該系列持續更新，喜歡請一鍵三連，感謝各位大佬。
QT5.14.2 參考官方QT助手

QTreeWidget Class

The QTreeWidget class provides a tree view that uses a predefined tree model. More…
QTreeWidget類提供了一個使用預定義樹模型的樹視圖。

Header:#include
qmake:QT += widgets
Inherits:QTreeView

List of all members, including inherited members
所有成員的列表，包括繼承的成員
Obsolete members
過時的成員

properties

columnCount : int
topLevelItemCount : const int

Public Functions

默認構造函數

QTreeWidget::QTreeWidget(QWidget *parent = nullptr)

示例：

// 創建 QTreeWidget 對象
QTreeWidget *tree = new QTreeWidget;
tree->setColumnCount(3);                            // 設置列數為 3
tree->setHeaderLabels({ "Name", "Value", "Data" });   // 設置列標簽
tree->header()->setSectionResizeMode(QHeaderView::ResizeToContents); // 自適應列寬

默認析構函數

QTreeWidget::~QTreeWidget()

添加根節點void addTopLevelItem(QTreeWidgetItem *item)

示例：

// 創建根節點
QTreeWidgetItem *root = new QTreeWidgetItem(tree);
root->setText(0, "Root");
root->setText(1, "0");
root->setData(2, Qt::UserRole, "root data");
tree->addTopLevelItem(root);

添加多個根節點void addTopLevelItems(const QList<QTreeWidgetItem *> &items)

示例：

// 創建根節點
QTreeWidgetItem *root = new QTreeWidgetItem(tree);
root->setText(0, "Root");
root->setText(1, "0");
root->setData(2, Qt::UserRole, "root data");
//tree->addTopLevelItem(root);
QList<QTreeWidgetItem* > all_root_list;
all_root_list.push_back(root);
QTreeWidgetItem *root1 = new QTreeWidgetItem(tree);
root1->setText(0, "Root2");
all_root_list.push_back(root1);
tree->addTopLevelItems(all_root_list);

關閉編輯void closePersistentEditor(QTreeWidgetItem *item, int column = 0)

關閉item編輯器，如果是關閉的則此函數無效。
先打開看效果是這樣的：

tree->openPersistentEditor(root);

然后再調用closePersistentEditor

tree->openPersistentEditor(root);
tree->closePersistentEditor(root);

獲取列數int columnCount() const

qDebug() << "tree->columnCount:"<<tree->columnCount();

返回當前選中列int currentColumn() const

默認-1，點擊選中哪列返回列號，索引從0開始。

qDebug() << "tree->currentColumn:" << tree->currentColumn();
connect(tree, &QTreeWidget::itemClicked, this, [=] {qDebug() << "tree->currentColumn:" << tree->currentColumn();
});

返回當前選中QTreeWidgetItem *currentItem() const

默認是NULL

QTreeWidgetItem* selectItem = tree->currentItem();

沒用void editItem(QTreeWidgetItem *item, int column = 0)

查找滿足條件的item返回QList<QTreeWidgetItem *> findItems(const QString &text, Qt::MatchFlags flags, int column = 0) const

查找包含字符串ro的item，以字符串不分大小寫匹配（第二個參數是匹配規則為枚舉類型詳見qt官方文檔說明）

QList<QTreeWidgetItem*> find_items = tree->findItems("ro",Qt::MatchContains);
for (auto item:find_items)
{qDebug() << item->text(0);
}

返回表頭QTreeWidgetItem *headerItem() const

QTreeWidgetItem* hearderItem = tree->headerItem();
qDebug() << hearderItem->text(0);
qDebug() << hearderItem->text(1);
qDebug() << hearderItem->text(2);
qDebug() << hearderItem->text(3);

返回index索引根據item int indexOfTopLevelItem(QTreeWidgetItem *item) const

只能獲取到top節點索引

qDebug() << tree->indexOfTopLevelItem(nullptr);
qDebug() << tree->indexOfTopLevelItem(root);
qDebug() << tree->indexOfTopLevelItem(child2);
qDebug() << tree->indexOfTopLevelItem(root1);

在指定索引位置插入新的top節點void insertTopLevelItem(int index, QTreeWidgetItem *item)

插入qstring超過列數則不顯示

QStringList insertitem;
insertitem << "insertroot" << "i2" << "2133" << "122344";
tree->insertTopLevelItem(1, new QTreeWidgetItem(insertitem));

插入多個top節點void insertTopLevelItems(int index, const QList<QTreeWidgetItem *> &items)

QStringList insertitem;
insertitem << "insertroot" << "i2" << "2133";
QList<QTreeWidgetItem*> qtree_widget_list;
qtree_widget_list.push_back(new QTreeWidgetItem(insertitem));
insertitem.clear();
insertitem << "insertroot2";
qtree_widget_list.push_back(new QTreeWidgetItem(insertitem));
tree->insertTopLevelItems(0, qtree_widget_list);

遞歸訪問所有根節點 返回一個模擬節點作為所有根節點的父節點QTreeWidgetItem *invisibleRootItem() const

以該形式遍歷所有根節點：

QTreeWidgetItem* one = tree->invisibleRootItem();
int nums = one->childCount();
for (int i=0;i<nums;++i)
{qDebug() << one->child(i)->text(0);
}

節點是否為可編輯狀態bool isPersistentEditorOpen(QTreeWidgetItem *item, int column = 0) const

獲取item是否為可編輯狀態，qt5.10之后版本才有這個函數

qDebug()<< tree->isPersistentEditorOpen(root);
tree->openPersistentEditor(root);
qDebug() << tree->isPersistentEditorOpen(root);
tree->closePersistentEditor(root);
qDebug() << tree->isPersistentEditorOpen(root);

不分層級獲取上層相鄰節點QTreeWidgetItem *itemAbove(const QTreeWidgetItem *item) const

只能獲取到展開節點，所以開始之前先調用expandAll()，否則獲取到的為顯示的相鄰節點。
若沒有顯示出來的上層節點則返回空指針。

tree->expandAll();
QTreeWidgetItem* t1 = tree->itemAbove(root);
if (t1)qDebug() << t1->text(0);
t1 = tree->itemAbove(child1);
if (t1)qDebug() << t1->text(0);
t1 = tree->itemAbove(root1);
if (t1)qDebug() << t1->text(0);

根據坐標返回節點QTreeWidgetItem *itemAt(const QPoint &p) const

樹形控件內部坐標，左上角為0，0點，如果對應坐標沒有節點返回NULL

QPoint* p1 = new QPoint(0, 0);
QTreeWidgetItem* t1 = tree->itemAt(*p1);
if (t1)qDebug() << t1->text(0);
QPoint* p2 = new QPoint(0, 40);
t1 = tree->itemAt(*p2);
if (t1)qDebug() << t1->text(0);

同上直接輸入坐標QTreeWidgetItem *itemAt(int x, int y) const

同上：

返回顯示出的下層節點QTreeWidgetItem *itemBelow(const QTreeWidgetItem *item) const

同itemAbove，只是取得下層節點，沒有下層則返回空指針