DynamicVirtualScroll.js

@@ -62,7 +62,7 @@ export function virtualScrollDriver(props, oldState, getRenderedItemHeight)
             if (!lastItemSize)
             {
                 // Some required items in the end are missing
-                lastItemSize = 0;
+                return newState;
             }
             lastItemsHeight += lastItemSize < props.minRowHeight ? props.minRowHeight : lastItemSize;
             lastVisibleItems++;
@@ -80,7 +80,7 @@ export function virtualScrollDriver(props, oldState, getRenderedItemHeight)
             ? newState.avgRowHeight
             : oldState.avgRowHeight;
     }
-    newState.targetHeight = newState.avgRowHeight * newState.scrollHeightInItems + newState.viewportHeight;
+    newState.targetHeight = newState.avgRowHeight * newState.scrollHeightInItems;
     const scrollTop = props.scrollTop;
     let scrollPos = scrollTop / (newState.targetHeight - newState.viewportHeight);
     if (scrollPos > 1)

README.md

@@ -5,12 +5,12 @@ of visible items and skip items that are offscreen. You may also have heard abou
 "buffered render" or "windowed render" - it's the same.
 
 There are plenty of virtual scroll implementations for JS.
-Some of them are part of a larger UI library (ag-grid, ExtJS and so on), some of them are more
+Some of them are part of a larger UI library (ag-grid, ExtJS and so on),
-standalone (react-virtualized, react-window, ngx-virtual-scroller, ngx-ui-scroll, react-dynamic-virtual-list).
+some of them are more standalone (react-virtualized, react-window, ngx-virtual-scroller, react-dynamic-virtual-list).
 
 However, there is a thing that they all miss: dynamic (and unknown apriori) row heights.
 Some implementations allow to set different row heights for items, but you must calculate
-all heights before rendering; some allow dynamic row heights, but have bugs and act weird or don't really work;
+all heights before rendering; some allow dynamic row heights, but have bugs and do not really work;
 others just force you to use fixed row height. Most implementations are also tied to some specific
 UI component or framework and are unusable with other ones.
 
@@ -67,64 +67,7 @@ What to do with it:
 * also note that you MUST set `overflow-anchor: none` on your scroll container. You'll end up with
   `virtualScrollDriver()` not able to finish updating in Chrome if you don't.
 
-# Usage with React
+# Usage example with React
-
-There is a reference virtual list implementation for React.
-
-It is usually sufficient for almost everything, including grids. Sad thing about grids (virtualized tables)
-in HTML is that automatic table-like layout is slow in browsers, so in fact the best way to implement
-them is via simple virtualized lists of \<div>'s with absolutely positioned cells inside.
-
-```
-import React from 'react';
-import { VirtualScrollList } from 'dynamic-virtual-scroll/VirtualScrollList.es5.js';
-
-class MyList extends React.Component
-{
-    renderItem = (i) =>
-    {
-        if (!this.items[i])
-            return null;
-        return <div style={{minHeight: '20px'}}>{this.items[i].title}</div>;
-    }
-
-    render()
-    {
-        return <VirtualScrollList
-            totalItems={this.items.length}
-            renderItem={this.renderItem}
-            minRowHeight={20}
-        />;
-    }
-}
-```
-
-Description of VirtualScrollList parameters:
-
-- totalItems: required, total number of items in the list.
-- minRowHeight: required, minimal possible item height in the list.
-- renderItem: required, function that renders item by index as React element(s).
-- viewportHeight: optional, viewport height to use for virtual scrolling.
-  May be used in case when it can't be determined automatically by VirtualScroll,
-  for example inside an animated element with css maxHeight.
-- header: optional, React element(s) to unconditionally render in the beginning of
-  the list. The intended usage is to render fixed header row with CSS position: sticky
-  over the scrolled content.
-- headerHeight: optional. In case there is a fixed header, this must be its height
-  in pixels.
-- All other parameters (className, style, onClick, etc) are passed as-is to the
-  underlying root \<div> of the list.
-
-VirtualScrollList contains some extra shenanigans to make sure the scroll position
-preserves when the total number of items changes. Also it has two extra methods:
-
-- `list.scrollToItem(itemIndex)` - positions the list at `itemIndex`. The index may
-  contain fractional part, in that case the list will be positioned at the corresponding
-  % of height of the item.
-- `list.getItemScrollPos()` - returns current scroll position in items. The returned
-  index may contain fractional part and may be used as input to `list.scrollToItem()`.
-
-# Simpler React example
 
 See `DynamicVirtualScrollExample.js`.
 

VirtualScrollList.js

@@ -1,239 +0,0 @@
-/**
- * A simple React list with virtual scrolling based on dynamic-virtual-scroll driver
- * USUALLY sufficient for everything including grids (using absolute sizing of cells).
- * Just because browsers can't do virtualized grid or table layouts efficiently.
- */
-
-import React from 'react';
-import ReactDOM from 'react-dom';
-import PropTypes from 'prop-types';
-
-import { virtualScrollDriver } from 'dynamic-virtual-scroll';
-
-export class VirtualScrollList extends React.Component
-{
-    static propTypes = {
-        className: PropTypes.string,
-        style: PropTypes.object,
-        totalItems: PropTypes.number.isRequired,
-        minRowHeight: PropTypes.number.isRequired,
-        viewportHeight: PropTypes.number,
-        header: PropTypes.any,
-        headerHeight: PropTypes.number,
-        renderItem: PropTypes.func.isRequired,
-    }
-
-    state = {
-        targetHeight: 0,
-        topPlaceholderHeight: 0,
-        firstMiddleItem: 0,
-        middleItemCount: 0,
-        middlePlaceholderHeight: 0,
-        lastItemCount: 0,
-        scrollTo: 0,
-        scrollTimes: 0,
-    }
-
-    setItemRef = []
-    itemRefs = []
-    itemRefCount = []
-
-    makeRef(i)
-    {
-        this.setItemRef[i] = (e) =>
-        {
-            // If the new row instance is mounted before unmouting the old one,
-            // we get called 2 times in wrong order: first with the new instance,
-            // then with null telling us that the old one is unmounted.
-            // We track reference count to workaround it.
-            this.itemRefCount[i] = (this.itemRefCount[i]||0) + (e ? 1 : -1);
-            if (e || !this.itemRefCount[i])
-            {
-                this.itemRefs[i] = e;
-            }
-        };
-    }
-
-    renderItems(start, count, is_end)
-    {
-        let r = [];
-        for (let i = 0; i < count; i++)
-        {
-            let item = this.props.renderItem(i+start);
-            if (item)
-            {
-                if (!this.setItemRef[i+start])
-                {
-                    this.makeRef(i+start);
-                }
-                r.push(<item.type {...item.props} key={i+start} ref={this.setItemRef[i+start]} />);
-            }
-        }
-        return r;
-    }
-
-    render()
-    {
-        if (this.state.totalItems && this.props.totalItems != this.state.totalItems &&
-            this.state.scrollTimes <= 0 && this.viewport && this.viewport.offsetParent)
-        {
-            // Automatically preserve scroll position when item count changes...
-            // But only when the list is on-screen! We'll end up with an infinite update loop if it's off-screen.
-            this.state.scrollTo = this.getItemScrollPos();
-            this.state.scrollTimes = 2;
-        }
-        const props = { ...this.props };
-        for (const k in VirtualScrollList.propTypes)
-        {
-            delete props[k];
-        }
-        return (<div
-            {...props}
-            className={this.props.className}
-            style={{
-                position: 'relative',
-                ...(this.props.style||{}),
-                overflowAnchor: 'none',
-            }}
-            ref={this.setViewport}
-            onScroll={this.onScroll}>
-            {this.props.header}
-            {this.state.targetHeight > 0
-                ? <div key="target" style={{position: 'absolute', top: 0, left: '-5px', width: '1px', height: this.state.targetHeight+'px'}}></div>
-                : null}
-            {this.state.topPlaceholderHeight
-                ? <div style={{height: this.state.topPlaceholderHeight+'px'}} key="top"></div>
-                : null}
-            {this.renderItems(this.state.firstMiddleItem, this.state.middleItemCount)}
-            {this.state.middlePlaceholderHeight
-                ? <div style={{height: this.state.middlePlaceholderHeight+'px'}} key="mid"></div>
-                : null}
-            {this.renderItems(this.props.totalItems-this.state.lastItemCount, this.state.lastItemCount, true)}
-        </div>);
-    }
-
-    setViewport = (e) =>
-    {
-        this.viewport = e;
-    }
-
-    getRenderedItemHeight = (index) =>
-    {
-        if (this.itemRefs[index])
-        {
-            const e = ReactDOM.findDOMNode(this.itemRefs[index]);
-            if (e)
-            {
-                // MSIE sometimes manages to report non-integer element heights for elements of an integer height...
-                // Non-integer element sizes are allowed in getBoundingClientRect, one notable example of them
-                // are collapsed table borders. But we still ignore less than 1/100 of a pixel difference.
-                return Math.round(e.getBoundingClientRect().height*100)/100;
-            }
-        }
-        return 0;
-    }
-
-    onScroll = () =>
-    {
-        this.driver();
-        if (this.props.onScroll)
-        {
-            this.props.onScroll(this.viewport);
-        }
-    }
-
-    componentDidUpdate = () =>
-    {
-        let changed = this.driver();
-        if (!changed && this.state.scrollTimes > 0 && this.props.totalItems > 0 &&
-            this.viewport && this.viewport.offsetParent)
-        {
-            // FIXME: It would be better to find a way to put this logic back into virtual-scroll-driver
-            let pos = this.state.scrollTo;
-            if (pos > this.state.scrollHeightInItems)
-            {
-                pos = this.state.scrollHeightInItems;
-            }
-            if (this.state.targetHeight)
-            {
-                this.viewport.scrollTop = Math.round((this.state.targetHeight - this.state.viewportHeight)*pos/this.state.scrollHeightInItems);
-                this.setState({ scrollTimes: this.state.scrollTimes - 1 });
-            }
-            else
-            {
-                const el = ReactDOM.findDOMNode(this.itemRefs[Math.floor(pos)]);
-                if (el)
-                {
-                    this.viewport.scrollTop = el.offsetTop - (this.props.headerHeight||0) + el.offsetHeight*(pos-Math.floor(pos));
-                }
-                this.setState({ scrollTimes: 0 });
-            }
-        }
-    }
-
-    componentDidMount()
-    {
-        this.driver();
-    }
-
-    scrollToItem = (pos) =>
-    {
-        // Scroll position must be recalculated twice, because first render
-        // may change the average row height. In fact, it must be repeated
-        // until average row height stops changing, but twice is usually sufficient
-        this.setState({ scrollTo: pos, scrollTimes: 2 });
-    }
-
-    getItemScrollPos = () =>
-    {
-        if (this.state.targetHeight)
-        {
-            // Virtual scroll is active
-            let pos = this.viewport.scrollTop / (this.state.targetHeight - this.state.viewportHeight);
-            return pos * this.state.scrollHeightInItems;
-        }
-        else
-        {
-            // Virtual scroll is inactive
-            let avgr = this.viewport.scrollHeight / this.state.totalItems;
-            return this.viewport.scrollTop / avgr;
-        }
-    }
-
-    driver = () =>
-    {
-        if (!this.viewport || !this.viewport.offsetParent)
-        {
-            // Fool tolerance - do nothing if we are hidden
-            return false;
-        }
-        const newState = virtualScrollDriver(
-            {
-                totalItems: this.props.totalItems,
-                minRowHeight: this.props.minRowHeight,
-                viewportHeight: this.props.viewportHeight || (this.viewport.clientHeight-(this.props.headerHeight||0)),
-                scrollTop: this.viewport.scrollTop,
-            },
-            this.state,
-            this.getRenderedItemHeight
-        );
-        if (newState.viewportHeight || this.state.viewportHeight)
-        {
-            return this.setStateIfDiffers(newState);
-        }
-        return false;
-    }
-
-    setStateIfDiffers(state, cb)
-    {
-        for (const k in state)
-        {
-            if (this.state[k] != state[k])
-            {
-                this.setState(state, cb);
-                return true;
-            }
-        }
-        return false;
-    }
-}

package.json

@@ -1,6 +1,6 @@
 {
   "name": "dynamic-virtual-scroll",
-  "version": "1.0.15",
+  "version": "1.0.0",
   "author": {
     "name": "Vitaliy Filippov",
     "email": "vitalif@yourcmc.ru",
@@ -16,8 +16,7 @@
     "dynamic",
     "virtual-list",
     "virtual-scroll",
-    "lazy-rendering",
+    "lazy-rendering"
-    "react"
   ],
   "repository": {
     "type": "git",
@@ -37,8 +36,6 @@
   "files": [
     "DynamicVirtualScroll.es5.js",
     "DynamicVirtualScroll.js",
-    "VirtualScrollList.es5.js",
-    "VirtualScrollList.js",
     "DynamicVirtualScrollExample.js",
     "README.md"
   ],
@@ -62,7 +59,7 @@
     "webpack-cli": "^3.1.2"
   },
   "scripts": {
-    "build": "eslint DynamicVirtualScroll.js && webpack --mode=production --optimize-minimize && (babel DynamicVirtualScroll.js > DynamicVirtualScroll.es5.js) && (babel VirtualScrollList.js > VirtualScrollList.es5.js)",
+    "build": "eslint Dynamic*.js && webpack --mode=production --optimize-minimize && babel DynamicVirtualScroll.js > DynamicVirtualScroll.es5.js",
     "watch-dev": "NODE_ENV=development webpack --mode=development -w",
     "watch": "webpack --mode=production -w --optimize-minimize"
   }