Child Layouts not getting added Properly
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I'm new to qt and exploring it .Basically Im adding three child layouts to a Parent layout.But after having added the third layout,my first layout disappears. This is my code:
MainWindow::MainWindow(QWidget *parent) :
QWidget(parent),
ui(new Ui::MainWindow)
{this->setGeometry(500,650,1000,1000);
QVBoxLayout *parentLayout = new QVBoxLayout(this);
QVBoxLayout *l1 = new QVBoxLayout();
QWidget *lw1 = new QWidget;
lw1->setMaximumHeight(50);
lw1->setStyleSheet("background-color:brown");
l1->addWidget(lw1);QHBoxLayout *l2 = new QHBoxLayout;
QLabel *label = new QLabel("Industry");
label->setStyleSheet("color:white");
label->setMaximumWidth(300);
l2->addWidget(label);QComboBox *cb = new QComboBox;
cb->addItem("Movie");
cb->setStyleSheet("background-color:white");
cb->setMaximumHeight(50);
l2->addWidget(cb);parentLayout->addLayout(l1);
parentLayout->addLayout(l2);//If I run till here I see the added two child layouts.
QWidget *w3 = new QWidget;
w3->setStyleSheet("background-color:white");QVBoxLayout *l3 = new QVBoxLayout();
l3->addWidget(w3);//parentLayout->addLayout(l3);
//If I uncomment the above line then I see only layouts l2 and l3 from the top and not l1}
Basically what I need is a Layout which in turn containing multiple subLayouts of varied sizes.Could someone highlight me where am I doing mistake.Any help will be really useful.
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hi,
I assume this is the default MainWindow from QtCreator ProjectWizard.
in that case,
thisalready has a layout and you can not simply assign a new onechange this
@Adit said in Child Layouts not getting added Properly:
QVBoxLayout *parentLayout = new QVBoxLayout(this);
to
QVBoxLayout *parentLayout = new QVBoxLayout(ui->centralWidget);
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Following on from @J-Hilk's doubtless-correct analysis:
QVBoxLayout *parentLayout = new QVBoxLayout(this);
If you ran this from a debugger, did you not get a warning message saying "warning adding a layout to ... which already has an existing layout"?
QVBoxLayout *parentLayout = new QVBoxLayout(ui->centralWidget);
Is this the same as
QVBoxLayout *parentLayout = new QVBoxLayout(); ui->centralWidget->setLayout(parentLayout);?
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@JonB said in Child Layouts not getting added Properly:
QVBoxLayout *parentLayout = new QVBoxLayout(ui->centralWidget);
Is this the same as
QVBoxLayout *parentLayout = new QVBoxLayout();
ui->centralWidget.seLayout(parentLayout);?
yes, with the setLayout call, the Layout gets reparented to centralWidget.
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Guys , here my MainWindow is not a QMainWindow,instead ,it inherits from QWidget.Moreover I dont use the .ui form and I create the UI dynamically.
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@Adit
what's the ui-pointer for than?MainWindow::MainWindow(QWidget *parent) :
QWidget(parent),
ui(new Ui::MainWindow)
{
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Sorry @J-Hilk ,but Im not using it .I tried to add both setMinimumHeight and setMaximumHeight and it works now.Could you tell me when these two functions should be used?
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@Adit What about http://doc.qt.io/qt-5/qwidget.html#setLayout ?
You created a layout (parentLayout), but you did not tell your MainWindow widget to use it.
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But I have set the MainWindow widget as parent to the Top-Layout created and it works!
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@Adit
It gets a bit tricky when you add Layouts to Layouts.it should also work, if you specify strechfactors for the addes layouts e.g
parentLayout->setStretch(0,1); parentLayout->setStretch(1,1); parentLayout->setStretch(2,1);
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I guess stretch factors can be 0 or 1 (contract and expand) right?What if we have multiple Layouts of specific sizes ?
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@Adit said in Child Layouts not getting added Properly:
I guess stretch factors can be 0 or 1 (contract and expand) right?What if we have multiple Layouts of specific sizes ?
no, 0 means, take as much space, as possible, defined by the sizepolicy and sizehint of the Widget/Layout
in this case a stretch factor of 1 for each element results in the following space for the layouts, 1/3, 1/3 and 1/3.
With for example
parentLayout->setStretch(0,1); parentLayout->setStretch(1,1); parentLayout->setStretch(2,2);the layouts take up 1/4, 1/4, 1/2 of the available space.
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If we are using this setStretch() method, then can we use setMaximumWidth() and setMaximumHeight() methods?
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@Adit yes, the stretch is applied until min and max sizes are hit and as long as no contradicting QSizePolizies are set (like fixed size)
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Could you suggest me some idea to build a complex layout(i.e sublayouts of varying sizes)?Could you suggest me an opensource project for building a resolution independent UI.
