Inside Android KTX

Talk given at Kotlin Night 2018 Milan, A Kotlin Perspective and Droidcon Turin 2018

1. Inside Android KTX
2. Rob
3. Such magic Much tech NOPE
4. animator = ObjectAnimator.ofFloat(view, View.ALPHA, 0f, 1f)
5. animator = ObjectAnimator.ofFloat(view, View.ALPHA, 0f, 1f) animator.doOnStartT{ ... }T animator.doOnEndT{ ... }T animator.doOnCancelT{ ... }T animator.doOnRepeatT{ ... }T animator.doOnPauseT{ ... }T animator.doOnResumeT{ ... }T
6. animatorT= ObjectAnimator.ofFloat(view, View.ALPHA, 0f, 1f) animator.doOnStartT{ ... }T animator.doOnEndT{ ... }T animator.doOnCancelT{ ... }T animator.doOnRepeatT{ ... }T animator.doOnPauseT{ ... }T animator.doOnResumeT{ ... }T Animator.doOnStart
7. funTAnimator.doOnStart(action:T(anim:JAnimator)T->KUnit) T= addListener(onStartT=Taction) animator.doOnStartT{ ... }
8. fun Animator.addListener(T onEnd:T((animator:TAnimator)T->TUnit)?T=Tnull,T onStart:T((animator:TAnimator)T-> Unit)?T=Tnull,T onCancel:T((animator:TAnimator)T-> Unit)?T=Tnull,T onRepeat:T((animator:TAnimator)T-> Unit)?T=TnullT ):TAnimator.AnimatorListenerT{T valTlistenerT=TobjectT:TAnimator.AnimatorListenerT{TT overrideTfunTonAnimationRepeat(animator:TAnimator)T{T onRepeat?.invoke(animator) }T overrideTfunTonAnimationEnd(animator:TAnimator)T{T onEnd?.invoke(animator) }T overrideTfunTonAnimationCancel(animator:TAnimator)T{T onCancel?.invoke(animator) }T overrideTfunTonAnimationStart(animator:TAnimator)T{T onStart?.invoke(animator)
9. onRepeat:T((animator:TAnimator)T-> Unit)?T=TnullT ):TAnimator.AnimatorListenerT{T valTlistenerT=TobjectT:TAnimator.AnimatorListenerT{TT overrideTfunTonAnimationRepeat(animator:TAnimator)T{T onRepeat?.invoke(animator) }T overrideTfunTonAnimationEnd(animator:TAnimator)T{T onEnd?.invoke(animator) }T overrideTfunTonAnimationCancel(animator:TAnimator)T{T onCancel?.invoke(animator) }T overrideTfunTonAnimationStart(animator:TAnimator)T{T onStart?.invoke(animator) }T }T addListener(listener) returnTlistener }T
10. fun Animator.addListener(T onEnd:T((animator:TAnimator)T->TUnit)?T=Tnull,T onStart:T((animator:TAnimator)T-> Unit)?T=Tnull,T onCancel:T((animator:TAnimator)T-> Unit)?T=Tnull,T onRepeat:T((animator:TAnimator)T-> Unit)?T=TnullT ):TAnimator.AnimatorListenerT{T valTlistenerT=TobjectT:TAnimator.AnimatorListenerT{TT overrideTfunTonAnimationRepeat(animator:TAnimator)T{T onRepeat?.invoke(animator) }T overrideTfunTonAnimationEnd(animator:TAnimator)T{T onEnd?.invoke(animator) }T overrideTfunTonAnimationCancel(animator:TAnimator)T{T onCancel?.invoke(animator) }T overrideTfunTonAnimationStart(animator:TAnimator)T{T onStart?.invoke(animator) }T }T addListener(listener) returnTlistener }T
11. val actual = context.systemService<Type>()
12. val actual = context.systemService<Type>() @RequiresApi(23) inline fun <reified T> Context.systemService() = getSystemService(T::class.java)
13. val actual = context.systemService<Type>() @RequiresApi(23) inline fun <reified T> Context.systemService() = getSystemService(T::class.java)
14. val actual = context.systemService<Type>() @RequiresApi(23) inline fun <reified T> Context.systemService() = getSystemService(T::class.java)
15. val actual = context.systemService<Type>() @RequiresApi(23) inline fun <reified T> Context.systemService() = getSystemService(T::class.java) inline reified
16. inline reified Body is copied over at compile time Type passed is preserved
17. inline reified Body is copied over at compile time Type passed is preserved
18. inline reified Body is copied over at compile time Type passed is preserved
19. context.withStyledAttributes(T ... intArrayOf(android.R.attr.textColorPrimary) )T{ val resourceId = getResourceId(0, -1) ... }T context.withStyledAttributes(
20. context.withStyledAttributes(…){…}T context.withStyledAttributes( inline fun Context.withStyledAttributes( ... attrs: IntArray, ... block: TypedArray.() -> Unit ) { val typedArray = obtainStyledAttributes(...) try { typedArray.block() } finally { typedArray.recycle() } }
21. inline fun Context.withStyledAttributes( ... attrs: IntArray, ... block: TypedArray.() -> Unit ) { val typedArray = obtainStyledAttributes(...) try { typedArray.block() } finally { typedArray.recycle() } } context.withStyledAttributes(…){…}T context.withStyledAttributes(
22. valT(a,Tr,Tg,Tb)T=T0x337f3010
23. valT(a,Tr,Tg,Tb)T=T0x337f3010
24. valT(a,Tr,Tg,Tb)T=T0x337f3010
25. valT(a,Tr,Tg,Tb)T=T0x337f3010
26. valT(a,Tr,Tg,Tb)T=T0x337f3010
27. valT(a,Tr,Tg,Tb)T=T0x337f3010
28. inline operator fun @receiver:ColorInt Int.component1() = (this shr 24) and 0xff inline operator fun @receiver:ColorInt Int.component2() = (this shr 16) and 0xff inline operator fun @receiver:ColorInt Int.component3() = (this shr 8) and 0xff inline operator fun @receiver:ColorInt Int.component4() = this and 0xff valT(a,Tr,Tg,Tb)T=T0x337f3010
29. inline operator fun @receiver:ColorInt Int.component1() = (this shr 24) and 0xff inline operator fun @receiver:ColorInt Int.component2() = (this shr 16) and 0xff inline operator fun @receiver:ColorInt Int.component3() = (this shr 8) and 0xff inline operator fun @receiver:ColorInt Int.component4() = this and 0xff valT(a,Tr,Tg,Tb)T=T0x337f3010
30. inline operator fun @receiver:ColorInt Int.component1() = (this shr 24) and 0xff inline operator fun @receiver:ColorInt Int.component2() = (this shr 16) and 0xff inline operator fun @receiver:ColorInt Int.component3() = (this shr 8) and 0xff inline operator fun @receiver:ColorInt Int.component4() = this and 0xff valT(a,Tr,Tg,Tb)T=T0x337f3010
31. inline operator fun @receiver:ColorInt Int.component1() = (this shr 24) and 0xff inline operator fun @receiver:ColorInt Int.component2() = (this shr 16) and 0xff inline operator fun @receiver:ColorInt Int.component3() = (this shr 8) and 0xff inline operator fun @receiver:ColorInt Int.component4() = this and 0xff valT(a,Tr,Tg,Tb)T=T0x337f3010
32. inline operator fun @receiver:ColorInt Int.component1() = (this shr 24) and 0xff inline operator fun @receiver:ColorInt Int.component2() = (this shr 16) and 0xff inline operator fun @receiver:ColorInt Int.component3() = (this shr 8) and 0xff inline operator fun @receiver:ColorInt Int.component4() = this and 0xff valT(a,Tr,Tg,Tb)T=T0x337f3010
33. valT(a,Tr,Tg,Tb)T=T0x337f3010 inline operator fun @receiver:ColorInt Int.component1()T= (thisTshrT24)TandT0xff inline operator fun @receiver:ColorInt Int.component2()T= (thisTshrT16)TandT0xff inline operator fun @receiver:ColorInt Int.component3()T= (thisTshrT8)TandT0xff inline operator fun @receiver:ColorInt Int.component4()T= thisTandT0xff
34. valT(a,Tr,Tg,Tb)T=T0x337f3010 operatorTfun Int.component1()T= (thisTshrT24)TandT0xff operatorTfun Int.component2()T= (thisTshrT16)TandT0xff operatorTfun Int.component3()T= (thisTshrT8)TandT0xff operatorTfun Int.component4()T= thisTandT0xff
35. valT(a,Tr,Tg,Tb)T=T0x337f3010 operatorTfun Int.component1() = (thisTshrT24) and 0xff operatorTfun Int.component2()T= (thisTshrT16)TandT0xff operatorTfun Int.component3()T= (thisTshrT8)TandT0xff operatorTfun Int.component4()T= thisTandT0xff
36. valT(a,Tr,Tg,Tb)T=T0x337f3010 operatorTfun Int.component1() = (this shr 24) and 0xff 0x337f3010.alpha val Int.alpha get() = (this shr 24) and 0xff
37. valT(a,Tr,Tg,Tb)T=T0x337f3010 operatorTfun Int.component1() = (this shr 24) and 0xff 0x337f3010.alpha val Int.alpha get() = (this shr 24) and 0xff
38. valT(a,Tr,Tg,Tb)T=T0x337f3010 operatorTfun Int.component1() = (this shr 24) and 0xff 0x337f3010.alpha val Int.alpha get() = (this shr 24) and 0xff
39. val path = path1 + path2
40. val path = path1 + path2 inline operator fun Path.plus(p: Path): Path = Path(this).apply { op(p, Path.Op.UNION) }
41. val path = path1 + path2 val path = path1 and path2
42. val path = path1 + path2 val path = path1 and path2 inline infix fun Path.and(p: Path) = this + p
43. varTcalledT=T0T handler.postDelayed(10)T{T called++ }T Outer scope
44. varTcalledT=T0T handler.postDelayed(10)T{T called++ }T inline fun Handler.postDelayed( crossinline action: () -> Unit) = Runnable { action() }
45. varTcalledT=T0T handler.postDelayed(10)T{T called++ }T inline fun Handler.postDelayed( crossinline action: () -> Unit) = Runnable { action() } fun foo() { ordinaryFunction { return } } ❌
46. varTcalledT=T0T handler.postDelayed(10)T{T called++ }T inline fun Handler.postDelayed( crossinline action: () -> Unit) = Runnable { action() } fun foo() { ordinaryFunction { return@ordinaryFunction } }
47. varTcalledT=T0T handler.postDelayed(10)T{T called++ }T inline fun Handler.postDelayed( crossinline action: () -> Unit) = Runnable { action() } fun foo() { ordinaryFunction f1@{ return@f1 } }
48. varTcalledT=T0T handler.postDelayed(10)T{T called++ }T inline fun Handler.postDelayed( crossinline action: () -> Unit) = Runnable { action() } fun foo() { inlineFunction { return } } ✅
49. varTcalledT=T0T handler.postDelayed(10)T{T called++ }T inline fun Handler.postDelayed( crossinline action: () -> Unit) = Runnable { action() } fun hasZeros(ints: List<Int>): Boolean { ints.forEach { if (it == 0) return true } return false }
50. varTcalledT=T0T handler.postDelayed(10)T{T called++ }T inline fun Handler.postDelayed( crossinline action: () -> Unit) = Runnable { action() }
51. fun f1()T{T f2 {T return //ERROR return@f2 }T f3 {T return //f1 return@f3 }T f4 {T return //ERROR return@f4 }T }T
52. fun f2(f: ()T-> Unit) inline fun f3(f: ()T-> Unit) inline fun f4(crossinline f: ()T-> Unit) fun f1()T{T f2 {T return //ERROR return@f2 }T f3 {T return //f1 return@f3 }T f4 {T return //ERROR return@f4 }T }T
53. fun f2(f: ()T-> Unit) inline fun f3(f: ()T-> Unit) inline fun f4(crossinline f: ()T-> Unit) fun f1()T{T f2 {T return //ERROR return@f2 }T f3 {T return //f1 return@f3 }T f4 {T return //ERROR return@f4 }T }T
54. fun f2(f: ()T-> Unit) inline fun f3(f: ()T-> Unit) inline fun f4(crossinline f: ()T-> Unit) fun f1()T{T f2 {T return //ERROR return@f2 }T f3 {T return //f1 return@f3 }T f4 {T return //ERROR return@f4 }T }T
56. funTshow(v:TView)T{T v.animate()T .setDuration(200)T .alphaBy(0f)T .alpha(1f)T .start()T }T
57. funTView.show()T{T animate()T .setDuration(200)T .alphaBy(0f)T .alpha(1f)T .start()T }T
58. funTView.show()T{T animate()T .setDuration(200)T .alphaBy(0f)T .alpha(1f)T .start()T }T funTView.hide()T{T animate()T .setDuration(200)T .alphaBy(1f)T .alpha(0f)T .start()T }T
59. funTView.show()T{T animate()T .setDuration(200)T .alphaBy(0f)T .alpha(1f)T .start()T }T funTView.hide()T{T animate()T .setDuration(200)T .alphaBy(1f)T .alpha(0f)T .start()T }T
60. fun View.update(T callback: ViewPropertyAnimator.()T->TViewPropertyAnimator )T{T animate()T .setDuration(200)T .callback()T .start()T }T
61. fun View.update(T callback: ViewPropertyAnimator.()T->TViewPropertyAnimator )T{T animate()T .setDuration(200)T .callback()T .start()T }T
62. funTView.update(T callback: ViewPropertyAnimator.()T->TViewPropertyAnimator )T{T animate()T .setDuration(200)T .callback()T .start()T }T fun View.show() { update { alphaBy(0f) .alpha(1f) } } funTView.hide()T{T updateT{T scaleXBy(1f) .scaleYBy(1f) .scaleX(0f) .scaleY(0f) }T }T
63. funTView.update(T callback: ViewPropertyAnimator.()T->TViewPropertyAnimator )T{T animate()T .setDuration(200)T .callback()T .start()T }T fun View.show() { update { alphaBy(0f) .alpha(1f) } } funTView.hide()T{T updateT{T scaleXBy(1f) .scaleYBy(1f) .scaleX(0f) .scaleY(0f) }T }T
65. open.nytimes.com @nytdev github.com/NYTimes developers.nytimes.com
66. QA & speakerdeck.com/tiwiz/inside-android-ktx