From fddf2892cde66336453505ded0fecaac464b3ad1 Mon Sep 17 00:00:00 2001
From: antelle <dmitryvit@gmail.com>
Date: Sat, 20 Mar 2021 19:17:57 +0100
Subject: [PATCH] fix #1580: high memory usage on large files, virtual
 scrolling of entries

---
 app/scripts/framework/views/view.js |   2 +-
 app/scripts/views/app-view.js       |   3 +-
 app/scripts/views/list-view.js      | 132 +++++++++++++++++++++++++---
 app/styles/areas/_list.scss         |  32 +++++--
 app/templates/list-item-table.hbs   |  22 ++---
 app/templates/list-mode-list.hbs    |   3 +
 app/templates/list-mode-table.hbs   |  11 +++
 app/templates/list-table.hbs        |  13 ---
 8 files changed, 171 insertions(+), 47 deletions(-)
 create mode 100644 app/templates/list-mode-list.hbs
 create mode 100644 app/templates/list-mode-table.hbs
 delete mode 100644 app/templates/list-table.hbs

diff --git a/app/scripts/framework/views/view.js b/app/scripts/framework/views/view.js
index 529fa866..f3e7fe48 100644
--- a/app/scripts/framework/views/view.js
+++ b/app/scripts/framework/views/view.js
@@ -251,7 +251,6 @@ class View extends EventEmitter {
                 FocusManager.setModal(null);
             }
         }
-        this.emit(visible ? 'show' : 'hide');
         if (this.el) {
             this.el.classList.toggle('show', !!visible);
             this.el.classList.toggle('hide', !visible);
@@ -259,6 +258,7 @@ class View extends EventEmitter {
                 Tip.hideTips(this.el);
             }
         }
+        this.emit(visible ? 'show' : 'hide');
     }
 
     isHidden() {
diff --git a/app/scripts/views/app-view.js b/app/scripts/views/app-view.js
index a04f9dfd..6dcb231e 100644
--- a/app/scripts/views/app-view.js
+++ b/app/scripts/views/app-view.js
@@ -202,7 +202,6 @@ class AppView extends View {
         this.views.menu.show();
         this.views.menuDrag.$el.parent().show();
         this.views.listWrap.show();
-        this.views.list.show();
         this.views.listDrag.show();
         this.views.details.show();
         this.views.footer.show();
@@ -211,6 +210,8 @@ class AppView extends View {
         this.hideSettings();
         this.hideKeyChange();
         this.hideImportCsv();
+
+        this.views.list.show();
     }
 
     hideOpenFile() {
diff --git a/app/scripts/views/list-view.js b/app/scripts/views/list-view.js
index a52bc85a..1cabffa1 100644
--- a/app/scripts/views/list-view.js
+++ b/app/scripts/views/list-view.js
@@ -68,12 +68,20 @@ class ListView extends View {
         this.readTableColumnsEnabled();
 
         this.items = new SearchResultCollection();
+        this.renderedItems = new Map();
     }
 
     render() {
+        if (!this.isVisible()) {
+            this.pendingRender = true;
+            return;
+        }
+        this.pendingRender = false;
+
         if (!this.itemsEl) {
             super.render();
             this.itemsEl = this.$el.find('.list__items>.scroller');
+            this.itemsEl.on('scroll', () => this.renderVisibleItems());
             this.views.search.render();
             this.setTableView();
 
@@ -84,9 +92,9 @@ class ListView extends View {
             });
         }
         if (this.items.length) {
-            const itemTemplate = this.getItemTemplate();
             const itemsTemplate = this.getItemsTemplate();
             const noColor = AppSettingsModel.colorfulIcons ? '' : 'grayscale';
+
             const presenter = new EntryPresenter(
                 this.getDescField(),
                 noColor,
@@ -99,16 +107,28 @@ class ListView extends View {
                 }
             });
             presenter.columns = columns;
-            let itemsHtml = '';
-            this.items.forEach((item) => {
-                presenter.present(item);
-                itemsHtml += itemTemplate(presenter, DefaultTemplateOptions);
-            }, this);
+            this.presenter = presenter;
+
+            presenter.present(this.items[0]);
+            const itemTemplate = this.getItemTemplate();
+            const itemsHtml = itemTemplate(presenter, DefaultTemplateOptions);
+
             const html = itemsTemplate(
                 { itemsHtml, columns: this.tableColumns },
                 DefaultTemplateOptions
             );
             this.itemsEl.html(html);
+            this.itemsContainerEl = this.itemsEl.find('.list__items-container:first')[0];
+
+            const firstListItem = this.itemsContainerEl.firstElementChild;
+            this.itemHeight = firstListItem.getBoundingClientRect().height;
+
+            this.renderedItems = new Map([[0, firstListItem]]);
+
+            const totalHeight = this.itemHeight * this.items.length;
+            this.itemsContainerEl.style.minHeight = totalHeight + 'px';
+
+            this.renderVisibleItems();
         } else {
             this.itemsEl.html(this.emptyTemplate({}, DefaultTemplateOptions));
         }
@@ -117,16 +137,12 @@ class ListView extends View {
 
     getItemsTemplate() {
         if (this.model.settings.tableView) {
-            return require('templates/list-table.hbs');
+            return require('templates/list-mode-table.hbs');
         } else {
-            return this.renderPlainItems;
+            return require('templates/list-mode-list.hbs');
         }
     }
 
-    renderPlainItems(data) {
-        return data.itemsHtml;
-    }
-
     getItemTemplate() {
         if (this.model.settings.tableView) {
             return require('templates/list-item-table.hbs');
@@ -135,6 +151,88 @@ class ListView extends View {
         }
     }
 
+    renderVisibleItems() {
+        if (!this.isVisible()) {
+            return;
+        }
+
+        const scrollEl = this.itemsEl[0];
+        const rect = scrollEl.getBoundingClientRect();
+
+        const pxTop = scrollEl.scrollTop;
+        const pxHeight = rect.height;
+        const itemHeight = this.itemHeight;
+        const renderedItems = this.renderedItems;
+
+        let firstIx = Math.max(0, Math.floor(pxTop / itemHeight));
+        let lastIx = Math.min(this.items.length - 1, Math.ceil((pxTop + pxHeight) / itemHeight));
+
+        const visibleCount = lastIx - firstIx;
+        firstIx = Math.max(0, firstIx - visibleCount);
+        lastIx = Math.min(this.items.length - 1, lastIx + visibleCount);
+
+        const itemTemplate = this.getItemTemplate();
+        const presenter = this.presenter;
+
+        let itemsHtml = '';
+        const renderedIndices = [];
+
+        for (let ix = firstIx; ix <= lastIx; ix++) {
+            const item = this.items[ix];
+            if (renderedItems.has(ix)) {
+                continue;
+            }
+            presenter.present(item);
+            itemsHtml += itemTemplate(presenter, DefaultTemplateOptions);
+            renderedIndices.push(ix);
+        }
+
+        const tempEl = document.createElement('div');
+        tempEl.innerHTML = itemsHtml;
+        const renderedElements = [...tempEl.children];
+
+        for (let i = 0; i < renderedElements.length; i++) {
+            const el = renderedElements[i];
+            const ix = renderedIndices[i];
+            this.itemsContainerEl.append(el);
+            el.style.top = ix * itemHeight + 'px';
+            renderedItems.set(ix, el);
+        }
+
+        const maxRenderedItems = visibleCount * 5;
+
+        if (renderedItems.size > maxRenderedItems) {
+            for (const [ix, el] of this.renderedItems) {
+                if (ix < firstIx || ix > lastIx) {
+                    el.remove();
+                    renderedItems.delete(ix);
+                }
+            }
+        }
+    }
+
+    ensureItemRendered(ix) {
+        if (this.renderedItems.has(ix)) {
+            return;
+        }
+
+        const item = this.items[ix];
+        const itemTemplate = this.getItemTemplate();
+
+        this.presenter.present(item);
+        const itemHtml = itemTemplate(this.presenter, DefaultTemplateOptions);
+
+        const tempEl = document.createElement('div');
+        tempEl.innerHTML = itemHtml;
+
+        const [el] = tempEl.children;
+
+        this.itemsContainerEl.append(el);
+        el.style.top = ix * this.itemHeight + 'px';
+
+        this.renderedItems.set(ix, el);
+    }
+
     getDescField() {
         return this.model.sort.replace('-', '');
     }
@@ -203,7 +301,12 @@ class ListView extends View {
     }
 
     selectItem(item) {
+        this.presenter.activeEntryId = item.id;
         this.model.activeEntryId = item.id;
+
+        const ix = this.items.indexOf(item);
+        this.ensureItemRendered(ix);
+
         Events.emit('entry-selected', item);
         this.itemsEl.find('.list__item--active').removeClass('list__item--active');
         const itemEl = document.getElementById(item.id);
@@ -220,6 +323,9 @@ class ListView extends View {
 
     viewShown() {
         this.views.search.show();
+        if (this.pendingRender) {
+            this.render();
+        }
     }
 
     viewHidden() {
@@ -248,6 +354,7 @@ class ListView extends View {
     viewResized(size) {
         this.setSize(size);
         this.throttleSetViewSizeSetting(size);
+        this.renderVisibleItems();
     }
 
     throttleSetViewSizeSetting = throttle((size) => {
@@ -256,6 +363,7 @@ class ListView extends View {
 
     filterChanged(filter) {
         this.items = filter.entries;
+        this.renderedItems = new Map();
         this.render();
     }
 
diff --git a/app/styles/areas/_list.scss b/app/styles/areas/_list.scss
index 72d375aa..a832d725 100644
--- a/app/styles/areas/_list.scss
+++ b/app/styles/areas/_list.scss
@@ -119,20 +119,29 @@
     }
 
     &__table {
-        border-collapse: collapse;
-        width: calc(100% - 2px);
-        td,
-        th {
+        &-body {
+            position: relative;
+        }
+        &-row {
+            display: flex;
+            align-items: center;
+            width: 100%;
+        }
+        &-cell {
             padding: $base-padding;
             text-align: left;
+            flex-grow: 1;
+            flex-shrink: 0;
+            flex-basis: 0;
             &:first-child {
                 text-align: center;
+                padding: 0;
+                width: 3em;
+                flex-basis: 3em;
+                flex-grow: 0;
+                flex-shrink: 0;
             }
         }
-        th:first-child {
-            padding: 0;
-            width: 3em;
-        }
         &-options {
             @include icon-btn();
             cursor: pointer;
@@ -140,10 +149,13 @@
     }
 
     &__item {
-        padding: $base-padding;
+        left: 0;
         white-space: nowrap;
         text-overflow: ellipsis;
         overflow: hidden;
+        position: absolute;
+        top: 0;
+        box-sizing: border-box;
         @include nomobile {
             @include area-selectable();
             &--active,
@@ -163,7 +175,9 @@
             @include nomobile {
                 border-radius: var(--block-border-radius);
             }
+            padding: $base-padding;
             margin: 0 $small-spacing;
+            width: calc(100% - #{$small-spacing * 2});
         }
 
         &--expired {
diff --git a/app/templates/list-item-table.hbs b/app/templates/list-item-table.hbs
index 92f5f79a..71e19cd1 100644
--- a/app/templates/list-item-table.hbs
+++ b/app/templates/list-item-table.hbs
@@ -1,16 +1,16 @@
-<tr class="list__item list__item--table {{#if active}}list__item--active{{/if}} {{#if expired}}list__item--expired{{/if}}" id="{{id}}" draggable="true">
-    <td>
+<div class="list__item list__item--table list__table-row {{#if active}}list__item--active{{/if}} {{#if expired}}list__item--expired{{/if}}" id="{{id}}" draggable="true">
+    <div class="list__table-cell">
         {{~#if customIcon~}}
             <img src="{{customIcon}}" class="list__item-icon list__item-icon--custom {{#if color}}{{color}}{{/if}}" />
         {{~else~}}
             <i class="fa fa-{{icon}} {{#if color}}{{color}}-color{{/if}} list__item-icon"></i>
         {{~/if~}}
-    </td>
-    {{#if columns.title}}<td>{{#if title}}{{title}}{{else}}({{res 'noTitle'}}){{/if}}</td>{{/if}}
-    {{#if columns.user}}<td>{{user}}</td>{{/if}}
-    {{#if columns.url}}<td>{{url}}</td>{{/if}}
-    {{#if columns.tags}}<td>{{tags}}</td>{{/if}}
-    {{#if columns.notes}}<td>{{notes}}</td>{{/if}}
-    {{#if columns.groupName}}<td>{{groupName}}</td>{{/if}}
-    {{#if columns.fileName}}<td>{{fileName}}</td>{{/if}}
-</tr>
+    </div>
+    {{#if columns.title}}<div class="list__table-cell">{{#if title}}{{title}}{{else}}({{res 'noTitle'}}){{/if}}</div>{{/if}}
+    {{#if columns.user}}<div class="list__table-cell">{{user}}</div>{{/if}}
+    {{#if columns.url}}<div class="list__table-cell">{{url}}</div>{{/if}}
+    {{#if columns.tags}}<div class="list__table-cell">{{tags}}</div>{{/if}}
+    {{#if columns.notes}}<div class="list__table-cell">{{notes}}</div>{{/if}}
+    {{#if columns.groupName}}<div class="list__table-cell">{{groupName}}</div>{{/if}}
+    {{#if columns.fileName}}<div class="list__table-cell">{{fileName}}</div>{{/if}}
+</div>
diff --git a/app/templates/list-mode-list.hbs b/app/templates/list-mode-list.hbs
new file mode 100644
index 00000000..7d034852
--- /dev/null
+++ b/app/templates/list-mode-list.hbs
@@ -0,0 +1,3 @@
+<div class="list__list list__items-container">
+    {{{itemsHtml}}}
+</div>
diff --git a/app/templates/list-mode-table.hbs b/app/templates/list-mode-table.hbs
new file mode 100644
index 00000000..dc6c62cd
--- /dev/null
+++ b/app/templates/list-mode-table.hbs
@@ -0,0 +1,11 @@
+<div class="list__table">
+    <div class="list__table-head list__table-row">
+        <div class="list__table-cell"><i class="fa fa-bars muted-color list__table-options"></i></div>
+        {{#each columns as |col|}}
+            {{#if col.enabled}}<div class="list__table-cell">{{Res col.name}}</div>{{/if}}
+        {{/each}}
+    </div>
+    <div class="list__table-body list__items-container">
+        {{{itemsHtml}}}
+    </div>
+</div>
diff --git a/app/templates/list-table.hbs b/app/templates/list-table.hbs
deleted file mode 100644
index 1741d462..00000000
--- a/app/templates/list-table.hbs
+++ /dev/null
@@ -1,13 +0,0 @@
-<table class="list__table">
-    <thead>
-        <tr>
-            <th><i class="fa fa-bars muted-color list__table-options"></i></th>
-            {{#each columns as |col|}}
-                {{#if col.enabled}}<th>{{Res col.name}}</th>{{/if}}
-            {{/each}}
-        </tr>
-    </thead>
-    <tbody>
-        {{{itemsHtml}}}
-    </tbody>
-</table>