Account for floating point errors in right-to-left test in domPosInText

marijnh · marijnh · commit 6e7f5fe0ec72 · 2025-11-15T23:49:05.000+01:00
FIX: Fix an issue where computing a document position from screen coordinates would sometimes go wrong in right-to-left text. See https://discuss.codemirror.net/t/clicking-at-end-of-line-in-rtl-text-places-cursor-at-wrong-location-in-chrome/9571
diff --git a/src/cursor.ts b/src/cursor.ts
@@ -112,7 +112,7 @@ function domPosInText(node: Text, x: number, y: number): {node: Node, offset: nu
           // Check for RTL on browsers that support getting client
           // rects for empty ranges.
           let rectBefore = textRange(node, i).getBoundingClientRect()
-          if (rectBefore.left == rect.right) after = !right
+          if (Math.abs(rectBefore.left - rect.right) < 0.1) after = !right
         }
         if (dy <= 0) return {node, offset: i + (after ? 1 : 0)}
         closestOffset = i + (after ? 1 : 0)

Original file line number	Diff line number	Diff line change
`@@ -112,7 +112,7 @@ function domPosInText(node: Text, x: number, y: number): {node: Node, offset: nu`
`112`	`112`	`// Check for RTL on browsers that support getting client`
`113`	`113`	`// rects for empty ranges.`
`114`	`114`	`let rectBefore = textRange(node, i).getBoundingClientRect()`
`115`		`- if (rectBefore.left == rect.right) after = !right`
	`115`	`+ if (Math.abs(rectBefore.left - rect.right) < 0.1) after = !right`
`116`	`116`	`}`
`117`	`117`	`if (dy <= 0) return {node, offset: i + (after ? 1 : 0)}`
`118`	`118`	`closestOffset = i + (after ? 1 : 0)`