File size: 2,739 Bytes
63522a5 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 | import {
useCallback,
useEffect,
useRef,
useState,
type RefObject,
} from "react";
/** Movement required before a mouse gesture is treated as a scroll drag. */
const DRAG_COMMIT_PX = 2;
/**
* Mouse drag-to-scroll for a horizontal `overflow-x-auto` container. Touch
* input keeps the browser's native panning; only primary-button mouse drags
* are handled. After a committed drag, the click that follows mouseup is
* suppressed so child buttons are not activated by the drag release.
*/
export function useDragScroll(scrollRef: RefObject<HTMLElement | null>) {
const [isDragging, setIsDragging] = useState(false);
const startXRef = useRef(0);
const startScrollLeftRef = useRef(0);
const dragCommittedRef = useRef(false);
const handleMouseDown = useCallback(
(event: React.MouseEvent) => {
const element = scrollRef.current;
if (event.button !== 0 || !element) {
return;
}
dragCommittedRef.current = false;
startXRef.current = event.clientX;
startScrollLeftRef.current = element.scrollLeft;
setIsDragging(true);
},
[scrollRef],
);
const handleClickCapture = useCallback((event: React.MouseEvent) => {
if (!dragCommittedRef.current) {
return;
}
dragCommittedRef.current = false;
event.preventDefault();
event.stopPropagation();
}, []);
const handleDragStart = useCallback((event: React.DragEvent) => {
// Child <img> elements would otherwise start a native image drag.
event.preventDefault();
}, []);
useEffect(() => {
if (!isDragging) {
return undefined;
}
const handleMouseMove = (event: MouseEvent) => {
const element = scrollRef.current;
if (!element) {
return;
}
// The mouseup can be missed when released outside the window; end the
// drag once the primary button is no longer held.
if ((event.buttons & 1) === 0) {
setIsDragging(false);
return;
}
if (!dragCommittedRef.current) {
if (Math.abs(event.clientX - startXRef.current) < DRAG_COMMIT_PX) {
return;
}
dragCommittedRef.current = true;
}
event.preventDefault();
element.scrollLeft =
startScrollLeftRef.current - (event.clientX - startXRef.current);
};
const handleMouseUp = () => setIsDragging(false);
document.addEventListener("mousemove", handleMouseMove);
document.addEventListener("mouseup", handleMouseUp);
return () => {
document.removeEventListener("mousemove", handleMouseMove);
document.removeEventListener("mouseup", handleMouseUp);
};
}, [isDragging, scrollRef]);
return { handleMouseDown, handleClickCapture, handleDragStart };
}
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