Qt5模型/视图结构-视图(View)

实现自定义的View，可继承自QAbstractItemView类，对所需的纯虚函数进行重定义与实现，对于QAbstractItemView类中的纯虚函数，在子类中必须进行重定义，但不一定要实现，可根据需要选择实现。

DEMO

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <QStandardItem>
#include <QTableView>
#include <QMenuBar>
#include <QMenu>
#include <QAction>
#include <QSplitter>
#include "histogramview.h"

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();
    void creatAction();
    void creatMenu();
    void setupModel();
    void setupView();
    void openFile(QString);
public slots:
    void slotOpen();
private:
    QMenu *fileMenu;
    QAction *openAct;
    QStandardItemModel *model;
    QTableView *table;
    QSplitter *splitter;
    HistogramView *histogram;
};

#endif // MAINWINDOW_H

histogramview.h

#ifndef HISTOGRAMVIEW_H
#define HISTOGRAMVIEW_H

#include <QAbstractItemView>
#include <QItemSelectionModel>
#include <QRegion>
#include <QMouseEvent>
#include <QList>

//自定义HistogramView类继承自QAbstractItemView类，用于对表格数据进行柱状图显示
class HistogramView:public QAbstractItemView
{
    Q_OBJECT
public:
    HistogramView(QWidget *parent=0);
    //虚函数的声明
    //QAbstractItemView类中的纯虚函数，这些纯虚函数不一定要实现，可以根据
    //需要选择性的实现，但一定要声明
    QRect visualRect(const QModelIndex &index) const;
    void scrollTo(const QModelIndex &index,ScrollHint hint=EnsureVisible);
    //当鼠标在视图中单击或位置发生改变时触发，它返回鼠标所在点的QModelIndex值，若鼠标
    //处在某个数据项的区域中，则返回此数据的Index值，否则返回一个空的Index
    QModelIndex indexAt(const QPoint &point) const;
    //为selections赋初值
    void setSelectionModel(QItemSelectionModel *selectionModel);
    QRegion itemRegion(QModelIndex index);
    void paintEvent(QPaintEvent *);
    //柱状统计图可以被鼠标单击选择，选中后以不同的方式显现
    void mousePressEvent(QMouseEvent *event);
protected slots:
    //当数据项发生改变时,此槽函数将响应
    void selectionChanged(const QItemSelection &selected,const QItemSelection &deselected);
    //当模型中的数据发生变更时，此槽函数响应
    void dataChanged(const QModelIndex &topLeft,
                     const QModelIndex &bottomRight);
protected:
    //虚函数声明
    QModelIndex moveCursor(QAbstractItemView::CursorAction cursorAction,
                           Qt::KeyboardModifiers modifiers);
    int horizontalOffset() const;
    int verticalOffset() const;
    bool isIndexHidden(const QModelIndex &index) const;
    //将位于QRect内的数据项按照SelectionFlags(描述被选择的数据项以何种方式进行更新)
    //指定的方式进行更新。
    void setSelection(const QRect &rect,QItemSelectionModel::SelectionFlags flags);
    QRegion visualRegionForSelection(const QItemSelection &selection) const;
private:
    QItemSelectionModel *selections;  //用于保存与视图选择项相关的内容
    QList<QRegion> MRegionList;  //用于保存其中某一类型柱状图的区域范围，而每个区域是QList中的一个值
    QList<QRegion> FRegionList;
    QList<QRegion> SRegionList;
};

#endif // HISTOGRAMVIEW_H

mainwindow.cpp

#include "mainwindow.h"
#include <QFileDialog>
#include <QFile>
#include <QTextStream>
#include <QStringList>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    creatAction();
    creatMenu();
    setupModel();
    setupView();
    setWindowTitle(tr("View Example"));
    resize(600,600);
}

MainWindow::~MainWindow()
{

}

void MainWindow::creatAction()
{
    openAct=new QAction(tr("打开"),this);
    connect(openAct,SIGNAL(triggered(bool)),
            this,SLOT(slotOpen()));
}

void MainWindow::creatMenu()
{
    fileMenu=new QMenu(tr("文件"),this);
    fileMenu->addAction(openAct);
    menuBar()->addMenu(fileMenu);
}
//新建一个model,并设置表头数据
void MainWindow::setupModel()
{
    model=new QStandardItemModel(4,4,this);
    model->setHeaderData(0,Qt::Horizontal,tr("部门"));
    model->setHeaderData(1,Qt::Horizontal,tr("男"));
    model->setHeaderData(2,Qt::Horizontal,tr("女"));
    model->setHeaderData(3,Qt::Horizontal,tr("退休"));
}
void MainWindow::setupView()
{
    /*
    table=new QTableView;  //新建一个QTableView
    table->setModel(model);  //为QTableView对象设置相同的Model
    QItemSelectionModel *selectionModel=new QItemSelectionModel(model);
    table->setSelectionModel(selectionModel);
    //连接选择模型的selectionModel()信号与QTabelView对象的selectionChanged()槽函数
    //以便使自定义的HistogramView对象中的选择变化能够反映到QTabelView对象的显示中
    connect(selectionModel,SIGNAL(selectionChanged(QItemSelection,
                                                   QItemSelection)),
                                  table,SLOT(selectionChanged(QItemSelection,
                                                              QItemSelection)));
    splitter=new QSplitter;
    splitter->setOrientation(Qt::Vertical);
    splitter->addWidget(table);
    setCentralWidget(splitter);
    */

    splitter=new QSplitter;
    splitter->setOrientation(Qt::Vertical);

    histogram=new HistogramView(splitter);  //新建一个Histogram对象
    histogram->setModel(model);  //为HistogramView对象设置相同的Model

    table=new QTableView;
    table->setModel(model);

    QItemSelectionModel *selectionModel=new QItemSelectionModel (model);
    table->setSelectionModel(selectionModel);
    histogram->setSelectionModel(selectionModel); //新建的QItemSelectionModel
                                                 //对象作为QTableView对象和HistogramView
                                                 //对象使用的选择模型

    splitter->addWidget(table);
    splitter->addWidget(histogram);

    setCentralWidget(splitter);

    //连接槽函数，以便使QTableView对象中的选择变化能够反映到自定义的HistogramView对象的显示中
    connect(selectionModel,SIGNAL(selectionChanged(QItemSelection,QItemSelection)),
            table,SLOT(selectionChanged(QItemSelection,QItemSelection)));
    connect(selectionModel,SIGNAL(selectionChanged(QItemSelection,QItemSelection)),
            histogram,SLOT(selectionChanged(QItemSelection,QItemSelection)));


}
//slotOpne()槽函数完成打开标准文件对话框
void MainWindow::slotOpen()
{
    QString name;
    name=QFileDialog::getOpenFileName(this,"打开",".","histogram files(*.txt)");

    if(!name.isEmpty())
    {
        openFile(name);
    }
}
//openFile()函数完成打开所选的文件的内容
void MainWindow::openFile(QString path)
{
    if(!path.isEmpty())
    {
        QFile file(path);
        if(file.open(QFile::ReadOnly | QFile::Text))
        {
            QTextStream stream(&file);
            QString line;
            model->removeRows(0,model->rowCount(QModelIndex()),
                              QModelIndex());
            int row=0;
            do
            {
                line=stream.readLine();
                if(!line.isEmpty())
                {
                    model->insertRows(row,1,QModelIndex());
                    QStringList pieces=line.split(",",QString::SkipEmptyParts);
                    model->setData(model->index(row,0,QModelIndex()),
                                   pieces.value(0));
                    model->setData(model->index(row,1,QModelIndex()),
                                   pieces.value(1));
                    model->setData(model->index(row,2,QModelIndex()),
                                   pieces.value(2));
                    model->setData(model->index(row,3,QModelIndex()),
                                   pieces.value(3));
                    row++;

                }

            }while(!line.isEmpty());
            file.close();
        }
    }  //end if(!path.isEmpty())
}

histogramview.cpp

#include "histogramview.h"
#include <QPainter>

HistogramView::HistogramView(QWidget *parent):QAbstractItemView(parent)
{

}
//paintEvent()函数完成柱状统计图绘制的工作
void HistogramView::paintEvent(QPaintEvent *)
{
    //以viewport()作为绘图设备新建一个QPainter对象
    QPainter painter(viewport());
    painter.setPen(Qt::black);
    int x0=40;
    int y0=250;
    /*完成了x,y坐标轴的绘制,并标注坐标轴的变量*/
    //y坐标轴
    painter.drawLine(x0,y0,40,30);
    painter.drawLine(38,32,40,30);
    painter.drawLine(40,30,42,32);
    painter.drawText(20,30,tr("人数"));
    for(int i=0;i<5;i++)
    {
        painter.drawLine(-1,-i*50,1,-i*50);
        painter.drawText(-20,-i*50,tr("%1").arg(i*5));
    }
    //x轴
    painter.drawLine(x0,y0,540,250);
    painter.drawLine(538,248,540,250);
    painter.drawLine(540,250,538,252);
    painter.drawText(545,250,tr("部门"));
    int posD=x0+20;
    int row;
    for(row=0;row<model()->rowCount(rootIndex());row++)
    {
        QModelIndex index=model()->index(row,0,rootIndex());
        QString dep=model()->data(index).toString();
        painter.drawText(posD,y0+20,dep);
        posD+=50;
    }
    /*完成了表格第1列数据的柱状统计图的绘制*/
    //男
    int posM=x0+20;
    MRegionList.clear();
    for(row=0;row<model()->rowCount(rootIndex());row++)
    {
        QModelIndex index=model()->index(row,1,rootIndex());
        int male=model()->data(index).toDouble();
        int width=10;
        //使用不同画刷颜色区别选中与未被选中的数据项
        if(selections->isSelected(index))
        {
            //Qt::Dense3Pattern是QBrush style
            //如果被选中，则画刷的style改变
            painter.setBrush(QBrush(QColor(91,75,0,255),Qt::Dense3Pattern));
        }
        else
        {
            painter.setBrush(Qt::blue);
        }
        //根据当前数据项的值按照比例绘制一个方形表示此项数据
        painter.drawRect(QRect(posM,y0-male*10,width,male*10));


        QRegion regionM(posM,y0-male*10,width,male*10);
        //将此数据所占据的区域保存到MRegionList列表中，为后面的数据项做准备
        MRegionList.insert(row,regionM);
        posM+=50;
    } //end for(row=0;row<model()->rowCount(rootIndex());row++)


    /*完成了表格第2列数据的柱状统计图绘制*/
    //女
    int posF=x0+30;
    FRegionList.clear();
    for(row=0;row<=model()->rowCount(rootIndex());row++)
    {
        QModelIndex index=model()->index(row,2,rootIndex());
        int female=model()->data(index).toDouble();
        int width=10;
        if(selections->isSelected(index))
        {
            painter.setBrush(QBrush(Qt::red,Qt::Dense3Pattern));
        }
        else
        {
            painter.setBrush(Qt::red);
        }
        painter.drawRect(QRect(posF,y0-female*10,width,female*10));
        QRegion regionF(posF,y0-female*10,width,female*10);
        FRegionList.insert(row,regionF);
        posF+=50;
    }  //end for(row=0;row<=model()->rowCount(rootIndex());row++)
    /*完成了表格第3列数据的柱状统计图的绘制*/
    //退休
    int posS=x0+40;
    SRegionList.clear();
    for(row=0;row<=model()->rowCount(rootIndex());row++)
    {
        QModelIndex index=model()->index(row,3,rootIndex());
        int retire=model()->data(index).toDouble();
        int width=10;
        if(selections->isSelected(index))
        {
            painter.setBrush(QBrush(Qt::green,Qt::Dense3Pattern));
        }
        else
        {
            painter.setBrush(Qt::green);
        }
        painter.drawRect(QRect(posS,y0-retire*10,width,retire*10));
        QRegion regionS(posS,y0-retire*10,width,retire*10);
        SRegionList.insert(row,regionS);
        posS+=50;
    }  //end for(row=0;row<=model()->rowCount(rootIndex());row++)
}
//dataChanged函数实现当model中的数据更改时，调用绘图设备的update()函数
//进行更新，反映数据的变化
void HistogramView::dataChanged(const QModelIndex &topLeft,
                                const QModelIndex &bottomRight)
{
    QAbstractItemView::dataChanged(topLeft,bottomRight);
    viewport()->update();
}
//setSelectionModel()函数为selections赋初值
void HistogramView::setSelectionModel(QItemSelectionModel *selectionModel)
{
    selections=selectionModel;
}
//selectionChanged()函数中完成当数据项发生变化时调用update()函数
//重绘绘图设备即可工作
void HistogramView::selectionChanged(const QItemSelection &selected,
                                     const QItemSelection &deselected)
{
    viewport()->update();
}
//鼠标按下事件函数mousePressEvent(),在调用setSelection()函数时确定鼠标单击
//点是否在某个数据项的区域内，并设置选择项
void HistogramView::mousePressEvent(QMouseEvent *event)
{
    QAbstractItemView::mousePressEvent(event);
    setSelection(QRect(event->pos().x(),event->pos().y(),1,1),
                 QItemSelectionModel::SelectCurrent);
}
void HistogramView::setSelection(const QRect &rect,
                                 QItemSelectionModel::SelectionFlags flags)
{
    int rows=model()->rowCount(rootIndex());  //获取总行数
    int columns=model()->columnCount(rootIndex());  //获取总列数

    //用于保存被选中的数据项的Index值,此处只实现了用鼠标单击选择，而没有实现
    //鼠标拖曳框选，因此，鼠标动作只可能选中一个数据项。若实现框选，则可使用
    //QModelIndexList来保存所有被选中的数据项的Index值
    QModelIndex selectedIndex;
    for(int row=0;row<rows;++row)
    {
        for(int column=1;column<columns;++column)
        {
            QModelIndex index=model()->index(row,column,rootIndex());
            QRegion region=itemRegion(index);  //返回指定index的数据项所占用的区域
            if(!region.intersected(rect).isEmpty())
                selectedIndex=index;
        }
    }
    if(selectedIndex.isValid())
        selections->select(selectedIndex,flags);
    else
    {
        QModelIndex noIndex;
        selections->select(noIndex,flags);
    }
}
QModelIndex HistogramView::indexAt(const QPoint &point) const
{
    QPoint newPoint(point.x(),point.y());
    QRegion region;
    //男 列
    foreach(region,MRegionList)  //检查当前点是否处于第一列(男)数据的区域中
    {
        if(region.contains(newPoint))
        {
            int row=MRegionList.indexOf(region);
            QModelIndex index=model()->index(row,1,rootIndex());
            return index;
        }
    }
    //女 列
    foreach(region,FRegionList)
    {
        if(region.contains(newPoint))
        {
            int row=FRegionList.indexOf(region);
            QModelIndex index=model()->index(row,2,rootIndex());
            return index;
        }
    }
    //合计 列
    foreach(region,FRegionList)
    {
        if(region.contains(newPoint))
        {
            int row=FRegionList.indexOf(region);
            QModelIndex index=model()->index(row,2,rootIndex());
            return index;
        }
    }
    return QModelIndex();
}
QRect HistogramView::visualRect(const QModelIndex &index)const{}
void HistogramView::scrollTo(const QModelIndex &index,ScrollHint){}
QModelIndex HistogramView::moveCursor(QAbstractItemView::CursorAction cursorAction, Qt::KeyboardModifiers modifiers){}
int HistogramView::horizontalOffset()const{}
int HistogramView::verticalOffset()const{}
bool HistogramView::isIndexHidden(const QModelIndex &index)const{}
QRegion HistogramView::visualRegionForSelection(const QItemSelection & selection)const{}
QRegion HistogramView::itemRegion(QModelIndex index)
{
    QRegion region;
    if (index.column() == 1)		//男
        region = MRegionList[index.row()];
    if (index.column() == 2)		//女
        region = FRegionList[index.row()];
    if (index.column() == 3)		//退休
        region = SRegionList[index.row()];
    return region;
}

main.cpp

#include "mainwindow.h"
#include <QApplication>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

注意.pro文件如下

#-------------------------------------------------
#
# Project created by QtCreator 2018-09-05T19:29:45
#
#-------------------------------------------------

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

TARGET = CH803
TEMPLATE = app

DEFINES += QT_DEPRECATED_WARNINGS  #新增加的

SOURCES += main.cpp
        mainwindow.cpp 
    histogramview.cpp

HEADERS  += mainwindow.h 
    histogramview.h

在该目录下新建文件histogram.txt

E:QTCH803uild-CH803-Desktop_Qt_5_6_2_MinGW_32bit-Debug

内容如下

一部,12,3,5
二部,16,4,0
三部,18,4,2
四部,10,3,1
五部,11,4,3
六部,12,2,4
七部,14,3,5
八部,9,1,1

运行效果如下

备注
这个程序里有几个函数我还是没搞懂，不太清楚其中的逻辑

void HistogramView::setSelection(const QRect &rect,
                                 QItemSelectionModel::SelectionFlags flags)

QModelIndex HistogramView::indexAt(const QPoint &point) const

参考资料《Qt5开发及实例》