/**
* 浣胯疆瀛愬け鏁�
*
* @param clearCaches if true then cached views will be clear
*/
public void invalidateWheel(boolean clearCaches) {
if (clearCaches) {
recycle.clearAll();
if (itemsLayout != null) {
itemsLayout.removeAllViews();
}
scrollingOffset = 0;
} else if (itemsLayout != null) {
// cache all items
recycle.recycleItems(itemsLayout, firstItem, new ItemsRange());
}
invalidate();
}
/**
* 杩斿洖鐗瑰畾鐨刬tem
*
* @param index the item index
* @return item view or empty view if index is out of bounds
*/
private View getItemView(int index) {
if (viewAdapter == null || viewAdapter.getItemsCount() == 0) {
return null;
}
int count = viewAdapter.getItemsCount();
if (!isValidItemIndex(index)) {
return viewAdapter.getEmptyItem(recycle.getEmptyItem(), itemsLayout);
} else {
while (index < 0) {
index = count + index;
}
}
index %= count;
return viewAdapter.getItem(index, recycle.getItem(), itemsLayout);
}
/** 閲嶅缓鏂扮殑璁＄畻鏂规硶 */
private void buildViewForMeasuring() {
// clear all items
if (itemsLayout != null) {
recycle.recycleItems(itemsLayout, firstItem, new ItemsRange());
} else {
createItemsLayout();
}
// add views
int addItems = visibleItems / 2;
for (int i = currentItem + addItems; i >= currentItem - addItems; i--) {
if (addViewItem(i, true)) {
firstItem = i;
}
}
}
/**
* 濡傛灉鏈夊繀瑕侀噸鏂伴噸寤鸿疆瀛愮殑item鍜岀紦瀛樻病鏈夌敤鐨刬tem
*
* @return true if items are rebuilt
*/
private boolean rebuildItems() {
boolean updated = false;
ItemsRange range = getItemsRange();
if (itemsLayout != null) {
int first = recycle.recycleItems(itemsLayout, firstItem, range);
updated = firstItem != first;
firstItem = first;
} else {
createItemsLayout();
updated = true;
}
if (!updated) {
updated = firstItem != range.getFirst() || itemsLayout.getChildCount() != range.getCount();
}
if (firstItem > range.getFirst() && firstItem <= range.getLast()) {
for (int i = firstItem - 1; i >= range.getFirst(); i--) {
if (!addViewItem(i, true)) {
break;
}
firstItem = i;
}
} else {
firstItem = range.getFirst();
}
int first = firstItem;
for (int i = itemsLayout.getChildCount(); i < range.getCount(); i++) {
if (!addViewItem(firstItem + i, false) && itemsLayout.getChildCount() == 0) {
first++;
}
}
firstItem = first;
return updated;
}