Upgrade to Pro
— share decks privately, control downloads, hide ads and more …
Speaker Deck
Features
Speaker Deck
PRO
Sign in
Sign up for free
Search
Search
Layout Traversals (GDG Devfest 2014)
Search
Lucas Rocha
November 15, 2014
Technology
9
520
Layout Traversals (GDG Devfest 2014)
Presented at GDG Devfest London 2014
Lucas Rocha
November 15, 2014
Tweet
Share
More Decks by Lucas Rocha
See All by Lucas Rocha
Layout Traversals (Droidcon Turin 2015)
lucasr
16
590
Design-Engineering Workflow
lucasr
2
400
Custom Layouts
lucasr
34
2k
Introducing Smoothie
lucasr
7
480
Bringing Firefox to Android
lucasr
6
510
A Million Times Pattrn
lucasr
6
410
Mozilla & Mobile
lucasr
2
180
The State of Firefox Mobile
lucasr
1
2.1k
Other Decks in Technology
See All in Technology
require(ESM)とECMAScript仕様
uhyo
4
1k
M5と自作基板をくっつけてみた〜M5 Japan Tour 2024 Spring 福冈 (Fukuoka|福岡)〜
keropiyo
0
170
LayerXにおけるLLMプロダクト開発の今までとこれから
layerx
PRO
4
760
Documentação de Produtos: Artefatos essenciais na prática
rigolon
1
170
開発パフォーマンスを最大化するための開発体制
ham0215
7
1.2k
リテール金融(キャッシュレス・ネット銀行・ネット証券)の競争環境と経済圏
8maki
0
1.6k
Next.js に疲れた私は Vue3 に癒やされた
akagire
0
140
【NW X Security JAWS#3】L3-4:AWS環境のIPv6移行に向けて知っておきたいこと
shotashiratori
1
680
実例で紹介するRAG導入時の知見と精度向上の勘所
yamahiro
5
1.7k
ゼロから始めるVue.jsコミュニティ貢献 / first-vuejs-community-contribution-link-and-motivation
lmi
1
150
Cracking the KubeCon CfP
inductor
2
270
TechFeed Experts Night#27 〜 フロントエンドフレームワーク最前線 (Svelte)
baseballyama
2
600
Featured
See All Featured
Building a Modern Day E-commerce SEO Strategy
aleyda
22
6.4k
Gamification - CAS2011
davidbonilla
77
4.6k
Product Roadmaps are Hard
iamctodd
45
9.7k
Git: the NoSQL Database
bkeepers
PRO
423
63k
Testing 201, or: Great Expectations
jmmastey
30
6.4k
How GitHub (no longer) Works
holman
305
140k
The Power of CSS Pseudo Elements
geoffreycrofte
62
5k
A Philosophy of Restraint
colly
197
16k
Facilitating Awesome Meetings
lara
43
5.6k
I Don’t Have Time: Getting Over the Fear to Launch Your Podcast
jcasabona
22
1.6k
How to Create Impact in a Changing Tech Landscape [PerfNow 2023]
tammyeverts
21
1.6k
No one is an island. Learnings from fostering a developers community.
thoeni
16
2.1k
Transcript
LAYOUT TRAVERSALS Devfest London, 2014
LUCAS ROCHA +LucasRocha | @lucasratmundo
None
BE DELIBERATE Less handwaviness in your UI code
UI TOOLKITS Layout + Rendering + Input Events
TICK TOCK VSYNC sets the pace.
CHOREOGRAPHER f1 f2 f3 f4 f5 . . . .
. . VSYNC (60fps) Resize view Redraw view Input Events
CHOREOGRAPHER public void onVsync(long timestampNanos, int builtInDisplayId, int frame) {
... scheduleVsync(); ... } ... void doFrame(long frameTimeNanos, int frame) { ... if (!mFrameScheduled) { return; } ... doCallbacks(Choreographer.CALLBACK_INPUT, frameTimeNanos); doCallbacks(Choreographer.CALLBACK_ANIMATION, frameTimeNanos); doCallbacks(Choreographer.CALLBACK_TRAVERSAL, frameTimeNanos); ... } Choreographer.java
ViewRootImpl Connects WindowManager with the View framework
ViewRootImpl *
FRAMEWORK Measure + Layout + Draw
TRAVERSAL * performTraversals() f2 performTraversals()
MEASURE * measure(int, int) f2 M M M M M
M → onMeasure(int, int) measureHierarchy(...)
LAYOUT * f2 M L M L M L M
L M L M L layout(int, int, int, int) → onLayout(boolean, int, int, int, int) performLayout()
DRAW * f2 M L D M L D M
L D M L D M L D M L D draw(Canvas) → onDraw(Canvas) performDraw()
CHANGES Resize, redraw & animate.
* requestLayout() f1 f2 f3 f4 f5 . . .
. . .
requestLayout() public void requestLayout() { ... if (mParent != null
&& !mParent.isLayoutRequested()) { mParent.requestLayout(); } ... } void scheduleTraversals() { ... mTraversalBarrier = mHandler.getLooper().postSyncBarrier(); mChoreographer.postCallback( Choreographer.CALLBACK_TRAVERSAL, mTraversalRunnable, null); ... } View.java ViewRootImpl.java
* Invalidate(...) f1 f2 f3 f4 f5 . . .
. . .
invalidate(...) public void invalidateInternal(...) { ... mPrivateFlags |= PFLAG_DIRTY; ...
if (mParent != null && mAttachInfo != null && l < r && t < b) { final Rect damage = mAttachInfo.mTmpInvalRect; damage.set(l, t, r, b); mParent.invalidateChild(this, damage); } ... } View.java
* postOnAnimation() f1 f2 f3 f4 f5 . . .
. . . ValueAnimator ...
postOnAnimation() public void postOnAnimation(Runnable action) { ... attachInfo.mViewRootImpl.mChoreographer.postCallback( Choreographer.CALLBACK_ANIMATION, action,
null); ... } void doFrame(long frameTimeNanos, int frame) { ... doCallbacks(Choreographer.CALLBACK_INPUT, frameTimeNanos); doCallbacks(Choreographer.CALLBACK_ANIMATION, frameTimeNanos); doCallbacks(Choreographer.CALLBACK_TRAVERSAL, frameTimeNanos); ... } View.java Choreographer.java
LAZY MEASURE Multi-MeasureSpec cache, invalidated in requestLayout()
LAZY MEASURE public final void measure(int widthMeasureSpec, int heightMeasureSpec) {
... int cacheIndex = mMeasureCache.indexOfKey(key); if (cacheIndex < 0 || sIgnoreMeasureCache) { onMeasure(widthMeasureSpec, heightMeasureSpec); mPrivateFlags3 &= ~PFLAG3_MEASURE_NEEDED_BEFORE_LAYOUT; } else { long value = mMeasureCache.valueAt(cacheIndex); setMeasuredDimensionRaw((int) (value >> 32), (int) value); mPrivateFlags3 |= PFLAG3_MEASURE_NEEDED_BEFORE_LAYOUT; } ... } View.java
LAZY MEASURE public void layout(int l, int t, int r,
int b) { if ((flags & PFLAG3_MEASURE_NEEDED_BEFORE_LAYOUT) != 0) { onMeasure(mOldWidthMeasureSpec, mOldHeightMeasureSpec); mPrivateFlags3 &= ~PFLAG3_MEASURE_NEEDED_BEFORE_LAYOUT; } ... } View.java
BASIC TIPS 1. No layout requests during layout 2. No
layout requests during animations 3. Invalidate regions when possible
PERFORMANCE 1. Simplify your view hierarchy 2. Avoid multi-pass measurement
GO CUSTOM Simplify view hierarchy, performance, missing features. http://lucasr.org/?p=3920
TREE OBSERVER Use OnPreDrawListener!
TRANSITIONS http://lucasr.org/?p=3902
OnPreDrawListener // 1. Save layout state and wait for next
frame. getViewTreeObserver().addOnPreDrawListener(new OnPreDrawListener() { @Override public boolean onPreDraw() { getViewTreeObserver().removeOnPreDrawListener(this); // 2. Restore original layout state. // 3. Trigger animators towards new layout state. } }
PROBE IT! Intercept view methods. Dissect layout traversals. https://github.com/lucasr/probe
OVERRIDE VIEW METHODS public class DrawGreen extends Interceptor { private
final Paint mPaint; public DrawGreen() { mPaint = new Paint(); mPaint.setColor(Color.GREEN); } @Override public void onDraw(View view, Canvas canvas) { canvas.drawPaint(mPaint); } }
DEPLOY public final class MainActivity extends Activity { @Override protected
void onCreate(Bundle savedInstanceState) { Probe.deploy(this, new DrawGreen(), new Filter.ViewId(R.id.view2)); super.onCreate(savedInstanceState); setContentView(R.id.main_activity); } }
WRAP VIEW METHODS public class LogRequestLayout extends Interceptor { @Override
public void requestLayout(View view) { super.requestLayout(view); Log.d(LOGTAG, “requestLayout() on ” + view); } }
QUESTIONS? +LucasRocha | @lucasratmundo