Qt4.8.1学习笔记1—QTreeWidget控件的使用



Qt的介绍以及安装这里就记录了，先说一下QtGUI的基础“信号(SIGNAL)与槽(SLOT)”。

其实信号与槽的概念很好理解，跟MFC的消息与响应机制类似，只不过MFC的消息响应机制的实现是利用回调函数，而Qt更加的简单。如下就可以将一个信号与一个槽绑定，槽其实就是个响应函数：connect(delButton,
SIGNAL(clicked()), this, SLOT(on_del_button()));

 

所谓的信号，就是用户对窗口的一种操作，比如点击左键，双击左键，点击右键，双击右键，点下按钮等等，不同的控件对应不同的一些信号。一个控件有哪些信号和槽，可以查阅Qt4.1帮助文档。

关于信号与槽的关系，我们举个例子：

吴三桂杀了朱国治举兵造反，消息很快传遍天下，耿精忠，尚可喜收到信号，也做出反应跟着反了，康熙收到了吴三桂造反的消息，甚是气愤，于是乎派兵镇压，王辅臣也收到了吴三桂的造反的消息，但是王辅臣不做任何反应，不管他将来怎么打算，但是他当时是没有反应的。

康熙，吴三桂，耿精忠，尚可喜，王辅臣都是我们窗体上的控件，吴三桂造反这个行为就产生了一个信号，这个信号天下皆知，康熙，耿精忠，尚可喜等收到信号都做出了响应的动作（槽），王辅臣静观其变，不做任何反应。

1,一个信号可以对应N个槽（N>=0）

2,N个信号绑定一个槽（N>=0）

connect(delButton, SIGNAL(clicked()), this, SLOT(on_del_button()));

格式如上，第一个参数是按钮控件的对象名，第二个参数就是这个按钮控件能产生的一种信号，第三个参数是需要作出响应的控件，这里用this表示当前窗口，第四个参数就是槽了，其实就是自己定义实现的一个函数。

 

基本的信号与槽了解之后，我们使用一些常用控件，如QPushButton，QLabel，QLineEdit，QTreeWidget等来实现如下程序：



上面程序中包含了QTreeWidget控件的常用操作，比如增加根节点，增加节点，给一个节点增加子节点，删除节点，节点上移，节点下移，修改节点的名字（操作顺序与图中的按钮顺序一致），一下是源码：

//window.h
#ifndef __WINDOW_H__
#define __WINDOW_H__

#include <QDialog>
#include <QMainWindow>
#include <QLineEdit>
#include <QString>
#include <QLayout>
#include <QLabel>
#include <QPoint>
#include <QMenu>
#include <QCursor>
#include <QIcon>
#include <QTreeWidget>
#include <QTreeWidgetItem>
#include <QPushButton>

class Window : public QMainWindow
{
Q_OBJECT
public:
Window(QWidget *parent = NULL);

private:
void AddTreeNode(QTreeWidgetItem * item,const QString str1);
void AddTreeRoot(const QString str);

QTreeWidget *tree;
QLineEdit *line;

private slots:
/*增加树的根节点*/
void on_add_class_button();
/*给当前结点增加兄弟节点*/
void on_add_val_button();
/*给当前结点增加子节点*/
void on_add_child_button();
/*删除节点*/
void on_del_button();
/*节点上移*/
void on_up_button();
/*节点下移*/
void on_down_button();
/*显示右键菜单栏*/
void showRightMenu();
/*点击节点时，将节点的名称显示在LineEdit控件中*/
void clicked ( const QModelIndex & index);
/*根据LineEdit中输入的值，改变当前Item的name*/
void changeTreeItemName();
};

#endif


//window.cpp
#include "window.h"

Window::Window(QWidget *parent):QMainWindow(parent)
{
tree = new QTreeWidget;
tree->setContextMenuPolicy(Qt::CustomContextMenu);
tree->setColumnCount(1);
tree->setHeaderLabel("Name");

QTreeWidgetItem *initRoot = new QTreeWidgetItem(QStringList("Frame"));
tree->addTopLevelItem(initRoot);
QTreeWidgetItem *child = new QTreeWidgetItem(QStringList("NewVal"));
child->setText(0,QString("Val"));
initRoot->addChild(child);

QHBoxLayout *leftLayout = new QHBoxLayout;
leftLayout->addWidget(tree);

QVBoxLayout *rightLayout = new QVBoxLayout;

QPushButton* addClassButton = new QPushButton(/*tr("add_class")*/);
addClassButton->setIcon(QIcon(tr("./images/add.png")));
QPushButton* addValButton = new QPushButton(tr("add_val"));
QPushButton* delButton = new QPushButton(/*tr("del")*/);
delButton->setIcon(QIcon(tr("./images/delete.png")));
QPushButton* upButton = new QPushButton();
upButton->setIcon(QIcon(tr("./images/up.png")));
QPushButton* downButton = new QPushButton();
downButton->setIcon(QIcon(tr("./images/down.png")));
QPushButton* addChild = new QPushButton(tr("add child"));

rightLayout->addWidget(addClassButton);
rightLayout->addWidget(addValButton);
rightLayout->addWidget(addChild);
rightLayout->addWidget(delButton);
rightLayout->addWidget(upButton);
rightLayout->addWidget(downButton);

QHBoxLayout *rightdownLayout = new QHBoxLayout;
QLabel* lab = new QLabel("select");
line = new QLineEdit;

rightdownLayout->addWidget(lab);
rightdownLayout->addWidget(line);

rightLayout->addLayout(rightdownLayout);

rightLayout->addStretch();

QHBoxLayout *mainLayout = new QHBoxLayout;
mainLayout->addLayout(leftLayout);
mainLayout->addLayout(rightLayout);
mainLayout->setStretch(0, 3);
mainLayout->setStretch(1, 1);

QWidget *mainWidget = new QWidget;
mainWidget->setLayout(mainLayout);

setCentralWidget(mainWidget);

connect(tree, SIGNAL(customContextMenuRequested(QPoint)), this, SLOT(showRightMenu()));

connect(addClassButton, SIGNAL(clicked()), this, SLOT(on_add_class_button()));
connect(addChild, SIGNAL(clicked()), this, SLOT(on_add_child_button()));
connect(addValButton, SIGNAL(clicked()), this, SLOT(on_add_val_button()));
connect(delButton, SIGNAL(clicked()), this, SLOT(on_del_button()));
connect(upButton, SIGNAL(clicked()), this, SLOT(on_up_button()));
connect(downButton, SIGNAL(clicked()), this, SLOT(on_down_button()));

connect(tree, SIGNAL(clicked ( const QModelIndex &)), this, SLOT(clicked ( const QModelIndex &)));

connect(line, SIGNAL(textChanged(const QString&)), this, SLOT(changeTreeItemName()));
}

/******************************************private******************************************/
void Window::AddTreeNode(QTreeWidgetItem * item,const QString str1)
{
if (item->parent() != NULL)
{
QStringList fonts;
fonts<<str1<<str1;
QTreeWidgetItem* newitem = new QTreeWidgetItem(fonts);
item->parent()->addChild(newitem);
}
}
void Window::AddTreeRoot(const QString str)
{
QStringList fonts;
fonts<<str<<str;
QTreeWidgetItem *note1 = new QTreeWidgetItem(fonts);
tree->addTopLevelItem(note1);
}
/******************************************SLOTS******************************************/
/*增加树的根节点*/
void Window::on_add_class_button()
{
QTreeWidgetItem *Root = new QTreeWidgetItem(QStringList("DataFrame"));
tree->addTopLevelItem(Root);
QTreeWidgetItem *child = new QTreeWidgetItem(QStringList("NewVal"));
Root->addChild(child);
}
/*给当前结点增加兄弟节点*/
void Window::on_add_val_button()
{
QTreeWidgetItem * item= tree->currentItem();

if (item == NULL || item->parent() == NULL) {
return;
}
else
{
QTreeWidgetItem* child = new QTreeWidgetItem(QStringList("NewVal"));
item->parent()->addChild(child);
}
}

/*给当前结点增加子节点*/
void Window::on_add_child_button()
{
if (NULL != tree->currentItem())
{
QTreeWidgetItem* newItem = new QTreeWidgetItem(QStringList("NewVal"));
tree->currentItem()->addChild(newItem);
}
}

/*删除节点*/
void Window::on_del_button()
{
QTreeWidgetItem * currentItem = tree->currentItem();

if(currentItem==NULL)
{
return;
}
//Èç¹ûûÓи¸½Úµã¾ÍÖ±½Óɾ³ý
if(currentItem->parent()==NULL)
{
delete tree->takeTopLevelItem(tree->currentIndex().row());
}
else
{
//Èç¹ûÓи¸½Úµã¾ÍÒªÓø¸½ÚµãµÄtakeChildɾ³ý½Úµã
delete currentItem->parent()->takeChild(tree->currentIndex().row());
}
}
/*节点上移*/
void Window::on_up_button()
{
if (tree->currentItem() == NULL)
{
return;
}

QTreeWidgetItem* parent = tree->currentItem()->parent();
QTreeWidgetItem* curItem = tree->currentItem();
if (parent == NULL || parent->indexOfChild(curItem) <= 0)
{
return;
}

int curIndex = parent->indexOfChild(curItem);

QList<QTreeWidgetItem*> oldChildren = parent->takeChildren();
QList<QTreeWidgetItem*> newChildren;

for (int i = 0; i < curIndex - 1; ++i)
{
newChildren.append(oldChildren.at(i));
}

newChildren.append(oldChildren.at(curIndex));
newChildren.append(oldChildren.at(curIndex-1));

for (int i = curIndex + 1; i < oldChildren.size(); ++i)
{
newChildren.append(oldChildren.at(i));
}

parent->addChildren(newChildren);

tree->setCurrentItem(parent->child(curIndex - 1));
}
/*节点下移*/
void Window::on_down_button()
{
if (tree->currentItem() == NULL)
{
return;
}

QTreeWidgetItem* parent = tree->currentItem()->parent();
QTreeWidgetItem* curItem = tree->currentItem();
if (parent == NULL || parent->indexOfChild(curItem) == parent->childCount() - 1)
{
return;
}

int curIndex = parent->indexOfChild(curItem);

QList<QTreeWidgetItem*> oldChildren = parent->takeChildren();
QList<QTreeWidgetItem*> newChildren;

for (int i = 0; i < curIndex; ++i)
{
newChildren.append(oldChildren.at(i));
}

newChildren.append(oldChildren.at(curIndex+1));
newChildren.append(oldChildren.at(curIndex));
for (int i = curIndex + 1; i < oldChildren.size(); ++i)
{
newChildren.append(oldChildren.at(i));
}

parent->addChildren(newChildren);

tree->setCurrentItem(parent->child(curIndex + 1));
}
/*显示右键菜单栏*/
void Window::showRightMenu()
{
QMenu* menu = new QMenu(tree);
QAction* addAction = new QAction(tr("New"), this);
QAction* delAction = new QAction(tr("Del"), this);
QAction* modifyAction = new QAction(tr("Modify"), this);

menu->addAction(addAction);
menu->addAction(delAction);
menu->addAction(modifyAction);

menu->exec(QCursor::pos());
}

/*点击节点时，将节点的名称显示在LineEdit控件中*/
void Window::clicked ( const QModelIndex & index)
{
if (tree->currentItem() == NULL)
{
return;
}

if (tree->currentItem()->parent() == NULL)
{
line->setText( tree->currentItem()->text(0) );
return;
}

line->setText( tree->currentItem()->text(0) );
}
/*根据LineEdit中输入的值，改变当前Item的name*/
void Window::changeTreeItemName()
{
if (tree->currentItem() == NULL)
{
return;
}
tree->currentItem()->setText(0,line->text());
}



//main.cpp
#include <QApplication>
#include <QDialog>
#include "window.h"

int main(int argc, char *argv[])
{
QApplication a(argc, argv);
Window *mainWindow = new Window;

mainWindow->resize(300, 160);
mainWindow->setWindowTitle(QWidget::tr("Qt Test"));
mainWindow->show();

return a.exec();
}


代码中使用了图标，添加方法是在源文件目录下新建images文件夹，随便放几张图片，名称改为代码中的名称即可。

Ubuntu下编译命令:

qmake –project

qmake XXX.pro

make