Add Voronoi blend method

.vscode/settings.json

@@ -39,6 +39,7 @@
         "tcnksm",
         "tdewolff",
         "Vogel",
+        "Voronoi",
         "xmax",
         "xmin",
         "ymax",

bin/stitch/blend-methods.go

@@ -8,6 +8,7 @@ package main
 import (
 	"image"
 	"image/color"
+	"math"
 	"sort"
 )
 
@@ -82,3 +83,67 @@ func (b BlendMethodMedian) Draw(tiles []*ImageTile, destImage *image.RGBA) {
 		}
 	}
 }
+
+// BlendMethodVoronoi maps every pixel to the tile with the closest center point distance.
+// The result is basically a Voronoi partitioning.
+type BlendMethodVoronoi struct {
+	BlendTileLimit int // If larger than 0, limits blending to the n newest tiles by file modification time.
+}
+
+// Draw implements the StitchedImageBlendMethod interface.
+func (b BlendMethodVoronoi) Draw(tiles []*ImageTile, destImage *image.RGBA) {
+	bounds := destImage.Bounds()
+
+	if b.BlendTileLimit > 0 {
+		// Sort tiles by date.
+		sort.Slice(tiles, func(i, j int) bool { return tiles[i].modTime.After(tiles[j].modTime) })
+	}
+
+	// List of images corresponding to the "tiles" list.
+	// Can contain empty/nil entries for images that failed to load.
+	images := []*image.RGBA{}
+	for _, tile := range tiles {
+		images = append(images, tile.GetImage())
+	}
+
+	// Create arrays to be reused every pixel.
+	var col color.RGBA
+	var centerDistSqrMin int
+
+	for iy := bounds.Min.Y; iy < bounds.Max.Y; iy++ {
+		for ix := bounds.Min.X; ix < bounds.Max.X; ix++ {
+			point := image.Point{ix, iy}
+			count := 0
+			centerDistSqrMin = math.MaxInt
+
+			// Iterate through all images and create a list of colors.
+			for _, img := range images {
+				if img != nil {
+					if point.In(img.Bounds()) {
+						center := img.Bounds().Min.Add(img.Bounds().Max).Div(2)
+						centerDiff := point.Sub(center)
+						distSqr := centerDiff.X*centerDiff.X + centerDiff.Y*centerDiff.Y
+						if centerDistSqrMin > distSqr {
+							centerDistSqrMin = distSqr
+							col = img.RGBAAt(point.X, point.Y)
+						}
+						count++
+						// Limit number of tiles to blend.
+						// Will be ignored if the blend tile limit is 0.
+						if count == b.BlendTileLimit {
+							break
+						}
+					}
+				}
+			}
+
+			// If there were no images to get data from, ignore the pixel.
+			if count == 0 {
+				continue
+			}
+
+			col.A = 255
+			destImage.SetRGBA(ix, iy, col)
+		}
+	}
+}