RecyclerView设置分割线
RecyclerView的分割线去设置布局？太low了！
RecyclerView提供了一个类设置分割线，我们需继承 RecyclerView.ItemDecoration
然后绘制分割线。
代码如下：
public class DividerItemDecoration extends RecyclerView.ItemDecoration {
/**
* RecyclerView布局方向，设置默认的
*/
private int mOrientation = LinearLayoutManager.VERTICAL;
/**
* 分割线宽度
*/
private int mItemSize = 1;
/**
* 画笔
*/
private Paint mPaint;
private Drawable mDivider;
private static final int[] ATTRS = new int[]{
android.R.attr.listDivider
};
public DividerItemDecoration(Context context, int orientation) {
this.mOrientation = orientation;
if (orientation != LinearLayoutManager.VERTICAL && orientation != LinearLayoutManager.HORIZONTAL) {
throw new IllegalArgumentException("请传入正确参数");
}
mItemSize = (int) TypedValue.applyDimension(mItemSize, TypedValue.COMPLEX_UNIT_DIP, context.getResources().getDisplayMetrics());
mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
mPaint.setColor(Color.BLUE);
/*设置填充*/
mPaint.setStyle(Paint.Style.FILL);
}
public DividerItemDecoration(Context context, int orientation,String na) {
final TypedArray a = context.obtainStyledAttributes(ATTRS);
mDivider = a.getDrawable(0);
a.recycle();
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
super.onDraw(c, parent, state);
if (mOrientation == LinearLayoutManager.VERTICAL) {
drawVertical(c, parent);
} else {
drawHorizontal(c, parent);
}
}
/**
* 绘制纵向 item 分割线
*
* @param canvas
* @param parent
*/
private void drawVertical(Canvas canvas, RecyclerView parent) {
final int left = parent.getPaddingLeft();
final int right = parent.getMeasuredWidth() - parent.getPaddingRight();
final int childSize = parent.getChildCount();
for (int i = 0; i < childSize; i++) {
final View child = parent.getChildAt(i);
RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) child.getLayoutParams();
final int top = child.getBottom() + layoutParams.bottomMargin;
final int bottom = top + mItemSize;
if (mPaint==null){
canvas.drawRect(left, top, right, bottom, mPaint);
}else {
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(canvas);
}
}
}
/**
* 绘制横向 item 分割线
*
* @param canvas
* @param parent
*/
private void drawHorizontal(Canvas canvas, RecyclerView parent) {
final int top = parent.getPaddingTop();
final int bottom = parent.getMeasuredHeight() - parent.getPaddingBottom();
final int childSize = parent.getChildCount();
for (int i = 0; i < childSize; i++) {
final View child = parent.getChildAt(i);
RecyclerView.LayoutParams layoutParams = (RecyclerView.LayoutParams) child.getLayoutParams();
final int left = child.getRight() + layoutParams.rightMargin;
final int right = left + mItemSize;
if (mPaint==null){
canvas.drawRect(left, top, right, bottom, mPaint);
}else {
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(canvas);
}
}
}
//设置偏移量
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
super.getItemOffsets(outRect, view, parent, state);
if (mOrientation == LinearLayoutManager.VERTICAL) {
outRect.set(0, 0, 0, mItemSize);
} else {
outRect.set(0, 0, mItemSize, 0);
}
}
}
首先获取到布局的方向，根据方向绘制间隔 也就是在onDraw方法中。先判断后执行。
绘制间隔线有两种方法一种是画笔直接画，一种是自定义Drawable绘制。这里给了两个构造方法，两个参数的是画笔
三个参数的是Drawable，第三个参数直接传null就行了。
最后要设置偏移量，在getItemOffsets中。
上面只是线性布局的分割线的设置，网格布局的分割线怎么设置呢？
网格布局的分割线则比较麻烦，直接上代码
public class DividerGridItemDecoration extends RecyclerView.ItemDecoration {
private static final int[] ATTRS = new int[]{android.R.attr.listDivider};
private Drawable mDivider;
public DividerGridItemDecoration(Context context) {
final TypedArray a = context.obtainStyledAttributes(ATTRS);
mDivider = a.getDrawable(0);
a.recycle();
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
drawHorizontal(c, parent);
drawVertical(c, parent);
}
private int getSpanCount(RecyclerView parent) {
// 列数
int spanCount = -1;
RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
spanCount = ((GridLayoutManager) layoutManager).getSpanCount();
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
spanCount = ((StaggeredGridLayoutManager) layoutManager).getSpanCount();
}
return spanCount;
}
/**
* 绘制纵向分割线
*
*/
public void drawHorizontal(Canvas c, RecyclerView parent) {
int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
.getLayoutParams();
final int left = child.getLeft() - params.leftMargin;
final int right = child.getRight() + params.rightMargin
+ mDivider.getIntrinsicWidth();
final int top = child.getBottom() + params.bottomMargin;
final int bottom = top + mDivider.getIntrinsicHeight();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
public void drawVertical(Canvas c, RecyclerView parent) {
final int childCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
final View child = parent.getChildAt(i);
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child
.getLayoutParams();
final int top = child.getTop() - params.topMargin;
final int bottom = child.getBottom() + params.bottomMargin;
final int left = child.getRight() + params.rightMargin;
final int right = left + mDivider.getIntrinsicWidth();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
}
}
private boolean isLastColum(RecyclerView parent, int pos, int spanCount,
int childCount) {
RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
if ((pos + 1) % spanCount == 0) {// 如果是最后一列，则不需要绘制右边
return true;
}
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
int orientation = ((StaggeredGridLayoutManager) layoutManager)
.getOrientation();
if (orientation == StaggeredGridLayoutManager.VERTICAL) {
if ((pos + 1) % spanCount == 0) {// 如果是最后一列，则不需要绘制右边
return true;
}
} else {
childCount = childCount - childCount % spanCount;
if (pos >= childCount)// 如果是最后一列，则不需要绘制右边
return true;
}
}
return false;
}
private boolean isLastRaw(RecyclerView parent, int pos, int spanCount, int childCount) {
RecyclerView.LayoutManager layoutManager = parent.getLayoutManager();
if (layoutManager instanceof GridLayoutManager) {
childCount = childCount - childCount % spanCount;
if (pos >= childCount)// 如果是最后一行，则不需要绘制底部
return true;
} else if (layoutManager instanceof StaggeredGridLayoutManager) {
int orientation = ((StaggeredGridLayoutManager) layoutManager)
.getOrientation();
// StaggeredGridLayoutManager 且纵向滚动
if (orientation == StaggeredGridLayoutManager.VERTICAL) {
childCount = childCount - childCount % spanCount;
// 如果是最后一行，则不需要绘制底部
if (pos >= childCount)
return true;
} else { // StaggeredGridLayoutManager 且横向滚动
// 如果是最后一行，则不需要绘制底部
if ((pos + 1) % spanCount == 0) {
return true;
}
}
}
return false;
}
@Override
public void getItemOffsets(Rect outRect, int itemPosition, RecyclerView parent) {
int spanCount = getSpanCount(parent);
int childCount = parent.getAdapter().getItemCount();
if (isLastRaw(parent, itemPosition, spanCount, childCount)) {// 如果是最后一列，则不需要显示右边分割线
outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0);
} else if (isLastColum(parent, itemPosition, spanCount, childCount)) {// 如果是最后一行，则不需要显示底部分割线
outRect.set(0, 0, 0, mDivider.getIntrinsicHeight());
} else {
outRect.set(0, 0, mDivider.getIntrinsicWidth(),
mDivider.getIntrinsicHeight());
}
}
}
在onDraw中有连个方法：drawHorizontal 与drawVertical分别是绘制纵向分割线 绘制横向分割线
最后设置偏移量getItemOffsets这里就要做判断是否显示分割线
isLastRaw判断如果是最后一列，则不需要显示右边分割线
isLastColum如果是最后一行，则不需要显示底部分割线
使用：
recyclerView.addItemDecoration(new DividerGridItemDecoration(this));