How do you change a QGraphicsScene from another function? - c++

Question

My program has a QGraphicsView called SimulatorGV and it has a QGraphicsScene called Simulation. In the main function I have drawn a few rectangles and ellipses. I want to be able to draw on the same scene in another function too.
In essence, how do you add shapes to a scene from another function? (Which is called when a button on the user interface is pressed)
So far I've tried to pass the QGraphicsView to the other function? Below is the main ui function (irrelevant statements cut out):
{
ui->setupUi(this);
Simulation = new QGraphicsScene(this);
ui->SimulatorGV->setScene(Simulation);
Simulation->addRect(0,415,20,50,noPen,greyBrush);
Simulation->addRect(425,230,10,420,noPen,goldBrush);
Simulation->addEllipse(80,90,700,700,greyPen,noBrush);
Simulation->addRect(72,215,90,450,noPen,blackBrush);
}
In the header file I declared this function in the private slots:
void DrawingSimulation(QGraphicsView *SimulationGV);
Should it be like this instead?
void DrawingSimulation(QGraphicsScene *Simulation);
I called the function in another function like this:
DrawingSimulation(ui->SimulatorGV);
Should it be like this instead?
DrawingSimulation(ui->SimulatorGV->Simulation);
or?
DrawingSimulation(ui->Simulation);
This is the function I want to be able to draw on the scene from:
void RASP::DrawingSimulation(QGraphicsView *SimulationGV)
{
for (int i = 0; i < DisplayAlphaParticleNumber; i++)
{
if (ParticleLocation[i*6+3] != 0 || ParticleLocation[i*6+6] != 0)
{
ui->SimulatorGV->setScene(Simulation);
Simulation->addEllipse(ParticleLocation[i*6+3],ParticleLocation[i*6+4],10,10);
}
}
}
SimulatorGV is the name of the QGraphicsView in my ui form. RASP is the name of the project. ParticleLocation[i*6+3] is the x coordinate and [i*6+4] is the y coordinate.
Was I right to pass the QGraphicsView onto the varibale instead of the QGraphicsScene Simulation?
Did I pass it correctly?
In the DrawingSimulation function did I add the ellipse correctly?
Edit:
In essence, how do you add shapes to a scene from another function? (Which is called when a button on the user interface is pressed)
When a button is pressed this function is called:
void RASP::on_Button1_clicked()
{
//some values set
//some other functions called then the main one that leads to the drawingsimulation
mainfunction();
}
Then inside the mainfunction():
void RASP::mainfunction()
{
DrawingSimulation(); //is called
}
Now the function DrawingSimulation() which I would like to draw on the original scene in the RASP::RASP() (MyClass::MyClass) is called.
My previous attempt was to have a boolean function that is set true by the button then the addEllipse:
MyClass::MyClass()
{
ui->setupUi(this);
Simulation = new QGraphicsScene(this);
ui->SimulatorGV->setScene(Simulation);
Simulation->addRect(0,415,20,50,noPen,greyBrush);
Simulation->addRect(425,230,10,420,noPen,goldBrush);
Simulation->addEllipse(80,90,700,700,greyPen,noBrush);
Simulation->addRect(72,215,90,450,noPen,blackBrush);
if (SimulationRun == true)
{
for (int i = 0; i < DisplayAlphaParticleNumber; i++)
{
if (ParticleLocation[i*6+3] != 0 || ParticleLocation[i*6+6] != 0)
{
ui->SimulatorGV->setScene(Simulation);
Simulation->addEllipse(ParticleLocation[i*6+3],ParticleLocation[i*6+4],10,10);
}
}
}
}
and then in the button clicked function setting SimulationRun = to true.

Answer 1

Let's keep it simple.
If you have:
MyClass::MyClass() : ui(new Ui::MainWindow)
{
ui->setupUi(this);
Simulation = new QGraphicsScene(this);
ui->SimulatorGV->setScene(Simulation);
Simulation->addRect(0,415,20,50,noPen,greyBrush);
Simulation->addRect(425,230,10,420,noPen,goldBrush);
Simulation->addEllipse(80,90,700,700,greyPen,noBrush);
Simulation->addRect(72,215,90,450,noPen,blackBrush);
}
If this works, then, this will work too:
MyClass::MyClass() : ui(new Ui::MainWindow)
{
ui->setupUi(this);
Simulation = new QGraphicsScene(this); // supposing MyClass has a Simulation attribute of type QGraphicsScene
ui->SimulatorGV->setScene(Simulation);
addItems(); // calling function below
}
void MyClass::addItems()
{
// declared "void addItems();" in header file
addItems( Simulation ); // calling function below that could be static
}
void MyClass::addItems( QGraphicsScene* simu )
{
// declared "static void addItems(QGraphicsScene* simu);" in header file
simu->addRect(0,415,20,50,noPen,greyBrush);
simu->addRect(425,230,10,420,noPen,goldBrush);
simu->addEllipse(80,90,700,700,greyPen,noBrush);
simu->addRect(72,215,90,450,noPen,blackBrush);
}
Then, if this works, you now know how to modify the secene from "another function".
Finally, you should also have:
void MyClass::DrawingSimulation()
{
// declared "void DrawingSimulation();" in header file
DrawingSimulation( Simulation );
}
void MyClass::DrawingSimulation(QGraphicsScene *simu)
{
// declared "void DrawingSimulation(QGraphicsScene *simu);" in header file
for (int i = 0; i < DisplayAlphaParticleNumber; i++)
{
if (ParticleLocation[i*6+3] != 0 || ParticleLocation[i*6+6] != 0)
{
simu->addEllipse(ParticleLocation[i*6+3],ParticleLocation[i*6+4],10,10);
}
}
}
Note that DrawingSimulation() could also be a slot (declare it using public slots: in your header file. Then, if you connect it to the clicked() signal of a QPushButton of your GUI (for instance), it will be called when the button is clicked and ellipse will be added.
Like this:
MyClass::MyClass()
{
...
connect( ui->pushButton, SIGNAL(clicked()), this, SLOT(DrawingSimulation()) );
}