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I'm developing a little game in C++ Qt 4.6.3 and I stumbled upon a layout-issue. The layout I'm looking for is a 3x3 QGridLayout of which the central cell (1,1) holds the main widget (it's a board game). The (0,1)-cell should hold a QLabel displaying whos turn it is, the (1,0) and (1,2) cells are subdivided into QVBoxLayouts to hold a maximum of 3 scoreboards, and the (2,1)-cell also holds some kind of QLabel.

Image of the layout

This is what I've got so far: 

QGridLayout *mainLayout = new QGridLayout(this);
QVBoxLayout *leftLayout = new QVBoxLayout;
QVBoxLayout *rightLayout = new QVBoxLayout;  
mainLayout->addLayout(leftLayout,   1, 0, AlignTop);
mainLayout->addWidget(topText,      0, 1, AlignCenter);
mainLayout->addWidget(board,        1, 1);
mainLayout->addLayout(bottomText,   2, 1, AlignCenter);
mainLayout->addLayout(rightLayout,  1, 2, AlignTop);

Now, on MS Windows (laptop of my GF) I solved this by reimplementing the resizeEvent() function:

void Game::resizeEvent(QResizeEvent *)
{
    mainLayout->setRowMinimumHeight(1, 0.8 * height());
    mainLayout->setColMinimumWidth(1, 0.8 * height());
    // some other stuff
}

This worked fine! However, on Unix there seems to be a problem (or could it be due to a version difference? 4.6 vs 4.8). On calling the setRowMininmumHeight() method, it seems that another resize-event is issued, resulting in a recursive call! I want my application to work on both platforms, so clearly I had to find another solution. I fiddled around with setRowStretch() and setColStretch() but neither of those had the desired result. I tried all sorts of combinations but now I am quite stuck...

Does anyone have a solution to this seemingly easy problem?

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JorenHeit
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1 Answers1

4

You should use stretches rather than minimum sizes to solve the problem. Execute this code after adding the widgets to the layout to assign 80% of the height to the middle row:

mainLayout->setRowStretch(0, 1); // 10% for top row
mainLayout->setRowStretch(1, 8); // 80% for middle row
mainLayout->setRowStretch(2, 1); // 10% for bottom row

Note that minimum size constraints of the contained widgets are still respected (unless you set the size policy to ignored). So if you want to assign the whole height minus the two minimum sizes of the rows 0 and 2 (as you are saying they should be "as small as possible"), assign 100% to the middle row and 0% to the rows 0 and 2; they still respect the minimum sizes:

mainLayout->setRowMinimumHeight(0, 20); // 20px for top row
mainLayout->setRowMinimumHeight(2, 20); // 20px for bottom row
mainLayout->setRowStretch(0, 0);
mainLayout->setRowStretch(1, 1); // remaining height for middle row
mainLayout->setRowStretch(2, 0);
leemes
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  • Thanks! The documentation never made it clear to me that stretches could be used that way... I marked your answer as accepted, but there is still one slight issue. The widget in the (1,1) cell is aligned to the left, but when I try to align it in the center, it disappears. – JorenHeit May 31 '12 at 17:28
  • @user1428839 I remember that there is some strange behaviour of QLayout when you change the alignment of the widgets. I can't remember what the problem is. But it might have something to do with the size hints of the inner widget. Alignment only makes sense if the widget will not fill up the whole cell. A workaround would be to allow the widget to fill the cell and do the alignment within your widget by your own. You could try to find out more about QLayout + alignment as I don't use it that often, so I'm sorry I can't help you further. – leemes May 31 '12 at 17:56
  • Ah, thanks anyway! You made me realize that it could also be due to the inner workings of the Widget, which was the case indeed! :-) – JorenHeit May 31 '12 at 18:12