RecyclerView 添加分割线

1默认分割线

image.png

//默认分割线 水平分割线
                recyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.VERTICAL));
//默认分割线 竖直分割线
                recyclerView.addItemDecoration(new DividerItemDecoration(this, DividerItemDecoration.HORIZONTAL));

2自定义分割线样式

image.png

                dv = new DividerItemDecoration(this, DividerItemDecoration.VERTICAL);
                dh = new DividerItemDecoration(this, DividerItemDecoration.HORIZONTAL);
                dv.setDrawable(getResources().getDrawable(R.drawable.divideritemdecoration_v));
                dh.setDrawable(getResources().getDrawable(R.drawable.divideritemdecoration_h));
                recyclerView.addItemDecoration(dv);
                recyclerView.addItemDecoration(dh);

divideritemdecoration_v

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <size android:height="5dp"/>
    <gradient android:startColor="@android:color/holo_red_dark" android:angle="45"
        android:centerColor="@color/colorPrimaryDark"
        android:endColor="@android:color/holo_orange_dark"/>
</shape>

divideritemdecoration_h

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
<size android:width="5dp"/>
  <gradient android:startColor="@android:color/holo_green_light"
      android:angle="90"
      android:centerColor="@color/colorPrimaryDark"
      android:endColor="@android:color/holo_blue_dark"/>
</shape>

2自定义分割线样式 去除底部右边分割线

继承 RecyclerView.ItemDecoration
重写方法

• onDraw
• setDrawable
• getItemOffsets

 public void setDrawable(@NonNull Drawable drawable) {
        if (drawable == null) {
            throw new IllegalArgumentException("Drawable cannot be null.");
        } else {
            this.mDivider = drawable;
        }
    }

    public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
        if (parent.getLayoutManager() != null && this.mDivider != null) {
            if (this.mOrientation == 1) {
                this.drawVertical(c, parent); //绘制分割线要忽略最后一行
            } else {
                this.drawHorizontal(c, parent);//绘制分割线要忽略最后一列
            }

        }
    }
//  itemview的偏移就在此
    public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {
        if (this.mDivider == null) {
            outRect.set(0, 0, 0, 0);
        } else {
            if (this.mOrientation == 1) {
//最后一列不偏移
                outRect.set(0, 0, 0,parent.getAdapter().getItemCount()-parent.getChildAdapterPosition(view)<=parent.getAdapter().getItemCount()%spancount?0:this.mDivider.getIntrinsicHeight());
            } else {
//最后一行不偏移
                outRect.set(0, 0, parent.getChildAdapterPosition(view)%spancount!=(spancount-1)?this.mDivider.getIntrinsicWidth():0, 0);
            }

        }
    }

问题

我们的自定义分割线宽度过大导致 界面绘制时最后列右边留白，最后行底部留白
解决问题

// t top  l left  r right  b bottom
//偏移距离
//vindex  行
//hspancount 总行
//hindex  列
//spancount 总列

private int t(int vindex, int hspancount) {
        return vindex*mDivider_V.getIntrinsicHeight()/hspancount;
    }

    private int b(int vindex, int hspancount) {
        return (hspancount-1-vindex)*mDivider_V.getIntrinsicHeight()/hspancount;

    }

    private int l(int hindex) {
        return mDivider_H.getIntrinsicWidth()*hindex/spancount;
    }

    private int r(int hindex) {
        return (spancount-1-hindex)*mDivider_H.getIntrinsicWidth()/spancount;
    }

image.png

源码 https://github.com/fzbbihailantian/RecycleView