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package com.mapswithme.maps.widget.recycler;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.support.annotation.NonNull;
import android.support.v7.widget.RecyclerView;
import android.view.View;
/**
* Adds interior dividers to a RecyclerView with a GridLayoutManager.
*/
public class GridDividerItemDecoration extends RecyclerView.ItemDecoration
{
@NonNull
private final Drawable mHorizontalDivider;
@NonNull
private final Drawable mVerticalDivider;
private final int mNumColumns;
/**
* Sole constructor. Takes in {@link Drawable} objects to be used as
* horizontal and vertical dividers.
*
* @param horizontalDivider A divider {@code Drawable} to be drawn on the
* rows of the grid of the RecyclerView
* @param verticalDivider A divider {@code Drawable} to be drawn on the
* columns of the grid of the RecyclerView
* @param numColumns The number of columns in the grid of the RecyclerView
*/
public GridDividerItemDecoration(@NonNull Drawable horizontalDivider,
@NonNull Drawable verticalDivider, int numColumns)
{
mHorizontalDivider = horizontalDivider;
mVerticalDivider = verticalDivider;
mNumColumns = numColumns;
}
/**
* Draws horizontal and/or vertical dividers onto the parent RecyclerView.
*
* @param canvas The {@link Canvas} onto which dividers will be drawn
* @param parent The RecyclerView onto which dividers are being added
* @param state The current RecyclerView.State of the RecyclerView
*/
@Override
public void onDraw(Canvas canvas, RecyclerView parent, RecyclerView.State state)
{
drawHorizontalDividers(canvas, parent);
drawVerticalDividers(canvas, parent);
}
/**
* Determines the size and location of offsets between items in the parent
* RecyclerView.
*
* @param outRect The {@link Rect} of offsets to be added around the child view
* @param view The child view to be decorated with an offset
* @param parent The RecyclerView onto which dividers are being added
* @param state The current RecyclerView.State of the RecyclerView
*/
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state)
{
super.getItemOffsets(outRect, view, parent, state);
boolean childIsInLeftmostColumn = (parent.getChildAdapterPosition(view) % mNumColumns) == 0;
if (!childIsInLeftmostColumn)
outRect.left = mHorizontalDivider.getIntrinsicWidth();
boolean childIsInFirstRow = (parent.getChildAdapterPosition(view)) < mNumColumns;
if (!childIsInFirstRow)
outRect.top = mVerticalDivider.getIntrinsicHeight();
}
/**
* Adds horizontal dividers to a RecyclerView with a GridLayoutManager or
* its subclass.
*
* @param canvas The {@link Canvas} onto which dividers will be drawn
* @param parent The RecyclerView onto which dividers are being added
*/
private void drawHorizontalDividers(Canvas canvas, RecyclerView parent)
{
int parentTop = parent.getPaddingTop();
int parentBottom = parent.getHeight() - parent.getPaddingBottom();
for (int i = 0; i < mNumColumns; i++)
{
View child = parent.getChildAt(i);
RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
int parentLeft = child.getRight() + params.rightMargin;
int parentRight = parentLeft + mHorizontalDivider.getIntrinsicWidth();
mHorizontalDivider.setBounds(parentLeft, parentTop, parentRight, parentBottom);
mHorizontalDivider.draw(canvas);
}
}
/**
* Adds vertical dividers to a RecyclerView with a GridLayoutManager or its
* subclass.
*
* @param canvas The {@link Canvas} onto which dividers will be drawn
* @param parent The RecyclerView onto which dividers are being added
*/
private void drawVerticalDividers(Canvas canvas, RecyclerView parent)
{
int parentLeft = parent.getPaddingLeft();
int parentRight = parent.getWidth() - parent.getPaddingRight();
int childCount = parent.getChildCount();
int numRows = (childCount + (mNumColumns - 1)) / mNumColumns;
for (int i = 0; i < numRows - 1; i++)
{
View child = parent.getChildAt(i * mNumColumns);
RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
int parentTop = child.getBottom() + params.bottomMargin;
int parentBottom = parentTop + mVerticalDivider.getIntrinsicHeight();
mVerticalDivider.setBounds(parentLeft, parentTop, parentRight, parentBottom);
mVerticalDivider.draw(canvas);
}
}
}
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