Lightweight library to easy implement sectioning and sticky header.
Some decoration use drawable, which gives great performance compared to view.
Important!: this Drawable decorations tested only with LinearLayoutManager, with other it can work incorrectly
add repository in to root build.gradle
allprojects {
repositories {
google()
jcenter()
// this repository
maven {
url "https://dl.bintray.com/osome/decoration"
}
}
}
and add dependency
implementation "com.osome.decoration:sticky:<latest_version>"
Easiest way to integrate sticky header is view holder based decoration ViewHolderStickyDecoration
This decoration also support vertical GridLayoutManager(see example application)
Firstly, you should make implement yours Adapter this interface ViewHolderStickyDecoration.Condition like this:
class SectionItemAdapter : RecyclerView.Adapter<RecyclerView.ViewHolder>(), ViewHolderStickyDecoration.Condition {
override fun isHeader(position: Int): Boolean {
return getItem(position) is SectionItem
}
// other adapter's methods
}
and after it add decoration in to RecyclerView
recyclerView.addItemDecoration(ViewHolderStickyDecoration(recyclerView, adapter))
If you are use reverse layout
recyclerView.addItemDecoration(ViewHolderStickyDecoration(recyclerView, adapter, true))
For GridLayoutManager you should set up SpanSizeLookup, for example
val spanCount = 3
val lm = GridLayoutManager(recycler.context, spanCount)
lm.spanSizeLookup = object : GridLayoutManager.SpanSizeLookup() {
override fun getSpanSize(position: Int): Int {
// here we detect header and make it full width by set up max span
if (adapter.getItemViewType(position) == SectionItemAdapter.TYPE_HEADER)
return spanCount
return 1 // or other value which are you want
}
}
This decoration allows implement sectioning with drawable.
First step:
You should extends abstract class VerticalDrawableSectionDecor and implements two methods
class SectionDecor : VerticalDrawableSectionDecor() {
override fun getDrawable(position: Int, sectionBounds: Rect, child: View): Drawable {
// here you return drawable which will be drawn
}
override fun getSectionHeight(position: Int): Int {
// here you return section height.
// this value uses for calculate drawable bounds for draw
}
}
Second step: Implement interface ConditionItemDecorator.Condition with single method to determine for which adapter item will be drawn section
// here the first element and each 10th element will be split with section
val condition = ConditionItemDecorator.Condition { position ->
(itemProvider.get(position).value + 1) % 10 == 0 || position == 0
}
And finally
val decorator = ConditionItemDecorator(condition, SectionDecor())
recyclerView.addItemDecoration(decorator)
also you can add top and bottom margins for section, just override two methods
override fun getSectionMarginTop(): Int {
// return value for top space
}
override fun getSectionMarginBottom(): Int {
// return value for bottom space
}
In this case drawable will be drawn above item(for reverse layout too)
Full examples here and here
This decoration allows implement sectioning and sticky header with drawable.
First step: You should extends abstract class VerticalStickyDrawableDecor and implement three methods
class StickySectionDecor : VerticalStickyDrawableDecor() {
override fun getSectionHeight(position: Int): Int {
// here you return section height.
// this value uses for calculate drawable bounds for draw
// and by default will be used for header height
}
override fun getHeaderDrawable(position: Int, headerBounds: Rect): Drawable {
// here you return drawable which will be drawn for header
}
override fun getSectionDrawable(position: Int, sectionBounds: Rect, child: View): Drawable {
// here you return drawable which will be drawn for section
}
}
or for reverse layout
class StickySectionDecor : VerticalStickyDrawableDecor(true) { <==== here set in to constructor flag for reverse layout
override fun getSectionHeight(position: Int): Int {
// here you return section height.
// this value uses for calculate drawable bounds for draw
// and by default will be used for header height
}
override fun getHeaderDrawable(position: Int, headerBounds: Rect): Drawable {
// here you return drawable which will be drawn for header
}
override fun getSectionDrawable(position: Int, sectionBounds: Rect, child: View): Drawable {
// here you return drawable which will be drawn for section
}
}
Second step: Implement interface ConditionItemDecorator.Condition with single method to determine for which adapter item will be drawn section
// here the first element and each 10th element will be split with section
val condition = ConditionItemDecorator.Condition { position ->
(itemProvider.get(position).value + 1) % 10 == 0 || position == 0
}
And finally
val decorator = ConditionItemDecorator(condition, StickySectionDecor())
recyclerView.addItemDecoration(decorator)
also you can add top and bottom margins for header, just override two methods
override fun getHeaderMarginTop(): Int {
// return header top space
}
override fun getHeaderMarginBottom(): Int {
// return header bottom space
}
To simplify usage drawable decorator library contains also SimpleTextDrawable class.
This class allow build styled drawable
SimpleTextDrawable.Builder()
.setPaddingSymmetricDp(12, 4)
.setBackgroundColor(Color.LTGRAY)
.setTextGravity(SimpleTextDrawable.SimpleGravity.LEFT)
.setTextColor(Color.BLACK)
.setTextSizeDp(14)
.setTypeface(customTypeFace)
.build()