1 page.title=Selection 2 @jd:body 3 4 <p>Android 3.0 introduced the <em>long press</em> gesture—that is, a touch that's held in the same 5 position for a moment—as the global gesture to select data. This affects the way you should 6 handle multi-select and contextual actions in your apps.</p> 7 8 <div class="vspace size-1"> </div> 9 10 <div class="layout-content-row"> 11 <div class="layout-content-col span-6"> 12 13 <h4>What has changed?</h4> 14 <p>In previous versions of Android, the long press gesture was universally used to display contextual 15 actions for a given data item in a contextual menu.</p> 16 <p>This pattern changed with Android 3.0. The long press gesture is now used to select data, combining 17 contextual actions and selection management functions for selected data into a new element called 18 the contextual action bar (CAB).</p> 19 20 </div> 21 <div class="layout-content-col span-7"> 22 23 <img src="{@docRoot}design/media/selection_context_menu.png"> 24 <div class="figure-caption"> 25 Traditional use of the long press gesture to show contextual menus. 26 </div> 27 28 </div> 29 </div> 30 31 <h4>Using the contextual action bar (CAB)</h4> 32 <p>The selection CAB is a temporary action bar that overlays your app's current action bar while data 33 is selected. It appears after the user long presses on a selectable data item.</p> 34 35 <img src="{@docRoot}design/media/selection_cab_big.png"> 36 37 <div class="vspace size-1"> </div> 38 39 <div class="layout-content-row"> 40 <div class="layout-content-col span-6"> 41 42 <p>From here the user can:</p> 43 <ul> 44 <li>Select additional data items by touching them.</li> 45 <li>Trigger an action from the CAB that applies to all highlighted data items. The CAB then 46 automatically dismisses itself.</li> 47 <li>Dismiss the CAB via the navigation bar's Back button or the CAB's checkmark button. This removes 48 the CAB along with all selection highlights.</li> 49 </ul> 50 51 </div> 52 <div class="layout-content-col span-7"> 53 54 <img src="{@docRoot}design/media/selection_cab_example.png"> 55 56 </div> 57 </div> 58 59 <div class="layout-content-row"> 60 <div class="layout-content-col span-6"> 61 62 <h4>Selecting CAB actions</h4> 63 <p>You can decide which actions and elements appear in the CAB. Use the guidelines in the <a href="actionbar.html">Action Bar 64 pattern</a> to decide which items to surface at the top level and which to move to the 65 action overflow.</p> 66 <h4>Dynamically adjust CAB actions</h4> 67 <p>In most cases you need to adjust the actions in the CAB dynamically as the user adds more items to 68 the selection. Actions that apply to a single selected data item don't necessarily apply to multiple 69 selected data items of the same kind.</p> 70 71 </div> 72 <div class="layout-content-col span-7"> 73 74 <img src="{@docRoot}design/media/selection_adjusting_actions.png"> 75 <div class="figure-caption"> 76 Adjusting actions in the CAB as additional items are selected. 77 </div> 78 79 </div> 80 </div> 81 82 <h2 id="checklist">Checklist</h2> 83 84 <ul> 85 <li> 86 <p>Whenever your app supports the selection of multiple data items, make use of the contextual action 87 bar (CAB).</p> 88 </li> 89 <li> 90 <p>Reserve the long press gesture for selection exclusively. Don't use it to display traditional 91 contextual menus.</p> 92 </li> 93 <li> 94 <p>If you don't support multi-selection within a list, long press should do nothing.</p> 95 </li> 96 <li> 97 <p>Plan the actions you want to display inside of a CAB in the same way you would plan the actions 98 inside your app's action bar.</p> 99 </li> 100 </ul> 101
