@wordpress/block-editor
Version:
81 lines (80 loc) • 3.17 kB
JavaScript
// packages/block-editor/src/components/block-draggable/use-scroll-when-dragging.js
import { getScrollContainer } from "@wordpress/dom";
import { useCallback, useEffect, useRef } from "@wordpress/element";
var SCROLL_INACTIVE_DISTANCE_PX = 50;
var SCROLL_INTERVAL_MS = 25;
var PIXELS_PER_SECOND_PER_PERCENTAGE = 1e3;
var VELOCITY_MULTIPLIER = PIXELS_PER_SECOND_PER_PERCENTAGE * (SCROLL_INTERVAL_MS / 1e3);
function useScrollWhenDragging() {
const dragStartYRef = useRef(null);
const velocityYRef = useRef(null);
const scrollParentYRef = useRef(null);
const scrollEditorIntervalRef = useRef(null);
useEffect(
() => () => {
if (scrollEditorIntervalRef.current) {
clearInterval(scrollEditorIntervalRef.current);
scrollEditorIntervalRef.current = null;
}
},
[]
);
const startScrolling = useCallback((event) => {
dragStartYRef.current = event.clientY;
scrollParentYRef.current = getScrollContainer(event.target);
scrollEditorIntervalRef.current = setInterval(() => {
if (scrollParentYRef.current && velocityYRef.current) {
const newTop = scrollParentYRef.current.scrollTop + velocityYRef.current;
scrollParentYRef.current.scroll({
top: newTop
});
}
}, SCROLL_INTERVAL_MS);
}, []);
const scrollOnDragOver = useCallback((event) => {
if (!scrollParentYRef.current) {
return;
}
const scrollParentHeight = scrollParentYRef.current.offsetHeight;
const offsetDragStartPosition = dragStartYRef.current - scrollParentYRef.current.offsetTop;
const offsetDragPosition = event.clientY - scrollParentYRef.current.offsetTop;
if (event.clientY > offsetDragStartPosition) {
const moveableDistance = Math.max(
scrollParentHeight - offsetDragStartPosition - SCROLL_INACTIVE_DISTANCE_PX,
0
);
const dragDistance = Math.max(
offsetDragPosition - offsetDragStartPosition - SCROLL_INACTIVE_DISTANCE_PX,
0
);
const distancePercentage = moveableDistance === 0 || dragDistance === 0 ? 0 : dragDistance / moveableDistance;
velocityYRef.current = VELOCITY_MULTIPLIER * distancePercentage;
} else if (event.clientY < offsetDragStartPosition) {
const moveableDistance = Math.max(
offsetDragStartPosition - SCROLL_INACTIVE_DISTANCE_PX,
0
);
const dragDistance = Math.max(
offsetDragStartPosition - offsetDragPosition - SCROLL_INACTIVE_DISTANCE_PX,
0
);
const distancePercentage = moveableDistance === 0 || dragDistance === 0 ? 0 : dragDistance / moveableDistance;
velocityYRef.current = -VELOCITY_MULTIPLIER * distancePercentage;
} else {
velocityYRef.current = 0;
}
}, []);
const stopScrolling = () => {
dragStartYRef.current = null;
scrollParentYRef.current = null;
if (scrollEditorIntervalRef.current) {
clearInterval(scrollEditorIntervalRef.current);
scrollEditorIntervalRef.current = null;
}
};
return [startScrolling, scrollOnDragOver, stopScrolling];
}
export {
useScrollWhenDragging as default
};
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