当选中顶层的树形节点时，子节点全部被选中，当取消顶层树形节点时，子节点全部被取消选中状态，而当选中子节点时，父节点显示部分选中的状态。
要实现这种界面其实很简单的。在Qt的设计器中，拖出一个QTreeWidget，然后在主窗口中写一个函数init初始化界面，连接树形控件的节点改变 信号itemChanged(QTreeWidgetItem* item, int column)，实现这个信号的即可。下面是具体代码：
ui->setupUi(this); init(); connect(ui->treeWidget,SIGNAL(itemChanged(QTreeWidgetItem*,int)),this,SLOT(treeItemChanged(QTreeWidgetItem*,int))); void TreeWidgetTest::init()
{
ui.treeWidget->clear();
//第一个分组
QTreeWidgetItem *group1 = new QTreeWidgetItem(ui.treeWidget);
group1->setText(0, "group1");
group1->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
group1->setCheckState(0, Qt::Unchecked);
QTreeWidgetItem *subItem11 = new QTreeWidgetItem(group1);
subItem11->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
subItem11->setText(0, "subItem11");
subItem11->setCheckState(0, Qt::Unchecked);
QTreeWidgetItem *subItem12 = new QTreeWidgetItem(group1);
subItem12->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
subItem12->setText(0, "subItem12");
subItem12->setCheckState(0, Qt::Unchecked);
QTreeWidgetItem *subItem13 = new QTreeWidgetItem(group1);
subItem13->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
subItem13->setText(0, "subItem13");
subItem13->setCheckState(0, Qt::Unchecked);
QTreeWidgetItem *subItem14 = new QTreeWidgetItem(group1);
subItem14->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
subItem14->setText(0, "subItem14");
subItem14->setCheckState(0, Qt::Unchecked);
//第二个分组
QTreeWidgetItem *group2 = new QTreeWidgetItem(ui.treeWidget);
group2->setText(0, "group2");
group2->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
group2->setCheckState(0, Qt::Unchecked);
QTreeWidgetItem *subItem21 = new QTreeWidgetItem(group2);
subItem21->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
subItem21->setText(0, "subItem21");
subItem21->setCheckState(0, Qt::Unchecked);
QTreeWidgetItem *subItem22 = new QTreeWidgetItem(group2);
subItem22->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
subItem22->setText(0, "subItem22");
subItem22->setCheckState(0, Qt::Unchecked);
QTreeWidgetItem *subItem23 = new QTreeWidgetItem(group2);
subItem23->setFlags(Qt::ItemIsUserCheckable | Qt::ItemIsEnabled | Qt::ItemIsSelectable);
subItem23->setText(0, "subItem23");
subItem23->setCheckState(0, Qt::Unchecked);
}
void holidayquery::treeItemChanged(QTreeWidgetItem *item, int column){ if(Qt::Checked == item->checkState(0)){ // 选中 int count = item->childCount(); if (count > 0){ for (int i = 0; i < count; i++){ //子节点也选中 item->child(i)->setCheckState(0, Qt::Checked) ; } }else{ //是子节点 updateParentItem(item); } }else if(Qt::Unchecked == item->checkState(0)){ // 未选中 int count = item->childCount(); if (count > 0){ for (int i = 0; i < count; i++){ item->child(i)->setCheckState(0, Qt::Unchecked); } }else{ updateParentItem(item); } }else { // Qt::PartiallyChecked == item->checkState(0) ui->textEdit->append("部分选中"); }}//void holidayquery::updateParentItem(QTreeWidgetItem* item){ QTreeWidgetItem *parent = item->parent(); if (parent == NULL){ return; } //选中的子节点个数 int selectedCount = 0; int childCount = parent->childCount(); for (int i = 0; i < childCount; i++){ QTreeWidgetItem *childItem = parent->child(i); if (childItem->checkState(0) == Qt::Checked){ selectedCount++; } } if (selectedCount <= 0){ //选中状态 parent->setCheckState(0, Qt::Unchecked); }else if(selectedCount > 0 && selectedCount < childCount){ //部分选中状态 parent->setCheckState(0, Qt::PartiallyChecked); }else if(selectedCount == childCount){ //未选中状态 parent->setCheckState(0, Qt::Checked); }// changeFromUser = true;}
上面需要注意的是，当用代码setCheckState后，会触发itemChanged事件，有时这个会带来麻烦，这时需要加一些标志来判断是由用户操作产生的还是程序本身代码产生的。
来源：oschina
链接：https://my.oschina.net/u/585898/blog/86672