Add DividerItemDecoration.kt

app/src/main/java/chat/rocket/android/widget/DividerItemDecoration.kt

+package chat.rocket.android.widget
+
+import android.content.Context
+import android.graphics.Canvas
+import android.graphics.drawable.Drawable
+import android.support.annotation.DrawableRes
+import android.support.v4.content.ContextCompat
+import android.support.v7.widget.RecyclerView
+
+/**
+ * Adds a default or custom divider to specific item views from the adapter's data set.
+ * @see RecyclerView.ItemDecoration
+ */
+class DividerItemDecoration() : RecyclerView.ItemDecoration() {
+    private lateinit var divider: Drawable
+    private var boundStart = 0
+    private var boundRight = 0
+
+    // Default divider will be used.
+    constructor(context: Context) : this() {
+        val attrs = intArrayOf(android.R.attr.listDivider)
+        val styledAttributes = context.obtainStyledAttributes(attrs)
+        divider = styledAttributes.getDrawable(0)
+        styledAttributes.recycle()
+    }
+
+    // Default divider with custom boundaries (start and right) will be used.
+    constructor(context: Context, boundStart: Int, boundRight: Int) : this() {
+        val attrs = intArrayOf(android.R.attr.listDivider)
+        val styledAttributes = context.obtainStyledAttributes(attrs)
+        divider = styledAttributes.getDrawable(0)
+        styledAttributes.recycle()
+
+        this.boundStart = boundStart
+        this.boundRight = boundRight
+    }
+
+    // Custom divider will be used.
+    constructor(context: Context, @DrawableRes drawableResId: Int) : this() {
+        val customDrawable = ContextCompat.getDrawable(context, drawableResId)
+        if (customDrawable != null) {
+            divider = customDrawable
+        }
+    }
+
+    override fun onDraw(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {
+        val left = parent.paddingLeft + boundStart
+        val right = (parent.width - parent.paddingRight) - boundRight
+
+        val childCount = parent.childCount
+        for (i in 0 until childCount) {
+            val child = parent.getChildAt(i)
+
+            val params = child.layoutParams as RecyclerView.LayoutParams
+
+            val top = child.bottom + params.bottomMargin
+            val bottom = top + divider.intrinsicHeight
+
+            divider.setBounds(left, top, right, bottom)
+            divider.draw(c)
+        }
+    }
+}
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