Get the MainWindow size

fem_dev

I have a MainWindow with a graphicsView widget.

I would like to match the sizes of the Main Window and the graphicsView widget.
I'm trying this:

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    setCentralWidget(ui->graphicsView);

    // Try to get the MainWindow size and set these values to the image size:
    int sizeX = this->size().width();
    int sizeY = this->size().height();

    // Create and init the image:
    QImage image = QImage(sizeX, sizeY, QImage::Format_RGB32);

    // Fill the image with colors:
    for (int x = 0; x < sizeX; x++) {
        for (int y = 0; y < sizeY; y++) {
            image.setPixel(x, y, qRgb(x * 256 / sizeX, y * 256 / sizeY, 200));
        }
    }

    // Create a graphics scene:
    QGraphicsScene* graphic = new QGraphicsScene(this);
    graphic->setSceneRect(0, 0, sizeX, sizeY);

    // Set the image:
    graphic->addPixmap(QPixmap::fromImage(image));

    // Try to fit in view:
    ui->graphicsView->fitInView(0, 0, sizeX, sizeY);

    // Display it on the UI:
    ui->graphicsView->setScene(graphic);
}

But the result is this window with scroll bars!!

How can I init the MainWindow and the graphicsView widget with the same size?

SGaist

Hi,

As suggested in the fitInView documentation, it's usual to call it in a resizeEvent re-implementation.

fem_dev

For now, I'm resolving this problem with this temporary source-code:

// Get the correct MainWindow size to use with graphicsView widget:
int width = this->size().width() - 20; // Magic number, but works
int height = this->size().height() - 40; // Magic number, but works

Christian Ehrlicher

Try to get the size when the widget is shown, not when you create it - then there are no valid size information available iirc.

SGaist

Hi,

As suggested in the fitInView documentation, it's usual to call it in a resizeEvent re-implementation.

fem_dev

@Christian-Ehrlicher thank you...
I understand your point, but now I have a logistic doubt.

I have only one QMainWindow and, inside of it, I have these two things: A QImage and a GraphicsView.
So, I need to set:
-> The QImage size
-> The graphicsView size

When the application starts, the QMainWindow appears and these values must be valids to create a good UI.

How could I set these values before the QMainWindow initialization?

fem_dev

@SGaist Yes, I'm using it in both cases:
1- On the QMainWindow constructor
2- On the resizeEvent()

It solves the problem!
Thank you again!

SGaist

You're welcome !

Since you have it working now please mark the thread as solved using the "Topic Tools" button so that other forum users may know a solution has been found :-)

Note that you can also mark an answer as the "thread correct answer" by using the three vertical dots on the right of each answer.