Medellín Android 2016-06-01: Loving Lean Layouts

La charla dé al primer meetup de Medellín Android.

1. LOVING LEAN LAYOUTS HUYEN TUE DAO 2016.06.01 MEDELLÍN ANDROID
2. LOVING LEAN LAYOUTS WHY LEAN LAYOUTS? FIND PROBLEMS FIX PROBLEMS GOOD PRACTICES
3. WHY LEAN LAYOUTS? • Complexity ∝ Resources (memory, CPU) • Complexity? • # of views • Depth of view hierarchy • (Really) # of measure() and layout() executions • Bad performance → UI/animations jank 3 #PERFMATTERS
4. WHY LEAN LAYOUTS? • Complexity ∝ effort to maintain/refactor • Readability • Complex views are hard to parse • Too nested → too indented • Stability: a change to one part affects other part 4 MAINTAINABILITY
5. HOW TO LAYOUT A VIEW HIERARCHY measure STEP 1 layout STEP 2 measure measure layout layout r
6. 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
7. STEP NO. 1 IN LOVING LEAN LAYOUTS FIND PROBLEMS
8. FIND PROBLEMS • SDK tool for visualizing view hierarchy • Used to be standalone; now in Device Monitor • Evaluates performance of measure(), layout(), and draw() phases • Best: use on physical device running 4.1 up • Do not use runtime numbers given in Hierarchy Viewer; completely inaccurate HIERARCHY VIEWER :
9. 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 • FrameMetricsListener API: Android N; framestats without 120 frame limit SYSTRACE + DUMPSYS :
10. STEP NO. 2 IN LOVING LEAN LAYOUTS FIX PROBLEMS
11. FIX PROBLEMS • Lint complains about things that are generally not good ideas. • Good candidates for things that you should fix first. • Don’t nest weights • Remove useless views • Don’t nest too much MAKE LINT HAPPY :
12. FIX PROBLEMS • Many different ways to do one thing: opt for simplest • Often attributes or other techniques can replace multiple views, e.g.: • TextView compound drawables • Spannable • Placeholder/divider → View or Space. • Sometimes you just need to pick the right view/layout. • Less views, less levels, less nesting • ConstraintLayout SIMPLIFY AND REDUCE :
13. FIX PROBLEMS SIMPLIFY AND REDUCE : <LinearLayout…>
 
 <ImageView…/>
 
 <TextView…/>
 
 </LinearLayout> <TextView…
 android:drawablePadding=“…"
 android:drawableEnd=“…"/> → 3 VIEWS, 2 LEVELS 1 VIEW, 1 LEVEL
14. FIX PROBLEMS SIMPLIFY AND REDUCE : <LinearLayout…>
 
 <TextView…
 style="@style/StyleA" />
 
 <TextView…
 style="@style/StyleB" />
 
 <TextView…
 style="@style/StyleA" />
 
 </LinearLayout> <TextView…/> + Spannables → 4 VIEWS, 2 LEVELS 1 VIEW, 1 LEVEL
15. FIX PROBLEMS SIMPLIFY AND REDUCE : <LinearLayout… >
 
 <LinearLayout…>
 
 <TextView… />
 
 <TextView… />
 
 </LinearLayout>
 
 <TextView… />
 
 </LinearLayout> 
 
 <RelativeLayout…>
 
 <TextView… />
 
 <TextView… />
 
 <TextView… />
 
 </RelativeLayout> → 5 VIEWS, 3 LEVELS 4 VIEW, 2 LEVEL
16. FIX PROBLEMS • Sometimes best option = custom ViewGroup. • Total control over measure/layout logic. • Mitigate double-layout phases. • Also: totally custom Views (draw all the things). • Start out with simple, straightforward layouts. • Balance performance gains with development effort. GO CUSTOM :
17. STEP NO. 3 IN LOVING LEAN LAYOUTS GOOD PRACTICES
18. GOOD PRACTICES • Anticipate and develop good habits • Use simplest solutions where possible • “Don’t do too much stuff.” • Fewer/flatter Views and ViewGroups. • Don’t use RelativeLayout at the root! • Don’t let problems accumulate. • Balance performance gains with development effort.
19. 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
20. 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 20
21. 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 21