Improve stitching speed and resource usage

- Use QuickSelect algorithm for median filtering
- Use lists of uint8 instead of int for median filtering
- Fix GridifyRectangle
- Remove HilbertifyRectangle
- Add profiling.go
- Remove Profile.bat
- Add median blend tile-limit flag
- Print stitch duration
- Reduce StitchedImage cache image height
- Reduce StitchedImageCacheGridSize
- Improve StitchedImage caching
- Improve ImageTile caching
- Separate entity and entities
- Update stitcher README.md
- Add comments

bin/stitch/Profile.bat

@@ -1 +0,0 @@
-go tool pprof -http=: ./stitch.exe cpu.prof

bin/stitch/README.md

@@ -30,6 +30,10 @@ example list of files:
 - Or run the program with parameters:
   - `divide int`
     A downscaling factor. 2 will produce an image with half the side lengths. Defaults to 1.
+  - `tile-limit int`
+    Limits median blending to the n newest tiles by file modification time.
+    If set to 0, all available tiles will be median blended.
+    If set to 1, only the newest tile will be used for any resulting pixel.
   - `input string`
     The source path of the image tiles to be stitched. Defaults to "./..//..//output")
   - `entities string`
@@ -53,7 +57,7 @@ To output the 100x100 area that is centered at the origin use:
 ./stitch -divide 1 -xmin -50 -xmax 50 -ymin -50 -ymax 50
 ```
 
-To enter the parameters inside of the program:
+To start the program interactively:
 
 ``` Shell Session
 ./stitch

bin/stitch/blend-methods.go

@@ -13,13 +13,14 @@ import (
 
 // BlendMethodMedian takes the given tiles and median blends them into destImage.
 type BlendMethodMedian struct {
-	LimitToNew int // If larger than 0, limits median blending to the `LimitToNew` newest tiles by file modification time.
+	BlendTileLimit int // If larger than 0, limits median blending to the n newest tiles by file modification time.
 }
 
+// Draw implements the StitchedImageBlendMethod interface.
 func (b BlendMethodMedian) Draw(tiles []*ImageTile, destImage *image.RGBA) {
 	bounds := destImage.Bounds()
 
-	if b.LimitToNew > 0 {
+	if b.BlendTileLimit > 0 {
 		// Sort tiles by date.
 		sort.Slice(tiles, func(i, j int) bool { return tiles[i].modTime.After(tiles[j].modTime) })
 	}
@@ -32,7 +33,7 @@ func (b BlendMethodMedian) Draw(tiles []*ImageTile, destImage *image.RGBA) {
 	}
 
 	// Create arrays to be reused every pixel.
-	rListEmpty, gListEmpty, bListEmpty := make([]int, 0, len(tiles)), make([]int, 0, len(tiles)), make([]int, 0, len(tiles))
+	rListEmpty, gListEmpty, bListEmpty := make([]uint8, 0, len(tiles)), make([]uint8, 0, len(tiles)), make([]uint8, 0, len(tiles))
 
 	for iy := bounds.Min.Y; iy < bounds.Max.Y; iy++ {
 		for ix := bounds.Min.X; ix < bounds.Max.X; ix++ {
@@ -45,43 +46,39 @@ func (b BlendMethodMedian) Draw(tiles []*ImageTile, destImage *image.RGBA) {
 				if img != nil {
 					if point.In(img.Bounds()) {
 						col := img.RGBAAt(point.X, point.Y)
-						rList, gList, bList = append(rList, int(col.R)), append(gList, int(col.G)), append(bList, int(col.B))
+						rList, gList, bList = append(rList, col.R), append(gList, col.G), append(bList, col.B)
 						count++
 						// Limit number of tiles to median blend.
-						// Will be ignored if LimitToNew is 0.
+						// Will be ignored if the blend tile limit is 0.
-						if count == b.LimitToNew {
+						if count == b.BlendTileLimit {
 							break
 						}
 					}
 				}
 			}
 
-			// If there were no images to get data from, ignore the pixel.
+			switch count {
-			if count == 0 {
+			case 0: // If there were no images to get data from, ignore the pixel.
 				continue
-			}
 
-			// Sort colors. Not needed if there is only one color.
+			case 1: // Only a single tile for this pixel.
-			if count > 1 {
+				r, g, b := uint8(rList[0]), uint8(gList[0]), uint8(bList[0])
-				sort.Ints(rList)
+				destImage.SetRGBA(ix, iy, color.RGBA{r, g, b, 255})
-				sort.Ints(gList)
-				sort.Ints(bList)
-			}
 
-			// Take the middle element of each color.
+			default: // Multiple overlapping tiles, median blend them.
-			var r, g, b uint8
+				var r, g, b uint8
-			switch count % 2 {
+				switch count % 2 {
-			case 0: // Even.
+				case 0: // Even.
-				r = uint8((rList[count/2-1] + rList[count/2]) / 2)
+					r = uint8((int(QuickSelectUInt8(rList, count/2-1)) + int(QuickSelectUInt8(rList, count/2))) / 2)
-				g = uint8((gList[count/2-1] + gList[count/2]) / 2)
+					g = uint8((int(QuickSelectUInt8(gList, count/2-1)) + int(QuickSelectUInt8(gList, count/2))) / 2)
-				b = uint8((bList[count/2-1] + bList[count/2]) / 2)
+					b = uint8((int(QuickSelectUInt8(bList, count/2-1)) + int(QuickSelectUInt8(bList, count/2))) / 2)
-			default: // Odd.
+				default: // Odd.
-				r = uint8(rList[(count-1)/2])
+					r = QuickSelectUInt8(rList, count/2)
-				g = uint8(gList[(count-1)/2])
+					g = QuickSelectUInt8(gList, count/2)
-				b = uint8(bList[(count-1)/2])
+					b = QuickSelectUInt8(bList, count/2)
+				}
+				destImage.SetRGBA(ix, iy, color.RGBA{r, g, b, 255})
 			}
-
-			destImage.SetRGBA(ix, iy, color.RGBA{r, g, b, 255})
 		}
 	}
 }

bin/stitch/entities.go

@@ -8,103 +8,12 @@ package main
 import (
 	"encoding/json"
 	"image"
-	"image/color"
 	"os"
 
 	"github.com/tdewolff/canvas"
 	"github.com/tdewolff/canvas/renderers/rasterizer"
 )
 
-//var entityDisplayFontFamily = canvas.NewFontFamily("times")
-//var entityDisplayFontFace *canvas.FontFace
-
-var entityDisplayAreaDamageStyle = canvas.Style{
-	FillColor:    color.RGBA{100, 0, 0, 100},
-	StrokeColor:  canvas.Transparent,
-	StrokeWidth:  1.0,
-	StrokeCapper: canvas.ButtCap,
-	StrokeJoiner: canvas.MiterJoin,
-	DashOffset:   0.0,
-	Dashes:       []float64{},
-	FillRule:     canvas.NonZero,
-}
-
-var entityDisplayMaterialAreaCheckerStyle = canvas.Style{
-	FillColor:    color.RGBA{0, 0, 127, 127},
-	StrokeColor:  canvas.Transparent,
-	StrokeWidth:  1.0,
-	StrokeCapper: canvas.ButtCap,
-	StrokeJoiner: canvas.MiterJoin,
-	DashOffset:   0.0,
-	Dashes:       []float64{},
-	FillRule:     canvas.NonZero,
-}
-
-var entityDisplayTeleportStyle = canvas.Style{
-	FillColor:    color.RGBA{0, 127, 0, 127},
-	StrokeColor:  canvas.Transparent,
-	StrokeWidth:  1.0,
-	StrokeCapper: canvas.ButtCap,
-	StrokeJoiner: canvas.MiterJoin,
-	DashOffset:   0.0,
-	Dashes:       []float64{},
-	FillRule:     canvas.NonZero,
-}
-
-var entityDisplayHitBoxStyle = canvas.Style{
-	FillColor:    color.RGBA{64, 64, 0, 64},
-	StrokeColor:  color.RGBA{0, 0, 0, 64},
-	StrokeWidth:  1.0,
-	StrokeCapper: canvas.ButtCap,
-	StrokeJoiner: canvas.MiterJoin,
-	DashOffset:   0.0,
-	Dashes:       []float64{},
-	FillRule:     canvas.NonZero,
-}
-
-var entityDisplayCollisionTriggerStyle = canvas.Style{
-	FillColor:    color.RGBA{0, 64, 64, 64},
-	StrokeColor:  color.RGBA{0, 0, 0, 64},
-	StrokeWidth:  1.0,
-	StrokeCapper: canvas.ButtCap,
-	StrokeJoiner: canvas.MiterJoin,
-	DashOffset:   0.0,
-	Dashes:       []float64{},
-	FillRule:     canvas.NonZero,
-}
-
-func init() {
-	//fontName := "NimbusRoman-Regular"
-
-	//if err := entityDisplayFontFamily.LoadLocalFont(fontName, canvas.FontRegular); err != nil {
-	//	log.Printf("Couldn't load font %q: %v", fontName, err)
-	//}
-
-	//entityDisplayFontFace = entityDisplayFontFamily.Face(48.0, canvas.White, canvas.FontRegular, canvas.FontNormal)
-}
-
-type Entity struct {
-	Filename   string          `json:"filename"`
-	Transform  EntityTransform `json:"transform"`
-	Children   []Entity        `json:"children"`
-	Components []Component     `json:"components"`
-	Name       string          `json:"name"`
-	Tags       []string        `json:"tags"`
-}
-
-type EntityTransform struct {
-	X        float32 `json:"x"`
-	Y        float32 `json:"y"`
-	ScaleX   float32 `json:"scaleX"`
-	ScaleY   float32 `json:"scaleY"`
-	Rotation float32 `json:"rotation"`
-}
-
-type Component struct {
-	TypeName string         `json:"typeName"`
-	Members  map[string]any `json:"members"`
-}
-
 type Entities []Entity
 
 func LoadEntities(path string) (Entities, error) {
@@ -123,124 +32,7 @@ func LoadEntities(path string) (Entities, error) {
 	return result, nil
 }
 
-func (e Entity) Draw(c *canvas.Context) {
+// Draw implements the StitchedImageOverlay interface.
-	x, y := float64(e.Transform.X), float64(e.Transform.Y)
-
-	for _, component := range e.Components {
-		switch component.TypeName {
-		case "AreaDamageComponent": // Area damage like in cursed rock.
-			var aabbMinX, aabbMinY, aabbMaxX, aabbMaxY float64
-			if member, ok := component.Members["aabb_min"]; ok {
-				if aabbMin, ok := member.([]any); ok && len(aabbMin) == 2 {
-					aabbMinX, _ = aabbMin[0].(float64)
-					aabbMinY, _ = aabbMin[1].(float64)
-				}
-			}
-			if member, ok := component.Members["aabb_max"]; ok {
-				if aabbMax, ok := member.([]any); ok && len(aabbMax) == 2 {
-					aabbMaxX, _ = aabbMax[0].(float64)
-					aabbMaxY, _ = aabbMax[1].(float64)
-				}
-			}
-			if aabbMinX < aabbMaxX && aabbMinY < aabbMaxY {
-				c.Style = entityDisplayAreaDamageStyle
-				c.DrawPath(x+aabbMinX, y+aabbMinY, canvas.Rectangle(aabbMaxX-aabbMinX, aabbMaxY-aabbMinY))
-			}
-			if member, ok := component.Members["circle_radius"]; ok {
-				if radius, ok := member.(float64); ok && radius > 0 {
-					// Theoretically we need to clip the damage area to the intersection of the AABB and the circle, but meh.
-					// TODO: Clip the area to the intersection of the box and the circle
-					cx, cy := (aabbMinX+aabbMaxX)/2, (aabbMinY+aabbMaxY)/2
-					c.Style = entityDisplayAreaDamageStyle
-					c.DrawPath(x+cx, y+cy, canvas.Circle(radius))
-				}
-			}
-
-		case "MaterialAreaCheckerComponent": // Checks for materials in the given AABB.
-			var aabbMinX, aabbMinY, aabbMaxX, aabbMaxY float64
-			if member, ok := component.Members["area_aabb"]; ok {
-				if aabb, ok := member.([]any); ok && len(aabb) == 4 {
-					aabbMinX, _ = aabb[0].(float64)
-					aabbMinY, _ = aabb[1].(float64)
-					aabbMaxX, _ = aabb[2].(float64)
-					aabbMaxY, _ = aabb[3].(float64)
-				}
-			}
-			if aabbMinX < aabbMaxX && aabbMinY < aabbMaxY {
-				c.Style = entityDisplayMaterialAreaCheckerStyle
-				c.DrawPath(x+aabbMinX, y+aabbMinY, canvas.Rectangle(aabbMaxX-aabbMinX, aabbMaxY-aabbMinY))
-			}
-
-		case "TeleportComponent":
-			var aabbMinX, aabbMinY, aabbMaxX, aabbMaxY float64
-			if member, ok := component.Members["source_location_camera_aabb"]; ok {
-				if aabb, ok := member.([]any); ok && len(aabb) == 4 {
-					aabbMinX, _ = aabb[0].(float64)
-					aabbMinY, _ = aabb[1].(float64)
-					aabbMaxX, _ = aabb[2].(float64)
-					aabbMaxY, _ = aabb[3].(float64)
-				}
-			}
-			if aabbMinX < aabbMaxX && aabbMinY < aabbMaxY {
-				c.Style = entityDisplayTeleportStyle
-				c.DrawPath(x+aabbMinX, y+aabbMinY, canvas.Rectangle(aabbMaxX-aabbMinX, aabbMaxY-aabbMinY))
-			}
-
-		case "HitboxComponent": // General hit box component.
-			var aabbMinX, aabbMinY, aabbMaxX, aabbMaxY float64
-			if member, ok := component.Members["aabb_min_x"]; ok {
-				aabbMinX, _ = member.(float64)
-			}
-			if member, ok := component.Members["aabb_min_y"]; ok {
-				aabbMinY, _ = member.(float64)
-			}
-			if member, ok := component.Members["aabb_max_x"]; ok {
-				aabbMaxX, _ = member.(float64)
-			}
-			if member, ok := component.Members["aabb_max_y"]; ok {
-				aabbMaxY, _ = member.(float64)
-			}
-			if aabbMinX < aabbMaxX && aabbMinY < aabbMaxY {
-				c.Style = entityDisplayHitBoxStyle
-				c.DrawPath(x+aabbMinX, y+aabbMinY, canvas.Rectangle(aabbMaxX-aabbMinX, aabbMaxY-aabbMinY))
-			}
-
-		case "CollisionTriggerComponent": // Checks if another entity is inside the given radius and box with the given width and height.
-			var width, height float64
-			path := &canvas.Path{}
-			if member, ok := component.Members["width"]; ok {
-				width, _ = member.(float64)
-			}
-			if member, ok := component.Members["height"]; ok {
-				height, _ = member.(float64)
-			}
-			if width > 0 && height > 0 {
-				path = canvas.Rectangle(width, height).Translate(-width/2, -height/2)
-			}
-			// Theoretically we need to clip the area to the intersection of the box and the circle, but meh.
-			// TODO: Clip the area to the intersection of the box and the circle
-			//if member, ok := component.Members["radius"]; ok {
-			//	if radius, ok := member.(float64); ok && radius > 0 {
-			//		path = path.Append(canvas.Circle(radius))
-			//		path.And()
-			//	}
-			//}
-			if !path.Empty() {
-				c.Style = entityDisplayCollisionTriggerStyle
-				c.DrawPath(x, y, path)
-			}
-
-		}
-	}
-
-	c.SetFillColor(color.RGBA{255, 255, 255, 128})
-	c.SetStrokeColor(color.RGBA{255, 0, 0, 255})
-	c.DrawPath(x, y, canvas.Circle(3))
-
-	//text := canvas.NewTextLine(entityDisplayFontFace, fmt.Sprintf("%s\n%s", e.Name, e.Filename), canvas.Left)
-	//c.DrawText(x, y, text)
-}
-
 func (e Entities) Draw(destImage *image.RGBA) {
 	destRect := destImage.Bounds()
 

bin/stitch/entity.go

@@ -0,0 +1,220 @@
+// Copyright (c) 2022 David Vogel
+//
+// This software is released under the MIT License.
+// https://opensource.org/licenses/MIT
+
+package main
+
+import (
+	"image/color"
+
+	"github.com/tdewolff/canvas"
+)
+
+//var entityDisplayFontFamily = canvas.NewFontFamily("times")
+//var entityDisplayFontFace *canvas.FontFace
+
+var entityDisplayAreaDamageStyle = canvas.Style{
+	FillColor:    color.RGBA{100, 0, 0, 100},
+	StrokeColor:  canvas.Transparent,
+	StrokeWidth:  1.0,
+	StrokeCapper: canvas.ButtCap,
+	StrokeJoiner: canvas.MiterJoin,
+	DashOffset:   0.0,
+	Dashes:       []float64{},
+	FillRule:     canvas.NonZero,
+}
+
+var entityDisplayMaterialAreaCheckerStyle = canvas.Style{
+	FillColor:    color.RGBA{0, 0, 127, 127},
+	StrokeColor:  canvas.Transparent,
+	StrokeWidth:  1.0,
+	StrokeCapper: canvas.ButtCap,
+	StrokeJoiner: canvas.MiterJoin,
+	DashOffset:   0.0,
+	Dashes:       []float64{},
+	FillRule:     canvas.NonZero,
+}
+
+var entityDisplayTeleportStyle = canvas.Style{
+	FillColor:    color.RGBA{0, 127, 0, 127},
+	StrokeColor:  canvas.Transparent,
+	StrokeWidth:  1.0,
+	StrokeCapper: canvas.ButtCap,
+	StrokeJoiner: canvas.MiterJoin,
+	DashOffset:   0.0,
+	Dashes:       []float64{},
+	FillRule:     canvas.NonZero,
+}
+
+var entityDisplayHitBoxStyle = canvas.Style{
+	FillColor:    color.RGBA{64, 64, 0, 64},
+	StrokeColor:  color.RGBA{0, 0, 0, 64},
+	StrokeWidth:  1.0,
+	StrokeCapper: canvas.ButtCap,
+	StrokeJoiner: canvas.MiterJoin,
+	DashOffset:   0.0,
+	Dashes:       []float64{},
+	FillRule:     canvas.NonZero,
+}
+
+var entityDisplayCollisionTriggerStyle = canvas.Style{
+	FillColor:    color.RGBA{0, 64, 64, 64},
+	StrokeColor:  color.RGBA{0, 0, 0, 64},
+	StrokeWidth:  1.0,
+	StrokeCapper: canvas.ButtCap,
+	StrokeJoiner: canvas.MiterJoin,
+	DashOffset:   0.0,
+	Dashes:       []float64{},
+	FillRule:     canvas.NonZero,
+}
+
+func init() {
+	//fontName := "NimbusRoman-Regular"
+
+	//if err := entityDisplayFontFamily.LoadLocalFont(fontName, canvas.FontRegular); err != nil {
+	//	log.Printf("Couldn't load font %q: %v", fontName, err)
+	//}
+
+	//entityDisplayFontFace = entityDisplayFontFamily.Face(48.0, canvas.White, canvas.FontRegular, canvas.FontNormal)
+}
+
+type Entity struct {
+	Filename   string          `json:"filename"`
+	Transform  EntityTransform `json:"transform"`
+	Children   []Entity        `json:"children"`
+	Components []Component     `json:"components"`
+	Name       string          `json:"name"`
+	Tags       []string        `json:"tags"`
+}
+
+type EntityTransform struct {
+	X        float32 `json:"x"`
+	Y        float32 `json:"y"`
+	ScaleX   float32 `json:"scaleX"`
+	ScaleY   float32 `json:"scaleY"`
+	Rotation float32 `json:"rotation"`
+}
+
+type Component struct {
+	TypeName string         `json:"typeName"`
+	Members  map[string]any `json:"members"`
+}
+
+func (e Entity) Draw(c *canvas.Context) {
+	x, y := float64(e.Transform.X), float64(e.Transform.Y)
+
+	for _, component := range e.Components {
+		switch component.TypeName {
+		case "AreaDamageComponent": // Area damage like in cursed rock.
+			var aabbMinX, aabbMinY, aabbMaxX, aabbMaxY float64
+			if member, ok := component.Members["aabb_min"]; ok {
+				if aabbMin, ok := member.([]any); ok && len(aabbMin) == 2 {
+					aabbMinX, _ = aabbMin[0].(float64)
+					aabbMinY, _ = aabbMin[1].(float64)
+				}
+			}
+			if member, ok := component.Members["aabb_max"]; ok {
+				if aabbMax, ok := member.([]any); ok && len(aabbMax) == 2 {
+					aabbMaxX, _ = aabbMax[0].(float64)
+					aabbMaxY, _ = aabbMax[1].(float64)
+				}
+			}
+			if aabbMinX < aabbMaxX && aabbMinY < aabbMaxY {
+				c.Style = entityDisplayAreaDamageStyle
+				c.DrawPath(x+aabbMinX, y+aabbMinY, canvas.Rectangle(aabbMaxX-aabbMinX, aabbMaxY-aabbMinY))
+			}
+			if member, ok := component.Members["circle_radius"]; ok {
+				if radius, ok := member.(float64); ok && radius > 0 {
+					// Theoretically we need to clip the damage area to the intersection of the AABB and the circle, but meh.
+					// TODO: Clip the area to the intersection of the box and the circle
+					cx, cy := (aabbMinX+aabbMaxX)/2, (aabbMinY+aabbMaxY)/2
+					c.Style = entityDisplayAreaDamageStyle
+					c.DrawPath(x+cx, y+cy, canvas.Circle(radius))
+				}
+			}
+
+		case "MaterialAreaCheckerComponent": // Checks for materials in the given AABB.
+			var aabbMinX, aabbMinY, aabbMaxX, aabbMaxY float64
+			if member, ok := component.Members["area_aabb"]; ok {
+				if aabb, ok := member.([]any); ok && len(aabb) == 4 {
+					aabbMinX, _ = aabb[0].(float64)
+					aabbMinY, _ = aabb[1].(float64)
+					aabbMaxX, _ = aabb[2].(float64)
+					aabbMaxY, _ = aabb[3].(float64)
+				}
+			}
+			if aabbMinX < aabbMaxX && aabbMinY < aabbMaxY {
+				c.Style = entityDisplayMaterialAreaCheckerStyle
+				c.DrawPath(x+aabbMinX, y+aabbMinY, canvas.Rectangle(aabbMaxX-aabbMinX, aabbMaxY-aabbMinY))
+			}
+
+		case "TeleportComponent":
+			var aabbMinX, aabbMinY, aabbMaxX, aabbMaxY float64
+			if member, ok := component.Members["source_location_camera_aabb"]; ok {
+				if aabb, ok := member.([]any); ok && len(aabb) == 4 {
+					aabbMinX, _ = aabb[0].(float64)
+					aabbMinY, _ = aabb[1].(float64)
+					aabbMaxX, _ = aabb[2].(float64)
+					aabbMaxY, _ = aabb[3].(float64)
+				}
+			}
+			if aabbMinX < aabbMaxX && aabbMinY < aabbMaxY {
+				c.Style = entityDisplayTeleportStyle
+				c.DrawPath(x+aabbMinX, y+aabbMinY, canvas.Rectangle(aabbMaxX-aabbMinX, aabbMaxY-aabbMinY))
+			}
+
+		case "HitboxComponent": // General hit box component.
+			var aabbMinX, aabbMinY, aabbMaxX, aabbMaxY float64
+			if member, ok := component.Members["aabb_min_x"]; ok {
+				aabbMinX, _ = member.(float64)
+			}
+			if member, ok := component.Members["aabb_min_y"]; ok {
+				aabbMinY, _ = member.(float64)
+			}
+			if member, ok := component.Members["aabb_max_x"]; ok {
+				aabbMaxX, _ = member.(float64)
+			}
+			if member, ok := component.Members["aabb_max_y"]; ok {
+				aabbMaxY, _ = member.(float64)
+			}
+			if aabbMinX < aabbMaxX && aabbMinY < aabbMaxY {
+				c.Style = entityDisplayHitBoxStyle
+				c.DrawPath(x+aabbMinX, y+aabbMinY, canvas.Rectangle(aabbMaxX-aabbMinX, aabbMaxY-aabbMinY))
+			}
+
+		case "CollisionTriggerComponent": // Checks if another entity is inside the given radius and box with the given width and height.
+			var width, height float64
+			path := &canvas.Path{}
+			if member, ok := component.Members["width"]; ok {
+				width, _ = member.(float64)
+			}
+			if member, ok := component.Members["height"]; ok {
+				height, _ = member.(float64)
+			}
+			if width > 0 && height > 0 {
+				path = canvas.Rectangle(width, height).Translate(-width/2, -height/2)
+			}
+			// Theoretically we need to clip the area to the intersection of the box and the circle, but meh.
+			// TODO: Clip the area to the intersection of the box and the circle
+			//if member, ok := component.Members["radius"]; ok {
+			//	if radius, ok := member.(float64); ok && radius > 0 {
+			//		path = path.Append(canvas.Circle(radius))
+			//		path.And()
+			//	}
+			//}
+			if !path.Empty() {
+				c.Style = entityDisplayCollisionTriggerStyle
+				c.DrawPath(x, y, path)
+			}
+
+		}
+	}
+
+	c.SetFillColor(color.RGBA{255, 255, 255, 128})
+	c.SetStrokeColor(color.RGBA{255, 0, 0, 255})
+	c.DrawPath(x, y, canvas.Circle(3))
+
+	//text := canvas.NewTextLine(entityDisplayFontFace, fmt.Sprintf("%s\n%s", e.Name, e.Filename), canvas.Left)
+	//c.DrawText(x, y, text)
+}

bin/stitch/image-tile.go

@@ -28,9 +28,11 @@ type ImageTile struct {
 
 	scaleDivider int // Downscales the coordinates and images on the fly.
 
-	image         image.Image   // Either a rectangle or an RGBA image. The bounds of this image are determined by the filename.
+	image      image.Image   // Either a rectangle or an RGBA image. The bounds of this image are determined by the filename.
-	imageMutex    *sync.RWMutex //
+	imageMutex *sync.RWMutex //
-	imageUsedFlag bool          // Flag signalling, that the image was used recently.
+
+	invalidationChan chan struct{} // Used to send invalidation requests to the tile's goroutine.
+	timeoutChan      chan struct{} // Used to determine whether the tile is still being accessed or not.
 }
 
 // NewImageTile returns an image tile object that represents the image at the given path.
@@ -54,7 +56,7 @@ func NewImageTile(path string, scaleDivider int) (ImageTile, error) {
 		return ImageTile{}, fmt.Errorf("error parsing %q to integer: %w", result[2], err)
 	}
 
-	width, height, err := getImageFileDimension(path)
+	width, height, err := GetImageFileDimension(path)
 	if err != nil {
 		return ImageTile{}, err
 	}
@@ -66,11 +68,13 @@ func NewImageTile(path string, scaleDivider int) (ImageTile, error) {
 	}
 
 	return ImageTile{
-		fileName:     path,
+		fileName:         path,
-		modTime:      modTime,
+		modTime:          modTime,
-		scaleDivider: scaleDivider,
+		scaleDivider:     scaleDivider,
-		image:        image.Rect(x/scaleDivider, y/scaleDivider, (x+width)/scaleDivider, (y+height)/scaleDivider),
+		image:            image.Rect(x/scaleDivider, y/scaleDivider, (x+width)/scaleDivider, (y+height)/scaleDivider),
-		imageMutex:   &sync.RWMutex{},
+		imageMutex:       &sync.RWMutex{},
+		invalidationChan: make(chan struct{}, 1),
+		timeoutChan:      make(chan struct{}, 1),
 	}, nil
 }
 
@@ -80,7 +84,11 @@ func NewImageTile(path string, scaleDivider int) (ImageTile, error) {
 func (it *ImageTile) GetImage() *image.RGBA {
 	it.imageMutex.RLock()
 
-	it.imageUsedFlag = true // Race condition may happen on this flag, but doesn't matter here.
+	// Clear the timeout chan to signal that the image is still being used.
+	select {
+	case <-it.timeoutChan:
+	default:
+	}
 
 	// Check if the image is already loaded.
 	if img, ok := it.image.(*image.RGBA); ok {
@@ -128,13 +136,43 @@ func (it *ImageTile) GetImage() *image.RGBA {
 
 	it.image = imgRGBA
 
-	// Free the image after some time.
+	// Clear any old invalidation request.
+	select {
+	case <-it.invalidationChan:
+	default:
+	}
+
+	// Fill timeout channel with one element.
+	// This is needed, as the ticker doesn't send a tick on initialization.
+	select {
+	case it.timeoutChan <- struct{}{}:
+	default:
+	}
+
+	// Free the image after some time or if requested externally.
 	go func() {
-		for it.imageUsedFlag {
+		// Set up watchdog that checks if the image is being used.
-			it.imageUsedFlag = false
+		ticker := time.NewTicker(5000 * time.Millisecond)
-			time.Sleep(1000 * time.Millisecond)
+		defer ticker.Stop()
+
+	loop:
+		for {
+			select {
+			case <-ticker.C:
+				// Try to send to the timeout channel.
+				select {
+				case it.timeoutChan <- struct{}{}:
+				default:
+					// Timeout channel is full because the tile image wasn't queried recently.
+					break loop
+				}
+			case <-it.invalidationChan:
+				// An invalidation was requested externally.
+				break loop
+			}
 		}
 
+		// Free image and other stuff.
 		it.imageMutex.Lock()
 		defer it.imageMutex.Unlock()
 		it.image = it.image.Bounds()
@@ -143,6 +181,18 @@ func (it *ImageTile) GetImage() *image.RGBA {
 	return imgRGBA
 }
 
+// Clears the cached image.
+func (it *ImageTile) Invalidate() {
+	it.imageMutex.RLock()
+	defer it.imageMutex.RUnlock()
+
+	// Try to send invalidation request.
+	select {
+	case it.invalidationChan <- struct{}{}:
+	default:
+	}
+}
+
 // The scaled image boundaries.
 // This matches exactly to what GetImage() returns.
 func (it *ImageTile) Bounds() image.Rectangle {

bin/stitch/image-tiles.go

@@ -10,13 +10,15 @@ import (
 	"path/filepath"
 )
 
+type ImageTiles []ImageTile
+
 // LoadImageTiles "loads" all images in the directory at the given path.
-func LoadImageTiles(path string, scaleDivider int) ([]ImageTile, error) {
+func LoadImageTiles(path string, scaleDivider int) (ImageTiles, error) {
 	if scaleDivider < 1 {
 		return nil, fmt.Errorf("invalid scale of %v", scaleDivider)
 	}
 
-	var imageTiles []ImageTile
+	var imageTiles ImageTiles
 
 	files, err := filepath.Glob(filepath.Join(path, "*.png"))
 	if err != nil {
@@ -34,3 +36,12 @@ func LoadImageTiles(path string, scaleDivider int) ([]ImageTile, error) {
 
 	return imageTiles, nil
 }
+
+// InvalidateAboveY invalidates all cached images that have no pixel at the given y coordinate or below.
+func (it ImageTiles) InvalidateAboveY(y int) {
+	for _, tile := range it {
+		if tile.Bounds().Max.Y <= y {
+			tile.Invalidate()
+		}
+	}
+}

bin/stitch/main.go

@@ -25,13 +25,14 @@ var flagEntitiesInputPath = flag.String("entities", filepath.Join(".", "..", "..
 var flagPlayerPathInputPath = flag.String("player-path", filepath.Join(".", "..", "..", "output", "player-path.json"), "The path to the player-path.json file.")
 var flagOutputPath = flag.String("output", filepath.Join(".", "output.png"), "The path and filename of the resulting stitched image.")
 var flagScaleDivider = flag.Int("divide", 1, "A downscaling factor. 2 will produce an image with half the side lengths.")
+var flagBlendTileLimit = flag.Int("tile-limit", 9, "Limits median blending to the n newest tiles by file modification time. If set to 0, all available tiles will be median blended.")
 var flagXMin = flag.Int("xmin", 0, "Left bound of the output rectangle. This coordinate is included in the output.")
 var flagYMin = flag.Int("ymin", 0, "Upper bound of the output rectangle. This coordinate is included in the output.")
 var flagXMax = flag.Int("xmax", 0, "Right bound of the output rectangle. This coordinate is not included in the output.")
 var flagYMax = flag.Int("ymax", 0, "Lower bound of the output rectangle. This coordinate is not included in the output.")
 
 func main() {
-	log.Printf("Noita MapCapture stitching tool v%s", version)
+	log.Printf("Noita MapCapture stitching tool v%s.", version)
 
 	flag.Parse()
 
@@ -59,11 +60,38 @@ func main() {
 
 		result, err := prompt.Run()
 		if err != nil {
-			log.Panicf("Error while getting user input: %v", err)
+			log.Panicf("Error while getting user input: %v.", err)
 		}
 		fmt.Sscanf(result, "%d", flagScaleDivider)
 	}
 
+	// Query the user, if there were no cmd arguments given.
+	if flag.NFlag() == 0 {
+		prompt := promptui.Prompt{
+			Label:     "Enter blend tile limit:",
+			Default:   fmt.Sprint(*flagBlendTileLimit),
+			AllowEdit: true,
+			Validate: func(s string) error {
+				var num int
+				_, err := fmt.Sscanf(s, "%d", &num)
+				if err != nil {
+					return err
+				}
+				if int(num) < 0 {
+					return fmt.Errorf("number must be at least 0")
+				}
+
+				return nil
+			},
+		}
+
+		result, err := prompt.Run()
+		if err != nil {
+			log.Panicf("Error while getting user input: %v.", err)
+		}
+		fmt.Sscanf(result, "%d", flagBlendTileLimit)
+	}
+
 	// Query the user, if there were no cmd arguments given.
 	if flag.NFlag() == 0 {
 		prompt := promptui.Prompt{
@@ -74,7 +102,7 @@ func main() {
 
 		result, err := prompt.Run()
 		if err != nil {
-			log.Panicf("Error while getting user input: %v", err)
+			log.Panicf("Error while getting user input: %v.", err)
 		}
 		*flagInputPath = result
 	}
@@ -89,7 +117,7 @@ func main() {
 
 		result, err := prompt.Run()
 		if err != nil {
-			log.Panicf("Error while getting user input: %v", err)
+			log.Panicf("Error while getting user input: %v.", err)
 		}
 		*flagEntitiesInputPath = result
 	}
@@ -97,7 +125,7 @@ func main() {
 	// Load entities if requested.
 	entities, err := LoadEntities(*flagEntitiesInputPath)
 	if err != nil {
-		log.Printf("Failed to load entities: %v", err)
+		log.Printf("Failed to load entities: %v.", err)
 	}
 	if len(entities) > 0 {
 		log.Printf("Got %v entities.", len(entities))
@@ -114,7 +142,7 @@ func main() {
 
 		result, err := prompt.Run()
 		if err != nil {
-			log.Panicf("Error while getting user input: %v", err)
+			log.Panicf("Error while getting user input: %v.", err)
 		}
 		*flagPlayerPathInputPath = result
 	}
@@ -122,22 +150,22 @@ func main() {
 	// Load player path if requested.
 	playerPath, err := LoadPlayerPath(*flagPlayerPathInputPath)
 	if err != nil {
-		log.Printf("Failed to load player path: %v", err)
+		log.Printf("Failed to load player path: %v.", err)
 	}
 	if len(playerPath) > 0 {
 		log.Printf("Got %v player path entries.", len(playerPath))
 		overlays = append(overlays, playerPath) // Add player path to overlay drawing list.
 	}
 
-	log.Printf("Starting to read tile information at \"%v\"", *flagInputPath)
+	log.Printf("Starting to read tile information at %q.", *flagInputPath)
 	tiles, err := LoadImageTiles(*flagInputPath, *flagScaleDivider)
 	if err != nil {
 		log.Panic(err)
 	}
 	if len(tiles) == 0 {
-		log.Panicf("Got no tiles inside of %v", *flagInputPath)
+		log.Panicf("Got no image tiles from %q.", *flagInputPath)
 	}
-	log.Printf("Got %v tiles", len(tiles))
+	log.Printf("Got %v tiles.", len(tiles))
 
 	totalBounds := image.Rectangle{}
 	for i, tile := range tiles {
@@ -147,17 +175,7 @@ func main() {
 			totalBounds = totalBounds.Union(tile.Bounds())
 		}
 	}
-	log.Printf("Total size of the possible output space is %v", totalBounds)
+	log.Printf("Total size of the possible output space is %v.", totalBounds)
-
-	/*profFile, err := os.Create("cpu.prof")
-	if err != nil {
-		log.Panicf("could not create CPU profile: %v", err)
-	}
-	defer profFile.Close()
-	if err := pprof.StartCPUProfile(profFile); err != nil {
-		log.Panicf("could not start CPU profile: %v", err)
-	}
-	defer pprof.StopCPUProfile()*/
 
 	// If the output rect is empty, use the rectangle that encloses all tiles.
 	outputRect := image.Rect(*flagXMin, *flagYMin, *flagXMax, *flagYMax)
@@ -190,7 +208,7 @@ func main() {
 
 		result, err := prompt.Run()
 		if err != nil {
-			log.Panicf("Error while getting user input: %v", err)
+			log.Panicf("Error while getting user input: %v.", err)
 		}
 		var xMin, yMin, xMax, yMax int
 		fmt.Sscanf(result, "%d,%d;%d,%d", &xMin, &yMin, &xMax, &yMax)
@@ -207,32 +225,34 @@ func main() {
 
 		result, err := prompt.Run()
 		if err != nil {
-			log.Panicf("Error while getting user input: %v", err)
+			log.Panicf("Error while getting user input: %v.", err)
 		}
 		*flagOutputPath = result
 	}
 
+	startTime := time.Now()
+
 	bar := pb.Full.New(0)
 	var wg sync.WaitGroup
 	done := make(chan struct{})
 
 	blendMethod := BlendMethodMedian{
-		LimitToNew: 1, // Limit median blending to the n newest tiles by file modification time.
+		BlendTileLimit: *flagBlendTileLimit, // Limit median blending to the n newest tiles by file modification time.
 	}
 
-	outputImage, err := NewStitchedImage(tiles, outputRect, blendMethod, 512, overlays)
+	outputImage, err := NewStitchedImage(tiles, outputRect, blendMethod, 64, overlays)
 	if err != nil {
-		log.Panicf("NewStitchedImage() failed: %v", err)
+		log.Panicf("NewStitchedImage() failed: %v.", err)
 	}
 	_, max := outputImage.Progress()
-	bar.SetTotal(int64(max)).Start().SetRefreshRate(1 * time.Second)
+	bar.SetTotal(int64(max)).Start().SetRefreshRate(250 * time.Millisecond)
 
 	// Query progress and draw progress bar.
 	wg.Add(1)
 	go func() {
 		defer wg.Done()
 
-		ticker := time.NewTicker(1 * time.Second)
+		ticker := time.NewTicker(250 * time.Millisecond)
 		for {
 			select {
 			case <-done:
@@ -247,13 +267,17 @@ func main() {
 		}
 	}()
 
-	log.Printf("Creating output file \"%v\"", *flagOutputPath)
+	log.Printf("Creating output file %q.", *flagOutputPath)
 	f, err := os.Create(*flagOutputPath)
 	if err != nil {
 		log.Panic(err)
 	}
 
-	if err := png.Encode(f, outputImage); err != nil {
+	encoder := png.Encoder{
+		CompressionLevel: png.DefaultCompression,
+	}
+
+	if err := encoder.Encode(f, outputImage); err != nil {
 		f.Close()
 		log.Panic(err)
 	}
@@ -264,6 +288,8 @@ func main() {
 	if err := f.Close(); err != nil {
 		log.Panic(err)
 	}
-	log.Printf("Created output file \"%v\"", *flagOutputPath)
+	log.Printf("Created output file %q in %v.", *flagOutputPath, time.Since(startTime))
 
+	//fmt.Println("Press the enter key to terminate the console screen!")
+	//fmt.Scanln()
 }

bin/stitch/player-path.go

@@ -53,6 +53,7 @@ func LoadPlayerPath(path string) (PlayerPath, error) {
 	return result, nil
 }
 
+// Draw implements the StitchedImageOverlay interface.
 func (p PlayerPath) Draw(destImage *image.RGBA) {
 	destRect := destImage.Bounds()
 

bin/stitch/profiling.go

@@ -0,0 +1,21 @@
+// Copyright (c) 2022 David Vogel
+//
+// This software is released under the MIT License.
+// https://opensource.org/licenses/MIT
+
+package main
+
+import (
+	_ "net/http/pprof"
+)
+
+func init() {
+	/*port := 1234
+
+	go func() {
+		http.ListenAndServe(fmt.Sprintf(":%d", port), nil)
+	}()
+	log.Printf("Profiler web server listening on port %d. Visit http://localhost:%d/debug/pprof", port, port)
+	log.Printf("To profile the next 10 seconds and view the profile interactively:\n  go tool pprof -http :8080 http://localhost:%d/debug/pprof/profile?seconds=10", port)
+	*/
+}

bin/stitch/stitched-image-cache.go

@@ -0,0 +1,133 @@
+// Copyright (c) 2022 David Vogel
+//
+// This software is released under the MIT License.
+// https://opensource.org/licenses/MIT
+
+package main
+
+import (
+	"image"
+	"image/color"
+	"runtime"
+	"sync"
+)
+
+// StitchedImageCache contains part of the actual image data of a stitched image.
+// This can be regenerated or invalidated at will.
+type StitchedImageCache struct {
+	sync.Mutex
+
+	stitchedImage *StitchedImage // The parent object.
+
+	rect  image.Rectangle // Position and size of the cached area.
+	image *image.RGBA     // Cached RGBA image. The bounds of this image are determined by the filename.
+}
+
+func NewStitchedImageCache(stitchedImage *StitchedImage, rect image.Rectangle) StitchedImageCache {
+	return StitchedImageCache{
+		stitchedImage: stitchedImage,
+		rect:          rect,
+	}
+}
+
+// Invalidate clears the cached image.
+func (sic *StitchedImageCache) Invalidate() {
+	sic.Lock()
+	defer sic.Unlock()
+	sic.image = nil
+}
+
+// Regenerate refills the cache image with valid image data.
+// This will block until there is a valid image, and it will *always* return a valid image.
+func (sic *StitchedImageCache) Regenerate() *image.RGBA {
+	sic.Lock()
+	defer sic.Unlock()
+
+	// Check if there is already a cache image.
+	if sic.image != nil {
+		return sic.image
+	}
+
+	si := sic.stitchedImage
+
+	cacheImage := image.NewRGBA(sic.rect)
+
+	// List of tiles that intersect with the to be generated cache image.
+	intersectingTiles := []*ImageTile{}
+	for i, tile := range si.tiles {
+		if tile.Bounds().Overlaps(sic.rect) {
+			tilePtr := &si.tiles[i]
+			intersectingTiles = append(intersectingTiles, tilePtr)
+		}
+	}
+
+	// Start worker threads.
+	workerQueue := make(chan image.Rectangle)
+	waitGroup := sync.WaitGroup{}
+	workers := (runtime.NumCPU() + 1) / 2
+	for i := 0; i < workers; i++ {
+		waitGroup.Add(1)
+		go func() {
+			defer waitGroup.Done()
+			for workload := range workerQueue {
+				// List of tiles that intersect with the workload chunk.
+				workloadTiles := []*ImageTile{}
+
+				// Get only the tiles that intersect with the workload bounds.
+				for _, tile := range intersectingTiles {
+					if tile.Bounds().Overlaps(workload) {
+						workloadTiles = append(workloadTiles, tile)
+					}
+				}
+
+				// Draw blended tiles into cache image.
+				// Restricted by the workload rectangle.
+				si.blendMethod.Draw(workloadTiles, cacheImage.SubImage(workload).(*image.RGBA))
+			}
+		}()
+	}
+
+	// Divide rect into chunks and push to workers.
+	for _, chunk := range GridifyRectangle(sic.rect, StitchedImageCacheGridSize) {
+		workerQueue <- chunk
+	}
+	close(workerQueue)
+
+	// Wait until all worker threads are done.
+	waitGroup.Wait()
+
+	// Draw overlays.
+	for _, overlay := range si.overlays {
+		if overlay != nil {
+			overlay.Draw(cacheImage)
+		}
+	}
+
+	// Update cached image.
+	sic.image = cacheImage
+	return cacheImage
+}
+
+// Returns the pixel color at x and y.
+func (sic *StitchedImageCache) RGBAAt(x, y int) color.RGBA {
+	// Fast path: The image is loaded.
+	sic.Lock()
+	if sic.image != nil {
+		defer sic.Unlock()
+		return sic.image.RGBAAt(x, y)
+	}
+	sic.Unlock()
+
+	// Slow path: The image data needs to be generated first.
+	// This will block until the cache is regenerated.
+	return sic.Regenerate().RGBAAt(x, y)
+}
+
+// Returns the pixel color at x and y.
+func (sic *StitchedImageCache) At(x, y int) color.Color {
+	return sic.RGBAAt(x, y)
+}
+
+func (sic *StitchedImageCache) Bounds() image.Rectangle {
+	return sic.rect
+}

bin/stitch/stitched-image.go

@@ -9,19 +9,17 @@ import (
 	"fmt"
 	"image"
 	"image/color"
-	"runtime"
-	"sync"
 )
 
 // StitchedImageCacheGridSize defines the worker chunk size when the cache image is regenerated.
-// TODO: Find optimal grid size that works good for tiles with lots and few overlap
+var StitchedImageCacheGridSize = 256
-var StitchedImageCacheGridSize = 512
 
 // StitchedImageBlendMethod defines how tiles are blended together.
 type StitchedImageBlendMethod interface {
 	Draw(tiles []*ImageTile, destImage *image.RGBA) // Draw is called when a new cache image is generated.
 }
 
+// StitchedImageOverlay defines an interface for arbitrary overlays that can be drawn over the stitched image.
 type StitchedImageOverlay interface {
 	Draw(*image.RGBA)
 }
@@ -29,37 +27,50 @@ type StitchedImageOverlay interface {
 // StitchedImage combines several ImageTile objects into a single RGBA image.
 // The way the images are combined/blended is defined by the blendFunc.
 type StitchedImage struct {
-	tiles       []ImageTile
+	tiles       ImageTiles
 	bounds      image.Rectangle
 	blendMethod StitchedImageBlendMethod
 	overlays    []StitchedImageOverlay
 
-	cacheHeight int
+	cacheRowHeight  int
-	cacheImage  *image.RGBA
+	cacheRows       []StitchedImageCache
+	cacheRowYOffset int // Defines the pixel offset of the first cache row.
 
-	queryCounter int
+	oldCacheRowIndex int
+	queryCounter     int
 }
 
 // NewStitchedImage creates a new image from several single image tiles.
-func NewStitchedImage(tiles []ImageTile, bounds image.Rectangle, blendMethod StitchedImageBlendMethod, cacheHeight int, overlays []StitchedImageOverlay) (*StitchedImage, error) {
+func NewStitchedImage(tiles ImageTiles, bounds image.Rectangle, blendMethod StitchedImageBlendMethod, cacheRowHeight int, overlays []StitchedImageOverlay) (*StitchedImage, error) {
 	if bounds.Empty() {
 		return nil, fmt.Errorf("given boundaries are empty")
 	}
 	if blendMethod == nil {
 		return nil, fmt.Errorf("no blending method given")
 	}
-	if cacheHeight <= 0 {
+	if cacheRowHeight <= 0 {
-		return nil, fmt.Errorf("invalid cache height of %d pixels", cacheHeight)
+		return nil, fmt.Errorf("invalid cache row height of %d pixels", cacheRowHeight)
 	}
 
-	return &StitchedImage{
+	stitchedImage := &StitchedImage{
 		tiles:       tiles,
 		bounds:      bounds,
 		blendMethod: blendMethod,
 		overlays:    overlays,
-		cacheHeight: cacheHeight,
+	}
-		cacheImage:  &image.RGBA{},
+
-	}, nil
+	// Generate cache image rows.
+	rows := bounds.Dy() / cacheRowHeight
+	var cacheRows []StitchedImageCache
+	for i := 0; i < rows; i++ {
+		rect := image.Rect(bounds.Min.X, bounds.Min.Y+i*cacheRowHeight, bounds.Max.X, bounds.Min.Y+(i+1)*cacheRowHeight)
+		cacheRows = append(cacheRows, NewStitchedImageCache(stitchedImage, rect.Intersect(bounds)))
+	}
+	stitchedImage.cacheRowHeight = cacheRowHeight
+	stitchedImage.cacheRowYOffset = -bounds.Min.Y
+	stitchedImage.cacheRows = cacheRows
+
+	return stitchedImage, nil
 }
 
 // ColorModel returns the Image's color model.
@@ -73,6 +84,10 @@ func (si *StitchedImage) Bounds() image.Rectangle {
 	return si.bounds
 }
 
+func (si *StitchedImage) At(x, y int) color.Color {
+	return si.RGBAAt(x, y)
+}
+
 // At returns the color of the pixel at (x, y).
 //
 // This is optimized to be read line by line (scanning), it will be much slower with random access.
@@ -81,25 +96,38 @@ func (si *StitchedImage) Bounds() image.Rectangle {
 //
 //	At(Bounds().Min.X, Bounds().Min.Y) // returns the top-left pixel of the image.
 //	At(Bounds().Max.X-1, Bounds().Max.Y-1) // returns the bottom-right pixel.
-//
+func (si *StitchedImage) RGBAAt(x, y int) color.RGBA {
-// This is not thread safe, don't call from several goroutines!
-func (si *StitchedImage) At(x, y int) color.Color {
-	p := image.Point{x, y}
-
 	// Assume that every pixel is only queried once.
 	si.queryCounter++
 
-	// Check if cached image needs to be regenerated.
+	// Determine the cache rowIndex index.
-	if !p.In(si.cacheImage.Bounds()) {
+	rowIndex := (y + si.cacheRowYOffset) / si.cacheRowHeight
-		rect := si.Bounds()
+	if rowIndex < 0 || rowIndex >= len(si.cacheRows) {
-		// TODO: Redo how the cache image rect is generated
+		return color.RGBA{}
-		rect.Min.Y = divideFloor(y, si.cacheHeight) * si.cacheHeight
-		rect.Max.Y = rect.Min.Y + si.cacheHeight
-
-		si.regenerateCache(rect)
 	}
 
-	return si.cacheImage.RGBAAt(x, y)
+	// Check if we advanced/changed the row index.
+	// This doesn't happen a lot, so stuff inside this can be a bit more expensive.
+	if si.oldCacheRowIndex != rowIndex {
+		// Pre generate the new row asynchronously.
+		newRowIndex := rowIndex + 1
+		if newRowIndex >= 0 && newRowIndex < len(si.cacheRows) {
+			go si.cacheRows[newRowIndex].Regenerate()
+		}
+
+		// Invalidate old cache row.
+		oldRowIndex := si.oldCacheRowIndex
+		if oldRowIndex >= 0 && oldRowIndex < len(si.cacheRows) {
+			si.cacheRows[oldRowIndex].Invalidate()
+		}
+
+		// Invalidate all tiles that are above the next row.
+		si.tiles.InvalidateAboveY((rowIndex+1)*si.cacheRowHeight - si.cacheRowYOffset)
+
+		si.oldCacheRowIndex = rowIndex
+	}
+
+	return si.cacheRows[rowIndex].RGBAAt(x, y)
 }
 
 // Opaque returns whether the image is fully opaque.
@@ -116,60 +144,3 @@ func (si *StitchedImage) Progress() (value, max int) {
 
 	return si.queryCounter, size.X * size.Y
 }
-
-// regenerateCache will regenerate the cache image at the given rectangle.
-func (si *StitchedImage) regenerateCache(rect image.Rectangle) {
-	cacheImage := image.NewRGBA(rect)
-
-	// List of tiles that intersect with the to be generated cache image.
-	intersectingTiles := []*ImageTile{}
-	for i, tile := range si.tiles {
-		if tile.Bounds().Overlaps(rect) {
-			tilePtr := &si.tiles[i]
-			intersectingTiles = append(intersectingTiles, tilePtr)
-		}
-	}
-
-	// Start worker threads.
-	workerQueue := make(chan image.Rectangle)
-	waitGroup := sync.WaitGroup{}
-	for i := 0; i < runtime.NumCPU(); i++ {
-		waitGroup.Add(1)
-		go func() {
-			defer waitGroup.Done()
-			for workload := range workerQueue {
-				// List of tiles that intersect with the workload chunk.
-				workloadTiles := []*ImageTile{}
-
-				// Get only the tiles that intersect with the destination image bounds.
-				for _, tile := range intersectingTiles {
-					if tile.Bounds().Overlaps(workload) {
-						workloadTiles = append(workloadTiles, tile)
-					}
-				}
-
-				// Blend tiles into image at the workload rectangle.
-				si.blendMethod.Draw(workloadTiles, cacheImage.SubImage(workload).(*image.RGBA))
-			}
-		}()
-	}
-
-	// Divide rect into chunks and push to workers.
-	for _, chunk := range gridifyRectangle(rect, StitchedImageCacheGridSize) {
-		workerQueue <- chunk
-	}
-	close(workerQueue)
-
-	// Wait until all worker threads are done.
-	waitGroup.Wait()
-
-	// Draw overlays.
-	for _, overlay := range si.overlays {
-		if overlay != nil {
-			overlay.Draw(cacheImage)
-		}
-	}
-
-	// Update cached image.
-	si.cacheImage = cacheImage
-}

bin/stitch/util.go

@@ -8,15 +8,45 @@ package main
 import (
 	"fmt"
 	"image"
-	"math"
 	"os"
-	"sort"
-
-	"github.com/google/hilbert"
 )
 
+// QuickSelect returns the kth smallest element of the given unsorted list.
+// This is faster than sorting the list and then selecting the wanted element.
+//
+// Source: https://rosettacode.org/wiki/Quickselect_algorithm#Go
+func QuickSelectUInt8(list []uint8, k int) uint8 {
+	for {
+		// Partition.
+		px := len(list) / 2
+		pv := list[px]
+		last := len(list) - 1
+		list[px], list[last] = list[last], list[px]
+
+		i := 0
+		for j := 0; j < last; j++ {
+			if list[j] < pv {
+				list[i], list[j] = list[j], list[i]
+				i++
+			}
+		}
+
+		// Select.
+		if i == k {
+			return pv
+		}
+		if k < i {
+			list = list[:i]
+		} else {
+			list[i], list[last] = list[last], list[i]
+			list = list[i+1:]
+			k -= i + 1
+		}
+	}
+}
+
 // Source: https://gist.github.com/sergiotapia/7882944
-func getImageFileDimension(imagePath string) (int, int, error) {
+func GetImageFileDimension(imagePath string) (int, int, error) {
 	file, err := os.Open(imagePath)
 	if err != nil {
 		return 0, 0, fmt.Errorf("can't open file %v: %w", imagePath, err)
@@ -31,9 +61,9 @@ func getImageFileDimension(imagePath string) (int, int, error) {
 	return image.Width, image.Height, nil
 }
 
-func gridifyRectangle(rect image.Rectangle, gridSize int) (result []image.Rectangle) {
+func GridifyRectangle(rect image.Rectangle, gridSize int) (result []image.Rectangle) {
-	for y := divideFloor(rect.Min.Y, gridSize); y < divideCeil(rect.Max.Y, gridSize); y++ {
+	for y := DivideFloor(rect.Min.Y, gridSize); y <= DivideCeil(rect.Max.Y-1, gridSize); y++ {
-		for x := divideFloor(rect.Min.X, gridSize); x < divideCeil(rect.Max.X, gridSize); x++ {
+		for x := DivideFloor(rect.Min.X, gridSize); x <= DivideCeil(rect.Max.X-1, gridSize); x++ {
 			tempRect := image.Rect(x*gridSize, y*gridSize, (x+1)*gridSize, (y+1)*gridSize)
 			intersection := tempRect.Intersect(rect)
 			if !intersection.Empty() {
@@ -45,33 +75,8 @@ func gridifyRectangle(rect image.Rectangle, gridSize int) (result []image.Rectan
 	return
 }
 
-func hilbertifyRectangle(rect image.Rectangle, gridSize int) ([]image.Rectangle, error) {
-	grid := gridifyRectangle(rect, gridSize)
-
-	gridX := divideFloor(rect.Min.X, gridSize)
-	gridY := divideFloor(rect.Min.Y, gridSize)
-
-	// Size of the grid in chunks
-	gridWidth := divideCeil(rect.Max.X, gridSize) - divideFloor(rect.Min.X, gridSize)
-	gridHeight := divideCeil(rect.Max.Y, gridSize) - divideFloor(rect.Min.Y, gridSize)
-
-	s, err := hilbert.NewHilbert(int(math.Pow(2, math.Ceil(math.Log2(math.Max(float64(gridWidth), float64(gridHeight)))))))
-	if err != nil {
-		return nil, err
-	}
-
-	sort.Slice(grid, func(i, j int) bool {
-		// Ignore out of range errors, as they shouldn't happen.
-		hilbertIndexA, _ := s.MapInverse(grid[i].Min.X/gridSize-gridX, grid[i].Min.Y/gridSize-gridY)
-		hilbertIndexB, _ := s.MapInverse(grid[j].Min.X/gridSize-gridX, grid[j].Min.Y/gridSize-gridY)
-		return hilbertIndexA < hilbertIndexB
-	})
-
-	return grid, nil
-}
-
 // Integer division that rounds to the next integer towards negative infinity.
-func divideFloor(a, b int) int {
+func DivideFloor(a, b int) int {
 	temp := a / b
 
 	if ((a ^ b) < 0) && (a%b != 0) {
@@ -82,7 +87,7 @@ func divideFloor(a, b int) int {
 }
 
 // Integer division that rounds to the next integer towards positive infinity.
-func divideCeil(a, b int) int {
+func DivideCeil(a, b int) int {
 	temp := a / b
 
 	if ((a ^ b) >= 0) && (a%b != 0) {

go.mod

@@ -6,7 +6,6 @@ require (
 	github.com/1lann/promptui v0.8.1-0.20220708222609-81fad96dd5e1
 	github.com/cheggaaa/pb/v3 v3.1.0
 	github.com/coreos/go-semver v0.3.0
-	github.com/google/hilbert v0.0.0-20181122061418-320f2e35a565
 	github.com/kbinani/screenshot v0.0.0-20210720154843-7d3a670d8329
 	github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646
 	github.com/tdewolff/canvas v0.0.0-20220627195642-6566432f4b20
@@ -21,7 +20,7 @@ require (
 	github.com/adrg/xdg v0.4.0 // indirect
 	github.com/benoitkugler/textlayout v0.1.3 // indirect
 	github.com/benoitkugler/textprocessing v0.0.2 // indirect
-	github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e // indirect
+	github.com/chzyer/readline v1.5.1 // indirect
 	github.com/dsnet/compress v0.0.1 // indirect
 	github.com/fatih/color v1.13.0 // indirect
 	github.com/gen2brain/shm v0.0.0-20200228170931-49f9650110c5 // indirect
@@ -36,7 +35,7 @@ require (
 	github.com/tdewolff/minify/v2 v2.11.10 // indirect
 	github.com/tdewolff/parse/v2 v2.6.0 // indirect
 	golang.org/x/image v0.0.0-20220617043117-41969df76e82 // indirect
-	golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 // indirect
+	golang.org/x/sys v0.0.0-20220808155132-1c4a2a72c664 // indirect
 	golang.org/x/text v0.3.7 // indirect
 	gopkg.in/yaml.v2 v2.4.0 // indirect
 )

go.sum

@@ -27,12 +27,15 @@ github.com/boombuler/barcode v1.0.1/go.mod h1:paBWMcWSl3LHKBqUq+rly7CNSldXjb2rDl
 github.com/cheekybits/is v0.0.0-20150225183255-68e9c0620927/go.mod h1:h/aW8ynjgkuj+NQRlZcDbAbM1ORAbXjXX77sX7T289U=
 github.com/cheggaaa/pb/v3 v3.1.0 h1:3uouEsl32RL7gTiQsuaXD4Bzbfl5tGztXGUvXbs4O04=
 github.com/cheggaaa/pb/v3 v3.1.0/go.mod h1:YjrevcBqadFDaGQKRdmZxTY42pXEqda48Ea3lt0K/BE=
-github.com/chzyer/logex v1.1.10 h1:Swpa1K6QvQznwJRcfTfQJmTE72DqScAa40E+fbHEXEE=
 github.com/chzyer/logex v1.1.10/go.mod h1:+Ywpsq7O8HXn0nuIou7OrIPyXbp3wmkHB+jjWRnGsAI=
-github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e h1:fY5BOSpyZCqRo5OhCuC+XN+r/bBCmeuuJtjz+bCNIf8=
+github.com/chzyer/logex v1.2.1 h1:XHDu3E6q+gdHgsdTPH6ImJMIp436vR6MPtH8gP05QzM=
+github.com/chzyer/logex v1.2.1/go.mod h1:JLbx6lG2kDbNRFnfkgvh4eRJRPX1QCoOIWomwysCBrQ=
 github.com/chzyer/readline v0.0.0-20180603132655-2972be24d48e/go.mod h1:nSuG5e5PlCu98SY8svDHJxuZscDgtXS6KTTbou5AhLI=
-github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1 h1:q763qf9huN11kDQavWsoZXJNW3xEE4JJyHa5Q25/sd8=
+github.com/chzyer/readline v1.5.1 h1:upd/6fQk4src78LMRzh5vItIt361/o4uq553V8B5sGI=
+github.com/chzyer/readline v1.5.1/go.mod h1:Eh+b79XXUwfKfcPLepksvw2tcLE/Ct21YObkaSkeBlk=
 github.com/chzyer/test v0.0.0-20180213035817-a1ea475d72b1/go.mod h1:Q3SI9o4m/ZMnBNeIyt5eFwwo7qiLfzFZmjNmxjkiQlU=
+github.com/chzyer/test v1.0.0 h1:p3BQDXSxOhOG0P9z6/hGnII4LGiEPOYBhs8asl/fC04=
+github.com/chzyer/test v1.0.0/go.mod h1:2JlltgoNkt4TW/z9V/IzDdFaMTM2JPIi26O1pF38GC8=
 github.com/coreos/go-semver v0.3.0 h1:wkHLiw0WNATZnSG7epLsujiMCgPAc9xhjJ4tgnAxmfM=
 github.com/coreos/go-semver v0.3.0/go.mod h1:nnelYz7RCh+5ahJtPPxZlU+153eP4D4r3EedlOD2RNk=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -61,8 +64,6 @@ github.com/go-pdf/fpdf v0.5.0/go.mod h1:HzcnA+A23uwogo0tp9yU+l3V+KXhiESpt1PMayhO
 github.com/go-pdf/fpdf v0.6.0 h1:MlgtGIfsdMEEQJr2le6b/HNr1ZlQwxyWr77r2aj2U/8=
 github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0 h1:DACJavvAHhabrF08vX0COfcOBJRhZ8lUbR+ZWIs0Y5g=
 github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0/go.mod h1:E/TSTwGwJL78qG/PmXZO1EjYhfJinVAhrmmHX6Z8B9k=
-github.com/google/hilbert v0.0.0-20181122061418-320f2e35a565 h1:KBAlCAY6eLC44FiEwbzEbHnpVlw15iVM4ZK8QpRIp4U=
-github.com/google/hilbert v0.0.0-20181122061418-320f2e35a565/go.mod h1:xn6EodFfRzV6j8NXQRPjngeHWlrpOrsZPKuuLRThU1k=
 github.com/jezek/xgb v0.0.0-20210312150743-0e0f116e1240 h1:dy+DS31tGEGCsZzB45HmJJNHjur8GDgtRNX9U7HnSX4=
 github.com/jezek/xgb v0.0.0-20210312150743-0e0f116e1240/go.mod h1:3P4UH/k22rXyHIJD2w4h2XMqPX4Of/eySEZq9L6wqc4=
 github.com/jung-kurt/gofpdf v1.0.0/go.mod h1:7Id9E/uU8ce6rXgefFLlgrJj/GYY22cpxn+r32jIOes=
@@ -134,10 +135,11 @@ golang.org/x/sys v0.0.0-20210423082822-04245dca01da/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20210927094055-39ccf1dd6fa6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20211025201205-69cdffdb9359/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220310020820-b874c991c1a5/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220412211240-33da011f77ad/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220503163025-988cb79eb6c6/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8 h1:0A+M6Uqn+Eje4kHMK80dtF3JCXC4ykBgQG4Fe06QRhQ=
+golang.org/x/sys v0.0.0-20220808155132-1c4a2a72c664 h1:v1W7bwXHsnLLloWYTVEdvGvA7BHMeBYsPcF0GLDxIRs=
-golang.org/x/sys v0.0.0-20220715151400-c0bba94af5f8/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220808155132-1c4a2a72c664/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.6/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=