From ecf8a23af28fcba6a48e35e72e0b6d9d57bbd440 Mon Sep 17 00:00:00 2001
From: Rose Hogenson <rosehogenson@posteo.net>
Date: Tue, 9 Jun 2026 21:40:56 -0700
Subject: Fix rounding

---
 ils.go | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

(limited to 'ils.go')

diff --git a/ils.go b/ils.go
index 71701c9..e40c6f7 100644
--- a/ils.go
+++ b/ils.go
@@ -125,6 +125,10 @@ func printImg(w io.Writer, img image.Image) {
 	}
 }
 
+func divRound(n, d int) int {
+	return (n + d/2) / d
+}
+
 type pixelAspectRatio struct {
 	x, y int
 }
@@ -142,7 +146,7 @@ func compositeImageRow(imagePaths []string, width, rowWidth, cellX int, aspectRa
 		if err != nil {
 			return nil, err
 		}
-		maxHeight = max(maxHeight, imageHeight*width/(imageWidth*aspectRatio.y/aspectRatio.x))
+		maxHeight = max(maxHeight, divRound(imageHeight*width*aspectRatio.x, imageWidth*aspectRatio.y))
 	}
 	bounds := image.Rect(0, 0, rowWidth, maxHeight)
 	result := image.NewRGBA(bounds)
@@ -152,10 +156,10 @@ func compositeImageRow(imagePaths []string, width, rowWidth, cellX int, aspectRa
 		if err != nil {
 			return nil, err
 		}
-		height := img.Bounds().Dy() * width / (img.Bounds().Dx() * aspectRatio.y / aspectRatio.x)
+		height := divRound(img.Bounds().Dy()*width*aspectRatio.x, img.Bounds().Dx()*aspectRatio.y)
 		imageWidth := max(width, cellX*runewidth.StringWidth(filepath.Base(filename)))
-		start := (offset*rowWidth + logicalWidth - 1) / logicalWidth
-		end := ((offset+imageWidth)*rowWidth + logicalWidth - 1) / logicalWidth
+		start := divRound(offset*rowWidth, logicalWidth)
+		end := divRound((offset+imageWidth)*rowWidth, logicalWidth)
 		offsetStart := start + (end-start-width)/2
 		dstBounds := image.Rect(offsetStart, (maxHeight-height)/2, offsetStart+width, (maxHeight-height)/2+height)
 		draw.BiLinear.Scale(result, dstBounds, img, img.Bounds(), draw.Src, nil)
@@ -244,12 +248,12 @@ func thumbnailFiles(w io.Writer, imagePaths []string, width, rowWidth, cellX, ce
 			if i > 0 {
 				offset += 2
 			}
-			start := (offset*rowWidth + thisRowWidth - 1) / thisRowWidth
+			start := divRound(offset*rowWidth, thisRowWidth)
 			fmt.Fprintf(w, "%*s", start-realOffset, "")
 			realOffset = start
 			fileNameWidth := runewidth.StringWidth(filepath.Base(filename))
 			offset += max(width, fileNameWidth)
-			end := (offset*rowWidth + thisRowWidth - 1) / thisRowWidth
+			end := divRound(offset*rowWidth, thisRowWidth)
 			padding := (end - start - fileNameWidth) / 2
 			fmt.Fprintf(w, "%*s%s", padding, "", filepath.Base(filename))
 			realOffset += padding + fileNameWidth
-- 
cgit v1.3.1