RecycleView使用了这么久,一直都是用margin做分割,一方面是自己比较懒,一方面是为了高效开发,一直没有自定义过。最近比较有空,就尝试写写。纸上得来终觉浅,还真的遇到不少问题。
首先来一次正确的打开方式:
public class DividerItemDecoration extends RecyclerView.ItemDecoration
{
/**
* RecyclerView的布局方向,默认先赋值
* 为纵向布局
* RecyclerView 布局可横向,也可纵向
* 横向和纵向对应的分割想画法不一样
* */
private int mOrientation = LinearLayoutManager.VERTICAL ;
private static final int[] ATTRS = new int[] { android.R.attr.listDivider };
/**
* item之间分割线的drawable
*/
private Drawable mDivider;
/**
* 构造方法传入布局方向,不可不传
* @param context
* @param orientation
*/
public DividerItemDecoration(Context context,int orientation) {
this.mOrientation = orientation;
if(orientation != LinearLayoutManager.VERTICAL && orientation != LinearLayoutManager.HORIZONTAL){
throw new IllegalArgumentException("请传入正确的参数") ;
}
final TypedArray a = context.obtainStyledAttributes(ATTRS);
mDivider = a.getDrawable(0);
a.recycle();
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State 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 + mDivider.getIntrinsicHeight() ;
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 + mDivider.getIntrinsicHeight();
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(canvas);
}
}
/**
* 设置item便宜的size
* @param outRect
* @param view
* @param parent
* @param state
*/
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
if(mOrientation == LinearLayoutManager.VERTICAL){
outRect.set(0,0,0, mDivider.getIntrinsicHeight());
}else {
outRect.set(0,0, mDivider.getIntrinsicHeight(),0);
}
}
}
代码基本copy自网上;
- 那么问题来了,如果我想简单设置个高度,不用系统的listDivider,自己画一个巨型分割线该怎么实现呢?我的做法如下:
public class DividerItemDecoration extends RecyclerView.ItemDecoration
{
/*
* RecyclerView的布局方向,默认先赋值
* 为纵向布局
* RecyclerView 布局可横向,也可纵向
* 横向和纵向对应的分割想画法不一样
* */
private int mOrientation = LinearLayoutManager.VERTICAL ;
/**
* item之间分割线的size,默认为1
*/
private int mItemSize = 1 ;
/**
* 绘制item分割线的画笔,和设置其属性
* 来绘制个性分割线
*/
private Paint mPaint ;
/**
* 构造方法传入布局方向,不可不传
* @param context
* @param orientation
*/
public DividerItemDecoration(Context context,int orientation) {
this.mOrientation = orientation;
if(orientation != LinearLayoutManager.VERTICAL && orientation != LinearLayoutManager.HORIZONTAL){
throw new IllegalArgumentException("请传入正确的参数") ;
}
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);
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State 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.getWidth() - 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 ;
canvas.drawRect(left,top,right,bottom,mPaint);
}
}
/**
* 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.getHeight() - 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 ;
canvas.drawRect(left,top,right,bottom,mPaint);
}
}
/**
* 设置item分割线的size
* @param outRect
* @param view
* @param parent
* @param state
*/
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
if(mOrientation == LinearLayoutManager.VERTICAL){
outRect.set(0,0,0,mItemSize);
}else {
outRect.set(0,0,mItemSize,0);
}
}
}
ok,运行:
mItemSize=1的时候,
貌似正常
增大宽度
private int mItemSize = 5 ;
ok,运行:
貌似还是正常
继续增大宽度
private int mItemSize = 6 ;
ok,运行:
我们的分割线被谁吃了!
为了看是没画出来还是没留出偏移空间,继续增大宽度
private int mItemSize = 100 ;
ok,运行:
还是这样,item之间的空隙并没有增加。
why?
- 我这个小菜鸟期待大神给我指点迷津。。。help me~