QT 创建者 - "QGraphicsScene" 不命名类型

我是QT新手，尝试自学。

根据示例/教程，我得到了这段代码。

目的是创建一个允许登录的简单界面。

My error:

mainwindow.h:22: error: 'QGraphicsScene' does not name a type
     QGraphicsScene *scene;

我没有找到一个解决方案，但只提到从UI中删除对象，并在实例化QGraphicsScene时使用this而不是ui->graphicsView。

我错过了什么?

头/mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QMainWindow>
#include <QtCore>
#include <QtGui>
namespace Ui {
class MainWindow;
}
class MainWindow : public QMainWindow
{
    Q_OBJECT
public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
private:
    Ui::MainWindow *ui;
    QGraphicsScene *scene;
};
#endif // MAINWINDOW_H

来源/mainwindow.cpp

#include "mainwindow.h"
//#include "ui_mainwindow.h"
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    scene = new QGraphicsScene(ui->graphicsView);
    scene->setSceneRect(ui->graphicsView->rect());
    ui->graphicsView->setScene(scene);
    ui->graphicsView->setFixedSize(400,400);
    QPixmap pixmap("res/logo/logo-black.png");
    scene->addPixmap(pixmap);
    ui->graphicsView->show();
}
MainWindow::~MainWindow()
{
    delete ui;
}

来源/main.cpp

#include "mainwindow.h"
#include <QApplication>
int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();
    return a.exec();
}

<?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>283</width>
    <height>415</height>
   </rect>
  </property>
  <property name="windowTitle">
   <string>MainWindow</string>
  </property>
  <widget class="QWidget" name="centralWidget">
   <widget class="QLineEdit" name="lineEdit">
    <property name="geometry">
     <rect>
      <x>120</x>
      <y>130</y>
      <width>141</width>
      <height>22</height>
     </rect>
    </property>
   </widget>
   <widget class="QLineEdit" name="lineEdit_2">
    <property name="geometry">
     <rect>
      <x>120</x>
      <y>170</y>
      <width>141</width>
      <height>22</height>
     </rect>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton">
    <property name="geometry">
     <rect>
      <x>90</x>
      <y>250</y>
      <width>91</width>
      <height>31</height>
     </rect>
    </property>
    <property name="text">
     <string>Login</string>
    </property>
   </widget>
   <widget class="QCheckBox" name="checkBox">
    <property name="geometry">
     <rect>
      <x>90</x>
      <y>220</y>
      <width>101</width>
      <height>20</height>
     </rect>
    </property>
    <property name="text">
     <string>Remeber Me</string>
    </property>
   </widget>
   <widget class="QLabel" name="label">
    <property name="geometry">
     <rect>
      <x>20</x>
      <y>130</y>
      <width>59</width>
      <height>14</height>
     </rect>
    </property>
    <property name="text">
     <string>Email</string>
    </property>
   </widget>
   <widget class="QLabel" name="label_2">
    <property name="geometry">
     <rect>
      <x>20</x>
      <y>170</y>
      <width>59</width>
      <height>14</height>
     </rect>
    </property>
    <property name="text">
     <string>Password</string>
    </property>
   </widget>
   <widget class="QPushButton" name="pushButton_2">
    <property name="geometry">
     <rect>
      <x>96</x>
      <y>310</y>
      <width>80</width>
      <height>22</height>
     </rect>
    </property>
    <property name="text">
     <string>Register</string>
    </property>
   </widget>
   <widget class="QGraphicsView" name="graphicsView">
    <property name="geometry">
     <rect>
      <x>80</x>
      <y>0</y>
      <width>121</width>
      <height>111</height>
     </rect>
    </property>
    <property name="autoFillBackground">
     <bool>false</bool>
    </property>
   </widget>
  </widget>
  <widget class="QMenuBar" name="menuBar">
   <property name="geometry">
    <rect>
     <x>0</x>
     <y>0</y>
     <width>283</width>
     <height>19</height>
    </rect>
   </property>
  </widget>
  <widget class="QToolBar" name="mainToolBar">
   <attribute name="toolBarArea">
    <enum>TopToolBarArea</enum>
   </attribute>
   <attribute name="toolBarBreak">
    <bool>false</bool>
   </attribute>
  </widget>
  <widget class="QStatusBar" name="statusBar"/>
 </widget>
 <layoutdefault spacing="6" margin="11"/>
 <resources/>
 <connections/>
</ui>

• 取消:#include "ui_mainwindow.h" in Sources/mainwindow.cpp

原因我没有在我的项目目录中看到ui_mainwindow.h，因此认为这是一个不必要的包含

• 添加#include <QGraphicsScene> in Headers/mainwindow.h

从文档页找到-更多的是"如果我添加这个会发生什么"的尝试，有<QtGui>包含<QGraphicsScene>的想法

谢谢