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
Deflating the LayoutInflater
Search
Saket Narayan
August 28, 2016
Programming
5
1.4k
Deflating the LayoutInflater
https://droidconin.talkfunnel.com/2016/86-deflating-the-layoutinflater
Saket Narayan
August 28, 2016
Tweet
Share
More Decks by Saket Narayan
See All by Saket Narayan
IllegalStateException: Can not perform this action after onSaveInstanceState
saketme
5
620
Building offline first apps
saketme
1
240
Other Decks in Programming
See All in Programming
AI駆動で0→1をやって見えた光と伸びしろ
passion0102
1
860
When Dependencies Fail: Building Antifragile Applications in a Fragile World
selcukusta
0
110
CSC305 Lecture 11
javiergs
PRO
0
280
Blazing Fast UI Development with Compose Hot Reload (droidcon London 2025)
zsmb
0
170
Ktorで簡単AIアプリケーション
tsukakei
0
110
kiroとCodexで最高のSpec駆動開発を!!数時間で web3ネイティブなミニゲームを作ってみたよ!
mashharuki
0
940
Towards Transactional Buffering of CDC Events @ Flink Forward 2025 Barcelona Spain
hpgrahsl
0
120
AIと人間の共創開発!OSSで試行錯誤した開発スタイル
mae616
2
820
React Nativeならぬ"Vue Native"が実現するかも?_新世代マルチプラットフォーム開発フレームワークのLynxとLynxのVue.js対応を追ってみよう_Vue Lynx
yut0naga1_fa
2
1.6k
マンガアプリViewerの大画面対応を考える
kk__777
0
340
開発組織の戦略的な役割と 設計スキル向上の効果
masuda220
PRO
10
1.7k
One Enishi After Another
snoozer05
PRO
0
160
Featured
See All Featured
jQuery: Nuts, Bolts and Bling
dougneiner
65
7.9k
Building Adaptive Systems
keathley
44
2.8k
Learning to Love Humans: Emotional Interface Design
aarron
274
41k
Side Projects
sachag
455
43k
Rails Girls Zürich Keynote
gr2m
95
14k
Improving Core Web Vitals using Speculation Rules API
sergeychernyshev
21
1.2k
Embracing the Ebb and Flow
colly
88
4.9k
Templates, Plugins, & Blocks: Oh My! Creating the theme that thinks of everything
marktimemedia
31
2.6k
Docker and Python
trallard
46
3.6k
Build your cross-platform service in a week with App Engine
jlugia
233
18k
Producing Creativity
orderedlist
PRO
347
40k
Why You Should Never Use an ORM
jnunemaker
PRO
59
9.6k
Transcript
Deflating the LayoutInflater Saket • Uncommon
Parts 1. What and how 2. Applications
Part 1, What is LayoutInflater
Converts View hierarchies written in XML into Java objects XML
<TextView android:layout_width="wrap_content" android:layout_height=“wrap_content" /> Java public class TextView extends View { ... }
Common Usages
Fragments @Override public View onCreateView(LayoutInflater, ViewGroup, Bundle) { return inflater.inflate(
R.layout.fragment_layout, container, false ); }
ViewHolders @Override public ViewHolder onCreateViewHolder(ViewGroup, int) { return new ViewHolder(inflater.inflate(
R.layout.fragment_layout, container, false )); }
Activities @Override protected void onCreate(Bundle savedState) { super.onCreate(savedState); setContentView(R.layout.activity_main); }
PhoneWindow.java (or AppCompatDelegateImplV7.java) @Override public void setContentView(int layoutRes) { mLayoutInflater.inflate(layoutRes,
mParent); }
How it works
LayoutInflater#inflate() A. XmlPullParser B. AttributeSet C. Creating View objects
LayoutInflater#inflate() A. XmlPullParser GSON, Moshi for JSON is the same
as XmlPullParser for XML
LayoutInflater#inflate() B. AttributeSet <ImageView android:layout_width="100dp" android:layout_height="100dp" android:src="@drawable/ic_done" android:contentDescription="Save" />
LayoutInflater#inflate() B. AttributeSet <ImageView android:layout_width="100dp" android:layout_height="100dp" android:src="@drawable/ic_done" android:contentDescription="Save" />
LayoutInflater#inflate() B. AttributeSet <ImageView android:layout_width="100dp" android:layout_height="100dp" android:src="@drawable/ic_done" android:contentDescription="Save" />
LayoutInflater#inflate() B. AttributeSet <ImageView android:layout_width="100dp" android:layout_height="100dp" android:src="@drawable/ic_done" android:contentDescription="Save" />
LayoutInflater#inflate() B. AttributeSet <ImageView android:layout_width="100dp" android:layout_height="100dp" android:src="@drawable/ic_done" android:contentDescription="Save" />
LayoutInflater#inflate() B. AttributeSet <ImageView android:layout_width="100dp" android:layout_height="100dp" android:src="@drawable/ic_done" android:contentDescription="Save" />
LayoutInflater#inflate() B. AttributeSet <ImageView android:layout_width="@dimen/list_icon" android:layout_height="@dimen/list_icon" android:src="@drawable/ic_done" android:contentDescription="Save" /> res/values/dimens.xml
LayoutInflater#inflate() B. AttributeSet Figures precedence of attributes <ImageView style="@style/Button.Save" android:layout_width="100dp"
android:layout_height="100dp" android:src=“@drawable/ic_done" />
LayoutInflater#inflate() B. AttributeSet Figures precedence of attributes <ImageView style="@style/Button.Save" android:layout_width="100dp"
android:layout_height="100dp" android:src=“@drawable/ic_done" />
LayoutInflater#inflate() B. AttributeSet Figures precedence of attributes <style name="Button.Save"> <item
name="android:layout_width">200dp</item> <item name="android:layout_height">200dp</item> </style>
LayoutInflater#inflate() B. AttributeSet Figures precedence of attributes <ImageView style="@style/Button.Save" android:layout_width="100dp"
android:layout_height="100dp" android:src=“@drawable/ic_done" />
Finding a View’s source Creating the View object using Reflection
LayoutInflater#inflate() C. Creating View Objects
Finding a View’s source Creating the View object using Reflection
LayoutInflater#inflate() C. Creating View Objects
Black magic Slow Reflection?
Delegate creation to “Factories” Instantiate View by itself (if #1
fails) Creating View Objects
Delegate creation to “Factories” Instantiate View by itself (if #1
fails) context.getClassLoader().loadClass(); Creating View Objects
Delegate creation to “Factories” Instantiate View by itself a) Custom
View b) Framework View Creating View Objects
a) Custom View: <android.support.v7.widget.RecyclerView android:layout_width="match_parent" android:layout_height=“match_parent" /> Creating View Objects
a) Custom View: Class<RecyclerView> clazz = ClassLoader#loadClass( "android.support.v7.widget.RecyclerView" ); RecyclerView
view = clazz.getConstructor().newInstance(); Creating View Objects
a) Framework View: <TextView android:layout_width="match_parent" android:layout_height="match_parent" /> Creating View Objects
a) Custom View: Class<TextView> clazz = ClassLoader#loadClass( "TextView" ); Creating
View Objects
a) Custom View: Class<TextView> clazz = ClassLoader#loadClass( "android.widget.TextView" ); Creating
View Objects
a) Custom View: Class<TextView> clazz = ClassLoader#loadClass( "android.widget.TextView" ); TextView
view = clazz.getConstructor().newInstance(); Creating View Objects
Delegate creation to “Factories” Instantiate View by itself Creating View
Objects
LayoutInflater Factories
Installing a Factory @Override protected void onCreate(Bundle savedState) { getLayoutInflater().setFactory2(...);
super.onCreate(savedState); }
Common Factories a) Activity public class Activity extends ContextThemeWrapper implements
LayoutInflater.Factory2 { }
Common Factories a) Activity
Common Factories a) Activity <LinearLayout> <fragment android:name="is.uncommon.ShinyFragment" android:layout_width="match_parent" android:layout_height="match_parent" />
</LinearLayout>
Common Factories a) Activity <LinearLayout> <fragment android:name="is.uncommon.ShinyFragment" android:layout_width="match_parent" android:layout_height="match_parent" />
</LinearLayout>
Common Factories b) AppCompat Continued in Part 2.
Part 2, Hooking into LayoutInflater
example, AppCompat How it back-ports material design to pre-Lollipop devices
android:theme
AppCompat Kitkat
AppCompat Kitkat
AppCompat <Button android:layout_width="match_parent" android:layout_height="match_parent" android:background="@drawable/custom_btn" /> custom_btn.xml <selector> @drawable/custom_btn_normal @drawable/custom_btn_focussed
@drawable/custom_btn_pressed </selector>
AppCompat <Button android:layout_width="match_parent" android:layout_height="match_parent" android:theme="@style/CustomButtonTheme" /> styles.xml <style name="CustomButtonTheme"> <item
name=“colorButtonNormal”>#09F</item> <item name=“colorControlHighlight">#07F</item> </style>
example, AppCompat AppCompatActivity @Override protected void onCreate(Bundle savedState) { installViewFactory();
... }
example, AppCompat AppCompatViewInflater.java implements LayoutInflater.Factory2 { ... }
example, AppCompat AppCompatViewInflater.java public View onCreateView(String viewName, ...) { if
("TextView".equals(viewName) { return new AppCompatTextView(); } ... }
example, AppCompat
example, Calligraphy How it applies custom fonts without using any
custom Views. <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" fontPath="fonts/Roboto-Bold.ttf" />
example, Calligraphy class CalligraphyLayoutInflater extends LayoutInflater { ... }
example, Calligraphy @Override View onCreateView(String name, AttributeSet) { View view
= super.onCreateView(...); if (view instanceOf TextView) { applyTypeface((TextView) view); } return view; }
example, Calligraphy @Override View onCreateView(String name, AttributeSet) { View view
= super.onCreateView(...); if (view instanceOf TextView) { applyTypeface((TextView) view); } return view; }
What if… We could do this? <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" formatter="IndianRupees"
/>
What if… We could do this? <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" formatter="IndianRupees"
/> 250000
What if… We could do this? <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" formatter="IndianRupees"
/> Ũ2,50,000
What if… Or this? <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" formatter="CreditCardNumber" />
What if… Or this? <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" formatter="CreditCardNumber" /> 4652
3700 0055 5032
What if… Or this? <EditText android:layout_width="wrap_content" android:layout_height="wrap_content" formatter="CreditCardNumber" /> 3400
123456 000032
What if… Or maybe this? <FrameLayout android:layout_width="wrap_content" android:layout_height=“wrap_content" paddings="16dp 20dp"
/>
WHAT IF I TOLD YOU IT’S POSSIBLE TO DO THAT?
Introducing, Balloon!
Balloon interface BalloonAttributeListener { void onApplyAttribute( View view, int attributeResId,
Object attributeValue ); }
Application#onCreate() Balloon.config() .registerAttr(R.attr.formatter, FormatterAttrListener) .build(); Balloon
Application#onCreate() Balloon.config() .registerAttr(R.attr.formatter, FormatterAttrListener) .build(); Balloon
Application#onCreate() Balloon.config() .registerAttr(R.attr.formatter, FormatterAttrListener) .build(); Balloon
Balloon class FormatterAttrListener implements BalloonAttributeListener <> { @Override void onApplyAttribute(EditText
view, int attrResId, String attrValue) { if ("IndianRupees".equals(attrValue)) { // Add rupee symbol and format digits } } }
Pros Composition > Inheritance Can be used for multiple types
of Views Quick
Cons “Experimental” No layout preview in Android Studio
Working class BalloonLayoutInflater extends LayoutInflater { ... }
Challenges Activity getLayoutInflater() -> return LayoutInflater
Challenges Activity getLayoutInflater() -> return LayoutInflater -> return BalloonLayoutInflater
Challenges public class BalloonContext extends Context { ... }
Challenges Activity @Override void attachBaseContext(Context base) { super.attachBaseContext(BalloonContext.wrap(base)); }
Challenges Activity @Override void attachBaseContext(Context base) { super.attachBaseContext(BalloonContext.wrap(base)); }
Challenges BalloonContext @Override Object getSystemService(String name) { if (LAYOUT_INFLATER_SERVICE.equals(name)) {
return new BalloonLayoutInflater(); } return super.getSystemService(name); }
Challenges BalloonContext @Override Object getSystemService(String name) { if (LAYOUT_INFLATER_SERVICE.equals(name)) {
return new BalloonLayoutInflater(); } return super.getSystemService(name); }
Challenges Activity getLayoutInflater() -> return BalloonLayoutInflater
saket.me/droidcon
Learnings Layout inflation is a slow process. Complex layouts can
affect an Activity’s startup time.
Learnings Why non-framework Views require their fully qualified names in
XML whereas framework Views don’t. <is.uncommon.FancyCustomView /> vs. <TextView />
That’s all folks!
Uncommon hello @ uncommon.is
Questions?