Keep the range-select anchor across taps in selection mode

[MiMoHo]

Problem

Range selection via long-press only works across two consecutive long-presses. As soon as the user taps a row in between (to select or skip it), the range anchor is lost and the next long-press selects only its own single row.

Concretely, MyRecyclerViewAdapter.viewClicked() always reset lastLongPressedItem = -1 at the end — including when the tap happened inside selection mode. So the common gesture:

1. tap a row to select it,
2. long-press a row several positions later expecting the rows in between to be selected,

does not fill the range, because the tap in step 1 already cleared the anchor. The same applies to “select one, skip one, select the next, then long-press further”.

Fix

While in selection mode, remember the tapped row as the range anchor instead of clearing it. A following long-press then fills in every row between the last touched row and the long-pressed row (which is exactly what itemLongClicked() already does when an anchor exists). Outside selection mode the anchor is cleared as before, so normal single-tap navigation is unchanged.

fun viewClicked(any: Any) {
    if (actModeCallback.isSelectable) {
        val currentPosition = adapterPosition - positionOffset
        val isSelected = selectedKeys.contains(getItemSelectionKey(currentPosition))
        toggleItemSelection(!isSelected, currentPosition, true)
        lastLongPressedItem = currentPosition   // keep the tap as the range anchor
    } else {
        itemClick.invoke(any)
        lastLongPressedItem = -1
    }
}

Behaviour / edge cases

• Not in selection mode: unchanged — itemClick fires and the anchor is cleared.
• Non-selectable positions (section headers etc.): still skipped, because toggleItemSelection() returns early for !getIsItemSelectable(pos), so the range fill only affects selectable rows.
• Drag-select (finger drag): unaffected — selectItemRange() resets lastLongPressedItem itself after a drag.
• Direction: itemLongClicked() uses min/max, so ranges fill both upward and downward.
• Deselect via tap: the anchor also moves to a row that was just deselected, so a following long-press ranges from there — which reads as “range from where I last touched”.

Testing

Verified by tracing every gesture path in viewClicked / viewLongClicked / itemLongClicked / toggleItemSelection / the drag path. A single-adapter behavioural change with no effect on non-selection navigation or drag-select.