Qt Custom chart gets smaller in size when added to a frame

The Qt Custom Chart from example looks like this:

But when I add it in another project where I added a frame named chartframe from Qt Designer and added this custom chart to it, it goes to a very small size.

Below is the code for mainwindow.cpp:

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    //![1]
        QLineSeries *series = new QLineSeries();
        *series << QPointF(0, 6) << QPointF(9, 4) << QPointF(15, 20) << QPointF(25, 12) << QPointF(29, 26);
        QChart *chart = new QChart();
        chart->legend()->hide();
        chart->addSeries(series);
    //![1]

    //![2]
        // Customize series
        QPen pen(QRgb(0xfdb157));
        pen.setWidth(5);
        series->setPen(pen);

        // Customize chart title
        QFont font;
        font.setPixelSize(18);
        chart->setTitleFont(font);
        chart->setTitleBrush(QBrush(Qt::white));
        chart->setTitle("Customchart example");

        // Customize chart background
        QLinearGradient backgroundGradient;
        backgroundGradient.setStart(QPointF(0, 0));
        backgroundGradient.setFinalStop(QPointF(0, 1));
        backgroundGradient.setColorAt(0.0, QRgb(0xd2d0d1));
        backgroundGradient.setColorAt(1.0, QRgb(0x4c4547));
        backgroundGradient.setCoordinateMode(QGradient::ObjectBoundingMode);
        chart->setBackgroundBrush(backgroundGradient);

        // Customize plot area background
        QLinearGradient plotAreaGradient;
        plotAreaGradient.setStart(QPointF(0, 1));
        plotAreaGradient.setFinalStop(QPointF(1, 0));
        plotAreaGradient.setColorAt(0.0, QRgb(0x555555));
        plotAreaGradient.setColorAt(1.0, QRgb(0x55aa55));
        plotAreaGradient.setCoordinateMode(QGradient::ObjectBoundingMode);
        chart->setPlotAreaBackgroundBrush(plotAreaGradient);
        chart->setPlotAreaBackgroundVisible(true);
    //![2]

    //![3]
        QCategoryAxis *axisX = new QCategoryAxis();
        QCategoryAxis *axisY = new QCategoryAxis();

        // Customize axis label font
        QFont labelsFont;
        labelsFont.setPixelSize(12);
        axisX->setLabelsFont(labelsFont);
        axisY->setLabelsFont(labelsFont);

        // Customize axis colors
        QPen axisPen(QRgb(0xd18952));
        axisPen.setWidth(2);
        axisX->setLinePen(axisPen);
        axisY->setLinePen(axisPen);

        // Customize axis label colors
        QBrush axisBrush(Qt::white);
        axisX->setLabelsBrush(axisBrush);
        axisY->setLabelsBrush(axisBrush);

        // Customize grid lines and shades
        axisX->setGridLineVisible(false);
        axisY->setGridLineVisible(false);
        axisY->setShadesPen(Qt::NoPen);
        axisY->setShadesBrush(QBrush(QColor(0x99, 0xcc, 0xcc, 0x55)));
        axisY->setShadesVisible(true);
    //![3]

    //![4]
    //
        axisX->append("Monday", 5);
        axisX->append("Tuesday", 10);
        axisX->append("Wednesday", 15);
        axisX->append("Thursday", 20);
        axisX->append("Friday", 25);
        axisX->append("Saturday", 30);
        axisX->append("Sunday", 35);
        axisX->setRange(0, 35);


        axisY->append("Normal", 10);
        axisY->append("Yellow", 20);
        axisY->append("Red", 30);
        axisY->setRange(0, 30);

        chart->addAxis(axisX, Qt::AlignBottom);
        chart->addAxis(axisY, Qt::AlignLeft);
        series->attachAxis(axisX);
        series->attachAxis(axisY);
    //![4]

    //![5]
        QChartView *chartView = new QChartView(chart);
        chartView->setRenderHint(QPainter::Antialiasing);
        chartView-> setParent(ui->chartframe);

    //![5]
    //!
    //!
//        MainWindow window;
//        window.setCentralWidget(chartView);

}

MainWindow::~MainWindow()
{
    delete ui;
}

And this is the code for main.cpp:

#include "mainwindow.h"

#include <QApplication>

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

    w.show();
    return a.exec();
}

Below is the code of mainwindow.ui:

<?xml version="1.0" encoding="UTF-8"?>
<ui version="4.0">
 <class>MainWindow</class>
 <widget class="QMainWindow" name="MainWindow">
  <property name="geometry">
   <rect>
    <x>0</x>
    <y>0</y>
    <width>800</width>
    <height>600</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralwidget">
   <widget class="QFrame" name="frame">
    <property name="geometry">
     <rect>
      <x>20</x>
      <y>30</y>
      <width>661</width>
      <height>421</height>
     </rect>
    </property>
    <property name="frameShape">
     <enum>QFrame::StyledPanel</enum>
    </property>
    <property name="frameShadow">
     <enum>QFrame::Raised</enum>
    </property>
    <layout class="QHBoxLayout" name="horizontalLayout">
     <item>
      <widget class="QFrame" name="frame_2">
       <property name="frameShape">
        <enum>QFrame::StyledPanel</enum>
       </property>
       <property name="frameShadow">
        <enum>QFrame::Raised</enum>
       </property>
       <layout class="QVBoxLayout" name="verticalLayout">
        <item>
         <widget class="QFrame" name="chartframe">
          <property name="frameShape">
           <enum>QFrame::StyledPanel</enum>
          </property>
          <property name="frameShadow">
           <enum>QFrame::Raised</enum>
          </property>
         </widget>
        </item>
        <item>
         <widget class="QPushButton" name="pushButton">
          <property name="text">
           <string>PushButton</string>
          </property>
         </widget>
        </item>
       </layout>
      </widget>
     </item>
     <item>
      <widget class="QFrame" name="frame_3">
       <property name="frameShape">
        <enum>QFrame::StyledPanel</enum>
       </property>
       <property name="frameShadow">
        <enum>QFrame::Raised</enum>
       </property>
       <layout class="QVBoxLayout" name="verticalLayout_2">
        <item>
         <widget class="QTextEdit" name="textEdit"/>
        </item>
        <item>
         <widget class="QLineEdit" name="lineEdit"/>
        </item>
       </layout>
      </widget>
     </item>
    </layout>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menubar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>800</width>
     <height>21</height>
    </rect>
   </property>
  </widget>
  <widget class="QStatusBar" name="statusbar"/>
 </widget>
 <resources/>
 <connections/>
</ui>

I will be waiting for a kind response. I am a beginner on the qt framework.

You must set a layout on chartframe, and then add chartView to that layout:

QChartView *chartView = new QChartView(chart);
chartView->setRenderHint(QPainter::Antialiasing);
QVBoxLayout *layout = new QVBoxLayout(ui->chartframe);
layout->addWidget(chartView);

You should also set a layout on the central widget. So, in Qt Designer, select centralWidget in the Object Inspector, and then click Lay Out Horizontally (on the toolbar). Then save and re-compile the ui.

You may also need to resize the window to see the chart properly.