TreeController.h TreeController.cpp
TreeModel.h TreeModel.cpp
TreeItem.c TreeItem.cpp
各個類職能劃分如下:
TreeController主要負責用戶的操作,例如加載qml文件,用戶主動加載數據,主動刪除數據,主動插入數據等。TreeModel主要存放數據(TreeItem爲TreeModel的成員,也是存放數據的)。QML的TreeView主要顯示數據。
重點在於QML的TreeView與TreeModel如何交互將數據正確顯示出來。
TreeModel.h頭文件如下:
class TreeModel : public QAbstractItemModel
{
Q_OBJECT
enum ItemRoles {
NAME = Qt::UserRole + 1,
SIMPLIFY
};
public:
TreeModel(QObject *parent = NULL);
~TreeModel();
void appendChild(const QModelIndex& index);
bool removeRows(int row, int count, QModelIndex parent);
QModelIndex parent(const QModelIndex &index) const;
Qt::ItemFlags flags(const QModelIndex &index) const;
QModelIndex index(int row, int column, const QModelIndex &parent = QModelIndex()) const;
int rowCount(const QModelIndex &parent = QModelIndex()) const;
int columnCount(const QModelIndex &parent = QModelIndex()) const;
QVariant data(const QModelIndex &index, int role) const;
QHash<int, QByteArray> roleNames() const;
private:
TreeItem *m_rootItem;
};
TreeItem.h頭文件如下:#ifndef TREEITEM_H
#define TREEITEM_H
#include <QList>
#include <QVariant>
#include <QStringList>
#include <QModelIndex>
class TreeItem
{
public:
TreeItem::TreeItem();
TreeItem(const QList<QVariant> &data, TreeItem* parent);
~TreeItem();
void appendChild(TreeItem *child);
void deleteAllChild();
TreeItem *child(int row);
int childCount() const;
int columnCount() const;
QVariant data(int column) const;
int row() const;
TreeItem *parent();
void setParent(TreeItem *parent);
private:
TreeItem *m_parentItem;
QList<TreeItem*> m_childItems;
QList<QVariant> m_itemData;
};
#endif
可以看出TreeModel是繼承自QAbstractItemModel,其中QVariant data(const QModelIndex &index, int role) const;成員函數和QHash<int, QByteArray> roleNames() const;成員函數比較關鍵,是QML讀取C++數據的關鍵函數。TreeModel.cpp源文件如下:
TreeModel::TreeModel(QObject *parent) :
QAbstractItemModel(parent), m_rootItem(NULL)
{
m_rootItem = new TreeItem;
QList<QVariant> list;
list.append("ZhongGuo");
list.append("ZhG");
auto item = new TreeItem(list, m_rootItem);
m_rootItem->appendChild(item);
QList<QVariant> BJ_List;
BJ_List.append("BeiJing");
BJ_List.append("BJ");
auto BJ_Item = new TreeItem(BJ_List, item);
item->appendChild(BJ_Item);
QList<QVariant> ShX_List;
ShX_List.append("ShannXi");
ShX_List.append("ShX");
QList<QVariant> XiAn_List;
XiAn_List.append("XiAn");
XiAn_List.append("XA");
QList<QVariant> XiAn_GaoXin_List;
XiAn_GaoXin_List.append("GaoXin");
XiAn_GaoXin_List.append("XA_GaoXin");
auto ShX_Item = new TreeItem(ShX_List, item);
auto XA_Item = new TreeItem(XiAn_List, ShX_Item);
auto XA_GX_Item = new TreeItem(XiAn_GaoXin_List, XA_Item);
item->appendChild(ShX_Item);
ShX_Item->appendChild(XA_Item);
XA_Item->appendChild(XA_GX_Item);
QList<QVariant> GuangDong_List;
GuangDong_List.append("GuangDong");
GuangDong_List.append("GD");
QList<QVariant> DongGuan;
DongGuan.append("DongGuan");
DongGuan.append("DG");
auto GuangDong_Item = new TreeItem(GuangDong_List, item);
auto DongGuan_Item = new TreeItem(DongGuan, GuangDong_Item);
item->appendChild(GuangDong_Item);
GuangDong_Item->appendChild(DongGuan_Item);
QList<QVariant> ShangHai;
ShangHai.append("ShangHai");
ShangHai.append("ShH");
auto ShangHai_Item = new TreeItem(ShangHai, item);
item->appendChild(ShangHai_Item);
}
TreeModel::~TreeModel()
{
delete m_rootItem;
}
int TreeModel::columnCount(const QModelIndex &parent) const
{
return 2;
//返回實際的列數 (實際是他返回了0,因爲根節點用的是無參的構造),TreeView控件會認爲表是空表,不獲取數據
if (parent.isValid())
{
return static_cast<TreeItem*>(parent.internalPointer())->columnCount();
}
else
{
return m_rootItem->columnCount();
}
}
QHash<int, QByteArray> TreeModel::roleNames() const
{
QHash<int, QByteArray> names(QAbstractItemModel::roleNames());
names[NAME] = "name";
names[SIMPLIFY] = "simplify";
return names;
}
QVariant TreeModel::data(const QModelIndex &index, int role) const
{
if (!index.isValid())
{
return QVariant();
}
switch (role)
{
case NAME:
{
return static_cast<TreeItem*>(index.internalPointer())->data(0);
}
case SIMPLIFY:
{
return static_cast<TreeItem*>(index.internalPointer())->data(1);
}
}
}
Qt::ItemFlags TreeModel::flags(const QModelIndex &index) const
{
if (!index.isValid())
{
return 0;
}
return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
}
QModelIndex TreeModel::index(int row, int column, const QModelIndex &parent) const
{
if (!hasIndex(row, column, parent))
{
return QModelIndex();
}
TreeItem *parentItem;
if (!parent.isValid())
{
parentItem = m_rootItem;
}
else
{
parentItem = static_cast<TreeItem*>(parent.internalPointer());
}
TreeItem *childItem = parentItem->child(row);
if (childItem)
{
return createIndex(row, column, childItem);
}
else
{
return QModelIndex();
}
}
QModelIndex TreeModel::parent(const QModelIndex &index) const
{
if (!index.isValid())
{
return QModelIndex();
}
TreeItem *childItem = static_cast<TreeItem*>(index.internalPointer());
TreeItem *parentItem = childItem->parent();
if (parentItem == m_rootItem)
{
return QModelIndex();
}
return createIndex(parentItem->row(), 0, parentItem);
}
int TreeModel::rowCount(const QModelIndex &parent) const
{
TreeItem *parentItem;
if (parent.column() > 0)
{
return 0;
}
if (!parent.isValid())
{
parentItem = m_rootItem;
}
else
{
parentItem = static_cast<TreeItem*>(parent.internalPointer());
}
return parentItem->childCount();
}
以上即爲TreeModel的源文件。TreeItem.cpp源文件如下:
#include "TreeItem.h"
TreeItem::TreeItem() :m_parentItem(NULL)
{
}
TreeItem::TreeItem(const QList<QVariant> &data, TreeItem* parent) : m_parentItem(NULL)
{
m_parentItem = parent;
m_itemData = data;
}
TreeItem::~TreeItem()
{
qDeleteAll(m_childItems);
}
void TreeItem::appendChild(TreeItem *item)
{
item->setParent(this);
m_childItems.append(item);
}
void TreeItem::deleteAllChild()
{
for (int index = 0; index < m_childItems.size(); index++)
{
m_childItems[index]->deleteAllChild();
}
qDeleteAll(m_childItems);
m_childItems.clear();
}
TreeItem *TreeItem::child(int row)
{
return m_childItems.value(row);
}
int TreeItem::childCount() const
{
return m_childItems.count();
}
int TreeItem::columnCount() const
{
return m_itemData.count();
//return 1;
}
QVariant TreeItem::data(int column) const
{
return m_itemData .value(column);
}
TreeItem *TreeItem::parent()
{
return m_parentItem;
}
void TreeItem::setParent(TreeItem *parent)
{
m_parentItem = parent;
}
int TreeItem::row() const
{
if (!m_parentItem) { return 0; }
return m_parentItem->m_childItems.indexOf(const_cast<TreeItem*>(this));
}
通過以上源文件可以看出,初始化的測試數據在TreeModel類的構造中傳入。通過roleNames()函數增加QAbstractItemModel的角色,使得在QML中可以使用字段name和simplify,當QML加載讀取數據時,通過枚舉的角色NAME和SIMPLIFY返回對應的數據,即爲要顯示的數據,這樣,就可以將C++的數據顯示到QML的TreeView中了,以上其他的一些成員函數,都是一些獲取數據個數的基本函數。
以上成員函數中,有一個比較特殊的函數:int TreeModel::columnCount(const QModelIndex &parent) const;因爲在創建根目錄時用的是無參構造m_rootItem = new TreeItem;所以QAbstractItemModel在調用hasChildren(const QModelIndex& parent)計算根的列數時,返回了0,導致TreeView控件會認爲表是空表,所以不獲取數據,最終顯示出來是空的,調用堆棧如下圖:
因此,在這裏用無參構造根節點時,可以手動設置返回的列數(例如本例中返回2)。
加載TreeView的QML文件如下TreeViewTest.qml:
import QtQuick 2.4
import QtQuick.Layouts 1.2
import QtQuick.Controls 1.4
import QtQuick.Controls.Styles 1.4
Rectangle {
id: root
property var ctrl
property var model
x:100
y:50
width: 800
height: 600
TreeView {
id:view
width: 500
TableViewColumn {
title: "Name"
role: "name"
width: 150
}
TableViewColumn {
title: "Simplify"
role: "simplify"
width: 200
}
model: root.model
itemDelegate: Item {
Text {
anchors.verticalCenter: parent.verticalCenter
color: "red"
elide: styleData.elideMode
text: styleData.value
}
}
property bool isCollapse: true
onClicked: {
console.log("onClicked:", index)
console.log("isExpanded:",isExpanded(index))
if (isCollapse)
{
console.log("expand")
emit: view.expand(index);
isCollapse = false;
}
else
{
console.log("collapse")
emit: view.collapse(index);
isCollapse = true;
}
/*if (isExpanded(index))
{
collapse(index);
}
else
{
expand(index);
}*/
}
}
}
這裏需要注意的是TreeView的bool isExpanded(QModelIndex index)在clicked(QModelIndex index)中的應用,運行起來可以查看打的isExpanded:的值。值得注意的是,當點擊根節點的三角進行展開收縮時,用isExpanded(QModelIndex index)函數獲取的返回值跟實際的展開狀態是反的,不點擊三角進行收縮展開是正常的(由於在點擊三角符號時,調用了一次原生的展開或收縮,然後又在clicked中調用了TreeView的expand(index);函數或發送emit: view.expand(index);信號,這會產生二次展開或收縮,負負得正,所以導致調用isExpanded(QModelIndex index)獲取的值不理想,,,這可以算是QML的一個Bug吧),因此本例中用了成員變量property bool isCollapse: true進行變換以完成想要的功能。
加載QML界面的TreeController.cpp主要加載與數據暴露如下:
void TreeController::onBtnClicked()
{
//m_view.setFlags(Qt::FramelessWindowHint | Qt::Window | Qt::WindowSystemMenuHint | Qt::WindowMinimizeButtonHint | Qt::WindowMaximizeButtonHint | Qt::WindowCloseButtonHint);
if (m_isInit) {
m_view.setTitle("LoadTest");
m_view.rootContext()->setContextProperty("win", this);
m_view.rootContext()->setContextProperty("quickView", &m_view);
#ifndef _DEBUG
m_view.setSource(QUrl("qrc:/ui/TreeViewTest.qml"));
#else
m_view.setSource(QUrl("ui/TreeViewTest.qml"));
#endif
m_item = m_view.rootObject();
QVariant v;
v.setValue(this);
m_item->setProperty("ctrl", v);
QVariant v1;
v1.setValue(&m_model);
m_item->setProperty("model", v1);
m_isInit = false;
}
m_view.show();
}
以上主要完成QML界面的加載和ctrl與model的暴露,其他窗口的操作(最小化最大化關閉)等操作函數在此忽略,有想了解更多技術的,可以掃描左側欄二維碼,關注本人公衆號【三個程序員】,接收更實時有料的推送。以上所有,完成了QML的TreeView加載數據並顯示,展示了樹控件TreeView的應用。
其效果如下圖:
關於QML的TreeView使用得上篇到此結束,下篇主要寫一些關於QML樹控件TreeView的插入與刪除操作,敬請期待!迫不及待想接收更多技術知識的朋友,可以掃描左側二維碼關注本人公衆號,您的肯定與支持是我前進的動力^_^.
完整的demo程序工程地址如下:QML樹控件TreeView的使用
【http://download.csdn.net/detail/shado_walker/9761108】