DroidKaigi 2016: Loving Lean Layouts

Huyen Tue Dao's talk at DroidKaigi 2016: "Loving Lean Layouts". Discusses why Android developers should strive to create efficient layouts and presents tricks and good practices for achieving this.

Transcript

1. LOVING LEAN LAYOUTS HUYEN TUE DAO 2016年2⽉月19⽇日
2. LOVING LEAN LAYOUTS WHY LEAN LAYOUTS? FIND PROBLEMS FIX PROBLEMS GOOD PRACTICES
3. WHY LEAN LAYOUTS? r r r r shallow simple simple lean + = shallow reduce views reduce levels in view tree 3
4. WHY LEAN LAYOUTS? • #perfmatters • Complexity ∝ Resources (memory, CPU) • No. of views, depth of view tree • No. of measure() and layout() executions • Bad performance → UI/animations jank • Maintainability • Complexity ∝ effort to maintain/refactor • Readability • Stability: a change to one part affects other part 4
5. WHERE’S THE PROBLEM? (HINT: SEVERAL PLACES) r Change in size/position starts measure/layout starting at root. r r r r Some layouts need multiple measure/layout passes, e.g. RelativeLayout Lists make many copies of same layout Deep hierarchies increase complexity and dependency
6. STEP NO. 1 IN LOVING LEAN LAYOUTS FIND PROBLEMS
7. FIND PROBLEMS • SDK tool for visualizing view hierarchy • Used to be standalone; now in Device Monitor • Tree representation of view hierarchy • Evaluates performance of measure(), layout(), and draw() phases • Best: use on physical device running 4.1 up HIERARCHY VIEWER :
8. FIND PROBLEMS • systrace: system + application process execution data → interactive reports • Frame rendering → how much time measure/layout takes up; warns of frames that exceed 16.6ms needed for 60fps • dumpsys: collects and dumps “interesting information” about system services status • adb shell dumpsys gfxinfo <PACKAGE_NAME> → perf info related to frames of animation • adb shell dumpsys gfxinfo <PACKAGE_NAME> framestats → detailed frame timing info; on Marshmallow SYSTRACE + DUMPSYS :
9. STEP NO. 2 IN LOVING LEAN LAYOUTS FIX PROBLEMS
10. FIX PROBLEMS • Lint complains about things that are generally not good ideas. • These things are good candidates for things that you should fix first. • Generally, straightforward: • Don’t nest weights • Remove useless views • Don’t nest too much MAKE LINT HAPPY :
11. FIX PROBLEMS • Many different ways to do one thing: opt for simplest • Often view attributes/features can replace multiple views. • TextView compound drawables • Spannable • LinearLayout → android:divider • If you need a placeholder/divider, just use a regular View. • Sometimes you just need to pick the right view/layout. SIMPLIFY AND REDUCE :
12. FIX PROBLEMS • Sometimes best option = custom ViewGroup. • Total control over measure/layout logic. • Mitigate double-layout phases from platform layouts. • Starting out? Try with simple, straightforward layouts. • Also: totally custom Views (draw all the things). • Balance performance benefits with development effort. GO CUSTOM :
13. STEP NO. 3 IN LOVING LEAN LAYOUTS GOOD PRACTICES
14. GOOD PRACTICES • Anticipate and develop good habits • Know how to identify possible problem areas • Use simplest solutions where possible • Fewer/flatter Views and ViewGroups • “Don’t do too much stuff.” • Don’t use RelativeLayout at the root! Romain and Chet said so. • Don’t let problems accumulate • Balance performance benefit with effort required
15. THANKS FOR COMING! https://github.com/queencodemonkey/Android-Loving-Lean-Layouts Huyen Tue Dao @queencodemonkey +HuyenTueDao huyen@randomlytyping.com randomlytyping.com youtube.com/androiddialogs speakerdeck.com/queencodemonkey
16. REFERENCES • Android Performance Patterns, Why 60fps? https://youtu.be/ CaMTIgxCSqU • Developing for Android: the Naughty Bits https://youtu.be/Q2qQoJlwqlk? t=36m4s • Hierarchy Viewer: http://developer.android.com/tools/help/hierarchy- viewer.html • Hierarchy Viewer Walkthrough: http://developer.android.com/tools/ performance/hierarchy-viewer/index.html • Testing Display Performance: http://developer.android.com/training/ testing/performance.html • Analyzing UI Performance with Systrace: http://developer.android.com/ tools/debugging/systrace.html 16
17. REFERENCES • Custom ViewGroups: https:// sriramramani.wordpress.com/2015/05/06/custom- viewgroups/ • Optimizing Layout Hierarchies: http:// developer.android.com/training/improving-layouts/ optimizing-layout.html • Android Performance Patterns, Double Layout Taxation: https://www.youtube.com/watch?v=dB3_vgS-Uqo • Android Performance Pattern, Invalidations, Layouts, and Performance: https://youtu.be/we6poP0kw6E 17