@uppy/utils/lib/VirtualList.js

Shared utility functions for Uppy Core and plugins maintained by the Uppy team.

import { jsx as _jsx } from "preact/jsx-runtime";
/**
 * Adapted from preact-virtual-list: https://github.com/developit/preact-virtual-list
 *
 * © 2016 Jason Miller
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * Adaptations:
 * - Added role=presentation to helper elements
 * - Tweaked styles for Uppy's Dashboard use case
 */
import { Component, h } from 'preact';
const STYLE_INNER = {
    position: 'relative',
    // Disabled for our use case: the wrapper elements around FileList already deal with overflow,
    // and this additional property would hide things that we want to show.
    //
    // overflow: 'hidden',
    width: '100%',
    minHeight: '100%',
};
const STYLE_CONTENT = {
    position: 'absolute',
    top: 0,
    left: 0,
    // Because the `top` value gets set to some offset, this `height` being 100% would make the scrollbar
    // stretch far beyond the content. For our use case, the content div actually can get its height from
    // the elements inside it, so we don't need to specify a `height` property at all.
    //
    // height: '100%',
    width: '100%',
    overflow: 'visible',
};
class VirtualList extends Component {
    constructor(props) {
        super(props);
        // The currently focused node, used to retain focus when the visible rows change.
        // To avoid update loops, this should not cause state updates, so it's kept as a plain property.
        this.focusElement = null;
        this.state = {
            offset: 0,
            height: 0,
        };
    }
    componentDidMount() {
        this.resize();
        window.addEventListener('resize', this.handleResize);
    }
    // TODO: refactor to stable lifecycle method
    componentWillUpdate() {
        if (this.base.contains(document.activeElement)) {
            this.focusElement = document.activeElement;
        }
    }
    componentDidUpdate() {
        // Maintain focus when rows are added and removed.
        if (this.focusElement?.parentNode &&
            document.activeElement !== this.focusElement) {
            this.focusElement.focus();
        }
        this.focusElement = null;
        this.resize();
    }
    componentWillUnmount() {
        window.removeEventListener('resize', this.handleResize);
    }
    handleScroll = () => {
        this.setState({ offset: this.base.scrollTop });
    };
    handleResize = () => {
        this.resize();
    };
    resize() {
        const { height } = this.state;
        if (height !== this.base.offsetHeight) {
            this.setState({
                height: this.base.offsetHeight,
            });
        }
    }
    render({ data, rowHeight, renderRow, overscanCount = 10, ...props }) {
        const { offset, height } = this.state;
        // first visible row index
        let start = Math.floor(offset / rowHeight);
        // actual number of visible rows (without overscan)
        let visibleRowCount = Math.floor(height / rowHeight);
        // Overscan: render blocks of rows modulo an overscan row count
        // This dramatically reduces DOM writes during scrolling
        if (overscanCount) {
            start = Math.max(0, start - (start % overscanCount));
            visibleRowCount += overscanCount;
        }
        // last visible + overscan row index + padding to allow keyboard focus to travel past the visible area
        const end = start + visibleRowCount + 4;
        // data slice currently in viewport plus overscan items
        const selection = data.slice(start, end);
        const styleInner = { ...STYLE_INNER, height: data.length * rowHeight };
        const styleContent = { ...STYLE_CONTENT, top: start * rowHeight };
        // The `role="presentation"` attributes ensure that these wrapper elements are not treated as list
        // items by accessibility and outline tools.
        return (_jsx("div", { onScroll: this.handleScroll, ...props, children: _jsx("div", { role: "presentation", style: styleInner, children: _jsx("div", { role: "presentation", style: styleContent, children: selection.map(renderRow) }) }) }));
    }
}
export default VirtualList;