实例：
.pro
1 QT += core gui
2
3 greaterThan(QT_MAJOR_VERSION, 4): QT += widgets
4
5 CONFIG += c++17
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 resource.qrc
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 }
mainwindow.h
1 #ifndef MAINWINDOW_H
2 #define MAINWINDOW_H
3
4 #include <QMainWindow>
5 #include <QPainter>
6 #include <QDebug>
7 #include <QtWidgets/QLabel>
8 #include <QtWidgets/QLineEdit>
9 #include <QtWidgets/QMainWindow>
10 #include <QtWidgets/QMenuBar>
11 #include <QtWidgets/QSlider>
12 #include <QtWidgets/QStatusBar>
13 #include <QtWidgets/QWidget>
14 #include <QtMath>
15
16 QT_BEGIN_NAMESPACE
17 namespace Ui { class MainWindow; }
18 QT_END_NAMESPACE
19
20 class MainWindow : public QMainWindow
21 {
22 Q_OBJECT
23
24 public:
25 MainWindow(QWidget *parent = nullptr);
26 ~MainWindow();
27 void paintEvent(QPaintEvent *e);
28 private slots:
29 void on_horizontalSlider_valueChanged(int value);
30
31 void on_horizontalSlider_2_valueChanged(int value);
32
33 private:
34 Ui::MainWindow *ui;
35 int m_y = 0;//
36 int m_l = 100;//
37 int m_nSize = 200;
38 QPoint m_oCentre;
39 int m_nCentreWidth = 6;// 中心点宽度
40 };
41 #endif // MAINWINDOW_H
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 setWindowTitle(QStringLiteral("Qt使用cos、sin绘制圆"));
10 }
11
12 MainWindow::~MainWindow()
13 {
14 delete ui;
15 }
16
17 void MainWindow::paintEvent(QPaintEvent *e)
18 {
19 m_oCentre.setX((m_nSize/2));
20 m_oCentre.setY((m_nSize/2));
21
22 int nDeviation = 0;
23 // 生成绘制
24 QPainter oLinePainter(this);
25 oLinePainter.setWindow(nDeviation, nDeviation, this->width(), this->height());
26 // 背景
27 QBrush objBrush(Qt::yellow, Qt::SolidPattern);
28 oLinePainter.fillRect(0, 0, m_nSize, m_nSize, objBrush);
29 // ---------------------画中心点--------------------------
30 QPainter oCentrePainter(this);
31 oCentrePainter.setWindow(nDeviation, nDeviation, this->width(), this->height());
32 QPen oCentrePen;
33 oCentrePen.setColor(Qt::red);
34 oCentrePen.setWidth(1);
35 oCentrePen.setStyle(Qt::SolidLine);
36 oCentrePainter.setPen(oCentrePen);
37
38 QBrush oCentreBrush(QColor(255,0,0), Qt::SolidPattern);
39 oCentrePainter.setBrush(oCentreBrush);
40
41 QPainterPath oCentreDrawPath;
42
43 oCentreDrawPath.addRect(m_oCentre.x(),
44 m_oCentre.y(),
45 m_nCentreWidth,
46 m_nCentreWidth);
47 //
48 oCentrePainter.drawPath(oCentreDrawPath);
49 // ---------------------画中心点--------------------------
50 float x = 0;
51 float y = 0;
52 float fPI = 3.14159265358979323;
53 x = sin(m_y*fPI/180)*m_l + m_oCentre.x();
54 y = -cos(m_y*fPI/180)*m_l + m_oCentre.x();
55
56
57 QPainter oPainter(this);
58 oCentrePainter.setWindow(nDeviation, nDeviation, this->width(), this->height());
59 QPen oPen;
60 oPen.setColor(Qt::blue);
61 oPen.setWidth(1);
62 oPen.setStyle(Qt::SolidLine);
63 oPainter.setPen(oPen);
64
65 QBrush oBrush(QColor(255,0,0), Qt::SolidPattern);
66 oPainter.setBrush(oBrush);
67
68 QPainterPath oDrawPath;
69
70 oDrawPath.addRect(x,
71 y,
72 m_nCentreWidth,
73 m_nCentreWidth);
74 //
75 oPainter.drawPath(oDrawPath);
76 }
77
78 void MainWindow::on_horizontalSlider_valueChanged(int value)
79 {
80 ui->label->setText(QString::number(value));
81 m_y = value;
82 this->repaint();
83 }
84
85 void MainWindow::on_horizontalSlider_2_valueChanged(int value)
86 {
87 ui->label_2->setText(QString::number(value));
88 m_l = value;
89 this->repaint();
90 }
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>678</width> 10 <height>234</height> 11 </rect> 12 </property> 13 <property name="windowTitle"> 14 <string>MainWindow</string> 15 </property> 16 <widget class="QWidget" name="centralwidget"> 17 <widget class="QSlider" name="horizontalSlider"> 18 <property name="geometry"> 19 <rect> 20 <x>260</x> 21 <y>20</y> 22 <width>341</width> 23 <height>22</height> 24 </rect> 25 </property> 26 <property name="maximum"> 27 <number>360</number> 28 </property> 29 <property name="orientation"> 30 <enum>Qt::Horizontal</enum> 31 </property> 32 </widget> 33 <widget class="QLabel" name="label"> 34 <property name="geometry"> 35 <rect> 36 <x>620</x> 37 <y>20</y> 38 <width>54</width> 39 <height>12</height> 40 </rect> 41 </property> 42 <property name="text"> 43 <string>TextLabel</string> 44 </property> 45 </widget> 46 <widget class="QLabel" name="label_2"> 47 <property name="geometry"> 48 <rect> 49 <x>620</x> 50 <y>60</y> 51 <width>54</width> 52 <height>12</height> 53 </rect> 54 </property> 55 <property name="text"> 56 <string>TextLabel</string> 57 </property> 58 </widget> 59 <widget class="QSlider" name="horizontalSlider_2"> 60 <property name="geometry"> 61 <rect> 62 <x>260</x> 63 <y>60</y> 64 <width>341</width> 65 <height>22</height> 66 </rect> 67 </property> 68 <property name="maximum"> 69 <number>150</number> 70 </property> 71 <property name="value"> 72 <number>100</number> 73 </property> 74 <property name="orientation"> 75 <enum>Qt::Horizontal</enum> 76 </property> 77 </widget> 78 </widget> 79 </widget> 80 <resources/> 81 <connections/> 82 </ui>
