gvc: replace disintegration/imaging with golang.org/x/image/draw

go.mod

@@ -4,7 +4,6 @@ go 1.23.0
 
 require (
 	github.com/corona10/goimagehash v1.1.0
-	github.com/disintegration/imaging v1.6.2
 	github.com/flopp/go-findfont v0.1.0
 	github.com/fogleman/gg v1.3.0
 	github.com/golang/freetype v0.0.0-20170609003504-e2365dfdc4a0

go.sum

@@ -1,7 +1,5 @@
 github.com/corona10/goimagehash v1.1.0 h1:teNMX/1e+Wn/AYSbLHX8mj+mF9r60R1kBeqE9MkoYwI=
 github.com/corona10/goimagehash v1.1.0/go.mod h1:VkvE0mLn84L4aF8vCb6mafVajEb6QYMHl2ZJLn0mOGI=
-github.com/disintegration/imaging v1.6.2 h1:w1LecBlG2Lnp8B3jk5zSuNqd7b4DXhcjwek1ei82L+c=
-github.com/disintegration/imaging v1.6.2/go.mod h1:44/5580QXChDfwIclfc/PCwrr44amcmDAg8hxG0Ewe4=
 github.com/fogleman/gg v1.3.0 h1:/7zJX8F6AaYQc57WQCyN9cAIz+4bCJGO9B+dyW29am8=
 github.com/fogleman/gg v1.3.0/go.mod h1:R/bRT+9gY/C5z7JzPU0zXsXHKM4/ayA+zqcVNZzPa1k=
 github.com/goccy/go-findfont v0.0.0-20250109093214-c2e12b298c75 h1:XIuIPArJ/7VuKj7uygrjl7yBYP+sTa58ljJzOxU4qDc=
@@ -12,9 +10,7 @@ github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646 h1:zYyBkD/k9seD2A7fsi6
 github.com/nfnt/resize v0.0.0-20180221191011-83c6a9932646/go.mod h1:jpp1/29i3P1S/RLdc7JQKbRpFeM1dOBd8T9ki5s+AY8=
 github.com/tetratelabs/wazero v1.10.1 h1:2DugeJf6VVk58KTPszlNfeeN8AhhpwcZqkJj2wwFuH8=
 github.com/tetratelabs/wazero v1.10.1/go.mod h1:DRm5twOQ5Gr1AoEdSi0CLjDQF1J9ZAuyqFIjl1KKfQU=
-golang.org/x/image v0.0.0-20191009234506-e7c1f5e7dbb8/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/image v0.21.0 h1:c5qV36ajHpdj4Qi0GnE0jUc/yuo33OLFaa0d+crTD5s=
 golang.org/x/image v0.21.0/go.mod h1:vUbsLavqK/W303ZroQQVKQ+Af3Yl6Uz1Ppu5J/cLz78=
-golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.19.0 h1:kTxAhCbGbxhK0IwgSKiMO5awPoDQ0RpfiVYBfK860YM=
 golang.org/x/text v0.19.0/go.mod h1:BuEKDfySbSR4drPmRPG/7iBdf8hvFMuRexcpahXilzY=

gvc/image_renderer.go

@@ -11,11 +11,11 @@ import (
 	"strings"
 	"sync"
 
-	"github.com/disintegration/imaging"
 	"github.com/flopp/go-findfont"
 	"github.com/fogleman/gg"
 	"github.com/goccy/go-graphviz/internal/wasm"
 	"github.com/golang/freetype/truetype"
+	"golang.org/x/image/draw"
 	"golang.org/x/image/font"
 	"golang.org/x/image/font/gofont/goregular"
 	"golang.org/x/image/font/opentype"
@@ -395,7 +395,7 @@ func (r *ImageRenderer) LoadImage(ctx context.Context, job *Job, shape *UserShap
 			bottomRightY := bf.UR().Y()
 			width := bottomRightX - topLeftX
 			height := bottomRightY - topLeftY
-			img = imaging.Resize(img, int(width), int(height), imaging.Lanczos)
+			img = resizeImage(img, int(width), int(height))
 			xPAD := defaultXPAD / 2.0
 			yPAD := defaultYPAD / 2.0
 			posX := (topLeftX + xPAD) * job.Scale().X()
@@ -410,6 +410,26 @@ func (r *ImageRenderer) LoadImage(ctx context.Context, job *Job, shape *UserShap
 	return nil
 }
 
+// resizeImage scales img to width x height with a Catmull-Rom kernel. A
+// zero width or height is derived from the other one so the aspect ratio
+// is preserved; when both are zero the image is returned as is.
+func resizeImage(img image.Image, width, height int) image.Image {
+	srcBounds := img.Bounds()
+	srcW, srcH := srcBounds.Dx(), srcBounds.Dy()
+	if srcW == 0 || srcH == 0 || (width <= 0 && height <= 0) {
+		return img
+	}
+	if width <= 0 {
+		width = max(1, int(float64(height)*float64(srcW)/float64(srcH)+0.5))
+	}
+	if height <= 0 {
+		height = max(1, int(float64(width)*float64(srcH)/float64(srcW)+0.5))
+	}
+	dst := image.NewNRGBA(image.Rect(0, 0, width, height))
+	draw.CatmullRom.Scale(dst, dst.Bounds(), img, srcBounds, draw.Src, nil)
+	return dst
+}
+
 type FontLoader func(ctx context.Context, job *Job, font *TextFont) (font.Face, error)
 
 var (

gvc/image_renderer_test.go

@@ -0,0 +1,44 @@
+package gvc
+
+import (
+	"image"
+	"image/color"
+	"testing"
+)
+
+func TestResizeImage(t *testing.T) {
+	src := image.NewNRGBA(image.Rect(0, 0, 40, 20))
+	for y := 0; y < 20; y++ {
+		for x := 0; x < 40; x++ {
+			src.Set(x, y, color.NRGBA{R: 200, G: 30, B: 30, A: 255})
+		}
+	}
+
+	tests := []struct {
+		name         string
+		width        int
+		height       int
+		wantW, wantH int
+	}{
+		{name: "both dimensions", width: 10, height: 10, wantW: 10, wantH: 10},
+		{name: "width only keeps the aspect ratio", width: 20, height: 0, wantW: 20, wantH: 10},
+		{name: "height only keeps the aspect ratio", width: 0, height: 5, wantW: 10, wantH: 5},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := resizeImage(src, tt.width, tt.height)
+			b := got.Bounds()
+			if b.Dx() != tt.wantW || b.Dy() != tt.wantH {
+				t.Fatalf("size = %dx%d, want %dx%d", b.Dx(), b.Dy(), tt.wantW, tt.wantH)
+			}
+			c := color.NRGBAModel.Convert(got.At(b.Min.X+b.Dx()/2, b.Min.Y+b.Dy()/2)).(color.NRGBA)
+			if c.R < 190 || c.A != 255 {
+				t.Fatalf("center pixel = %+v, want the source colour", c)
+			}
+		})
+	}
+
+	if got := resizeImage(src, 0, 0); got != image.Image(src) {
+		t.Fatal("a zero size must return the image unchanged")
+	}
+}