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fix(ui): restore Mermaid fullscreen wheel zoom #544

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Merged
su-fen merged 1 commit into from
Aug 18, 2026
Merged

fix(ui): restore Mermaid fullscreen wheel zoom #544

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19 changes: 11 additions & 8 deletions crates/agent-ui/src/components/MarkdownMermaidFullscreen.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@ import { useLocale } from "@liveagent/ui/i18n/index";
import { mermaid } from "@streamdown/mermaid";
import {
type PointerEvent as ReactPointerEvent,
type WheelEvent as ReactWheelEvent,
useCallback,
useEffect,
useId,
Expand Down Expand Up @@ -135,17 +136,18 @@ function MermaidFullscreenDialog({ chart, onClose }: { chart: string; onClose: (
});
}, []);

useEffect(() => {
const viewport = viewportRef.current;
if (!viewport) return;
const handleWheel = (event: WheelEvent) => {
const handleWheel = useCallback(
(event: ReactWheelEvent<HTMLDivElement>) => {
if (event.deltaY === 0) return;
// Handle the event during capture so SVG/portal handlers cannot swallow it
// before it reaches the fullscreen viewport. The viewport itself is not
// scrollable, so the wheel gesture should always control Mermaid zoom.
event.preventDefault();
event.stopPropagation();
changeZoom(event.deltaY > 0 ? -ZOOM_STEP : ZOOM_STEP);
};
viewport.addEventListener("wheel", handleWheel, { passive: false });
return () => viewport.removeEventListener("wheel", handleWheel);
}, [changeZoom]);
},
[changeZoom],
);

const resetView = useCallback(() => {
const originalViewBox = originalViewBoxRef.current;
Expand Down Expand Up @@ -179,6 +181,7 @@ function MermaidFullscreenDialog({ chart, onClose }: { chart: string; onClose: (
"relative min-h-0 flex-1 touch-none select-none overflow-hidden",
dragging ? "cursor-grabbing" : "cursor-grab",
)}
onWheelCapture={handleWheel}
onPointerDown={(event) => {
if (
event.button !== 0 ||
Expand Down
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