I Can Animate and So Can You (mdevcon)

A medium-length version of a talk I gave about Android animations at mdevcon in Amsterdam 2014.

Keynote version: http://goo.gl/7KuSxP

Transcript

1. I Can Animate and So Can You Daniel Lew, Mar. 8, 2014
2. Typical Animation Demo
3. What Can Be Done
4. Revelations
5. Revelation #1 Every animation is unique
6. Revelation #2 Animation code is not pretty
7. Revelation #3 Animations first Animate
8. Revelation #4 Animate for 4.x+
9. Ditch 2.x • Poor performance • Can't use modern tricks • Backup: NineOldAndroids
10. Ditch 3.x • Tiny userbase • ViewPropertyAnimator - Introduced 3.1 • TextureView - Introduced 4.0
11. Building Animations • Figure out what attributes to animate • Design View hierarchy • Measure attribute start/ end values • Setup and run animators
12. Determining Attributes • Alpha - every element • Translate - every row • Translate - details header/footer • Scale - details rows (a hardcore fake) • Fading background - not needed!
13. View Hierarchy • Animation informs View hierarchy • Here, rows go underneath split action bar
14. Measuring Views • Problem: Views not measured until sometime after inflation • ViewTreeObserver - lets you know when a View has been measured • Two options: OnGlobalLayoutListener, OnPreDrawListener
15. ViewTreeObserver Pattern ! final View view = findViewById(R.id.view); view.getViewTreeObserver().addOnPreDrawListener(new OnPreDrawListener() { public boolean onPreDraw() { view.getViewTreeObserver().removeOnPreDrawListener(this); // Measure here! return true; } });
16. Measuring "After" • Align to other existing Views • Create invisible "dummy" Views to animate towards
17. Running Animators • ObjectAnimator - animate! • AnimatorSet - synchronize multiple Animators • AnimatorListener - setup and cleanup • Canceling Animators w/ reverse()
18. Property Animators • Generic animation framework • Animates *any* value over time • Basic building block for most animations
19. ObjectAnimator • Type of property animator • Used for animating essential View properties • Position (or translation) • Rotation • Scale • Alpha • Can be used on custom View properties
20. ObjectAnimator // Uses setAlpha() and getAlpha() to animate ObjectAnimator.ofFloat(myView, "alpha", 0, 1).start(); ! ! ! // Uses built-in property to avoid reflection ObjectAnimator.ofFloat(myView, View.ALPHA, 1).start();
21. AnimatorSet ! ObjectAnimator one = ObjectAnimator.ofFloat(view1, "alpha", 1); ObjectAnimator two = ObjectAnimator.ofFloat(view2, "alpha", 1); ! AnimatorSet set = new AnimatorSet(); set.playTogether(one, two); set.start();
22. Animator Listeners ! ObjectAnimator anim = ObjectAnimator.ofFloat(view, "alpha", 1); anim.addListener(new AnimatorListenerAdapter() { public void onAnimationEnd(Animator animation) { // Clean-up code here } }); anim.start();
23. Reversing Course • ValueAnimator.reverse() • Useful for smoothly canceling an animator • Can recursively traverse AnimatorSet for ValueAnimators
24. Questions So Far?
25. Performance • Choppy animation == painful • Performance cannot be an afterthought • Smooth animations informs structure
26. Performance Breakdown • Layout - size/location of Views • Draw - what's inside Views • Render - pushing it on screen
27. Layout Performance • Initiated by View.requestLayout() • Slow - avoid at all costs • Can sneak up on you
28. Draw Performance • Initiated by View.invalidate() • How animations are run
29. Render Performance • Initiated every time pixels are put on screen • Varies with pixel count/ speed of device • Try to reduce overdraw
30. Profiling
31. Profile GPU Rendering • Blue - Draw • Red - Process • Orange - Execute • Green line - your goal
32. Show GPU Overdraw • Shows overdrawn pixels • Best to worst: nothing, blue, green, red, dark red • Some overdraw necessary, but reduce if possible
33. Other Profilers • Traceview - Breakdown of method calls • Systrace - Measures everything on system • OpenGL Traces - Every single OpenGL call
34. Profile Warnings • Profilers can be inaccurate • One profiling tool at a time, please • Profile multiple devices
35. Optimization: Layers • Layers store drawn Views for reuse • Reduces drawing during animation • Reduces overdraw during animation
36. Layers LinearLayout ImageView TextView TextView
37. Layers LinearLayout ImageView TextView TextView LinearLayout
38. Layer Pattern ! final View myView = findViewById(R.id.my_view); myView.setLayerType(View.LAYER_TYPE_HARDWARE, null); myView.animate() .translationX(50) .setListener(new AnimatorListenerAdapter() { public void onAnimationEnd(Animator animation) { myView.setLayerType(View.LAYER_TYPE_NONE, null); } }) .start();
39. Layer Caveats • Warning: redrawing a layer is *slower* than non-layer • DisplayLists will rebuild layers when necessary • Layering simple Views just hurts performance
40. Other Animation Tools
41. Custom Views • Custom Views easier than they sound! • Animate your own attributes • Simplify animation via isolation • Cheat for performance’s sake
42. set directions • View methods: setLeft(), setRight(), setTop(), setBottom() • Change layout without requesting layout! • Parent layout blows away values, may have to block
43. Drawable Animations • AnimationDrawable - frame animations • Custom animated Drawable in a View • Drawable.setCallback() • View.verifyDrawable()
44. SurfaceView and TextureView • Great for constantly animated View • SurfaceView is fast but is weird • TextureView is 4.0+, but can be moved around
45. Resources • Android: goo.gl/4aZIzM • DevBytes: goo.gl/QeTM9B • Chet Haase: graphics-geek.blogspot.com/ • Romain Guy: curious-creature.org • Google IO Sessions (esp. with Haase/Guy)
46. Thank You! • Blog: http://blog.danlew.net • Movies App Source: http://goo.gl/WiRTlQ • Twitter: @danlew42