Android Transitions

Transcript

1. 1.

   Transitions Bryan Herbst Android Engineer @ Target

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   Abrupt transitions are jarring

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   Smooth transitions provide continuity

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   Smooth transitions keep users engaged

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   Smooth transitions delight users

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   “In the world of material design, motion describes spatial relationships,

   functionality, and intention with beauty and fluidity.”
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   Android Transitions  Activity to Activity  Fragment to Fragment

    Scene to Scene (Views)
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   Hold on…  Requires API 21

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   Hold on…   Progressive enhancement, graceful degradation

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    Hold on…    Support APIs offer default behavior

    on older versions
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    Scenes Snapshot of a ViewGroup

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    Scene transition TransitionManager.beginDelayedTransition(rootView, new Fade()); button.setVisibility(View.INVISIBLE);

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    What is this black magic?

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    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
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    How it works 1. beginDelayedTransition() => Take a snapshot of

    ViewGroup
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    How it works 1. beginDelayedTransition() => Take a snapshot of

    ViewGroup 2. Update Views
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    Transition types  Fade  Explode  Slide  ChangeBounds

     AutoTransition  Fade  Move  Resize
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    What about property animation? ObjectAnimator.ofFloat(button, "alpha", 1f, 0f) .start();

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    What about property animation? button.animate().alpha(0f);

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    What about property animation? Fine if you want to think

    about Views individually
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    What about property animation? Fine if you want to think

    about Views individually Scenes allow us to think in groups
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    Activities With shared elements

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    Activity Transitions- setup  Request Window.FEATURE_ACTIVITY_TRANSITIONS and Window.FEATURE_CONTENT_TRANSITIONS in both

    Activities
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    Activity Transitions- setup   Set a transition name on

    the View in both Activities
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    What are these transition names? An ID for the transition

    framework
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    Rule #1 All animating Views must have a transition name

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    Rule #2 All transition names must be unique within a

    layout
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    Not a rule #1 Transition names don’t need to match

    between layouts
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    Activity Transitions- setup  Create a Bundle with ActivityOptions .makeSceneTransitionAnimation(activity,

    sharedView, viewTransitionName) .toBundle();
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    Activity Transitions- setup   Set your Transitions

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    Activity Transitions- setup    Call startActivity(intent, transitionBundle);

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    Specifying shared elements makeSceneTransitionAnimation(activity, sharedView, transitionName); We specify pairs of

    Views and transition names.
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    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)
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    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)
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    Activity transitions magic Captures Views in first Activity, then second

    Activity
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    Activity Transitions use the Window e.g. getWindow().setEnterTransition(new Fade());

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    Four transition types  Enter  Exit  Reenter 

    Return
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    Four transition types  Enter

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    Four transition types  Exit

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    Four transition types  Reenter

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    Four transition types  Return

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    Four transition types x2 with Shared elements

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    Or not Stick with enter and return for shared elements

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    Shared exit and reenter Allow for animation before the transition

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    Sample  Exit, shared enter, enter

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    Sample  Reenter, shared return, return

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    A note on timing Because sometimes Views don’t exist right

    away
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    Delayed transitions  postponeEnterTransition();  startPostponedEnterTransition();

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    WARNING!  Blocks transition

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    WARNING!  Blocks transition 

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    WARNING!    Prefetch or find clever alternatives

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    Fragment example

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    Transition setup setExitTransition(new Fade()); Fade out non-shared elements

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    Transition setup newFrag.setSharedElementEnterTransition(new AutoTransition()); AutoTransition shared elements

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    Transition setup newFrag.setEnterTransition(new Fade()); Fade in non-shared elements

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    Making the transition fragmentManager.beginTransaction() .replace(R.id.container, newFrag) .addSharedElement(sharedView, "transitionName") .commit();

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    What about delayed transitions?  Ugh. It isn’t good in

    Fragments.
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    I didn’t want to animate that!

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    Targets- includes <fade> <targets> <target android:includeId="@id/fancyWidget"/> <target android:includeClass=“com.example.FancyWidget"/> <target android:includeName=“fancyWidget"/>

    </targets> </fade>
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    Targets- excludes <fade> <targets> <target android:excludeId="@id/toolbar"/> <target android:excludeClass=“android.support.v7.widget.Toolbar"/> <target android:excludeName="toolbar"/>

    </targets> </fade>
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    Support for <21

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    Support for <21 ActivityOptions => ActivityOptionsCompat .makeSceneTransitionAnimation(activity, view, name)

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    Support for <21 startActivity(intent, transitionBundle); Has existed since API 16!

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    Support for <21 Transition names  android:transitionName="name" is ignored on

    older versions  ViewCompat.setTransitionName(view, “name);
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    Support for <21 Delaying transitions  supportPostponeEnterTransition();  supportStartPostponedEnterTransition();

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    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()); }