.pro
1 QT += core gui
2
3 greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
4
5 CONFIG += c++11
6
7 # The following define makes your compiler emit warnings if you use
8 # any Qt feature that has been marked deprecated (the exact warnings
9 # depend on your compiler). Please consult the documentation of the
10 # deprecated API in order to know how to port your code away from it.
11 DEFINES += QT_DEPRECATED_WARNINGS
12
13 # You can also make your code fail to compile if it uses deprecated APIs.
14 # In order to do so, uncomment the following line.
15 # You can also select to disable deprecated APIs only up to a certain version of Qt.
16 #DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000 # disables all the APIs deprecated before Qt 6.0.0
17
18 SOURCES += \
19 main.cpp \
20 mainwindow.cpp
21
22 HEADERS += \
23 mainwindow.h
24
25 FORMS += \
26 mainwindow.ui
27
28 # Default rules for deployment.
29 qnx: target.path = /tmp/$${TARGET}/bin
30 else: unix:!android: target.path = /opt/$${TARGET}/bin
31 !isEmpty(target.path): INSTALLS += target
32
33 RESOURCES += \
34
View Code
main.cpp
1 #include "mainwindow.h"
2
3 #include <QApplication>
4
5 int main(int argc, char *argv[])
6 {
7 QApplication a(argc, argv);
8 MainWindow w;
9 w.show();
10 return a.exec();
11
View Code
mainwindow.h
1 #ifndef MAINWINDOW_H
2 #define MAINWINDOW_H
3
4 #include <QMainWindow>
5 #include <QPainter>
6
7 QT_BEGIN_NAMESPACE
8 namespace Ui { class MainWindow; }
9 QT_END_NAMESPACE
10
11 class MainWindow : public QMainWindow
12 {
13 Q_OBJECT
14
15 public:
16 MainWindow(QWidget *parent = nullptr);
17 ~MainWindow();
18 void paintEvent(QPaintEvent *);
19
20 private:
21 Ui::MainWindow *ui;
22 };
23 #endif // MAINWINDOW_H
View Code
mainwindow.cpp
1 #include "mainwindow.h"
2 #include "ui_mainwindow.h"
3
4 MainWindow::MainWindow(QWidget *parent)
5 : QMainWindow(parent)
6 , ui(new Ui::MainWindow)
7 {
8 ui->setupUi(this);
9
10 setWindowTitle(QStringLiteral("QPainter实现图片的绘图、平移、缩放、旋转、扭曲"));
11 }
12
13 MainWindow::~MainWindow()
14 {
15 delete ui;
16 }
17
18 void MainWindow::paintEvent(QPaintEvent *)
19 {
20 // 绘图
21 QPainter painter(this);
22 QPixmap pix;
23 pix.load(":/new/prefix1/abc.png");
24 painter.drawPixmap(0,0,100,100,pix);
25
26 // 利用更改坐标原点实现平移
27 painter.translate(100,100); //将（100，100）设为坐标原点
28 painter.drawPixmap(0,0,100,100,pix);
29 painter.translate(-100, -100); //让图片的中心作为旋转的中心
30
31 // 实现图片的缩放
32 painter.translate(100,100); //将（100，100）设为坐标原点
33 qreal width = pix.width(); //获得以前图片的宽和高
34 qreal height = pix.height();
35
36 pix = pix.scaled(width*2,height*2,Qt::KeepAspectRatio);
37 //将图片的宽和高都扩大两倍，并且在给定的矩形内保持宽高的比值
38 painter.drawPixmap(100,100,pix);
39 painter.translate(-100, -100); //让图片的中心作为旋转的中心
40
41 // 实现图片的旋转
42 painter.translate(500, 400); //让图片的中心作为旋转的中心
43 painter.rotate(90); //顺时针旋转90度
44 painter.drawPixmap(0,0,100,100,pix);
45 painter.rotate(-90); //顺时针旋转90度
46 painter.translate(-500, -400); //让图片的中心作为旋转的中心
47
48 // 实现图片的扭曲
49 painter.translate(500, 500); //让图片的中心作为旋转的中心
50 painter.shear(0.5,0); //横向扭曲
51 painter.drawPixmap(0,0,100,100,pix);
52 painter.translate(-500, -500); //让图片的中心作为旋转的中心
53
View Code
mainwindow.ui
1 <?xml version="1.0" encoding="UTF-8"?>
2 <ui version="4.0">
3 <class>MainWindow</class>
4 <widget class="QMainWindow" name="MainWindow">
5 <property name="geometry">
6 <rect>
7 <x>0</x>
8 <y>0</y>
9 <width>800</width>
10 <height>600</height>
11 </rect>
12 </property>
13 <property name="windowTitle">
14 <string>MainWindow</string>
15 </property>
16 <widget class="QWidget" name="centralwidget"/>
17 <widget class="QMenuBar" name="menubar">
18 <property name="geometry">
19 <rect>
20 <x>0</x>
21 <y>0</y>
22 <width>800</width>
23 <height>22</height>
24 </rect>
25 </property>
26 </widget>
27 <widget class="QStatusBar" name="statusbar"/>
28 </widget>
29 <resources/>
30 <connections/>
31
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