diff options
Diffstat (limited to 'vendor/github.com/lucasb-eyer/go-colorful/soft_palettegen.go')
-rw-r--r-- | vendor/github.com/lucasb-eyer/go-colorful/soft_palettegen.go | 185 |
1 files changed, 0 insertions, 185 deletions
diff --git a/vendor/github.com/lucasb-eyer/go-colorful/soft_palettegen.go b/vendor/github.com/lucasb-eyer/go-colorful/soft_palettegen.go deleted file mode 100644 index 0154ac9..0000000 --- a/vendor/github.com/lucasb-eyer/go-colorful/soft_palettegen.go +++ /dev/null @@ -1,185 +0,0 @@ -// Largely inspired by the descriptions in http://lab.medialab.sciences-po.fr/iwanthue/ -// but written from scratch. - -package colorful - -import ( - "fmt" - "math" - "math/rand" -) - -// The algorithm works in L*a*b* color space and converts to RGB in the end. -// L* in [0..1], a* and b* in [-1..1] -type lab_t struct { - L, A, B float64 -} - -type SoftPaletteSettings struct { - // A function which can be used to restrict the allowed color-space. - CheckColor func(l, a, b float64) bool - - // The higher, the better quality but the slower. Usually two figures. - Iterations int - - // Use up to 160000 or 8000 samples of the L*a*b* space (and thus calls to CheckColor). - // Set this to true only if your CheckColor shapes the Lab space weirdly. - ManySamples bool -} - -// Yeah, windows-stype Foo, FooEx, screw you golang... -// Uses K-means to cluster the color-space and return the means of the clusters -// as a new palette of distinctive colors. Falls back to K-medoid if the mean -// happens to fall outside of the color-space, which can only happen if you -// specify a CheckColor function. -func SoftPaletteEx(colorsCount int, settings SoftPaletteSettings) ([]Color, error) { - - // Checks whether it's a valid RGB and also fulfills the potentially provided constraint. - check := func(col lab_t) bool { - c := Lab(col.L, col.A, col.B) - return c.IsValid() && (settings.CheckColor == nil || settings.CheckColor(col.L, col.A, col.B)) - } - - // Sample the color space. These will be the points k-means is run on. - dl := 0.05 - dab := 0.1 - if settings.ManySamples { - dl = 0.01 - dab = 0.05 - } - - samples := make([]lab_t, 0, int(1.0/dl*2.0/dab*2.0/dab)) - for l := 0.0; l <= 1.0; l += dl { - for a := -1.0; a <= 1.0; a += dab { - for b := -1.0; b <= 1.0; b += dab { - if check(lab_t{l, a, b}) { - samples = append(samples, lab_t{l, a, b}) - } - } - } - } - - // That would cause some infinite loops down there... - if len(samples) < colorsCount { - return nil, fmt.Errorf("palettegen: more colors requested (%v) than samples available (%v). Your requested color count may be wrong, you might want to use many samples or your constraint function makes the valid color space too small.", colorsCount, len(samples)) - } else if len(samples) == colorsCount { - return labs2cols(samples), nil // Oops? - } - - // We take the initial means out of the samples, so they are in fact medoids. - // This helps us avoid infinite loops or arbitrary cutoffs with too restrictive constraints. - means := make([]lab_t, colorsCount) - for i := 0; i < colorsCount; i++ { - for means[i] = samples[rand.Intn(len(samples))]; in(means, i, means[i]); means[i] = samples[rand.Intn(len(samples))] { - } - } - - clusters := make([]int, len(samples)) - samples_used := make([]bool, len(samples)) - - // The actual k-means/medoid iterations - for i := 0; i < settings.Iterations; i++ { - // Reassing the samples to clusters, i.e. to their closest mean. - // By the way, also check if any sample is used as a medoid and if so, mark that. - for isample, sample := range samples { - samples_used[isample] = false - mindist := math.Inf(+1) - for imean, mean := range means { - dist := lab_dist(sample, mean) - if dist < mindist { - mindist = dist - clusters[isample] = imean - } - - // Mark samples which are used as a medoid. - if lab_eq(sample, mean) { - samples_used[isample] = true - } - } - } - - // Compute new means according to the samples. - for imean := range means { - // The new mean is the average of all samples belonging to it.. - nsamples := 0 - newmean := lab_t{0.0, 0.0, 0.0} - for isample, sample := range samples { - if clusters[isample] == imean { - nsamples++ - newmean.L += sample.L - newmean.A += sample.A - newmean.B += sample.B - } - } - if nsamples > 0 { - newmean.L /= float64(nsamples) - newmean.A /= float64(nsamples) - newmean.B /= float64(nsamples) - } else { - // That mean doesn't have any samples? Get a new mean from the sample list! - var inewmean int - for inewmean = rand.Intn(len(samples_used)); samples_used[inewmean]; inewmean = rand.Intn(len(samples_used)) { - } - newmean = samples[inewmean] - samples_used[inewmean] = true - } - - // But now we still need to check whether the new mean is an allowed color. - if nsamples > 0 && check(newmean) { - // It does, life's good (TM) - means[imean] = newmean - } else { - // New mean isn't an allowed color or doesn't have any samples! - // Switch to medoid mode and pick the closest (unused) sample. - // This should always find something thanks to len(samples) >= colorsCount - mindist := math.Inf(+1) - for isample, sample := range samples { - if !samples_used[isample] { - dist := lab_dist(sample, newmean) - if dist < mindist { - mindist = dist - newmean = sample - } - } - } - } - } - } - return labs2cols(means), nil -} - -// A wrapper which uses common parameters. -func SoftPalette(colorsCount int) ([]Color, error) { - return SoftPaletteEx(colorsCount, SoftPaletteSettings{nil, 50, false}) -} - -func in(haystack []lab_t, upto int, needle lab_t) bool { - for i := 0; i < upto && i < len(haystack); i++ { - if haystack[i] == needle { - return true - } - } - return false -} - -const LAB_DELTA = 1e-6 - -func lab_eq(lab1, lab2 lab_t) bool { - return math.Abs(lab1.L-lab2.L) < LAB_DELTA && - math.Abs(lab1.A-lab2.A) < LAB_DELTA && - math.Abs(lab1.B-lab2.B) < LAB_DELTA -} - -// That's faster than using colorful's DistanceLab since we would have to -// convert back and forth for that. Here is no conversion. -func lab_dist(lab1, lab2 lab_t) float64 { - return math.Sqrt(sq(lab1.L-lab2.L) + sq(lab1.A-lab2.A) + sq(lab1.B-lab2.B)) -} - -func labs2cols(labs []lab_t) (cols []Color) { - cols = make([]Color, len(labs)) - for k, v := range labs { - cols[k] = Lab(v.L, v.A, v.B) - } - return cols -} |