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@momvart
Last active August 19, 2020 10:37
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An item decoration for recyclerview which adds margin between items.
import android.content.Context
import android.graphics.Rect
import android.util.LayoutDirection
import android.view.View
import androidx.annotation.DimenRes
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
class MarginItemDecoration(
private val marginLeft: Int,
private val marginTop: Int,
private val marginRight: Int,
private val marginBottom: Int
) : RecyclerView.ItemDecoration() {
companion object {
fun all(context: Context, @DimenRes resId: Int): MarginItemDecoration {
val margin = context.resources.getDimensionPixelSize(resId)
return MarginItemDecoration(margin, margin, margin, margin)
}
fun bottom(context: Context, @DimenRes resId: Int): MarginItemDecoration {
val margin = context.resources.getDimensionPixelSize(resId)
return MarginItemDecoration(0, 0, 0, margin)
}
}
override fun getItemOffsets(
outRect: Rect, view: View,
parent: RecyclerView, state: RecyclerView.State
) {
with(outRect) {
left = marginLeft
top = marginTop
right = marginRight
bottom = marginBottom
}
}
}
class MarginGridItemDecoration(private val margin: Int) : RecyclerView.ItemDecoration() {
private val halfMargin = margin / 2
override fun getItemOffsets(
outRect: Rect,
view: View,
parent: RecyclerView,
state: RecyclerView.State
) {
outRect.bottom = margin
val colCount = (parent.layoutManager as GridLayoutManager).spanCount
val (colIndex, colSize) = (view.layoutParams as GridLayoutManager.LayoutParams).run { spanIndex to spanSize }
val isRtl = parent.layoutDirection == LayoutDirection.RTL
if (colIndex == 0) //First column
outRect.setStart(isRtl, margin)
else //colIndex > 0 //Middle
outRect.setStart(isRtl, halfMargin)
if (colIndex + colSize == colCount) //Last column
outRect.setEnd(isRtl, margin)
else //colIndex + colSize < colCount //Middle
outRect.setEnd(isRtl, halfMargin)
}
}
fun Rect.setStart(isRtl: Boolean, start: Int) =
if (!isRtl) left = start
else right = start
fun Rect.setEnd(isRtl: Boolean, end: Int) =
if (!isRtl) right = end
else left = end
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