GUI for placing shapes in GraphicsView

Macive Xiong

@mrjj
In this case, I would like to create a new shape. When the user input the new value for x and y, it creates a new shape on that position.
Here's the GUI I modify

I added a button for creating a new shape every time I input a new value.

mrjj

@Macive-Xiong
ok. super.
so when button calls the slot, you
simply read the values, and insert the new item.
This way you know when to create.

Macive Xiong

@mrjj

OK, I put everything in the click button

void MainWindow::on_creat_btn_clicked()
{
    QBrush redBrush(Qt::red);
    QBrush blueBrush(Qt::blue);
    QPen blackpen(Qt::black);
    blackpen.setWidth(2);
    ellipse = scene->addEllipse(x, y, 10, 10,blackpen,redBrush);

}

Some suggestion for declaring the x and y ?? Thank you :)

mrjj

@Macive-Xiong

hi
the spinedit has a value function

so
int x= ui->spin1->value();
int y= ui->spin2->value();

Macive Xiong

@mrjj

OMG!! It works!!!! Thank you soooo much. And sorry for those dumb questions...I am a noob on Qt and trying to create multiple projects to practice. Next step I would like to add the different colors while create different shapes and area.

Thank you again:)

mrjj

@Macive-Xiong
No worries.
Beginner questions are very allowed/welcome here :)

To select color, you can use
http://doc.qt.io/qt-5/qcolordialog.html#details

its not much code to allow selection of color
QColor color = QColorDialog::getColor(Qt::yellow, this );
if( color.isValid() )
{
qDebug() << "Color Choosen : " << color.name();
}

for type of shape, you could use a QCombobox
http://doc.qt.io/qt-4.8/qcombobox.html
so it has list of types.

Macive Xiong

@mrjj

Thanks for your information. It's really helpful. And I must say, your kindness and patience are really important for the novice like me. Thanks again:)

mrjj

@Macive-Xiong
You are most welcome.
Are you new to c++ too?

Macive Xiong

@mrjj

Yep I kinda a new to C++. My projects are making connection with Qt and Arduino. Build a GUI on Qt and control Arduino. In this case, I would like to input position values on Qt and send these values to Arduino and do some math. Then send back to Qt and place the shape.

mrjj

@Macive-Xiong
ok. just asking as if really new to C++ , some dont really realize that
adding variables to mainwindow.h makes it accessible to all methods.

class MainWindow : public QMainWindow {
Q_OBJECT
public:
explicit MainWindow(QWidget* parent = 0);
~MainWindow();

private slots:
void on_pushButton_released();

void on_pushButton_3_released();

private:
Ui::MainWindow* ui;
<<<< good spot for variables.
};

Also, if you are going to use serial comm with Arduino
then this sample is super to start with
http://doc.qt.io/qt-5/qtserialport-terminal-example.html

Macive Xiong

@mrjj

OK, thanks for the information.
These are really helpful:)
Will ask more questions if I get more problem.

Macive Xiong

@mrjj

Hi, now I am facing a problem.
When I input the value, say x = 500, y = 0. The ellipse shows at the center of my GraphicsView. My GraphicsView's boundary is 512*512.

My code:

void MainWindow::on_creat_btn_clicked()
{
    QBrush redBrush(Qt::red);
    QBrush blueBrush(Qt::blue);
    QPen blackpen(Qt::black);
    blackpen.setWidth(1);

   int x  = ui->spin1->value();
   int y  = ui->spin2->value();

    
    ellipse = scene->addEllipse(x, y, 5, 5,blackpen,redBrush);



}

Any suggestion?? Thank you so much.

mrjj

well you should read
http://doc.qt.io/qt-5/graphicsview.html
section
Scene Coordinates

you can also define your own
scene->setSceneRect(-180, -90, 360, 180);

Short story.
0,0, might not be where u think it is :)