Qt-QPainter实现图片的绘图、平移、缩放、旋转、扭曲

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https://download.csdn.net/download/zhujianqiangqq/85500981     csdn代码包下载

.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     QtQPixmap.qrc

main.cpp

 1 #include "mainwindow.h"
 2 
 3 #include 
 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 
 5 #include 
 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

 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 }

 mainwindow.ui

 1 <?xml version="1.0" encoding="UTF-8"?>
 2 "4.0">
 3  <class>MainWindowclass>
 4  class="QMainWindow" name="MainWindow">
 5   "geometry">
 6    
 7     0
 8     0
 9     800
10     600
11    
12   
13   "windowTitle">
14    <string>MainWindowstring>
15   
16   class="QWidget" name="centralwidget"/>
17   class="QMenuBar" name="menubar">
18    "geometry">
19     
20      0
21      0
22      800
23      22
24     
25    
26   
27   class="QStatusBar" name="statusbar"/>
28  
29  
30  
31 

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