Android RecyclerView自定义横向分割线实现时间轴

最近项目用到时间轴，用RecyclerView来实现省时省力

首先设置横向LayoutManager

LinearLayoutManager linearLayoutManagerHorizontal = new LinearLayoutManager(this);
linearLayoutManagerHorizontal.setOrientation(LinearLayoutManager.HORIZONTAL);
mRecyclerView.setLayoutManager(linearLayoutManagerHorizontal);

接着写item布局，如下图时间轴中item只是垂直布局中一个ImageView，一个TextView.

时间轴的线是用自定义的ItemDecoration来实现。

有两个构造方法，一个不传居中参照Drawable则时间线以整个item居中，另一个反之。

public class RecyclerDivider extends RecyclerView.ItemDecoration {

private int dividerHeight;
private int dividerWidth;
private Paint mPaint;
private Drawable middleOfDrawable;

public RecyclerDivider(int color, int dividerHeight, int dividerWidth) {
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setColor(color);
mPaint.setStyle(Paint.Style.FILL);
this.dividerHeight = dividerHeight;
this.dividerWidth = dividerWidth;
}

public RecyclerDivider(int color, int dividerHeight, int dividerWidth, Drawable middleOfDrawable) {
this(color, dividerHeight, dividerWidth);
this.middleOfDrawable = middleOfDrawable;
}

@Override
public void onDraw(Canvas canvas, RecyclerView parent, RecyclerView.State state) {
final int childSize = parent.getChildCount();
for (int i = 0; i < childSize - 1; i++) {
final View child = parent.getChildAt(i);
RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) child.getLayoutParams();
int left = child.getRight() + layoutParams.rightMargin;
int right = left + dividerWidth;
int top = 0;
int bottom = 0;
if (middleOfDrawable != null) {
top = middleOfDrawable.getIntrinsicHeight() / 2 - dividerHeight;
bottom = middleOfDrawable.getIntrinsicWidth() / 2 + dividerHeight;
} else {
top = child.getHeight() / 2 - dividerHeight;
bottom = child.getHeight() / 2 + dividerHeight;
}
canvas.drawRect(left, top, right, bottom, mPaint);
}

}

@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
outRect.set(0, 0, dividerWidth, dividerHeight);
}

mRecyclerView.addItemDecoration(new RecyclerDivider(getResources().getColor(R.color.white), 2, 60, getResources().getDrawable(R.mipmap.ic)));