Qt Yin Yang Painting with Changeable Size

Filename: main.cpp
Source code:

#include <QApplication> 

#include <QGraphicsScene>

#include <QGraphicsView>

#include <QGraphicsEllipseItem>

int main(int argc, char *argv[])

{

    QApplication app(argc, argv);

    const int size = 500;

    QGraphicsScene scene;

    scene.setSceneRect( 0.0, 0.0, size+100, size+100 );

    QPen penWhite(Qt::white);

    QBrush brushWhite(Qt::white); //QBrush to fill-up shape with the color

    QPen penBlack(Qt::black);

    QBrush brushBlack(Qt::black); //QBrush to fill-up shape with the color

    //draw white big circle

    QPainterPath whiteBigCirlePainter;

    QPoint pointCircleCenter;

    pointCircleCenter.setX((size+100)/2);

    pointCircleCenter.setY((size+100)/2);

    whiteBigCirlePainter.addEllipse(pointCircleCenter, size/2, size/2);

    scene.addPath(whiteBigCirlePainter, penWhite, brushWhite);

    //draw black big semicircle to the right

    QPainterPath rightBlackSemicirclePath;

    rightBlackSemicirclePath.arcMoveTo((size+100)/2.0 - (size/2.0),

                                       (size+100)/2.0 - (size/2.0),

                                       size, size, 270);

    rightBlackSemicirclePath.arcTo((size+100)/2.0 - (size/2.0),

                                   (size+100)/2.0 - (size/2.0),

                                   size, size, 270, 180);

    scene.addPath(rightBlackSemicirclePath, penBlack, brushBlack);

    //draw black circle bottom

    QPainterPath blackCircleBottomPainter;

    QPoint pointCircleBottomCenter;

    pointCircleBottomCenter.setX((size+100)/2.0);

    pointCircleBottomCenter.setY((size+100)/2.0 + size/4.0);

    blackCircleBottomPainter.addEllipse(pointCircleBottomCenter, size/2/2, size/2/2);

    scene.addPath(blackCircleBottomPainter, penBlack, brushBlack);

    //draw white circle top

    QPainterPath whiteCircleTopPainter;

    QPoint pointCircleTopCenter;

    pointCircleTopCenter.setX((size+100)/2.0);

    pointCircleTopCenter.setY((size+100)/2.0 - size/4.0);

    whiteCircleTopPainter.addEllipse(pointCircleTopCenter, size/2/2, size/2/2);

    scene.addPath(whiteCircleTopPainter, penWhite, brushWhite);

    //draw white circle bottom eye

    QPainterPath whiteCircleBottomEyePainter;

    QPoint pointCircleBottomEyeCenter;

    pointCircleBottomEyeCenter.setX((size+100)/2.0);

    pointCircleBottomEyeCenter.setY((size+100)/2.0 + size/4.0);

    whiteCircleBottomEyePainter.addEllipse(pointCircleBottomEyeCenter, size/2/2/2/2, size/2/2/2/2);

    scene.addPath(whiteCircleBottomEyePainter, penWhite, brushWhite);

    //draw black circle top eye

    QPainterPath blackCircleTopEyePainter;

    QPoint pointCircleTopEyeCenter;

    pointCircleTopEyeCenter.setX((size+100)/2.0);

    pointCircleTopEyeCenter.setY((size+100)/2.0 - size/4.0);

    blackCircleTopEyePainter.addEllipse(pointCircleTopEyeCenter, size/2/2/2/2, size/2/2/2/2);

    scene.addPath(blackCircleTopEyePainter, penBlack, brushBlack);

    //draw big circle black outline

    QPainterPath bigCircleBlackOutlinePainter;

    bigCircleBlackOutlinePainter.addEllipse(pointCircleCenter, size/2, size/2);

    scene.addPath(bigCircleBlackOutlinePainter, penBlack, Qt::NoBrush);

    QGraphicsView view( &scene );

    view.setRenderHint(QPainter::Antialiasing); //antialias edges of primitives if possible

    view.setRenderHint(QPainter::HighQualityAntialiasing); //an OpenGL-specific rendering hint

    view.setWindowTitle("My Yin Yang Painting");

    view.show();

    return app.exec();

}
 

Project Output: ☯

Linux Mint Cinnamon: Install Qt for C++ GUI Programming

Start Menu > Administration > Software Manager

Search box > type > Qt-sdk
Double-click the Qt-sdk displayed result on one of the rows
Click the button Install
Wait until the download and installation actions completed

Start Menu > Programming > Qt Creator
Try to write some programs

Linux Mint Cinnamon: How to run Raptor Flowchart Programming App on Linux Mint using Wine Software?

How to run Raptor Flowchart Programming App on Linux Mint using Wine Software?

Start Menu > Administration > Software Manager
Enter your password to perform administrative tasks

Search box > type > Wine

Double-click the row Wine
Wine is Microsoft windows compatibility layer (meta-package)

Click the button Install
Wait until installation has finished

Start Menu > Wine > Configure Wine
Install “Wine Mono Installer”, click the button Install
Install “Wine Gecko Installer”, click the button Install
Wait until two installations have finished

Download Raptor portable app at
http://raptor.martincarlisle.com/RaptorPortable_4.0_Revision_6.paf.exe
Save the RaptorPortable_4.0_Revision_6.paf.exe in the home directory
Right-click “RaptorPortable_4.0_Revision_6.paf.exe” > Open With > Wine Windows Program Loader
Click the button Finish to finish the unzip process

To run the Raptor app on Linux Mint:
-- Right-click the RaptorPortable.exe in the RaptorPortable directory
-- Select "Open With" > "Wine Windows Program Loader"

Save your empty flowchart as the rap file extension
Draw a flowchart and check by yourself if your paper drawn flowchart is correct

Getting Started with C++ 2017 using gcc v6.1.0 32-bit

Steps are as follows:

Download gcc v6.1.0 32-bit from
ftp://ftp.equation.com/gcc/gcc-6.1.0-32.exe
Filename: gcc-6.1.0-32.exe

Install gcc 32-bit to "C:\gcc-6.1.0-32"

Please log off and log in again to configure the gcc for all users on this operating system.

Download and install Notepad++ from
https://notepad-plus-plus.org/download/

Open Notepad++
Save the new file as "cpp2017_eg1.cpp"

Filename: cpp2017_eg1.cpp
File content:
/********************/
#define __STDCPP_WANT_MATH_SPEC_FUNCS__ 1 //betaf(), beta()
#include <iostream>
#include <string>
#include <experimental/string_view>
#include <cmath>
using namespace std;

int main()
{ 
    cout << __cplusplus << endl; //201500

    //Hexadecimal literals
    int hex1 = 0xA;  
    cout << hex1 << endl; //10  
  
    experimental::string_view v = "hello world";
    v = v.substr(7);
    cout << v << endl; //orld

    //Mathematical special functions from C++ 2017
    cout << betaf(4.0f, 2.0f) << endl; //0.05

    int n = 4;
    int k = 2;
    cout << 1/( (n+1)*beta(n-k+1, k+1) ) << endl; //6
    // C(4,2)=4!/(2!2!)=4x3/2=6
  
    cout << expint(1) << endl; //1.89512, exponential integral
    cout << riemann_zeta(2) << endl; //1.64493          
  
    return 0;
}
/********************/

Program output: Open command prompt window

C:\my_folder_path> g++ --version
g++ (GCC) 6.1.0

C:\my_folder_path> g++ -std=c++17 cpp2017_eg1.cpp -o a.exe

C:\my_folder_path> a.exe
201500
10
orld
0.05
6
1.89512
1.64493

Step to uninstall GCC downloaded from
http://www.equation.com/servlet/equation.cmd?fa=fortran
* Open the system “Environment Variables” frame
* Delete the system variable named “EQ_LIBRARY_PATH” which contains the following variable value "C:\gcc-6.1.0-32\i686-pc-mingw32\lib"
* Delete the following two system path values from the system variable named “Path”:
*** "C:\gcc-6.1.0-32\bin;”
*** “C:\gcc-6.1.0-32\libexec\gcc\i686-pc-mingw32\6.1.0;"
* Delete the directory at “C:\gcc-6.1.0-32”

Qt C++: Solution for “error: variable 'QPointer label' has initializer but incomplete type”

Qt C++: Solution for “error: variable 'QPointer<QLabel> label' has initializer but incomplete type”

C++ Code with Error message:

void MainWindow::on_pushButton_clicked()

{

  QPointer<QLabel> label = ui->label1;

  label->setText("Label 1 text changed");

}

Solution:

You need to include the “#include <QPointer>“ at the top section in this implementation file.
 

Qt C++: Solution for “error: only constructors take member initializers” and “warning: no return statement in function returning non-void [-Wreturn-type]”

Qt C++: Solution for “error: only constructors take member initializers” and “warning: no return statement in function returning non-void [-Wreturn-type]”

C++ Code with Error and Warning messages:

class ClassName

{

private:

  QString s;

  double d;

public:

  ClassKName(QString s="noName", double d=0.0) : s(s), d(d)

  {

  }

};

Solution:

The constructor name is different from the class name.

Rename the constructor name ClassKName to be the same with ClassName without the extra letter ‘K’.
 

Qt C++: Programming Fundamental Concepts: if-else statement

Program title: if-else statement

C++ Code:

#include <QApplication> 

#include <QDebug>

#include <QMainWindow> //QMainWindow *window

#include <QLabel>

#include <QHBoxLayout> //layout->addWidget(label)

#include <QWidget> //centralWidget->setLayout(layout)

#include <QInputDialog>

#include <QString>

int main(int argc, char *argv[])

{

    QApplication app(argc, argv);

    QMainWindow *window = new QMainWindow();

    QLabel *label = new QLabel("No Result");

    QHBoxLayout *layout = new QHBoxLayout;

    layout->addWidget(label);

    QWidget *centralWidget = new QWidget(window); //centralWidget parent is the window

    centralWidget->setLayout(layout);

    window->setCentralWidget(centralWidget);

    window->setWindowTitle("My Main Window");

    window->resize(400, 400);

    window->show();

    int n = QInputDialog::getInt(window, "Input Dialog",

                                 "Enter a percentage", 25, //25 is the default value

                                 0, 100, 1); //min, max, step

    if(n>=50) {

        qDebug() << "Percentage is greater than or equal to fifty";

        QString s = "Percentage is greater than or equal to fifty";        

        label->setText(s);

    }

    else {

        qDebug() << "Percentage is less than fifty";

        QString s = "Percentage is less than fifty";

        label->setText(s);

    }

    return app.exec();

} 

Program Output: Vertical Toolbar > Run 

Advantages:
-- input dialog: built-in spin box for integer input
-- input dialog: can set default value
-- input dialog: built-in regular expression and input validation
-- input dialog: prevent input error

FuzzyCLIPS: Certainty Factor example

Enter the following code statement-by-statement in the FuzzyCLIPS's Dialog Window:

FuzzyCLIPS> (defrule organism-is-streptococcus
(declare (CF 0.7))
(stain positive)
(morphology coccus)
(growth chains)
=>
(assert (organism streptococcus))
)

FuzzyCLIPS> (assert (stain positive) CF 0.5)
FuzzyCLIPS> (assert (morphology coccus) CF 0.6)
FuzzyCLIPS> (assert (growth chains) CF 0.3)

FuzzyCLIPS> (run)
FuzzyCLIPS> (facts)
f-0     (stain positive) CF 0.50
f-1     (morphology coccus) CF 0.60
f-2     (growth chains) CF 0.30
f-3     (organism streptococcus) CF 0.21
For a total of 4 facts.

The certainty factor of the conclusion using hand calculations
= min(0,5,0.6,0.3) * 0.7
= 0.3 * 0.7 = 0.21

FuzzyCLIPS: How to change the program icon

Download the FuzzyCLIPS icon below to your computer and rename it to "fzclipswin.ico" with .ico file extension name. Copy this file to C:\Windows\System32\fzclipswin.ico.

Right-click on the fzclipwin.exe at C:\FuzzyCLIPS\pc-prjct\VC++\fzClips\fzclipswin\Release\fzclipswin.exe, select "Send to | Desktop (create shortcut)"

Right-click the fzclipwin shortcut on the desktop, select Properties.
Tab on the Shortcut.
Click on the button "Change Icon".
Browse to "C:\Windows\System32\fzclipswin.ico" and click the button OK.

OMNeT++: "Error in module (cModule) (id=1) during network setup..." Solution

Problem:

Frame title: Confirm
Frame content:
Error in module (cModule) "network name in ned file" (id=1) during network setup: Class "class name in cc file and simple name in ned file" not found -- perhaps its code was not linked in, or the class wasn't registered with Register_Class(), or in the case of modules and channels, with Define_Module()/Define_Channel().

Solution:

Right-click the project > select Build Project
In the console frame, you should get the following successful message: 12:34:56 Build Finished (took 5s.864ms)

Right-click the project > Run As > OMNeT++ Simulation

How to learn and interact with Mathematics on the browser using GeoGebra?

-- Browse to
http://app.geogebra.org/
-- Click on the Algebra link
--  On the left input textfield, type the following and then hit the enter key:
---- c =1
---- m = 2
---- y=mx + c
-- Click on "Toolbar > Angle of two lines with alpha icon > Slope". Click on the line to view the slope in triangle form
-- Go to the slider, drag to the left or drag to the right to change the c or m values
-- Other than Algebra section, try other Mathematics sections like Geometry, Spreadsheet, CAS, 3D Graphics, and Probability

An example from the above steps:

 
References
-- Animation: Move a Point, https://www.geogebra.org/m/n5ddtD86
-- Draw two functions in one graph with restricted domains, https://www.geogebra.org/m/GXC4GVEE

LibreOffice Writer: Do not Hyphen or Dash to break a word

Steps are:
-- Highlight a paragraph
-- Right-click and select Paragraph
-- Tab on "Text Flow"
-- Under Hyphenation section, untick the check box Automatically
Yeah