case xtermBrightBlue:
-		return 64
-	case xtermBrightMagenta:
-		return 65
-	case xtermBrightCyan:
-		return 66
-	case xtermBrightWhite:
-		return 67
+	case 0:
+		col = color.RGBA{R: 0x00, G: 0x00, B: 0x00, A: 0xff}
+	case 1:
+		col = color.RGBA{R: 0xcd, G: 0x00, B: 0x00, A: 0xff}
+	case 2:
+		col = color.RGBA{R: 0x00, G: 0xcd, B: 0x00, A: 0xff}
+	case 3:
+		col = color.RGBA{R: 0xcd, G: 0xcd, B: 0x00, A: 0xff}
+	case 4:
+		col = color.RGBA{R: 0x00, G: 0x00, B: 0xee, A: 0xff}
+	case 5:
+		col = color.RGBA{R: 0xcd, G: 0x00, B: 0xcd, A: 0xff}
+	case 6:
+		col = color.RGBA{R: 0x00, G: 0xcd, B: 0xcd, A: 0xff}
+	case 7:
+		col = color.RGBA{R: 0xe5, G: 0xe5, B: 0xe5, A: 0xff}
+	case 60:
+		col = color.RGBA{R: 0x7f, G: 0x7f, B: 0x7f, A: 0xff}
+	case 61:
+		col = color.RGBA{R: 0xff, G: 0x00, B: 0x00, A: 0xff}
+	case 62:
+		col = color.RGBA{R: 0x00, G: 0xff, B: 0x00, A: 0xff}
+	case 63:
+		col = color.RGBA{R: 0xff, G: 0xff, B: 0x00, A: 0xff}
+	case 64:
+		col = color.RGBA{R: 0x5c, G: 0x5c, B: 0xff, A: 0xff}
+	case 65:
+		col = color.RGBA{R: 0xff, G: 0x00, B: 0xff, A: 0xff}
+	case 66:
+		col = color.RGBA{R: 0x00, G: 0xff, B: 0xff, A: 0xff}
+	case 67:
+		col = color.RGBA{R: 0xff, G: 0xff, B: 0xff, A: 0xff}
 	default:
 		panic("not an xterm color")
 	}
+	return col.RGBA()
 }
 
+var xtermPalette = color.Palette{xtermColor(0), xtermColor(1), xtermColor(2), xtermColor(3), xtermColor(4), xtermColor(5), xtermColor(6), xtermColor(7), xtermColor(60), xtermColor(61), xtermColor(62), xtermColor(63), xtermColor(64), xtermColor(65), xtermColor(66), xtermColor(67)}
+
 func printImgXterm(w io.Writer, img image.Image) {
 	for y := 0; y < img.Bounds().Dy(); y += 2 {
 		if y > 0 {
@@ -201,9 +186,9 @@ func printImgXterm(w io.Writer, img image.Image) {
 			} else {
 				lo := 9
 				if y+1 < img.Bounds().Dy() && img.At(x, y+1) != color.Transparent {
-					lo = xtermColorCode(img.At(x, y+1))
+					lo = int(img.At(x, y+1).(xtermColor))
 				}
-				fmt.Fprintf(w, "\033[%dm\033[%dm▀", 30+xtermColorCode(hi), 40+lo)
+				fmt.Fprintf(w, "\033[%dm\033[%dm▀", 30+hi.(xtermColor), 40+lo)
 			}
 		}
 		fmt.Fprint(w, "\033[39m\033[49m")
@@ -237,23 +222,13 @@ func printImgBlock24(w io.Writer, img image.Image) {
 	}
 }
 
-func makePlan9ColorMap() map[color.Color]int {
-	m := make(map[color.Color]int)
-	for i, c := range palette.Plan9 {
-		m[c] = i
-	}
-	return m
-}
-
-var plan9ColorMap = makePlan9ColorMap()
-
 func scale100(c uint32) int {
 	return int(c) * 100 / 0xffff
 }
 
-func printImgSixel(w io.Writer, img image.Image) {
+func printImgSixel(w io.Writer, img image.PalettedImage) {
 	fmt.Fprint(w, "\033P7;1q")
-	for i, c := range palette.Plan9 {
+	for i, c := range img.ColorModel().(color.Palette)[1:] {
 		r, g, b, _ := c.RGBA()
 		fmt.Fprintf(w, "#%d;2;%d;%d;%d", i, scale100(r), scale100(g), scale100(b))
 	}
@@ -270,7 +245,7 @@ func printImgSixel(w io.Writer, img image.Image) {
 				fmt.Fprint(w, "?")
 			} else {
 				char := '?' + 1<<(y%6)
-				fmt.Fprintf(w, "#%d%c", plan9ColorMap[img.At(x, y)], char)
+				fmt.Fprintf(w, "#%d%c", img.ColorIndexAt(x, y)-1, char)
 			}
 		}
 	}
@@ -284,7 +259,7 @@ func printImg(w io.Writer, img image.Image) {
 	case modeBlock24:
 		printImgBlock24(w, img)
 	case modeSixel:
-		printImgSixel(w, img)
+		printImgSixel(w, img.(image.PalettedImage))
 	default:
 		panic("invalid mode")
 	}
@@ -342,7 +317,7 @@ func compositeImages(w io.Writer, images []img, width, imagesPerRow, cellX, cell
 	case modeSixel:
 		imageWidth = width * cellX
 		padding = cellX
-		colorPalette = palette.Plan9
+		colorPalette = palette.WebSafe
 	}
 	for row := range slices.Chunk(images, imagesPerRow) {
 		images := make([]image.Image, len(row))