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64 lines
2.0 KiB
64 lines
2.0 KiB
import {dom, Holder, IDisposable, MultiHolder} from 'grainjs';
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/**
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* Overrides the cursor style for the entire document.
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* @returns {Disposable} - a Disposable that restores the cursor style to its original value.
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*/
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export function documentCursor(type: 'ns-resize' | 'grabbing'): IDisposable {
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const cursorStyle: HTMLStyleElement = document.createElement('style');
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cursorStyle.innerHTML = `*{cursor: ${type}!important;}`;
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cursorStyle.id = 'cursor-style';
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document.head.appendChild(cursorStyle);
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const cursorOwner = {
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dispose() {
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if (this.isDisposed()) { return; }
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document.head.removeChild(cursorStyle);
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},
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isDisposed() {
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return !cursorStyle.isConnected;
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}
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};
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return cursorOwner;
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}
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/**
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* Helper function to create a movable element.
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* @param options Handlers for the movable element.
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*/
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export function movable<T>(options: {
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onMove: (dx: number, dy: number, state: T) => void,
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onStart: () => T,
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}) {
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return (el: HTMLElement) => {
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// Remember the initial position of the mouse.
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let startX = 0;
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let startY = 0;
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dom.onElem(el, 'mousedown', (md) => {
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// Only handle left mouse button.
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if (md.button !== 0) { return; }
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startX = md.clientX;
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startY = md.clientY;
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const state = options.onStart();
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// We create a holder first so that we can dispose elements earlier on mouseup, and have a fallback
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// in case of a situation when the dom is removed before mouseup.
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const holder = new Holder();
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const owner = MultiHolder.create(holder);
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dom.autoDisposeElem(el, holder);
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owner.autoDispose(dom.onElem(document, 'mousemove', (mv) => {
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const dx = mv.clientX - startX;
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const dy = mv.clientY - startY;
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options.onMove(dx, dy, state);
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}));
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owner.autoDispose(dom.onElem(document, 'mouseup', () => {
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holder.clear();
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}));
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owner.autoDispose(documentCursor('ns-resize'));
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md.stopPropagation();
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md.preventDefault();
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}, { useCapture: true });
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};
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}
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