1 files changed, 209 insertions, 0 deletions
diff --git a/vendor/github.com/Benau/tgsconverter/libtgsconverter/quantize_mediancut.go b/vendor/github.com/Benau/tgsconverter/libtgsconverter/quantize_mediancut.go
new file mode 100644
index 00000000..850708b9
--- /dev/null
+++ b/vendor/github.com/Benau/tgsconverter/libtgsconverter/quantize_mediancut.go
@@ -0,0 +1,209 @@
+package libtgsconverter
+
+import (
+	"image"
+	"image/color"
+	"sync"
+)
+
+type bucketPool struct {
+	sync.Pool
+	maxCap int
+	m      sync.Mutex
+}
+
+func (p *bucketPool) getBucket(c int) colorBucket {
+	p.m.Lock()
+	if p.maxCap > c {
+		p.maxCap = p.maxCap * 99 / 100
+	}
+	if p.maxCap < c {
+		p.maxCap = c
+	}
+	maxCap := p.maxCap
+	p.m.Unlock()
+	val := p.Pool.Get()
+	if val == nil || cap(val.(colorBucket)) < c {
+		return make(colorBucket, maxCap)[0:c]
+	}
+	slice := val.(colorBucket)
+	slice = slice[0:c]
+	for i := range slice {
+		slice[i] = colorPriority{}
+	}
+	return slice
+}
+
+var bpool bucketPool
+
+// aggregationType specifies the type of aggregation to be done
+type aggregationType uint8
+
+const (
+	// Mode - pick the highest priority value
+	mode aggregationType = iota
+	// Mean - weighted average all values
+	mean
+)
+
+// medianCutQuantizer implements the go draw.Quantizer interface using the Median Cut method
+type medianCutQuantizer struct {
+	// The type of aggregation to be used to find final colors
+	aggregation aggregationType
+	// The weighting function to use on each pixel
+	weighting func(image.Image, int, int) uint32
+	// Whether need to add a transparent entry after conversion
+	reserveTransparent bool
+}
+
+//bucketize takes a bucket and performs median cut on it to obtain the target number of grouped buckets
+func bucketize(colors colorBucket, num int) (buckets []colorBucket) {
+	if len(colors) == 0 || num == 0 {
+		return nil
+	}
+	bucket := colors
+	buckets = make([]colorBucket, 1, num*2)
+	buckets[0] = bucket
+
+	for len(buckets) < num && len(buckets) < len(colors) { // Limit to palette capacity or number of colors
+		bucket, buckets = buckets[0], buckets[1:]
+		if len(bucket) < 2 {
+			buckets = append(buckets, bucket)
+			continue
+		} else if len(bucket) == 2 {
+			buckets = append(buckets, bucket[:1], bucket[1:])
+			continue
+		}
+
+		left, right := bucket.partition()
+		buckets = append(buckets, left, right)
+	}
+	return
+}
+
+// palettize finds a single color to represent a set of color buckets
+func (q* medianCutQuantizer) palettize(p color.Palette, buckets []colorBucket) color.Palette {
+	for _, bucket := range buckets {
+		switch q.aggregation {
+		case mean:
+			mean := bucket.mean()
+			p = append(p, mean)
+		case mode:
+			var best colorPriority
+			for _, c := range bucket {
+				if c.p > best.p {
+					best = c
+				}
+			}
+			p = append(p, best.RGBA)
+		}
+	}
+	return p
+}
+
+// quantizeSlice expands the provided bucket and then palettizes the result
+func (q* medianCutQuantizer) quantizeSlice(p color.Palette, colors []colorPriority) color.Palette {
+	numColors := cap(p) - len(p)
+	reserveTransparent := q.reserveTransparent
+	if reserveTransparent {
+		numColors--
+	}
+	buckets := bucketize(colors, numColors)
+	p = q.palettize(p, buckets)
+	return p
+}
+
+func colorAt(m image.Image, x int, y int) color.RGBA {
+	switch i := m.(type) {
+	case *image.YCbCr:
+		yi := i.YOffset(x, y)
+		ci := i.COffset(x, y)
+		c := color.YCbCr{
+			i.Y[yi],
+			i.Cb[ci],
+			i.Cr[ci],
+		}
+		return color.RGBA{c.Y, c.Cb, c.Cr, 255}
+	case *image.RGBA:
+		ci := i.PixOffset(x, y)
+		return color.RGBA{i.Pix[ci+0], i.Pix[ci+1], i.Pix[ci+2], i.Pix[ci+3]}
+	default:
+		return color.RGBAModel.Convert(i.At(x, y)).(color.RGBA)
+	}
+}
+
+// buildBucketMultiple creates a prioritized color slice with all the colors in
+// the images.
+func (q* medianCutQuantizer) buildBucketMultiple(ms []image.Image) (bucket colorBucket) {
+	if len(ms) < 1 {
+		return colorBucket{}
+	}
+
+	bounds := ms[0].Bounds()
+	size := (bounds.Max.X - bounds.Min.X) * (bounds.Max.Y - bounds.Min.Y) * 2
+	sparseBucket := bpool.getBucket(size)
+
+	for _, m := range ms {
+		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
+			for x := bounds.Min.X; x < bounds.Max.X; x++ {
+				priority := uint32(1)
+				if q.weighting != nil {
+					priority = q.weighting(m, x, y)
+				}
+				c := colorAt(m, x, y)
+				if c.A == 0 {
+					if !q.reserveTransparent {
+						q.reserveTransparent = true
+					}
+					continue
+				}
+				if priority != 0 {
+					index := int(c.R)<<16 | int(c.G)<<8 | int(c.B)
+					for i := 1; ; i++ {
+						p := &sparseBucket[index%size]
+						if p.p == 0 || p.RGBA == c {
+							*p = colorPriority{p.p + priority, c}
+							break
+						}
+						index += 1 + i
+					}
+				}
+			}
+		}
+	}
+
+	bucket = sparseBucket[:0]
+	switch ms[0].(type) {
+	case *image.YCbCr:
+		for _, p := range sparseBucket {
+			if p.p != 0 {
+				r, g, b := color.YCbCrToRGB(p.R, p.G, p.B)
+				bucket = append(bucket, colorPriority{p.p, color.RGBA{r, g, b, p.A}})
+			}
+		}
+	default:
+		for _, p := range sparseBucket {
+			if p.p != 0 {
+				bucket = append(bucket, p)
+			}
+		}
+	}
+	return
+}
+
+// Quantize quantizes an image to a palette and returns the palette
+func (q* medianCutQuantizer) quantize(p color.Palette, m image.Image) color.Palette {
+	// Package quantize offers an implementation of the draw.Quantize interface using an optimized Median Cut method,
+	// including advanced functionality for fine-grained control of color priority
+	bucket := q.buildBucketMultiple([]image.Image{m})
+	defer bpool.Put(bucket)
+	return q.quantizeSlice(p, bucket)
+}
+
+// QuantizeMultiple quantizes several images at once to a palette and returns
+// the palette
+func (q* medianCutQuantizer) quantizeMultiple(p color.Palette, m []image.Image) color.Palette {
+	bucket := q.buildBucketMultiple(m)
+	defer bpool.Put(bucket)
+	return q.quantizeSlice(p, bucket)
+}