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