[Qt-interest] Shrinking parent widget when child hidden

[Brad Howes]

On Apr 1, 2010, at 12:07 PM, George Ryan wrote:

> Hello,
> 
> I have a dialog that I want to have vertically resize automatically when
> I hide one of its children in a vertical layout. For example:
> 
> ---------
> |  -----  |
> | | W1  | |
> |  -----  |
> |  -----  |
> | | W2  | |
> |  -----  |
> ---------
> 
> to
> 
> ---------
> |  -----  |
> | | W2  | |
> |  -----  |
> ---------
> 
> I have tried various combinations of layouts and setting minimum size
> hints, but I haven't yet come across a good solution.
> 
> Has anyone done this before or have a good idea on how to implement it?


This works for me:

// ParamEditor.h:
#include <QtGui/QDialog>

class QCheckBox;
class QFrame;
class QPushButton;

class ParamEditor : public QDialog
{
    Q_OBJECT
public:
    ParamEditor();

private slots:
    void advancedClicked( bool state );

private:
    void makeParam( const QString& name, bool advanced );

    QFrame* widgetContainer_;
    QCheckBox* advanced_;
    QPushButton* ok_;
};

// ParamEditor.cc
#include <QtGui/QApplication>
#include <QtGui/QCheckBox>
#include <QtGui/QFrame>
#include <QtGui/QHBoxLayout>
#include <QtGui/QLabel>
#include <QtGui/QPushButton>
#include <QtGui/QSpinBox>
#include <QtGui/QVBoxLayout>

#include "ParamEditor.h"

ParamEditor::ParamEditor()
    : QDialog( 0 ), advanced_( 0 )
{
    setModal( false );
    setWindowTitle( "Parameter Editor" );

    //
    // Create the layout for the entire window. This will hold two other
    // layouts, an hbox one for dialog buttons and another vbox one for the
    // adjustable widgets collection.
    //
    QVBoxLayout* vbox = new QVBoxLayout( this );
    vbox->setSizeConstraint( QLayout::SetFixedSize );
    vbox->setMargin( 9 );
    vbox->setSpacing( 6 );

    //
    // Place the adjust widget collection in a frame
    //
    widgetContainer_ = new QFrame( this );
    widgetContainer_->setFrameStyle( QFrame::NoFrame );
    vbox->addWidget( widgetContainer_ );
    vbox->addStretch( 1 );

    //
    // Create an hbox to hold the 'Advanced' checkbox and the OK button
    //
    QHBoxLayout* buttonLayout( new QHBoxLayout );
    vbox->addLayout( buttonLayout );

    advanced_ = new QCheckBox( "Advanced", this );
    advanced_->setChecked( false );

    //
    // Adjust the checkbox  tool tip to reflect its state
    //
    advancedClicked( false );
    connect( advanced_, SIGNAL( clicked( bool ) ),
	     SLOT( advancedClicked( bool ) ) );

    buttonLayout->addWidget( advanced_ );
    buttonLayout->addStretch();

    //
    // Simple OK button that will close the window
    //
    ok_ = new QPushButton( "OK", this );
    ok_->setEnabled( true );
    ok_->setToolTip( "Select to apply changes and close editor" );
    buttonLayout->addWidget( ok_ );
    connect( ok_, SIGNAL( clicked() ), SLOT( close() ) );

    //
    // Create another vbox layout for the widget collections
    //
    vbox = new QVBoxLayout( widgetContainer_ );
    vbox->setMargin( 9 );
    vbox->setSpacing( 6 );

    makeParam( "One", false );
    makeParam( "Two", false );
    makeParam( "Three", true );	// advanced
    makeParam( "Four", true );	// advanced
    makeParam( "Five", false );

    adjustSize();
}

void
ParamEditor::advancedClicked( bool state )
{
    if ( state )
	advanced_->setToolTip( "Click to hide advanced configuration "
			       "parameters" );
    else 
	advanced_->setToolTip( "Click to show advanced configuration "
			       "parameters" );
}

void
ParamEditor::makeParam( const QString& name, bool advanced )
{
    //
    // Create a new frame to group the label and QSpinBox for the parameter
    //
    QFrame* frame = new QFrame( widgetContainer_ );
    frame->setFrameStyle( QFrame::Box | QFrame::Sunken );
    widgetContainer_->layout()->addWidget( frame );

    //
    // Layout the label and spin box horizontally
    //
    QHBoxLayout* layout = new QHBoxLayout( frame );
    layout->setMargin( 6 );
    layout->addStretch();

    QLabel* label = new QLabel( name, frame );
    label->setAlignment( Qt::AlignRight | Qt::AlignVCenter );
    layout->addWidget( label );
    QSpinBox* value = new QSpinBox( frame );
    value->setValue( 0 );
    layout->addWidget( value );

    //
    // Advanced items are initially hidden
    //
    frame->setVisible( ! advanced );
    if ( advanced ) {

	//
	// Visibility of advanced items depends on the advanced checkbox state.
	//
	frame->setVisible( false );
	connect( advanced_, SIGNAL( clicked( bool ) ), frame,
		 SLOT( setVisible( bool ) ) );
    }
}

int
main( int argc, char* argv[] )
{
    QApplication* app = new QApplication( argc, argv );
    ParamEditor* paramEditor = new ParamEditor;
    paramEditor->show();
    paramEditor->raise();
    return app->exec();
}

# ParamEditor.pro
TEMPLATE = app
CONFIG += QT
TARGET = ParamEditor
DEPENDPATH += .
INCLUDEPATH += .

# Input
HEADERS += ParamEditor.h
SOURCES += ParamEditor.cc

-- 
Brad Howes
Group 42
MIT Lincoln Laboratory • 244 Wood St. • Lexington, MA 02173
Phone: 781.981.5292 • Fax: 781.981.3495 • Secretary: 781.981.7420