diff options
| -rw-r--r-- | .gitignore | 1 | ||||
| -rw-r--r-- | bench_test.go | 20 | ||||
| -rw-r--r-- | icat.go | 324 |
3 files changed, 345 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..b979372 --- /dev/null +++ b/.gitignore @@ -0,0 +1 @@ +/icat diff --git a/bench_test.go b/bench_test.go new file mode 100644 index 0000000..1e79a10 --- /dev/null +++ b/bench_test.go @@ -0,0 +1,20 @@ +package main + +import ( + "cmp" + "math/rand/v2" + "testing" +) + +func BenchmarkQuickSelect(b *testing.B) { + rng := rand.New(rand.NewPCG(0, 0)) + myTestCase := make([]int, 3840*2160) + for b.Loop() { + b.StopTimer() + for i := range myTestCase { + myTestCase[i] = rng.Int() + } + b.StartTimer() + quickSelect(myTestCase, len(myTestCase)/2, cmp.Compare) + } +} @@ -0,0 +1,324 @@ +// The icat command displays an image to the terminal using block characters. +package main + +import ( + "errors" + "flag" + "fmt" + "image" + "image/color" + _ "image/gif" + _ "image/jpeg" + _ "image/png" + "math" + "os" + "slices" + + _ "golang.org/x/image/bmp" + "golang.org/x/image/draw" + _ "golang.org/x/image/tiff" + _ "golang.org/x/image/webp" + "golang.org/x/sys/unix" + "roseh.moe/pkg/sixel" +) + +var ( + x = flag.Int("x", 0, "set image width in columns") + y = flag.Int("y", 0, "set image height in rows") + m = flagPrintMode(flag.CommandLine, "m", modeBlock24, "one of 'block', 'block24', or 'sixel'") +) + +type printMode int + +const ( + modeInvalid printMode = iota + modeBlock + modeBlock24 + modeSixel +) + +type printModeValue printMode + +func (m *printModeValue) String() string { + switch printMode(*m) { + case modeBlock: + return "block" + case modeBlock24: + return "block24" + case modeSixel: + return "sixel" + default: + return "invalid" + } +} + +func (m *printModeValue) Set(s string) error { + var mode printMode + switch s { + case "block": + mode = modeBlock + case "block24": + mode = modeBlock24 + case "sixel": + mode = modeSixel + default: + return fmt.Errorf("bad mode type %q, should be one of 'block', 'block24', or 'sixel'", s) + } + *m = printModeValue(mode) + return nil +} + +func flagPrintMode(fs *flag.FlagSet, name string, value printMode, usage string) *printMode { + fs.Var((*printModeValue)(&value), name, usage) + return &value +} + +func divRound[N ~int64 | ~int](n, d N) N { + return (n + d/2) / d +} + +func load(filename string) (image.Image, error) { + file := os.Stdin + if filename != "-" { + var err error + file, err = os.Open(filename) + if err != nil { + return nil, err + } + defer file.Close() + } + + img, _, err := image.Decode(file) + if err != nil { + return nil, fmt.Errorf("decode %q: %s", filename, err) + } + + return img, nil +} + +func sign(n int) float64 { + if n < 0 { + return -1 + } + if n > 0 { + return 1 + } + return 0 +} + +func floydRivest[S ~[]E, E any](array S, left, right, k int, cmp func(E, E) int) { + for right > left { + if right-left > 600 { + n := right - left + 1 + i := k - left + 1 + z := math.Log(float64(n)) + s := .5 * math.Exp(2*z/3) + sd := .5 * math.Sqrt(z*s*(float64(n)-s)/float64(n)) * sign(i-n/2) + newLeft := max(left, int(float64(k)-float64(i)*s/float64(n)+sd)) + newRight := min(right, int(float64(k)+float64(n-i)*s/float64(n)+sd)) + floydRivest(array, newLeft, newRight, k, cmp) + } + t := array[k] + i := left + j := right + array[left], array[k] = array[k], array[left] + if cmp(array[right], t) > 0 { + array[right], array[left] = array[left], array[right] + } + for i < j { + array[i], array[j] = array[j], array[i] + i++ + j-- + for ; cmp(array[i], t) < 0; i++ { + } + for ; cmp(array[j], t) > 0; j-- { + } + } + if cmp(array[left], t) == 0 { + array[left], array[j] = array[j], array[left] + } else { + j++ + array[j], array[right] = array[right], array[j] + } + if j <= k { + left = j + 1 + } + if k <= j { + right = j - 1 + } + } +} + +func quickSelect[S ~[]E, E any](list S, k int, cmp func(E, E) int) { + floydRivest(list, 0, len(list)-1, k, cmp) +} + +func bucketRange(colors []color.RGBA) color.RGBA { + if len(colors) == 0 { + return color.RGBA{} + } + var minR, minG, minB uint8 = math.MaxUint8, math.MaxUint8, math.MaxUint8 + var maxR, maxG, maxB uint8 + for _, c := range colors { + minR, maxR = min(minR, c.R), max(maxR, c.R) + minG, maxG = min(minG, c.G), max(maxG, c.G) + minB, maxB = min(minB, c.B), max(maxB, c.B) + } + return color.RGBA{R: maxR - minR, G: maxG - minG, B: maxB - minB} +} + +func cutOnce(colors []color.RGBA, bucketRange color.RGBA) [2][]color.RGBA { + if len(colors) == 0 { + return [...][]color.RGBA{colors, colors} + } + rRange, gRange, bRange := bucketRange.R, bucketRange.G, bucketRange.B + if rRange >= gRange && rRange >= bRange { + quickSelect(colors, len(colors)/2, func(x, y color.RGBA) int { return int(x.R) - int(y.R) }) + } else if gRange >= rRange && gRange >= bRange { + quickSelect(colors, len(colors)/2, func(x, y color.RGBA) int { return int(x.G) - int(y.G) }) + } else { + quickSelect(colors, len(colors)/2, func(x, y color.RGBA) int { return int(x.B) - int(y.B) }) + } + return [...][]color.RGBA{colors[:len(colors)/2], colors[len(colors)/2:]} +} + +func colorAvg(colors []color.RGBA) color.RGBA { + var r, g, b int64 + for _, c := range colors { + r += int64(c.R) + g += int64(c.G) + b += int64(c.B) + } + n := int64(len(colors)) + return color.RGBA{R: uint8(divRound(r, n)), G: uint8(divRound(g, n)), B: uint8(divRound(b, n)), A: 0xff} +} + +func medianCut(img image.Image) color.Palette { + var colors []color.RGBA + for y := img.Bounds().Min.Y; y < img.Bounds().Max.Y; y++ { + for x := img.Bounds().Min.X; x < img.Bounds().Max.X; x++ { + r, g, b, a := img.At(x, y).RGBA() + if a > 0 { + colors = append(colors, color.RGBA{R: uint8(r >> 8), G: uint8(g >> 8), B: uint8(b >> 8), A: 0xff}) + } + } + } + buckets := [][]color.RGBA{colors} + bucketRanges := []color.RGBA{{}} + for { + var bestRange uint8 + var bestIdx int + for i, rng := range bucketRanges { + r := max(rng.R, rng.G, rng.B) + if r >= bestRange { + bestRange = r + bestIdx = i + } + } + split := cutOnce(buckets[bestIdx], bucketRanges[bestIdx]) + buckets = slices.Replace(buckets, bestIdx, bestIdx+1, split[:]...) + if len(buckets) == 255 { + break + } + bucketRanges = slices.Replace(bucketRanges, bestIdx, bestIdx+1, bucketRange(split[0]), bucketRange(split[1])) + } + palette := color.Palette{color.Transparent} + for _, b := range buckets { + if len(b) > 0 { + palette = append(palette, colorAvg(b)) + } + } + return palette +} + +func printImg(img image.Image, maxX, maxY, pixelX, pixelY int) error { + x := min(img.Bounds().Dx(), maxX) + y := min(img.Bounds().Dy(), maxY) + + // Try not to stretch the image. + if y == 0 || x != 0 && img.Bounds().Dy()*x*pixelX <= img.Bounds().Dx()*y*pixelY { + y = divRound(img.Bounds().Dy()*x*pixelX, img.Bounds().Dx()*pixelY) + } else { + x = divRound(img.Bounds().Dx()*y*pixelY, pixelX*img.Bounds().Dy()) + } + + if x != img.Bounds().Dx() || y != img.Bounds().Dy() { + dst := image.NewRGBA(image.Rect(0, 0, x, y)) + draw.BiLinear.Scale(dst, dst.Bounds(), img, img.Bounds(), draw.Src, nil) + img = dst + } + + switch *m { + case modeBlock: + sixel.PrintXTerm16(os.Stdout, img) + case modeBlock24: + sixel.PrintBlock(os.Stdout, img) + case modeSixel: + sixel.Print(os.Stdout, img, medianCut(img)) + } + fmt.Println() + return nil +} + +func icat(args []string) error { + if len(args) == 0 { + return errors.New("missing positional argument") + } + if len(args) > 1 { + return errors.New("too many positional arguments") + } + file := args[0] + + cols := *x + lines := *y + pixelX := 2 + pixelY := 5 + if cols == 0 && lines == 0 { + ws, err := unix.IoctlGetWinsize(int(os.Stdout.Fd()), unix.TIOCGWINSZ) + if err != nil { + return err + } + cols = int(ws.Col) + lines = int(ws.Row) + lines-- // Leave a line for the status bar. + cellX, cellY := int(ws.Xpixel)/int(ws.Col), int(ws.Ypixel)/int(ws.Row) + if cellX == 0 && cellY == 0 { + cellX, cellY = 10, 20 + } + if *m == modeSixel { + cols *= cellX + lines *= cellY + } else { + pixelX, pixelY = cellX, cellY + } + } + switch *m { + case modeSixel: + pixelX, pixelY = 1, 1 + case modeBlock24: + lines *= 2 + pixelX *= 2 + } + + img, err := load(file) + if err != nil { + return err + } + + if err := printImg(img, cols, lines, pixelX, pixelY); err != nil { + return err + } + return nil +} + +func main() { + flag.Usage = func() { + fmt.Fprintf(os.Stderr, "Usage: icat FILE\n") + } + flag.Parse() + + if err := icat(flag.Args()); err != nil { + fmt.Fprintf(os.Stderr, "Failed: %s\n", err) + os.Exit(1) + } +} |