Selection Mode

Editable/multi-select lists are common in development, and with just a few lines of code, BRV can implement a selection mode: Demo

Multi-select List

1. Create the list:

   rv.linear().setup {
       addType<CheckModel>(R.layout.item_check_mode)
   }.models = getData
   

2. Add a field to the Model for storing the selection state: ```kotlin hl_lines="2" data class CheckModel( var checked: Boolean = false, var visibility: Boolean = false ) : BaseObservable() // BaseObservable is used for DataBinding

3. Listen for selection events:

   rv.linear().setup {
      addType<CheckModel>(R.layout.item_check_mode)
      onChecked { position, isChecked, isAllChecked ->
           val model = getModel<CheckModel>(position)
           model.checked = isChecked
           model.notifyChange() // Notify UI of data changes
      }
   }.models = getData
   

4. Trigger the selection event:

   rv.linear().setup {
      addType<CheckModel>(R.layout.item_check_mode)
      onChecked { position, isChecked, isAllChecked ->
           val model = getModel<CheckModel>(position)
           model.checked = isChecked
           model.notifyChange() // Notify UI of data changes
      }
   
      onClick(R.id.cb, R.id.item) {
           var checked = getModel<CheckModel>().checked
           setChecked(adapterPosition, !checked) // Trigger the selection event when clicking on a list item to select/deselect it
      }
   }.models = getData
   

Default Selection

If you want to default select certain items, you should use the setChecked function instead of directly setting the isChecked property to true in the Model (this won't trigger the selection callback).

For example, in the Demo, there is a line of code that defaults to selecting the first item:

// Toggle selection mode
tv_manage.setOnClickListener {
    adapter.toggle()
    rv.bindingAdapter.setChecked(0, true) // Select the first item initially
}

Data Changes

If the data positions change, such as with additions or deletions, use BindingAdapter.checkedPosition.clear() to clear the selected position collection (or perform necessary operations), otherwise data errors may occur, leading to the inability to single-select.

Functions

Common functions for selection mode support:

Function	Description
allChecked	Select or deselect all items
singleMode	Check if it is in single-selection mode
isCheckedAll	Check if all items are selected
checkedReverse	Reverse the selection
setChecked	Set whether the item at the specified position is selected
checkedSwitch	Toggle the selection state
setCheckableType	Specify the type(s) that can be selected
getCheckedModels	Get the collection of selected data models
checkedPosition	Collection of positions of selected items
checkedCount	Number of items selected
onChecked	Selection callback