Super simple, basic, bouncy RecyclerView in Kotlin.
This is in no-way the best sollution to this problem/feature, it was more just something I messed around with and wanted to test out sharing aac libraries via bintray too!
This is a simple, "bouncy" RecyclerView with a few extra features to help support some basic use cases. Its not physics based, its just a simple overscroll handler that animates back in place when released (touch up).
Below are some example uses and the attributes you can use to achieve those results.
Current version is at 0.0.5
To include SimpleBouncyRecyclerView in your project, add it to your App build.gradle dependency
dependencies {
compile "com.stanford:simplebouncyrecycler:0.0.5"
}You may also need to add jcenter to your repositories in your project build.gradle
repositories {
..
jcenter()
}Once included in your apps gradle, usage is very simple. Just add a com.stanford.simplebouncyrecycler.views.SimpleBouncyRecyclerView to your layout axml.
<com.stanford.simplebouncyrecycler.views.SimpleBouncyRecyclerView
android:id="@+id/list_view"
android:layout_width="match_parent"
android:layout_height="match_parent" />Thats it! By default, you should see your RecyclerView "bouncing". This works for both Vertical and Horizontal RecyclerViews.
- Note: Do NOT set the RecyclerView LayoutManager to something else.You can set Vertical/Horizontal scrolling via the 'orientation' attribute on the recyclerview itself, i.e.
<com.stanford.simplebouncyrecycler.views.SimpleBouncyRecyclerView
android:id="@+id/list_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal"/> //Additional orientation being setThe full optional settings would look like...
<com.stanford.simplebouncyrecycler.views.SimpleBouncyRecyclerView
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/list_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:startIndexOffset="2"
app:endIndexOffset="1"
app:startOverscrollColor="#dddddd"
app:endOverscrollColor="#000000FF"
app:friction="1.0"
app:tension="1.0" />Similarly, you can access these values in code too...
var simpleBouncyRecyclerView: SimpleBouncyRecyclerView = findViewById(R.id.list_view)
simpleBouncyRecyclerView.startIndexOffset = 1
simpleBouncyRecyclerView.endIndexOffset = 1
simpleBouncyRecyclerView.tension = 0.75f
simpleBouncyRecyclerView.friction = 1.0f
simpleBouncyRecyclerView.endOverscrollColor = Color.RED
simpleBouncyRecyclerView.startOverscrollColor = resources.getColor(R.color.colorAccent)There are a few settings you can apply both in the axml directly, and also in code via exposed properties in the SimpleBouncyRecyclerView.
friction - A 'faked' physics property that will alter how much you can 'pull' the recycler view, and how much it will overscroll on a fling. By default this is 1.0, the higher the value the less you will be able to 'pull' the recycler view (2.0 would half the amount, 0.5 would double it)
tension - A 'faked' physics property that simple alters the speed at which the recyler view will animate back into place. The default is 1.0. A higher value will result in the recyler view snapping back to its origin quicker. 2.0 would animate back twice as fast, 0.5 would animate back twice as slow.
startIndexOffset - This allows you to offset where the "bounce" happens at the start of the recyler view, for example after a Header Cell (see examples below). Default is 0 so the bounce is at the top of the recycler view.
endIndexOffset - This allows you to offset where the "bounce" happens at the end of the recyler view, for example after a Footer Cell (see examples below). Default is 0 so the bounce is at the bottom of the recycler view.
startOverscrollColor - This is a color resource to denote what the overscroll area at the start of the recyler view looks like. By default its transparent but you might have a usage where you want the color to match a Header Cell or something similar. See examples below.
endOverscrollColor - This is a color resource to denote what the overscroll area at the end of the recyler view looks like. By default its transparent but you might have a usage where you want the color to match a Footer Cell or something similar. See examples below.
This is the basic usage, no settings altered.
Next, you can see the effect of startIndexOffset, a header cell has been added thats inside the RecyclerView itself, when theres no offset set, the header also bounces, by setting startIndexOffset=1 in the axml, the header now remains static and is 'outside' the bounce.
Here you can see the same effect with endIndexOffset, a footer cell has been added and again you can see both before (endIndexOffset=0) shows the footer bouncing, and after (endIndexOffset=1) of the footer being outside the bounce.
The final examples show the usage of the startOverscrollColor (endOverscrollColor works in the same fashion, just at the end!). By default, the overscroll bounce region is transparent, but you may want to set a color for that region to produce different effects. New section cells have been added into the list (so now it goes, Header, Section, Items at the top).
The first gif shows the default behaviour when startIndexOffset=1 for the header cell. The Section cell bounces too and theres white space above it. The second gif shows how if you set startOverscrollColor to be the same as the section color, then it that overscroll region makes it appear like the section cell expands.
Similarly, you could set the offset to be startIndexOffset=2 so the top section also remains clamped. Again the first gif shows the default overscroll color of transaprent and the second gif shows the startOverscrollColor being set to the same color as the section, giving a similar illusion of the section cell expanding above, but with the text appeared to be clamped differently!
Really, you'll possibly find no use of the startOverscrollColor or endOverscrollColor but they are there for if you need them.