新建Qt项目，选择Qt Widgets Application，填入项目名称“ImageView”，点击完成。
在Qt Designer里会生成如图所示的几个文件：
此时我们右键删除imageviewer.ui这个文件，因为我们本次是用纯代码的方式生成界面，所以不需要这个ui文件了。
关键代码主要在imageviewer.h和imageviewer.cpp里。下面是代码：
imageviewer.h
1 #ifndef IMAGEVIEWER_H 2 #define IMAGEVIEWER_H
3
4 #include <QMainWindow>
5 #include <QLabel>
6 #include <QScrollArea>
7 #include <QMenu>
8 #include <QMenuBar>
9 #include <QToolBar>
10
11 namespace Ui { 12 class ImageViewer; 13 } 14
15 class ImageViewer : public QMainWindow 16 { 17 Q_OBJECT 18
19 public: 20 explicit ImageViewer(QWidget *parent = nullptr); 21 ~ImageViewer(); 22
23 void initMenu(); 24 void initToolBar(); 25 void initConnect(); 26
27 private: 28 Ui::ImageViewer *ui; 29 QLabel *imageLabel; 30 QScrollArea *scrollAera; 31
32 QMenu *fileMenu; 33 QMenu *viewMenu; 34 QMenu *helpMenu; 35
36 QToolBar *fileToolBar; 37
38 QAction *openAct; 39 QAction *printAct; 40 QAction *exitAct; 41 QAction *zoomInAct; 42 QAction *zoomOutAct; 43 QAction *normalSizeAct; 44 QAction *fitToWindowAct; 45 QAction *aboutAct; 46 QAction *aboutQtAct; 47
48 private slots: 49 void open(); 50 void print(); 51 void exit(); 52 void zoomIn(); 53 void zoomOut(); 54 void normalSize(); 55 void fitToWindow(); 56 void about(); 57 void aboutQt(); 58 }; 59
60 #endif // IMAGEVIEWER_H
imageviewer.cpp
1 #include "imageviewer.h"
2 #include "ui_imageviewer.h"
3
4 ImageViewer::ImageViewer(QWidget *parent) : 5 QMainWindow(parent), 6 ui(new Ui::ImageViewer) 7 { 8 ui->setupUi(this); 9
10 //initalize
11 initMenu(); 12 initToolBar(); 13 initConnect(); 14 } 15
16 ImageViewer::~ImageViewer() 17 { 18 delete ui; 19 } 20
21 void ImageViewer::initMenu() 22 { 23 //QMenuBar *menuBar = this->menuBar(); 24 //add three menus
25 fileMenu = new QMenu(tr("&File"),this); 26 viewMenu = new QMenu(tr("&View"),this); 27 helpMenu = new QMenu(tr("&About"),this); 28
29 //add actions and add it into corresponding menu
30 openAct = new QAction(tr("&Open"),this); 31 openAct -> setShortcut(tr("ctrl+O")); 32 printAct = new QAction(tr("&Print"),this); 33 printAct -> setShortcut(tr("ctrl+P")); 34 exitAct = new QAction(tr("&Exit"),this); 35 exitAct -> setShortcut(tr("ctrl+Q")); 36 fileMenu -> addAction(openAct); 37 fileMenu -> addAction(printAct); 38 fileMenu -> addSeparator(); 39 fileMenu -> addAction(exitAct); 40
41 zoomInAct = new QAction(tr("Zoom &In"),this); 42 zoomInAct -> setShortcut(tr("ctrl+=")); 43 zoomOutAct = new QAction(tr("Zoom &Out"),this); 44 zoomOutAct -> setShortcut(tr("ctrl+-")); 45 normalSizeAct = new QAction(tr("&Normal Size"),this); 46 normalSizeAct -> setShortcut(tr("ctrl+S")); 47 fitToWindowAct = new QAction(tr("&Fit to Window"),this); 48 fitToWindowAct -> setShortcut(tr("ctrl+F")); 49 viewMenu -> addAction(zoomInAct); 50 viewMenu -> addAction(zoomOutAct); 51 viewMenu -> addAction(normalSizeAct); 52 viewMenu -> addSeparator(); 53 viewMenu -> addAction(fitToWindowAct); 54
55 aboutAct = new QAction(tr("&About"),this); 56 aboutQtAct = new QAction(tr("&About Qt"),this); 57 helpMenu -> addAction(aboutAct); 58 helpMenu -> addAction(aboutQtAct); 59
60 //add menus to menubar
61 menuBar() -> addMenu(fileMenu); 62 menuBar() -> addMenu(viewMenu); 63 menuBar() -> addMenu(helpMenu); 64 } 65
66 void ImageViewer::initToolBar() 67 { 68 //add a toolbar and add its actions
69 fileToolBar = new QToolBar(this); 70
71 fileToolBar -> addAction(openAct); 72 fileToolBar -> addAction(printAct); 73 fileToolBar -> addAction(exitAct); 74
75 addToolBar(Qt::TopToolBarArea,fileToolBar); 76 } 77
78 void ImageViewer::initConnect() 79 { 80 //singals and slots
81 connect(openAct,SIGNAL(triggered),this,SLOT(open())); 82 connect(printAct,SIGNAL(triggered),this,SLOT(print())); 83 connect(exitAct,SIGNAL(triggered),this,SLOT(exit())); 84 connect(zoomInAct,SIGNAL(triggered),this,SLOT(zoomIn())); 85 connect(zoomOutAct,SIGNAL(triggered),this,SLOT(zoomOut())); 86 connect(normalSizeAct,SIGNAL(triggered),this,SLOT(normalSize())); 87 connect(fitToWindowAct,SIGNAL(triggered),this,SLOT(fitToWindow())); 88 connect(aboutAct,SIGNAL(triggered),this,SLOT(about())); 89 connect(aboutQtAct,SIGNAL(triggered),this,SLOT(aboutQt())); 90 } 91
92 //implement slot functions
93 void ImageViewer::open() 94 { 95
96 } 97
98 void ImageViewer::print() 99 { 100
101 } 102
103 void ImageViewer::exit() 104 { 105
106 } 107
108 void ImageViewer::zoomIn() 109 { 110
111 } 112
113 void ImageViewer::zoomOut() 114 { 115
116 } 117
118 void ImageViewer::normalSize() 119 { 120
121 } 122
123 void ImageViewer::fitToWindow() 124 { 125
126 } 127
128 void ImageViewer::about() 129 { 130
131 } 132
133 void ImageViewer::aboutQt() 134 { 135
136 }
界面效果如图：
