snapshot of https://github.com/tldraw/tldraw.git (main, 2026-09-23; blobs > 131072B omitted)

packages/commenting/src/ui/visual-viewport.ts

@@ -0,0 +1,27 @@
+// The visual viewport is the region actually on screen. The software keyboard (and pinch-zoom)
+// shrink it while leaving the layout viewport — and CSS `dvh` — unchanged, most notably on iOS.
+// So placing a panel above the keyboard means measuring against `window.visualViewport`, not CSS.
+// These helpers are the single place the commenting layer reads it.
+
+/** The on-screen viewport region in window coordinates, falling back to the layout viewport where
+ *  `visualViewport` is unavailable. `top`/`left` carry the viewport's own offset — on iOS this is
+ *  non-zero while the keyboard is open, and dropping it misplaces anything measured against it. */
+export interface VisibleViewport {
+	top: number
+	left: number
+	width: number
+	height: number
+	bottom: number
+	right: number
+}
+
+/** Read the visible viewport once. Call it inside a `visualViewport` resize/scroll handler to keep
+ *  a measurement current as the keyboard opens and closes. */
+export function getVisibleViewport(win: Window): VisibleViewport {
+	const vv = win.visualViewport
+	const top = vv ? vv.offsetTop : 0
+	const left = vv ? vv.offsetLeft : 0
+	const width = vv ? vv.width : win.innerWidth
+	const height = vv ? vv.height : win.innerHeight
+	return { top, left, width, height, bottom: top + height, right: left + width }
+}