ExpectAnim is a Android Kotlin library which give you support to describe your animation and run with Materialize design. If you’re not familiar with this new Android official language then you can see my some previous post:

• How to create first app with Kotlin?
• How Kotlin Anko make development easier?

Now come with this cool library and firstly you must see the demo which is given above:

How to implement ExpectAnim in your application

In your module

Maven

<dependency>
  <groupId>com.github.florent37</groupId>
  <artifactId>expectanim</artifactId>
  <version>1.0.3</version>
  <type>pom</type>
</dependency>

Gradle

compile 'com.github.florent37:expectanim:1.0.3'

Ivy

<dependency org='com.github.florent37' name='expectanim' rev='1.0.3'>
  <artifact name='expectanim' ext='pom' />
</dependency>

This code describe the image above

new ExpectAnim()

                .expect(avatar)
                .toBe(
                        bottomOfParent().withMarginDp(16),
                        leftOfParent().withMarginDp(16),
                        width(40).toDp().keepRatio()
                )

                .expect(name)
                .toBe(
                        toRightOf(avatar).withMarginDp(16),
                        sameCenterVerticalAs(avatar),
                        toHaveTextColor(Color.WHITE)
                )

                .expect(subname)
                .toBe(
                        toRightOf(name).withMarginDp(5),
                        sameCenterVerticalAs(name),
                        toHaveTextColor(Color.WHITE)
                )

                .expect(follow)
                .toBe(
                        rightOfParent().withMarginDp(4),
                        bottomOfParent().withMarginDp(12),
                        toHaveBackgroundAlpha(0f)
                )

                .expect(message)
                .toBe(
                        aboveOf(follow).withMarginDp(4),
                        rightOfParent().withMarginDp(4),
                        toHaveBackgroundAlpha(0f)
                )

                .expect(bottomLayout)
                .toBe(
                        atItsOriginalPosition()
                )

                .expect(content)
                .toBe(
                        atItsOriginalPosition(),
                        visible()
                )

                .toAnimation()
                .setDuration(1500)

                .start();

Follow scroll

Use setPercent to apply modify the current step of the animation

Example with a ScrollView

this.expectAnimMove = new ExpectAnim()
                .expect(username)
                .toBe(
                        toRightOf(avatar).withMarginDp(16),
                        sameCenterVerticalAs(avatar),
                        alpha(0.5f)
                )

                .expect(avatar)
                .toBe(
                        topOfParent(),
                        leftOfParent().withMarginDp(16),
                        scale(0.5f, 0.5f)
                )
                .expect(follow)
                .toBe(
                        rightOfParent().withMarginDp(16),
                        sameCenterVerticalAs(avatar)
                )

                .expect(backbground)
                .toBe(
                        height(height).withGravity(Gravity.LEFT|Gravity.START, Gravity.TOP)
                )

                .toAnimation();

scrollView.setOnScrollChangeListener(new NestedScrollView.OnScrollChangeListener() {
    @Override
    public void onScrollChange(NestedScrollView v, int scrollX, int scrollY, int oldScrollX, int oldScrollY) {
        final float percent = (scrollY * 1f) / v.getMaxScrollAmount();

        expectAnimMove.setPercent(percent);
    }
});

Apply directly

Use setNow to apply directly the transformation

new ExpectAnim()
                .expect(view)
                .toBe(
                        outOfScreen(Gravity.BOTTOM)
                )
                .toAnimation()
                .setNow();

Reset

Use reset to return to the initial state of views

expectAnim.reset():

List of expectations

new ExpectAnim()
                .expect(view)
                .toBe(

                    //.withMargin(marginPx)
                    //.withMarginDp(margin)
                    //.withMarginDimen(R.dimen.margin)

                    toRightOf(view)
                    toLeftOf(view)
                    belowOf(view)
                    aboveOf(view)

                    atItsOriginalPosition()


                    sameCenterAs(view, horizontal, vertical)
                    sameCenterHorizontalAs(view)
                    sameCenterVerticalAs(view)
                    centerInParent(horizontal, vertical)
                    centerVerticalInParent()
                    centerHorizontalInParent()

                    centerBetweenViews(view1, view2, horizontal, vertical)
                    centerBetweenViewAndParent(otherView, horizontal, vertical, toBeOnRight, toBeOnBottom)

                    topOfParent()
                    rightOfParent()
                    bottomOfParent()
                    leftOfParent()

                    alignBottom(otherView)
                    alignTop(otherView)
                    alignLeft(otherView)
                    alignRight(otherView)

                    outOfScreen(gravitiy)  //Gravity.LEFT / Gravity.RIGHT / Gravity.TOP / Gravity.BOTTOM

                    alpha(alpha)
                    sameAlphaAs(otherView)
                    visible()
                    invisible()

                    //.keepRatio()
                    //.withGravity(horizontalGravity, verticalGravity)

                    atItsOriginalScale()

                    scale(scaleX, scaleY)
                    height(height)
                    width(width)
                    sameScaleAs(otherView)
                    sameWidthAs(otherView)
                    sameHeightAs(otherView)


                    toHaveTextColor(textColor)
                    toHaveBackgroundAlpha(alpha)

                    rotated(rotation)
                    vertical(bottomOfViewAtLeft)
                    atItsOriginalRotation()
                )

Proguard

-keep class com.github.florent37.expectanim.*{ *; }
-dontwarn com.github.florent37.expectanim.**

Changelog

In version 1.0.1, it added rotations

In version 1.0.2 , Added flips rotations

flippedHorizontally() flippedVertically() flippedHorizontallyAndVertically() withCameraDistance(1000f)

And in latest version, it added Alpha 0 force view to be INVISIBLE`

Download

Hope you like this tutorial!!