Android Transitions

A tour of the Transitions framework in Android

1. Transitions Bryan Herbst Android Engineer @ Target
2. Abrupt transitions are jarring
3. Smooth transitions provide continuity
4. Smooth transitions keep users engaged
5. Smooth transitions delight users
6. “In the world of material design, motion describes spatial relationships, functionality, and intention with beauty and fluidity.”
7. Android Transitions  Activity to Activity  Fragment to Fragment  Scene to Scene (Views)
8. Hold on…  Requires API 21
9. Hold on…   Progressive enhancement, graceful degradation
10. Hold on…    Support APIs offer default behavior on older versions
11. Scenes Snapshot of a ViewGroup
12. Scene transition TransitionManager.beginDelayedTransition(rootView, new Fade()); button.setVisibility(View.INVISIBLE);
13. What is this black magic?
14. How it works 1. beginDelayedTransition() => Take a snapshot of ViewGroup 2. Update Views 3. On next layout pass, Android takes another snapshot and creates animations
15. How it works 1. beginDelayedTransition() => Take a snapshot of ViewGroup
16. How it works 1. beginDelayedTransition() => Take a snapshot of ViewGroup 2. Update Views
17. Transition types  Fade  Explode  Slide  ChangeBounds  AutoTransition  Fade  Move  Resize
18. What about property animation? ObjectAnimator.ofFloat(button, "alpha", 1f, 0f) .start();
19. What about property animation? button.animate().alpha(0f);
20. What about property animation? Fine if you want to think about Views individually
21. What about property animation? Fine if you want to think about Views individually Scenes allow us to think in groups
22. Activities With shared elements
23. Activity Transitions- setup  Request Window.FEATURE_ACTIVITY_TRANSITIONS and Window.FEATURE_CONTENT_TRANSITIONS in both Activities
24. Activity Transitions- setup   Set a transition name on the View in both Activities
25. What are these transition names? An ID for the transition framework
26. Rule #1 All animating Views must have a transition name
27. Rule #2 All transition names must be unique within a layout
28. Not a rule #1 Transition names don’t need to match between layouts
29. Activity Transitions- setup  Create a Bundle with ActivityOptions .makeSceneTransitionAnimation(activity, sharedView, viewTransitionName) .toBundle();
30. Activity Transitions- setup   Set your Transitions
31. Activity Transitions- setup    Call startActivity(intent, transitionBundle);
32. Specifying shared elements makeSceneTransitionAnimation(activity, sharedView, transitionName); We specify pairs of Views and transition names.
33. Specifying shared elements makeSceneTransitionAnimation(activity, sharedView, transitionName); We specify pairs of Views and transition names. The sharedView is the original view in our current layout (the starting state)
34. Specifying shared elements makeSceneTransitionAnimation(activity, sharedView, transitionName); We specify pairs of Views and transition names. The sharedView is the original view in our current layout (the starting state) The viewTransitionName is the name of the corresponding view in the new layout (the ending state)
35. Activity transitions magic Captures Views in first Activity, then second Activity
36. Activity Transitions use the Window e.g. getWindow().setEnterTransition(new Fade());
37. Four transition types  Enter  Exit  Reenter  Return
38. Four transition types  Enter
39. Four transition types  Exit
40. Four transition types  Reenter
41. Four transition types  Return
42. Four transition types x2 with Shared elements
43. Or not Stick with enter and return for shared elements
44. Shared exit and reenter Allow for animation before the transition
45. Sample  Exit, shared enter, enter
46. Sample  Reenter, shared return, return
47. A note on timing Because sometimes Views don’t exist right away
48. Delayed transitions  postponeEnterTransition();  startPostponedEnterTransition();
49. WARNING!  Blocks transition
50. WARNING!  Blocks transition 
51. WARNING!    Prefetch or find clever alternatives
52. Fragment example
53. Transition setup setExitTransition(new Fade()); Fade out non-shared elements
54. Transition setup newFrag.setSharedElementEnterTransition(new AutoTransition()); AutoTransition shared elements
55. Transition setup newFrag.setEnterTransition(new Fade()); Fade in non-shared elements
56. Making the transition fragmentManager.beginTransaction() .replace(R.id.container, newFrag) .addSharedElement(sharedView, "transitionName") .commit();
57. What about delayed transitions?  Ugh. It isn’t good in Fragments.
58. I didn’t want to animate that!
59. Targets- includes <fade> <targets> <target android:includeId="@id/fancyWidget"/> <target android:includeClass=“com.example.FancyWidget"/> <target android:includeName=“fancyWidget"/> </targets> </fade>
60. Targets- excludes <fade> <targets> <target android:excludeId="@id/toolbar"/> <target android:excludeClass=“android.support.v7.widget.Toolbar"/> <target android:excludeName="toolbar"/> </targets> </fade>
61. Support for <21
62. Support for <21 ActivityOptions => ActivityOptionsCompat .makeSceneTransitionAnimation(activity, view, name)
63. Support for <21 startActivity(intent, transitionBundle); Has existed since API 16!
64. Support for <21 Transition names  android:transitionName="name" is ignored on older versions  ViewCompat.setTransitionName(view, “name);
65. Support for <21 Delaying transitions  supportPostponeEnterTransition();  supportStartPostponedEnterTransition();
66. Support for <21 Specifying transitions The only place we need a version check if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) { getWindow().setEnterTransition(new Fade()); }