Question

I’m using QPushButton in my mineSweeping game.

After changing from easy mode to hard mode, the number of QPushButton is supposed to change from 9×9 to 30×16.

So, I add QPushButton with the largest number(which is of hard mode) to GridLayout in constructor of MainWindow.

btnArr = new QPushButton[HARD_WIDTH * HARD_HEIGHT]; // member element
int index = 0;
for (int i = 0; i < HARD_HEIGHT; ++i) {
    for (int j = 0; j < HARD_WIDTH; ++j) {
        ui->mainGrid->addWidget(&btnArr[index], i, j, 1, 1,
                                Qt::AlignCenter);
        ++index;
    }
}

Then if the user change mode(e.g.: easy mode to hard mode), resetBtn(HARD_WIDTH, HARD_HEIGHT); will be called.

void MainWindow::resetBtn(const int width, const int height)
{
    int index = 0;
    for (int i = 0; i < HARD_HEIGHT; ++i) {
        for (int j = 0; j < HARD_WIDTH; ++j) {
            if (j < width && i < height) {
                btnArr[index].setVisible(true);
            } else {
                btnArr[index].setVisible(false);
            }
            ++index;
        }
    }
}

The problem is that it seems the widget repaints each time setVisible is called. So in the hard mode case, it will be called 30×16 times, which caused strange effect like this:

So how can I set the widget not repaint during this loop?

Thanks in advance.

Answer 1

The total number of QPushButton is really big: 30×16 = 480!!! I don’t use to make people change their programming logic, but in this case I think that using QPushButtons is not the better approach. The layout must have a really bad time trying to move the objects as they are added, and perhaps you are reaching some internal limit in refresh time for the layout to be repainted.

What I would have done is a custom widget with a custom paintEvent method. There you can divide its width and height in the number of columns and rows that you wish and paint the cells with pixmaps as the game is played.

For the mouse interaction, the best would have been to override the mousePressEvent with a custom logic that calculates the mouse position in the grid and calls the corresponding methods or emits signals indicating the position of the event. Not very hard to code. You can also use the event->buttons() method to know which mouse button was pressed and emit different signals if you wish.

I don’t use to answer telling that it is better to change your whole program, but in this case I think you are going “the hard way”. I know this is not the kind of answer you are looking for, but consider this possibility.