How to make AppBars work with ListViews

Article
08/10/2016

[ This article is for Windows 8.x and Windows Phone 8.x developers writing Windows Runtime apps. If you’re developing for Windows 10, see the latest documentation ]

This how-to explains the interaction between the ListView and the AppBar to support these scenarios while following the AppBar best practices. Typically the ListView lets user pan collection of objects horizontally and select one of more of these objects to perform some actions. These actions are often exposed in the AppBar.

Prerequisites

Read Guidelines for AppBars and Guidelines for ListView controls.

Instructions

Step 1: Maintain the AppBar promises

Invocation: if an AppBar is present users should be able to invoke it or hide it via the standard mechanisms at any time.
If there is no command to be exposed until an object is selected, no AppBar should be shown
Commands that are present irrespective of selection should be in the action area of the AppBar, with very few exceptions on the right of the AppBar

Step 2: Support selection and multi-selection

Show the AppBar programmatically on selection.
Show commands specific to selection in contextual section of the AppBar (on the left except for very few exceptions).
Show additional commands if needed when more than one object is selected (e.g. clear selection).
Hide commands that are contextual to selection.

Here is the HTML for an AppBar with commands.

<!-- AppBar with contextual commands for a ListView -->
<!-- BEGINTEMPLATE: Template code for AppBar -->
<div id="scenarioAppBar" data-win-control="WinJS.UI.AppBar">
    <button data-win-control="WinJS.UI.AppBarCommand" data-win-options="{id:'cmdAdd',label:'Add',icon:'add',section:'primary',extraClass:'singleSelect',tooltip:'Add item'}"></button>
    <button data-win-control="WinJS.UI.AppBarCommand" data-win-options="{id:'cmdSelectAll',label:'Select All',icon:'selectall',section:'primary',extraClass:'multiSelect',tooltip:'Select All'}"></button>
    <button data-win-control="WinJS.UI.AppBarCommand" data-win-options="{id:'cmdClearSelection',label:'Clear Selection',icon:'clearselection',section:'primary',extraClass:'multiSelect',tooltip:'Clear Selection'}"></button>
    <hr data-win-control="WinJS.UI.AppBarCommand" data-win-options="{type:'separator',section:'primary',extraClass:'multiSelect'}" />
    <button data-win-control="WinJS.UI.AppBarCommand" data-win-options="{id:'cmdDelete',label:'Delete',icon:'delete',section:'primary',extraClass:'multiSelect',tooltip:'Delete item'}"></button>
</div>
<!-- ENDTEMPLATE -->

When AppBar is initialized, selection contextual commands are hidden.

function initAppBar() {
    var appBarDiv = document.getElementById("scenarioAppBar");
    var appBar    = document.getElementById("scenarioAppBar").winControl;
    // Add event listeners
    document.getElementById("cmdAdd").addEventListener("click", doClickAdd, false);
    document.getElementById("cmdDelete").addEventListener("click", doClickDelete, false);
    document.getElementById("cmdSelectAll").addEventListener("click", doClickSelectAll, false);
    document.getElementById("cmdClearSelection").addEventListener("click", doClickClearSelection, false);
    appBar.addEventListener("beforeopen", doAppBarShow, false);
    appBar.addEventListener("beforeclose", doAppBarHide, false);        
    // Hide selection group of commands
    appBar.hideCommands(appBarDiv.querySelectorAll('.multiSelect'));
    // Disable AppBar until in full screen mode
    appBar.disabled = true;
}

This function shows the AppBar and shows contextual commands upon selection.

function doSelectItem() {
    var appBarDiv = document.getElementById("scenarioAppBar");
    var appBar =    document.getElementById('scenarioAppBar').winControl;
    var listView =  document.getElementById("scenarioListView").winControl;
    var count = listView.selection.count();
    if (count > 0) {
        // Show multi-select commands in AppBar
        appBar.showOnlyCommands(appBarDiv.querySelectorAll('.win-command'));
        appBar.open();
    } else {
        // Hide multi-select commands in AppBar
        appBar.close();
        appBar.showOnlyCommands(appBarDiv.querySelectorAll('.singleSelect'));
    }
}

Step 3: Adjust scrollbar position

To support scrolling while the AppBar is visible, like for multi-selection, the scrollbar needs to be placed so that it is above the AppBar. Because of localization, you should expect AppBar button labels to be one line longer than English-only labels. When placing the scrollbar, you should account for that extra line. So for example, a single label AppBar that is 88px tall for English should become 108 px tall with two lines labels.

Design your ListView so that the scrollbar has a 108px clearance for the AppBar. Then adjust the position of the scroll bar so it's visible and in the right position depending on whether the AppBar is present.

/* This function slides the ListView scrollbar into view if occluded by the AppBar */
function doAppBarShow() {
    var listView = document.getElementById("scenarioListView");
    var appBar = document.getElementById("scenarioAppBar");
    var appBarHeight = appBar.offsetHeight;
    }
}

/* This function slides the ListView scrollbar back to its original position */
function doAppBarHide() {
    var listView = document.getElementById("scenarioListView");
    var appBar = document.getElementById("scenarioAppBar");
    var appBarHeight = appBar.offsetHeight;
    }
}

Step 4: Support scrolling and zooming.

To support zooming and vertical scrolling, you should place the AppBar and LitView in peer divs and make sure zoom only applies to the ListView div and not the whole page.

<!-- Full screen container for ListView -->
<div id="scenarioFullscreen">
    <button id="scenarioHideListView">Hide ListView</button>
    <header aria-label="Header content" role="banner">
        <button id="scenarioBackButton" class="win-backbutton" aria-label="Back"></button>
        <div class="titlearea win-type-ellipsis">
            <h1 class="titlecontainer" tabindex="0">
                <span class="pagetitle">Ice cream</span>
            </h1>
        </div>
    </header>
    <section role="container">
        <div id="scenarioListView"
            data-win-control="WinJS.UI.ListView"
            data-win-options="{ itemTemplate: smallListIconTextTemplate, selectionMode: 'multi', tapBehavior: 'toggleSelect', swipeBehavior: 'select', layout: { type: WinJS.UI.GridLayout, maxRows: 4 }}" >
        </div>
    </section>
</div>    
<!-- AppBar with contextual commands for a ListView -->
<!-- BEGINTEMPLATE: Template code for AppBar -->
<div id="scenarioAppBar" data-win-control="WinJS.UI.AppBar">
    <button data-win-control="WinJS.UI.AppBarCommand" data-win-options="{id:'cmdAdd',label:'Add',icon:'add',section:'primary',extraClass:'singleSelect',tooltip:'Add item'}"></button>
    <button data-win-control="WinJS.UI.AppBarCommand" data-win-options="{id:'cmdSelectAll',label:'Select All',icon:'selectall',section:'primary',extraClass:'multiSelect',tooltip:'Select All'}"></button>
    <button data-win-control="WinJS.UI.AppBarCommand" data-win-options="{id:'cmdClearSelection',label:'Clear Selection',icon:'clearselection',section:'primary',extraClass:'multiSelect',tooltip:'Clear Selection'}"></button>
    <hr     data-win-control="WinJS.UI.AppBarCommand" data-win-options="{type:'separator',section:'primary',extraClass:'multiSelect'}" />
    <button data-win-control="WinJS.UI.AppBarCommand" data-win-options="{id:'cmdDelete',label:'Delete',icon:'delete',section:'primary',extraClass:'multiSelect',tooltip:'Delete item'}"></button>
</div>
<!-- ENDTEMPLATE -->

Remarks

Interactions between ListView and AppBar can benefit some applications. Follow these simple best practices and you can align with the recommended user experience.

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