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https://github.com/arunkumar9t2/transition-x
{ } Declarative Kotlin DSL for choreographing Android transitions
https://github.com/arunkumar9t2/transition-x
android animations dsl kotlin transitions ux
Last synced: 3 days ago
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{ } Declarative Kotlin DSL for choreographing Android transitions
- Host: GitHub
- URL: https://github.com/arunkumar9t2/transition-x
- Owner: arunkumar9t2
- License: apache-2.0
- Created: 2018-07-26T17:12:51.000Z (over 6 years ago)
- Default Branch: master
- Last Pushed: 2019-08-24T16:13:57.000Z (over 5 years ago)
- Last Synced: 2025-01-13T21:07:36.252Z (11 days ago)
- Topics: android, animations, dsl, kotlin, transitions, ux
- Language: Kotlin
- Homepage:
- Size: 17.3 MB
- Stars: 512
- Watchers: 14
- Forks: 17
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# Transition X
**Kotlin DSL for choreographing Android Transitions**
[](https://circleci.com/gh/arunkumar9t2/transition-x/tree/master)[  ](https://bintray.com/arunkumar9t2/maven/transition-x/_latestVersion) [](https://arunkumar9t2.github.io/transition-x/transitionx/index.html) [](http://androidweekly.net/#335)
`TransitionManager` makes it easy to animate simple changes to layout without needing to explicitly calculate and specify `from` and `to` like `Animator` or `Animation` expects. When you call `TransitionManager.beginDelayedTransition(layout, transition)` before updating a layout, the framework automatically does a diff on before and after states and animates the difference.
`Transition X` is intended to simplify construction of these `Transition` instances to take full advantage of the framework and provide a clear, concise, type safe and extensible DSL using Kotlin language features.
I highly recommend reading the introduction blog post on [my blog.](https://arunkumar.dev/transtition-x-declarative-kotlin-dsl-for-choreographing-android-transitions/)
# Download
- Add repository to your project level `build.gradle` file.
```groovy
allprojects {
repositories {
jcenter()
}
}
```
- Add library dependency to module level `build.gradle` file.
```groovy
dependencies{
implementation 'in.arunkumarsampath:transition-x:1.1.0'
}
```
# Introduction
As shown above, instead of creating XML files and later inflating them using `TransitionInflator`, it is possible to create `Transition` instances directly using `tranistionSet{}` block provided by the DSL.
With _**Transition X**_, the construction and usage can be greatly simplified with a `prepareTransition` extension added to `ViewGroup`.
For example:
```Kotlin
constraintLayout.prepareTransition {
fadeOut {
startDelay = 100
}
moveResize {
pathMotion = ArcMotion()
}
fadeIn()
+textView // Add textView as target using '+' operator
exclude() // Exclude all recyclerViews
ease {
standardEasing // Applies FastOutSlowInInterpolator
}
}
// Performing layout changes here will be animated just like
// calling TransitionManager.beginDelayedTransition()
```
All blocks are type-safe and has IDE auto complete support thanks to Kotlin.
# Getting Started
## Writing your first transition
TransitionSet's can be built programmatically like shown below.
```kotlin
val transition = TransitionSet().apply {
addTransition(ChangeBounds().apply {
startDelay = 100
setPathMotion(ArcMotion())
})
}
```
The Transition X equivalent would be:
```kotlin
val transition = transitionSet {
moveResize {
startDelay = 100
pathMotion = ArcMotion()
}
}
```
Some of the transition names are **opinionated** to better express their intent and promote clear code. Here `ChangeBounds` transition usually animates a `View`'s height, width, or location on screen hence the name `moveResize` to better convey what it does.
## Working with custom transitions
In case you have a custom transition class and want to use with the DSL, it is easy to do so.
- If your transition has a `public no arg` constructor then the transition can be added using `customTransition{}` method, transition-x takes care of instantiating the transition. Below example shows usage of `ChangeCardColor` which animates a `CardView`'s `cardBackground` property.
```kotlin
constraintLayout.prepareTransition {
customTransition {
+colorChangeCardView
}
}
```
- If your transition does not have `public no arg` constructor then, you can instantiate the transition yourself and then use `customTransition(transition) {}` instead to add the transition and configure it.
### Accessing custom properties
In addition to the common properties like `startDelay`, `interpolator`, etc, if your transition has custom properties then `customProperties {}` block can be used.
```kotlin
constraintLayout.prepareTransition {
customTransition {
+colorChangeCardView
customProperties {
myProperty = "hi"
}
}
}
```
## Adding, removing and excluding targets
The DSL provides simplified syntax to deal with targets by talking to `Transition`'s add/exclude/remove API.
- Use `+` operator or `add()` to add targets of type `String (Transition Name)` or `View` or `Resource Id`.
```kotlin
transitionSet {
+"TransitionName"
+userIconView
add(userIconView)
}
```
- Use `-` operator or `remove()` to remove targets of type `String (Transition Name)` or `View` or `Resource Id`.
```kotlin
transitionSet {
-"TransitionName"
-userIconView
remove(userIconView)
}
```
- `exclude` and `excludeChildren` methods are provided for excluding targets which can be useful in advanced transitions. It can be used on `Views`, `Resource Ids` or `Type`
```kotlin
transitionSet {
exclude()
exclude(R.id.accentBackground)
excludeChildren(constraintLayout)
}
```
## Interpolators
- **Interpolators** can be directly added using `interpolator` property.
```kotlin
transitionSet {
moveResize()
slide()
interpolator = FastOutLinearInInterpolator()
}
```
- **Easing** - DSL provides a dedicated `ease` block to add interpolators recommended by [material design spec](https://material.io/design/motion/speed.html#easing).
- `standardEasing` - Recommended for views that move within visible area of the layout. Uses `FastOutSlowInInterpolator`
- `decelerateEasing` - Recommended for views that appear/enter outside visible bounds of the layout. Uses `LinearOutSlowInInterpolator`
- `accelerateEasing` - Recommended for Views that exit visible bounds of the layout. Uses `FastOutLinearInInterpolator`
```kotlin
transitionSet {
moveResize()
ease {
decelerateEasing
}
}
```
## Nesting transitions
Often, for fined grained transitions it it necessary to add different transition sets for different targets. It is simple to nest multiple transition sets just by using `transitionSet {}` recursively.
```kotlin
transitionSet {
auto {
+"View 1"
}
transitionSet {
moveResize()
slide()
+"View 2"
}
transitionSet {
sequentially()
fadeOut()
moveResize()
fadeIn()
}
}
```
## Adding listeners to transitions
Transition-X makes it easy to react to `Transition` lifecycle by providing lifecycle methods like `onEnd`, `onStart` which internally uses `Transition.addListener`.
Example:
```kotlin
rootCoordinatorLayout.prepareTransition {
onStart {
// Transition Started!
}
moveResize {
+image1
}
onEnd {
// Transition Ended!
}
}
```
## Additional transitions
The library packages additional transitions not present in the support library and the plan is to add more commonly used transitions to provide a full package. Currently the following transitions are packaged:
- `ChangeText`: Animates changes to a `TextView.text` property.
- `ChangeColor`: Animates changes to `View.background` if it is a `ColorDrawable` or changes to `TextView.textColor` if the target is a `TextView`.
# Samples
Sample
DSL
Demo
Snackbar animation
Snackbar is anchored below FAB. moveResize is used on on FAB since its position changes. Slide is used on Snackbar since it's visibility changes.
constraintLayout.prepareTransition {
moveResize {
+fab
}
slide {
+snackbarMessage
}
ease {
decelerateEasing
}
}
snackbarMessage.toggleGone()
Cascade animation
It is possible to write normal logical code in the prepareTransition block. Here we add moveResize using loops and by adding a start delay based on position, we can emulate a cascade transition.
constraintLayout.prepareTransition {
texts.forEachIndexed { position, view ->
moveResize {
+view
startDelay = ((position + 1) * 150).toLong()
}
}
moveResize { +fab }
ease {
decelerateEasing
}
}
// Layout changes
(if (defaultState) constraint1 else constraint2)
.applyTo(constraintLayout)
Custom Transition
In the following example, ChangeCardColor is a custom transition that animates cardBackgroundColor property of MaterialCardView .
constraintLayout.prepareTransition {
customTransition<ChangeCardColor> {
+cardView
}
changeColor {
+textView
}
duration = 1000
}
// Layout changes
cardView.setCardBackgroundColor(color)
textView.setTextColor(calcForegroundWhiteOrBlack(color))
Arc motion
Here the imageView's gravity is changed from START | CENTER_VERTICAL to TOP | CENTER_HORIZONTAL. By using a pathMotion it is possible to control the motion of the animation to follow material guidelines' arc motion.
frameLayout.prepareTransition {
moveResize {
pathMotion = ArcMotion()
+userIconView
}
}
Advanced choreography
By using techniques above and coupling it with further customization via lifecycle listeners such as onEnd or onPause it is possible to have finer control over the entire transition process. In the example below, notice how different views are configured with different parameters for transition type, interpolation and ordering.
constraintLayout.prepareTransition {
auto {
ease {
standardEasing
}
exclude(metamorphosisDesc2)
}
transitionSet {
fade()
slide()
ease {
accelerateEasing
}
+metamorphosisDesc2
}
changeImage { add(*imageViews) }
onEnd {
constraintLayout.prepareTransition {
moveResize()
changeText {
+collapseButton
changeTextBehavior
= ChangeText.CHANGE_BEHAVIOR_OUT_IN
}
}
collapseButton.setText(R.string.collapse)
}
duration = 300
}
expandConstraint.applyTo(constraintLayout)
metamorphosisDesc2.isGone = false
metamorphosisDesc.isGone = true
Shared element transition
Transition instances created by the DSL can be directly used with activity.window.sharedElementEnterTransition or fragment.sharedElementEnterTransition.
fragment.sharedElementEnterTransition = transitionSet {
transitionSet {
changeImage()
moveResize()
changeClipBounds()
scaleRotate()
ease {
standardEasing
}
duration = 375
+cartItem.cartImageTransitionName()
}
transitionSet {
ease {
standardEasing
}
moveResize()
scaleRotate()
add(cartItem.name, cartItem.price)
duration = 375
}
}
Demo - WIP.
Animated Bottom Navigation
Bottom navigation animation implmentend using custom choreography instead of relying on AutoTransition. The implementation uses ConstraintLayout to define the layouts and then simply show/hides the labels and adds tint to the icons. TransitionManager does the rest.
transitionSet {
fadeOut()
moveResize {
startDelay = 50
ease {
standardEasing
}
}
fadeIn {
startDelay = 50
}
changeColor {
navItems.map { it.text }.forEach { text -> add(text) }
+constraintLayout
}
customTransition {
navItems.map { it.icon }.forEach { icon -> add(icon) }
}
}
# Tasks
- [x] Initial release of Kotlin DSL
- [x] Provide samples for Shared Element Transitions
- [x] Package common transition within the library module
- [ ] Add wiki with best practices and gotchas.
# Contributions
Contributions are welcome! I would greatly appreciate creating an issue to discuss major changes before submitting a PR directly.
How you can help:
- Improving test coverage.
- Finding the DSL not sufficient for your case? Create an issue so we can discuss.
- Adding more animation samples to the sample app.
# License
Copyright 2019, Arunkumar.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.