最近需要用到Tree Widget树形控件，现将自己的一些理解记录下来。
Tree Widget在项目控件组（Item Widgets）里面可以找到。这种控件其实有时还是很有用处的，我主要利用的是带有复选框的树形控件。结果如图所示;
当选中顶层的树形节点时，子节点全部被选中；当取消选择顶层树形节点时，子节点的选中状态将全部被取消，二当选中子节点是，父节点显示部分选中的状态。
几个主要的函数：
setCheckState设置复选框；
ItemIsUserCheckable 项目上是否有复选框
ItemIsEnabled 项目上是否没有被禁用（Enabled可用/Disabled禁用）
ItemIsSelectable 项目是否可以选中
代码：
在mainwindow.h中插入一下代码：
void init();
void updateParentItem(QTreeWidgetItem *item);
public slots:
void treeItemChanged(QTreeWidgetItem* item,int column);在mainwindow构造函数中添加：
init();
connect(ui->treeWidget,SIGNAL(itemChanged(QTreeWidgetItem*,int)),this,SLOT(treeItemChanged(QTreeWidgetItem*,int)));init函数的实现;
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,"subItem11");
subItem13->setCheckState(0,Qt::Unchecked);
QTreeWidgetItem* subItem14=new QTreeWidgetItem(group1);
subItem14->setFlags(Qt::ItemIsUserCheckable|Qt::ItemIsEnabled|Qt::ItemIsSelectable);
subItem14->setText(0,"subItem12");
subItem14->setCheckState(0,Qt::Unchecked);
QTreeWidgetItem* group2=new QTreeWidgetItem(ui->treeWidget);
group2->setText(0,"group2");
group2->setFlags(Qt::ItemIsUserCheckable|Qt::ItemIsEnabled|Qt::ItemIsSelectable);
group2->setCheckState(0,Qt::Unchecked);
QTreeWidgetItem* subItem1=new QTreeWidgetItem(group2);
subItem1->setFlags(Qt::ItemIsUserCheckable|Qt::ItemIsEnabled|Qt::ItemIsSelectable);
subItem1->setText(0,"subItem11");
subItem1->setCheckState(0,Qt::Unchecked);
QTreeWidgetItem* subItem2=new QTreeWidgetItem(group2);
subItem2->setFlags(Qt::ItemIsUserCheckable|Qt::ItemIsEnabled|Qt::ItemIsSelectable);
subItem2->setText(0,"subItem12");
subItem2->setCheckState(0,Qt::Unchecked);
QTreeWidgetItem* subItem3=new QTreeWidgetItem(group2);
subItem3->setFlags(Qt::ItemIsUserCheckable|Qt::ItemIsEnabled|Qt::ItemIsSelectable);
subItem3->setText(0,"subItem11");
subItem3->setCheckState(0,Qt::Unchecked);
QTreeWidgetItem* subItem4=new QTreeWidgetItem(group2);
subItem4->setFlags(Qt::ItemIsUserCheckable|Qt::ItemIsEnabled|Qt::ItemIsSelectable);
subItem4->setText(0,"subItem12");
subItem4->setCheckState(0,Qt::Unchecked);
QTreeWidgetItem* group3=new QTreeWidgetItem(ui->treeWidget);
group3->setText(0,"group3");
group3->setFlags(Qt::ItemIsAutoTristate|Qt::ItemIsEnabled|Qt::ItemIsSelectable);
group3->setCheckState(0,Qt::Unchecked);
QTreeWidgetItem* subItem111=new QTreeWidgetItem(group3);
subItem111->setFlags(Qt::ItemIsAutoTristate|Qt::ItemIsEnabled|Qt::ItemIsSelectable);
subItem111->setText(0,"subItem111");
subItem111->setCheckState(0,Qt::Unchecked);
QTreeWidgetItem* subItem112=new QTreeWidgetItem(group3);
subItem112->setFlags(Qt::ItemIsAutoTristate|Qt::ItemIsEnabled|Qt::ItemIsSelectable);
subItem112->setText(0,"subItem112");
subItem112->setCheckState(0,Qt::Unchecked);treeItemChanged函数的实现;
QString itemText=item->text(0);
//选中
if(Qt::Checked ==item->checkState(0))//全选check打勾
{
QTreeWidgetItem* parent=item->parent();//定义一个节点
int count=item->childCount();//子节点的数目
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))//存在未选中
{
int count=item->childCount();
if(count>0)
{
for(int i=0;i<count;i++)
{
item->child(i)->setCheckState(0,Qt::Unchecked);
}
}
else
{
updateParentItem(item);
}
}updateParentItem 函数的实现;
QTreeWidgetItem* parent=item->parent();
if(parent==NULL)
{
return;
}
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)
{
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)
{
parent->setCheckState(0,Qt::Checked);
}最终实现的就是第一张图的效果。
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