Qt高级——Qt数据可视化性能优化

一、数据可视化简介

1、数据可视化简介

数据可视化即采用图形图表等对采集的数据进行展示，可以非常直观的查看传感器采集到的数据。本文将使用Qt的标准组件QTableWidget、标准模型、自定义模型分别实现对数据的表格展示。

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2、系统环境

个人PC：ThinkPad T450
操作系统：RHEL7.3 WorkStation
内存容量：8G
磁盘容量：SSD 100G
CPU：Intel(R) Core(TM) i5-5200U CPU @ 2.20GHz

二、标准界面组件实现

1、代码实现

MainWindow.h文件：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include 
#include 
#include 
#include 
#include 
#include 

struct Student
{
    char name[16];
    char id[24];
    char sex[8];
    int age;
    char phone[16];
    char hobby[24];
    char company[16];
};

class MainWindow : public QWidget
{
    Q_OBJECT
public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();
    /**
     * @brief 生成数据
     * @param size，生成数据的规模
     */
    void generateData(int size);
private:
    /**
     * @brief 生成一行数据
     * @param item，数据项
     * @return 返回数据项链表
     */
    QList generateRow(const Student& item);
private:
    QTableWidget* m_table;
};

#endif // MAINWINDOW_H

MainWindow.cpp文件：

#include "MainWindow.h"
#include 

MainWindow::MainWindow(QWidget *parent) : QWidget(parent)
{
    m_table = new QTableWidget(this);
    QVBoxLayout* layout = new QVBoxLayout;
    layout->addWidget(m_table);
    setLayout(layout);
    QStringList header;
    header << "Name" << "ID" << "Sex" << "Age" << "Phone" << "Hobby" << "Company";
    m_table->setHorizontalHeaderLabels(header);
    m_table->setColumnCount(7);
}

MainWindow::~MainWindow()
{

}
// 头部插入实现
void MainWindow::generateData(int size)
{
    Student* zhangsan = (Student*)malloc(sizeof(Student));
    memset(zhangsan, 0, sizeof(Student));
    strncpy(zhangsan->name, "zhangsan", strlen("zhangsan"));
    strncpy(zhangsan->id, "53302219861001xxxx", strlen("53302219861001xxxx"));
    strncpy(zhangsan->sex, "M", strlen("M"));
    zhangsan->age = 33;
    strncpy(zhangsan->phone, "18910108888", strlen("18910108888"));
    strncpy(zhangsan->hobby, "BasketBall, Play", strlen("BasketBall, Play"));
    strncpy(zhangsan->company, "Alibaba", strlen("Alibaba"));

    for(int i = 0; i < size; i++)
    {
        m_table->insertRow(0);
        QList items1 = generateRow(*zhangsan);
        for(int k = 0; k < items1.size(); k++)
        {
            m_table->setItem(0, k, items1.at(k));
        }
    }
    delete zhangsan;
    qDebug() << sizeof(Student);

}
// 尾部插入实现
void MainWindow::generateData(int size)
{
    Student* zhangsan = (Student*)malloc(sizeof(Student));
    memset(zhangsan, 0, sizeof(Student));
    strncpy(zhangsan->name, "zhangsan", strlen("zhangsan"));
    strncpy(zhangsan->id, "53302219861001xxxx", strlen("53302219861001xxxx"));
    strncpy(zhangsan->sex, "M", strlen("M"));
    zhangsan->age = 33;
    strncpy(zhangsan->phone, "18910108888", strlen("18910108888"));
    strncpy(zhangsan->hobby, "BasketBall, Play", strlen("BasketBall, Play"));
    strncpy(zhangsan->company, "Alibaba", strlen("Alibaba"));

    for(int i = 0; i < size; i++)
    {
        m_table->insertRow(i);
        QList items1 = generateRow(*zhangsan);
        for(int k = 0; k < items1.size(); k++)
        {
            m_table->setItem(i, k, items1.at(k));
        }
    }
    delete zhangsan;
    qDebug() << sizeof(Student);

}

QList MainWindow::generateRow(const Student &item)
{
    QList ret;
    QTableWidgetItem* name = new QTableWidgetItem();
    name->setData(Qt::DisplayRole, QString("%1").arg(item.name));
    ret.append(name);
    QTableWidgetItem* id = new QTableWidgetItem();
    id->setData(Qt::DisplayRole, QString("%1").arg(item.id));
    ret.append(id);
    QTableWidgetItem* sex = new QTableWidgetItem();
    sex->setData(Qt::DisplayRole, QString("%1").arg(item.sex));
    ret.append(sex);
    QTableWidgetItem* age = new QTableWidgetItem();
    age->setData(Qt::DisplayRole, QString("%1").arg(item.age));
    ret.append(age);
    QTableWidgetItem* phone = new QTableWidgetItem();
    phone->setData(Qt::DisplayRole, QString("%1").arg(item.phone));
    ret.append(phone);
    QTableWidgetItem* hobby = new QTableWidgetItem();
    hobby->setData(Qt::DisplayRole, QString("%1").arg(item.hobby));
    ret.append(hobby);
    QTableWidgetItem* company = new QTableWidgetItem();
    company->setData(Qt::DisplayRole, QString("%1").arg(item.company));
    ret.append(company);
    return ret;
}

main.cpp文件：

#include "MainWindow.h"
#include 

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.generateData(500000);
    w.show();

    return a.exec();
}

2、性能分析
Student结构体如下：

struct Student
{
    char name[16];
    char id[24];
    char sex[8];
    int age;
    char phone[16];
    char hobby[24];
    char company[16];
};

Student结构体大小为108字节，根据生成的不同数量规模的数据，其程序占用的内存如下：
Qt高级——Qt数据可视化性能优化
根据上述数据，在大规模数据量下，使用QTableWidget展示数据时，每条数据实际占用的内存是数据本身大小的15倍，数据量越大插入越耗时，头部插入耗时远远大于尾部追加插入。

三、标准模型实现

1、代码实现

StudentTableModel.h文件：

#ifndef STUDENTTABLEMODEL_H
#define STUDENTTABLEMODEL_H

#include 
#include 

struct Student
{
    char name[16];
    char id[24];
    char sex[8];
    int age;
    char phone[16];
    char hobby[24];
    char company[16];
};

class StudentTableModel : public QStandardItemModel
{
    Q_OBJECT
public:
    StudentTableModel();
    /**
     * @brief 生成数据
     * @param size，数据规模
     */
    void generateData(int size);
    /**
     * @brief 生成一行数据
     * @param item，数据对象
     * @return 返回数据项链表
     */
    QList generateRow(const Student& item);
    /**
     * @brief 追加一行
     * @param item，数据对象
     */
    void appendRow(const Student& item);

private:
    QStandardItem* m_root;//模型虚拟根节点
};

#endif // STUDENTTABLEMODEL_H

StudentTableModel.cpp文件：

#include "StudentTableModel.h"

StudentTableModel::StudentTableModel()
{
    m_root = invisibleRootItem();
}

void StudentTableModel::generateData(int size)
{
    Student* zhangsan = (Student*)malloc(sizeof(Student));
    memset(zhangsan, 0, sizeof(Student));
    strncpy(zhangsan->name, "zhangsan", strlen("zhangsan"));
    strncpy(zhangsan->id, "53302219861001xxxx", strlen("53302219861001xxxx"));
    strncpy(zhangsan->sex, "M", strlen("M"));
    zhangsan->age = 33;
    strncpy(zhangsan->phone, "18910108888", strlen("18910108888"));
    strncpy(zhangsan->hobby, "BasketBall, Play", strlen("BasketBall, Play"));
    strncpy(zhangsan->company, "Alibaba", strlen("Alibaba"));

    for(int i = 0; i < size; i++)
    {
        QList items1 = generateRow(*zhangsan);
        // 尾部追加
        m_root->appendRow(items1);
        // 头部插入
        m_root->insertRow(0, items1);
    }
    delete zhangsan;
}

QList StudentTableModel::generateRow(const Student &item)
{
    QList ret;
    QStandardItem* name = new QStandardItem();
    name->setData(QString("%1").arg(item.name), Qt::DisplayRole);
    ret.append(name);
    QStandardItem* id = new QStandardItem();
    id->setData(QString("%1").arg(item.id), Qt::DisplayRole);
    ret.append(id);
    QStandardItem* sex = new QStandardItem();
    sex->setData(QString("%1").arg(item.sex), Qt::DisplayRole);
    ret.append(sex);
    QStandardItem* age = new QStandardItem();
    age->setData(QString("%1").arg(item.age), Qt::DisplayRole);
    ret.append(age);
    QStandardItem* phone = new QStandardItem();
    phone->setData(QString("%1").arg(item.phone), Qt::DisplayRole);
    ret.append(phone);
    QStandardItem* hobby = new QStandardItem();
    hobby->setData(QString("%1").arg(item.hobby), Qt::DisplayRole);
    ret.append(hobby);
    QStandardItem* company = new QStandardItem();
    company->setData(QString("%1").arg(item.company), Qt::DisplayRole);
    ret.append(company);
    return ret;
}

MainWindow.h文件：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include 
#include 
#include 
#include 
#include "StudentTableModel.h"

class MainWindow : public QWidget
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();
    void generateData(int size);
private:
    QTableView* m_tableView;
    StudentTableModel* m_model;
};

#endif // MAINWINDOW_H

MainWindow.cpp文件：

#include "MainWindow.h"

MainWindow::MainWindow(QWidget *parent): QWidget(parent)
{
    m_tableView = new QTableView(this);
    QVBoxLayout* layout = new QVBoxLayout;
    layout->addWidget(m_tableView);
    setLayout(layout);
    m_model = new StudentTableModel();
    m_tableView->setModel(m_model);
    QStringList header;
    header << "Name" << "ID" << "Sex" << "Age" << "Phone" << "Hobby" << "Company";
    m_model->setHorizontalHeaderLabels(header);
}

MainWindow::~MainWindow()
{

}

void MainWindow::generateData(int size)
{
    m_model->generateData(size);
}

main.cpp文件：

#include "MainWindow.h"
#include 

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    w.generateData(500000);

    return a.exec();
}

2、性能分析

根据生成的不同数量规模的数据，其程序占用的内存如下：
Qt高级——Qt数据可视化性能优化
使用QStandardItemModel与QTableView展示数据，每条数据实际占用内存的大小是数据本身大小的15倍，数据量越大插入越耗时，头部插入耗时远远大于尾部追加插入，其性能表现与QTableWidget相当。

四、自定义模型实现

1、代码实现

StudentTableModel.h文件：

#ifndef STUDENTTABLEMODEL_H
#define STUDENTTABLEMODEL_H

#include 
#include 
#include 
#include 
#include 

struct Student
{
    char name[16];
    char id[24];
    char sex[8];
    int age;
    char phone[16];
    char hobby[24];
    char company[16];
};

class StudentTableModel : public QAbstractTableModel
{
    Q_OBJECT
public:
    StudentTableModel(QObject* parent = NULL);
    virtual int rowCount(const QModelIndex &parent) const;
    virtual int columnCount(const QModelIndex &parent) const;
    virtual QVariant data(const QModelIndex &index, int role) const;
    virtual QVariant headerData(int section, Qt::Orientation orientation, int role) const;
    virtual Qt::ItemFlags flags(const QModelIndex &index) const;
    virtual bool setData(const QModelIndex &index, const QVariant &value, int role = Qt::EditRole);
    virtual bool insertRows(int position, int rows, const QModelIndex &index = QModelIndex());
    virtual bool removeRows(int position, int rows, const QModelIndex &index = QModelIndex());
    void appendRow(const Student& item);
    void setHorizontalHeaderLabels(const QStringList& header);
private:
    QStringList m_headers;
    QList m_itemList;
};

#endif // STUDENTTABLEMODEL_H

StudentTableModel.cpp文件：

#include "StudentTableModel.h"

StudentTableModel::StudentTableModel(QObject *parent): QAbstractTableModel(parent)
{
}

int StudentTableModel::rowCount(const QModelIndex &parent) const
{
    Q_UNUSED(parent);
    return m_itemList.size();
}

int StudentTableModel::columnCount(const QModelIndex &parent) const
{
    Q_UNUSED(parent);
    return m_headers.size();
}

QVariant StudentTableModel::data(const QModelIndex &index, int role) const
{
    if (!index.isValid())
        return QVariant();

    if (index.row() >= m_itemList.size() || index.row() < 0)
        return QVariant();

    if (role == Qt::DisplayRole)
    {
        int row = index.row();
        Student* data = m_itemList.at(row);
        int column = index.column();
        switch(column)
        {
        case 0:
            return QString("%1").arg(data->name);
        case 1:
            return QString("%1").arg(data->id);
        case 2:
            return QString("%1").arg(data->sex);
        case 3:
            return data->age;
        case 4:
            return QString("%1").arg(data->phone);
        case 5:
            return QString("%1").arg(data->hobby);
        case 6:
            return QString("%1").arg(data->company);
        }
    }
    return QVariant();
}

QVariant StudentTableModel::headerData(int section, Qt::Orientation orientation, int role) const
{
    if (role != Qt::DisplayRole)
        return QVariant();

    if (orientation == Qt::Horizontal)
    {
        return m_headers.at(section);
    }
    return QVariant();
}

bool StudentTableModel::insertRows(int position, int rows, const QModelIndex &index)
{
    Q_UNUSED(index);
    beginInsertRows(QModelIndex(), position, position + rows - 1);

    for (int row = 0; row < rows; ++row)
    {
//        m_itemList.insert(position, );
    }

    endInsertRows();
    return true;
}

bool StudentTableModel::removeRows(int position, int rows, const QModelIndex &index)
{
    Q_UNUSED(index);
    beginRemoveRows(QModelIndex(), position, position + rows - 1);

    for (int row = 0; row < rows; ++row)
        m_itemList.removeAt(position);

    endRemoveRows();
    return true;
}

void StudentTableModel::appendRow(const Student &item)
{
    Student* data = (Student*)malloc(sizeof(Student));
    memset(data, 0, sizeof(Student));
    strncpy(data->name, item.name, strlen(item.name));
    strncpy(data->id, item.id, strlen(item.id));
    strncpy(data->sex, item.sex, strlen(item.sex));
    data->age = item.age;
    strncpy(data->phone, item.phone, strlen(item.phone));
    strncpy(data->hobby, item.hobby, strlen(item.hobby));
    strncpy(data->company, item.company, strlen(item.company));
    int row = m_itemList.size();
    insertRows(0, 1);
    m_itemList.append(data);
//    m_itemList.insert(0, data);
}

void StudentTableModel::setHorizontalHeaderLabels(const QStringList &header)
{
    m_headers = header;
}

bool StudentTableModel::setData(const QModelIndex &index, const QVariant &value, int role)
{
    if (index.isValid() && role == Qt::EditRole)
    {
        int row = index.row();
        // mpdify data

        emit(dataChanged(index, index));
        return true;
    }
    return false;
}

Qt::ItemFlags StudentTableModel::flags(const QModelIndex &index) const
{
    if (!index.isValid())
        return Qt::ItemIsEnabled;
    return QAbstractTableModel::flags(index) | Qt::ItemIsEditable;
}

MainWindow.h文件：

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include 
#include 
#include 
#include "StudentTableModel.h"

class MainWindow : public QWidget
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = 0);
    ~MainWindow();

    void generateData(int size);
private:
    StudentTableModel* m_model;
    QTableView* m_tableView;
};

#endif // MAINWINDOW_H

MainWindow.cpp文件：

#include "MainWindow.h"

MainWindow::MainWindow(QWidget *parent): QWidget(parent)
{
    m_tableView = new QTableView(this);
    m_model = new StudentTableModel();
    QVBoxLayout* layout = new QVBoxLayout;
    layout->addWidget(m_tableView);
    setLayout(layout);

    QStringList header;
    header << "Name" << "ID" << "Sex" << "Age" << "Phone" << "Hobby" << "Company";
    m_model->setHorizontalHeaderLabels(header);
    m_tableView->setUpdatesEnabled(true);
    m_tableView->setModel(m_model);
}

MainWindow::~MainWindow()
{

}

void MainWindow::generateData(int size)
{
    Student* zhangsan = (Student*)malloc(sizeof(Student));
    memset(zhangsan, 0, sizeof(Student));
    strncpy(zhangsan->name, "zhangsan", strlen("zhangsan"));
    strncpy(zhangsan->id, "53302219861001xxxx", strlen("53302219861001xxxx"));
    strncpy(zhangsan->sex, "M", strlen("M"));
    zhangsan->age = 33;
    strncpy(zhangsan->phone, "18910108888", strlen("18910108888"));
    strncpy(zhangsan->hobby, "BasketBall, Play", strlen("BasketBall, Play"));
    strncpy(zhangsan->company, "Alibaba", strlen("Alibaba"));

    for(int i = 0; i < size; i++)
    {
        m_model->appendRow(*zhangsan);
    }

    delete zhangsan;
}

main.cpp文件：

#include "MainWindow.h"
#include 

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    w.generateData(1000000);

    return a.exec();
}

2、性能分析
根据生成的不同数量规模的数据，其程序占用的内存如下：
Qt高级——Qt数据可视化性能优化
使用QAbstractTableModel派生类与QTableView展示数据，每条数据实际占用内存的大小是数据本身大小的1.5倍，数据量越大插入越耗时，由于底层数据结构采用链表实现，头部插入耗时与尾部追加插入耗时相当，但内存空间占用大幅下降。
将底层数据结构换成QVector，根据生成的不同数量规模的数据，其程序占用的内存如下：
Qt高级——Qt数据可视化性能优化
使用QVector作为模型的底层数据结构存储数据，其内存占用与QList相当，尾部追加插入耗时与QList相当，但头部插入比QList耗时较多。

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Qt高级——Qt数据可视化性能优化