Trying to create a direction indicator. Other methods than QPainter?

[Wosch]

I'm currently using QPainter and designed my lamps for the direction indicator. I want to change the mainwindow by clicking a button. So when I click the button for the left direction indicator, the mainwindow should update the background-colour of my polygon for the left blinker every second. Is there any better method than using QPainter?

Thanks for your answers.

[mrjj]

Hi
What would make it a better method than QPainter ?
Also how do u draw the poly?
Using painter ?

[Wosch]

@mrjj yes right now I'm using the painter. I've created a paintevent and then used the qpainter to create the polygons. But i don't know, if i can edit the paintevent and the specific painter, so that the indicators change the colour every time skip. This is all happening in the mainwindow.cpp.

[mrjj]

@Wosch
it sounds fine to me but not sure what
"direction indicator. " really is. How it should be drawn but
painter is fast and flexible.

[Wosch]

@mrjj it should look like the blinker in your car or better like the dashboard. So when i press the button for the left blinker, the left arrow should switch from white to yellow and back in a time scale. But i'm not sure how to call the qtpaintevent in another method(button pressed()) so i can change the painter I created for the arrows.

[jsulm]

@Wosch No need to call paintEvent from other method. In you button slot you simply set a variable. In your paintEvent you check the value of this variable and depending on it draw what needs to be drown.

void MainWindow::onButtonCliecked()
{
    drawArrow = true;
}

void MainWindowPaintEvent(...)
{
    if (drawArrow) {
        // Draw arrow
    }
}

[mrjj]

@Wosch
Hi
To triggers something to re-draw, you can call its update()
You will never call its paintEvent directly.

So to add to @jsulm

often you would do
void MainWindow::onButtonCliecked()
{
drawArrow = true;
update();
}

to make it redraw as soon as you change arrow

[J.Hilk]

@Wosch hi, since you're specifically asking for an alternative, I'll post a custom class (of a QPushButton in this case) that has a "blinking-functionality" using Q_Property and StyleSheets

#ifndef CBUTTON_H
#define CBUTTON_H

#include <QStyle>
#include <QPushButton>
#include <QTimer>

class cButton : public QPushButton
{
    Q_OBJECT
    Q_PROPERTY(bool state READ isState WRITE changeState)

public:
    explicit cButton(QWidget * parent = 0) :  QPushButton(parent){
        this->setStyleSheet("QPushButton{background-color: black;}
                                                 QPushButton[state = true]{background-color: red;}");
        changeTimer.setInterval(1000);
        connect(&changeTimer, &QTimer::timeout, this, cButton::flipState);
    }
    void start(){changeTimer.start());
    void stop(){changeTimer.stop());

    bool isState(){return state;}

public slots:
   void flipState(){changeState(!isState());}

    void changeState(bool b){
        if(state != b){
             state = b;
             style()->unpolish(this);
             style()->polish(this);
            repaint();
       }
    }

protected:
    QTimer changeTimer;
    bool state = false;

};

#endif // CBUTTON_H

[Wosch]

@J-Hilk @jsulm @mrjj Thank you guys. That's what i was looking for.