最近项目中，有需求去写一个九宫格的菜单，因为之前有用RecycleView，知道去设置不同的setLayoutManager，就会呈现出不同的列表样式。列表样式出来，但是还要加分隔线啊，到这里，就需要去重写RecyclerView.ItemDecoration，可以定制各种各样的分割线。
下面是我们需求需要的分割线：
上面就是我们需要的分割线，我们需求需要的是第二种，list.size()%column!=0时，bottomline占满屏幕宽度。这里我顺便把不占满屏幕的bottomline也画出来了。
这里mColumn默认为3，大家可以根据需求，来随意设置你需要的mColumn的值
具体写法：
public class RecyclerGridDecoration extends RecyclerView.ItemDecoration {
private int[] attrs = new int[]{
android.R.attr.listDivider
};
private Drawable divider;
private int mColumn;
private Context mContext;
private int mTotalCount;
private boolean isAllScreen;
public RecyclerGridDecoration(Context context, int column, int totalCount) {
super();
mContext = context;
TypedArray typedArray = context.obtainStyledAttributes(attrs);
divider = typedArray.getDrawable(0);
mTotalCount = totalCount;
mColumn = column;
}
//bottomLine是否占满屏幕
public void isAllScreen(boolean isAllScreen) {
this.isAllScreen = isAllScreen;
}
@Override
public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {
super.onDraw(c, parent, state);
drawLine(parent, c);
}
private void drawLine(RecyclerView parent, Canvas c) {
Paint paint = new Paint();
paint.setColor(mContext.getResources().getColor(R.color.colorAccent));
//设置画笔的宽度，这里的宽度需要和getItemOffsets()方法中的
//left、top、right、bottom值的关系处理好，否则显示的效果会不理想
paint.setStrokeWidth(Px2DpUtil.dp2px(mContext, 0.5f));
//获得RecyclerView中总条目数量
int childCount = parent.getChildCount();
mTotalCount = parent.getChildCount();
for (int i = 0; i < childCount; i++) {
//假设如果有一个header，就需要if判断i==0的情况，不需要去画线。
// 几个header就需要去处理几次，即continue几次
// if (i == 0) {
// //如果是第一个item，我们就不用画边框了
// continue;
// }
//获取每个子View，画上边框
View childView = parent.getChildAt(i);
//先获得子View在屏幕上的位置和它自身的宽高，利用这些参数去画线
float x = childView.getX();
float y = childView.getY();
float width = childView.getWidth();
float height = childView.getHeight();
if (i % mColumn == 0) {
View view = parent.getChildAt(i);
float x1 = view.getX();
float y1 = view.getY();
//top
c.drawLine(x1, y1, ScreenUtil.getScreenWidth(), y1, paint);
}
if ((i + 1) % mColumn != 0) {
//right
c.drawLine(x + width, y, x + width, y + height, paint);
}
int remainder = mTotalCount % mColumn;
int temp = mTotalCount - i;
if (isAllScreen) {
//不满足list.size()%column==0，bottomLine全屏
if ((temp <= remainder) || (temp <= mColumn && remainder == 0)) {
//bottom
c.drawLine(x, y + height, ScreenUtil.getScreenWidth(), y + height, paint);
//right
c.drawLine(x + width, y, x + width, y + height + divider.getIntrinsicHeight() / 2, paint);
}
} else {//不满足list.size()%column==0，bottomLine不全屏
if ((temp <= remainder) || (temp <= mColumn && remainder == 0)) {
//bottom
c.drawLine(x, y + height, x + width, y + height, paint);
//right
c.drawLine(x + width, y, x + width, y + height + divider.getIntrinsicHeight() / 2, paint);
}
}
}
}
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State
state) {
int left = 0;
int top = 0;
int right = 0;
int bottom = 0;
int position = parent.getChildLayoutPosition(view);
int remainder = mTotalCount % mColumn;
int temp = mTotalCount - position;
//这里判断，是为了list.size()%column==0且是最后一列
//或者最后一列有余数，在这两种情况下，才需要去画bottomLine
if ((temp <= remainder) || (temp <= mColumn && remainder == 0)) {
//设置bottom留的边框值，这样画的bottomLine才能看见
bottom = divider.getIntrinsicHeight();
}
outRect.set(left, top, right, bottom);
}
}
使用方式：
public class RecyclerViewGridManagerActivity extends AppCompatActivity {
private int mColumn;
private RecyclerView mRv;
private RecyclerView mRv1;
private RecyclerView mRv2;
List<Image> lists = new ArrayList<>();
List<Image> lists1 = new ArrayList<>();
List<Image> lists2 = new ArrayList<>();
@Override
protected void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_recycler_view_grid_manager_layout);
mRv = (RecyclerView) findViewById(R.id.id_rv);
mRv1 = (RecyclerView) findViewById(R.id.id_rv1);
mRv2 = (RecyclerView) findViewById(R.id.id_rv2);
//list.size()
int count = 6;
for (int i = 0; i < count; i++) {
Image image = new Image();
image.setTitle("title" + i);
image.setResId(R.drawable.ic_launcher);
lists.add(image);
}
//列数
mColumn = 3;
noramlBottom();
//修改list.size()
count = 7;
for (int i = 0; i < count; i++) {
Image image = new Image();
image.setTitle("title" + i);
image.setResId(R.drawable.ic_launcher);
lists1.add(image);
}
remainderNum();
//再一次修改list.size()
count = 8;
for (int i = 0; i < count; i++) {
Image image = new Image();
image.setTitle("title" + i);
image.setResId(R.drawable.ic_launcher);
lists2.add(image);
}
remainderNum1();
}
//正常画bottomline
private void noramlBottom() {
final RecyclerGridDecoration2 lineService = new RecyclerGridDecoration2(this, mColumn, lists.size());
GridLayoutManager managerService = new GridLayoutManager(this, mColumn);
mRv.addItemDecoration(lineService);
mRv.setLayoutManager(managerService);
GridAdapter mGridAdapter = new GridAdapter(this);
mGridAdapter.append(lists);
mRv.setAdapter(mGridAdapter);
}
//有余数，bottomLine全屏
private void remainderNum() {
final RecyclerGridDecoration2 lineService = new RecyclerGridDecoration2(this, mColumn, lists1.size());
lineService.isAllScreen(true);
GridLayoutManager managerService = new GridLayoutManager(this, mColumn);
mRv1.addItemDecoration(lineService);
mRv1.setLayoutManager(managerService);
GridAdapter mGridAdapter = new GridAdapter(this);
mGridAdapter.append(lists1);
mRv1.setAdapter(mGridAdapter);
}
//有余数，bottomLine不全屏
private void remainderNum1() {
final RecyclerGridDecoration2 lineService = new RecyclerGridDecoration2(this, mColumn, lists2.size());
GridLayoutManager managerService = new GridLayoutManager(this, mColumn);
mRv2.addItemDecoration(lineService);
mRv2.setLayoutManager(managerService);
GridAdapter mGridAdapter = new GridAdapter(this);
mGridAdapter.append(lists2);
mRv2.setAdapter(mGridAdapter);
}
//Model
class Image {
private String title;
private int resId;
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
public int getResId() {
return resId;
}
public void setResId(int resId) {
this.resId = resId;
}
}
//Adapter
class GridAdapter extends RecyclerView.Adapter<GridAdapter.GridHolder> {
private Context mContext;
private List<Image> lists;
public GridAdapter(Context context) {
mContext = context;
}
public void append(List<Image> list) {
lists = list;
notifyDataSetChanged();
}
@Override
public GridAdapter.GridHolder onCreateViewHolder(ViewGroup parent, int viewType) {
return new GridHolder(LayoutInflater.from(mContext).inflate(R.layout.recycler_grid_item, parent, false));
}
@Override
public void onBindViewHolder(GridAdapter.GridHolder holder, int position) {
holder.ivIcon.setImageResource(lists.get(position).getResId());
holder.tvTitle.setText(lists.get(position).getTitle());
}
@Override
public int getItemCount() {
return lists.size();
}
class GridHolder extends RecyclerView.ViewHolder {
private ImageView ivIcon;
private TextView tvTitle;
public GridHolder(View itemView) {
super(itemView);
ivIcon = (ImageView) itemView.findViewById(R.id.iv_icon);
tvTitle = (TextView) itemView.findViewById(R.id.tv_title);
GridLayoutManager.LayoutParams params = (GridLayoutManager.LayoutParams) itemView.getLayoutParams();
params.width = LinearLayout.LayoutParams.MATCH_PARENT;
params.height = ScreenUtil.getScreenWidth() / mColumn;
itemView.setLayoutParams(params);
}
}
}
}
activity.xml
<?xml version="1.0" encoding="utf-8"?>
<ScrollView
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:text="list.size()%column=0时,正常画"
android:textColor="@color/black"
android:textSize="20sp"/>
<android.support.v7.widget.RecyclerView
android:id="@+id/id_rv"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:text="list.size()%column有余数时,bottomline 全屏"
android:textColor="@color/black"
android:textSize="20sp"/>
<android.support.v7.widget.RecyclerView
android:id="@+id/id_rv1"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="20dp"/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5dp"
android:text="list.size()%column有余数时,bottomline 不全屏"
android:textColor="@color/black"
android:textSize="20sp"/>
<android.support.v7.widget.RecyclerView
android:id="@+id/id_rv2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginBottom="20dp"
android:layout_marginTop="20dp"/>
</LinearLayout>
</ScrollView>
recycler_grid_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:clickable="true"
android:orientation="vertical">
<ImageView
android:id="@+id/iv_icon"
android:layout_width="40dp"
android:layout_height="40dp"
android:layout_gravity="center_horizontal"
tools:background="#d71345"
android:scaleType="centerCrop"/>
<TextView
android:id="@+id/tv_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center"
android:layout_marginTop="10dp"
tools:text="标题"
/>
</LinearLayout>
好了，自定义ItemDecoration到这里就全部结束了，感谢观看。
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