Qt中树形控件Tree Widget的使用方法汇总

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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