Customized Layoutmanager

Qt 3.0.5

previous page next page

Customized Layoutmanager

This examples demonstrates how to write customized layout (geometry) managers like card layouts, border layout and flow layouts.

Header file of the flow layout:

/****************************************************************************
** $Id:  qt/flow.h   3.0.5   edited Oct 12 2001 $
**
** Definition of simple flow layout for custom layout example
**
** Created : 979899
**
** Copyright (C) 1997 by Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#ifndef FLOW_H
#define FLOW_H

#include <qlayout.h>
#include <qptrlist.h>

class SimpleFlow : public QLayout
{
public:
    SimpleFlow( QWidget *parent, int border=0, int space=-1,
                const char *name=0 )
        : QLayout( parent, border, space, name ),
        cached_width(0) {}
    SimpleFlow( QLayout* parent, int space=-1, const char *name=0 )
        : QLayout( parent, space, name ),
        cached_width(0) {}
    SimpleFlow( int space=-1, const char *name=0 )
        : QLayout( space, name ),
        cached_width(0) {}

    ~SimpleFlow();

    void addItem( QLayoutItem *item);
    bool hasHeightForWidth() const;
    int heightForWidth( int ) const;
    QSize sizeHint() const;
    QSize minimumSize() const;
    QLayoutIterator iterator();
    QSizePolicy::ExpandData expanding() const;

protected:
    void setGeometry( const QRect& );

private:
    int doLayout( const QRect&, bool testonly = FALSE );
    QPtrList<QLayoutItem> list;
    int cached_width;
    int cached_hfw;

};

#endif

Implementation of the flow layout:

/****************************************************************************
** $Id:  qt/flow.cpp   3.0.5   edited Oct 12 2001 $
**
** Implementing your own layout: flow example
**
** Copyright (C) 1996 by Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#include "flow.h"

class SimpleFlowIterator :public QGLayoutIterator
{
public:
    SimpleFlowIterator( QPtrList<QLayoutItem> *l ) :idx(0), list(l)  {}
    uint count() const;
    QLayoutItem *current();
    QLayoutItem *next();
    QLayoutItem *takeCurrent();

private:
    int idx;
    QPtrList<QLayoutItem> *list;

};

uint SimpleFlowIterator::count() const
{
    return list->count();
}

QLayoutItem *SimpleFlowIterator::current()
{
    return idx < int(count()) ? list->at(idx) : 0;
}

QLayoutItem *SimpleFlowIterator::next()
{
    idx++; return current();
}

QLayoutItem *SimpleFlowIterator::takeCurrent()
{
    return idx < int(count()) ? list->take( idx ) : 0;
}

SimpleFlow::~SimpleFlow()
{
    deleteAllItems();
}


int SimpleFlow::heightForWidth( int w ) const
{
    if ( cached_width != w ) {
        //Not all C++ compilers support "mutable" yet:
        SimpleFlow * mthis = (SimpleFlow*)this;
        int h = mthis->doLayout( QRect(0,0,w,0), TRUE );
        mthis->cached_hfw = h;
        return h;
    }
    return cached_hfw;
}

void SimpleFlow::addItem( QLayoutItem *item)
{
    list.append( item );
}

bool SimpleFlow::hasHeightForWidth() const
{
    return TRUE;
}

QSize SimpleFlow::sizeHint() const
{
    return minimumSize();
}

QSizePolicy::ExpandData SimpleFlow::expanding() const
{
    return QSizePolicy::NoDirection;
}

QLayoutIterator SimpleFlow::iterator()
{
    return QLayoutIterator( new SimpleFlowIterator( &list ) );
}

void SimpleFlow::setGeometry( const QRect &r )
{
    QLayout::setGeometry( r );
    doLayout( r );
}

int SimpleFlow::doLayout( const QRect &r, bool testonly )
{
    int x = r.x();
    int y = r.y();
    int h = 0;          //height of this line so far.
    QPtrListIterator<QLayoutItem> it(list);
    QLayoutItem *o;
    while ( (o=it.current()) != 0 ) {
        ++it;
        int nextX = x + o->sizeHint().width() + spacing();
        if ( nextX - spacing() > r.right() && h > 0 ) {
            x = r.x();
            y = y + h + spacing();
            nextX = x + o->sizeHint().width() + spacing();
            h = 0;
        }
        if ( !testonly )
            o->setGeometry( QRect( QPoint( x, y ), o->sizeHint() ) );
        x = nextX;
        h = QMAX( h,  o->sizeHint().height() );
    }
    return y + h - r.y();
}

QSize SimpleFlow::minimumSize() const
{
    QSize s(0,0);
    QPtrListIterator<QLayoutItem> it(list);
    QLayoutItem *o;
    while ( (o=it.current()) != 0 ) {
        ++it;
        s = s.expandedTo( o->minimumSize() );
    }
    return s;
}

Header file of the border layout:

/****************************************************************************
** $Id:  qt/border.h   3.0.5   edited Oct 12 2001 $
**
** Definition of simple flow layout for custom layout example
**
** Created : 979899
**
** Copyright (C) 1997 by Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#ifndef BORDER_H
#define BORDER_H

#include <qlayout.h>
#include <qptrlist.h>

class BorderWidgetItem : public QWidgetItem
{
public:
    BorderWidgetItem( QWidget *w )
        : QWidgetItem( w )
    {}

    void setGeometry( const QRect &r )
    { widget()->setGeometry( r ); }

};

class BorderLayout : public QLayout
{
public:
    enum Position {
        West = 0,
        North,
        South,
        East,
        Center
    };

    struct BorderLayoutStruct
    {
        BorderLayoutStruct( QLayoutItem *i, Position p ) {
            item = i;
            pos = p;
        }

        QLayoutItem *item;
        Position pos;
    };

    enum SizeType {
        Minimum = 0,
        SizeHint
    };

    BorderLayout( QWidget *parent, int border = 0, int autoBorder = -1,
                  const char *name = 0 )
        : QLayout( parent, border, autoBorder, name ), cached( 0, 0 ), mcached( 0, 0 ),
          sizeDirty( TRUE ), msizeDirty( TRUE )
    {}

    BorderLayout( QLayout* parent, int autoBorder = -1, const char *name = 0 )
        : QLayout( parent, autoBorder, name  ), cached( 0, 0 ), mcached( 0, 0 ),
          sizeDirty( TRUE ), msizeDirty( TRUE )
    {}

    BorderLayout( int autoBorder = -1, const char *name = 0 )
        : QLayout( autoBorder, name ), cached( 0, 0 ), mcached( 0, 0 ),
          sizeDirty( TRUE ), msizeDirty( TRUE )
    {}

    ~BorderLayout();

    void addItem( QLayoutItem *item );

    void addWidget( QWidget *widget, Position pos );
    void add( QLayoutItem *item, Position pos );

    bool hasHeightForWidth() const;

    QSize sizeHint() const;
    QSize minimumSize() const;

    QLayoutIterator iterator();

    QSizePolicy::ExpandData expanding() const;

protected:
    void setGeometry( const QRect &rect );

private:
    void doLayout( const QRect &rect, bool testonly = FALSE );
    void calcSize( SizeType st );

    QPtrList<BorderLayoutStruct> list;
    QSize cached, mcached;
    bool sizeDirty, msizeDirty;

};

#endif

Implementation of the border layout:

/****************************************************************************
** $Id:  qt/border.cpp   3.0.5   edited Oct 12 2001 $
**
** Implementing your own layout: flow example
**
** Copyright (C) 1996 by Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#include "border.h"

class BorderLayoutIterator : public QGLayoutIterator
{
public:
    BorderLayoutIterator( const QPtrList<BorderLayout::BorderLayoutStruct> *l )
        : idx( 0 ) , list( (QPtrList<BorderLayout::BorderLayoutStruct>*)l )
    {}

    uint count() const;
    QLayoutItem *current();
    BorderLayout::BorderLayoutStruct *currentStruct();
    void toFirst();
    QLayoutItem *next();
    QLayoutItem *takeCurrent();
    BorderLayoutIterator &operator++();

private:
    int idx;
    QPtrList<BorderLayout::BorderLayoutStruct> *list;

};

uint BorderLayoutIterator::count() const
{
    return list->count();
}

QLayoutItem *BorderLayoutIterator::current()
{
    return idx < (int)count() ? list->at( idx )->item : 0;
}

BorderLayout::BorderLayoutStruct *BorderLayoutIterator::currentStruct()
{
    return idx < (int)count() ? list->at( idx ) : 0;
}

void BorderLayoutIterator::toFirst()
{
    idx = 0;
}

QLayoutItem *BorderLayoutIterator::next()
{
    idx++;
    return current();
}

QLayoutItem *BorderLayoutIterator::takeCurrent()
{
    BorderLayout::BorderLayoutStruct *b
        = idx < int( list->count() ) ? list->take(  idx  ) : 0;
    QLayoutItem *item =  b ? b->item : 0;
    delete b;
    return item;
}

BorderLayoutIterator &BorderLayoutIterator::operator++()
{
    next();
    return *this;
}

BorderLayout::~BorderLayout()
{
    deleteAllItems();
}


void BorderLayout::addItem( QLayoutItem *item )
{
    add( item, West );
}

void BorderLayout::addWidget( QWidget *widget, Position pos )
{
    add( new BorderWidgetItem( widget ), pos );
}

void BorderLayout::add( QLayoutItem *item, Position pos )
{
    list.append( new BorderLayoutStruct( item, pos ) );
    sizeDirty = TRUE; msizeDirty = TRUE;
    calcSize( SizeHint ); calcSize( Minimum );
}

bool BorderLayout::hasHeightForWidth() const
{
    return FALSE;
}

QSize BorderLayout::sizeHint() const
{
    return cached;
}

QSize BorderLayout::minimumSize() const
{
    return cached;
}

QSizePolicy::ExpandData BorderLayout::expanding() const

{
    return QSizePolicy::BothDirections;
}

QLayoutIterator BorderLayout::iterator()
{
    return QLayoutIterator( new BorderLayoutIterator( &list ) );
}

void BorderLayout::setGeometry( const QRect &rct )
{
    QLayout::setGeometry( rct );
    doLayout( rct );
}

void BorderLayout::doLayout( const QRect &rct, bool /*testonly*/ )
{
    int ew = 0, ww = 0, nh = 0, sh = 0;
    int h = 0;

    BorderLayoutIterator it( &list );
    BorderLayoutStruct *o;
    BorderLayoutStruct *center = 0;
    while ( ( o = it.currentStruct() ) != 0 ) {
        ++it;

        if ( o->pos == North ) {
            o->item->setGeometry( QRect( rct.x(), nh, rct.width(), o->item->sizeHint().height() ) );
            nh += o->item->geometry().height() + spacing();
        }
        if ( o->pos == South ) {
            o->item->setGeometry( QRect( o->item->geometry().x(), o->item->geometry().y(),
                                         rct.width(), o->item->sizeHint().height() ) );
            sh += o->item->geometry().height() + spacing();
            o->item->setGeometry( QRect( rct.x(), rct.y() + rct.height() - sh + spacing(),
                                         o->item->geometry().width(), o->item->geometry().height() ) );
        }
        if ( o->pos == Center )
            center = o;
    }

    h = rct.height() - nh - sh;

    it.toFirst();
    while ( ( o = it.currentStruct() ) != 0 ) {
        ++it;

        if ( o->pos == West ) {
            o->item->setGeometry( QRect( rct.x() + ww, nh, o->item->sizeHint().width(), h ) );
            ww += o->item->geometry().width() + spacing();
        }
        if ( o->pos == East ) {
            o->item->setGeometry( QRect( o->item->geometry().x(), o->item->geometry().y(),
                                         o->item->sizeHint().width(), h ) );
            ew += o->item->geometry().width() + spacing();
            o->item->setGeometry( QRect( rct.x() + rct.width() - ew + spacing(), nh,
                                         o->item->geometry().width(), o->item->geometry().height() ) );
        }
    }

    if ( center )
        center->item->setGeometry( QRect( ww, nh, rct.width() - ew - ww, h ) );
}

void BorderLayout::calcSize( SizeType st )
{
    if ( ( st == Minimum && !msizeDirty ) ||
         ( st == SizeHint && !sizeDirty ) )
        return;

    int w = 0, h = 0;

    BorderLayoutIterator it( &list );
    BorderLayoutStruct *o;
    while ( ( o = it.currentStruct() ) != 0 ) {
        ++it;
        if ( o->pos == North ||
             o->pos == South ) {
            if ( st == Minimum )
                h += o->item->minimumSize().height();
            else
                h += o->item->sizeHint().height();
        }
        else if ( o->pos == West ||
                  o->pos == East ) {
            if ( st == Minimum )
                w += o->item->minimumSize().width();
            else
                w += o->item->sizeHint().width();
        } else {
            if ( st == Minimum ) {
                h += o->item->minimumSize().height();
                w += o->item->minimumSize().width();
            }
            else {
                h += o->item->sizeHint().height();
                w += o->item->sizeHint().width();
            }
        }
    }

    if ( st == Minimum ) {
        msizeDirty = FALSE;
        mcached = QSize( w, h );
    } else {
        sizeDirty = FALSE;
        cached = QSize( w, h );
    }

    return;
}

Header file of the card layout:

/****************************************************************************
** $Id:  qt/card.h   3.0.5   edited Oct 12 2001 $
**
** Definition of simple flow layout for custom layout example
**
** Created : 979899
**
** Copyright (C) 1997 by Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#ifndef CARD_H
#define CARD_H

#include <qlayout.h>
#include <qptrlist.h>

class CardLayout : public QLayout
{
public:
    CardLayout( QWidget *parent, int dist )
        : QLayout( parent, 0, dist ) {}
    CardLayout( QLayout* parent, int dist)
        : QLayout( parent, dist ) {}
    CardLayout( int dist )
        : QLayout( dist ) {}
    ~CardLayout();

    void addItem( QLayoutItem *item );
    QSize sizeHint() const;
    QSize minimumSize() const;
    QLayoutIterator iterator();
    void setGeometry( const QRect &rect );

private:
    QPtrList<QLayoutItem> list;

};

#endif

Implementation of the card layout:

/****************************************************************************
** $Id:  qt/card.cpp   3.0.5   edited Oct 12 2001 $
**
** Implementing your own layout: flow example
**
** Copyright (C) 1996 by Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#include "card.h"

class CardLayoutIterator :public QGLayoutIterator
{
public:
    CardLayoutIterator( QPtrList<QLayoutItem> *l )
        : idx( 0 ), list( l )  {}

    QLayoutItem *current();
    QLayoutItem *next();
    QLayoutItem *takeCurrent();

private:
    int idx;
    QPtrList<QLayoutItem> *list;
};

QLayoutItem *CardLayoutIterator::current()
{
    return idx < int( list->count() ) ? list->at( idx ) : 0;
}

QLayoutItem *CardLayoutIterator::next()
{
    idx++; return current();
}

QLayoutItem *CardLayoutIterator::takeCurrent()
{
    return idx < int( list->count() ) ?list->take( idx ) : 0;
}



QLayoutIterator CardLayout::iterator()
{
    return QLayoutIterator(  new CardLayoutIterator( &list )  );
}

CardLayout::~CardLayout()
{
    deleteAllItems();
}

void CardLayout::addItem(  QLayoutItem *item  )
{
    list.append( item );
}

void CardLayout::setGeometry( const QRect &rct )
{
    QLayout::setGeometry( rct );

    QPtrListIterator<QLayoutItem> it( list );
    if ( it.count() == 0 )
        return;

    QLayoutItem *o;

    int i = 0;

    int w = rct.width() - ( list.count() - 1 ) * spacing();
    int h = rct.height() - ( list.count() - 1 ) * spacing();

    while ( ( o=it.current() ) != 0 ) {
        ++it;
        QRect geom( rct.x() + i * spacing(), rct.y() + i * spacing(),
                    w, h  );
        o->setGeometry(  geom  );
        ++i;
    }
}

QSize CardLayout::sizeHint() const
{
    QSize s(0,0);
    int n = list.count();
    if ( n > 0 )
        s = QSize(100,70); //start with a nice default size
    QPtrListIterator<QLayoutItem> it(list);
    QLayoutItem *o;
    while ( (o=it.current()) != 0 ) {
        ++it;
        s = s.expandedTo( o->minimumSize() );
    }
    return s + n*QSize(spacing(),spacing());
}

QSize CardLayout::minimumSize() const
{
    QSize s(0,0);
    int n = list.count();
    QPtrListIterator<QLayoutItem> it(list);
    QLayoutItem *o;
    while ( (o=it.current()) != 0 ) {
        ++it;
        s = s.expandedTo( o->minimumSize() );
    }
    return s + n*QSize(spacing(),spacing());
}

Main:

/****************************************************************************
** $Id:  qt/main.cpp   3.0.5   edited Oct 12 2001 $
**
** Main for custom layout example
**
** Copyright (C) 1996 by Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#include "flow.h"
#include "border.h"
#include "card.h"

#include <qapplication.h>
#include <qlabel.h>
#include <qcolor.h>
#include <qgroupbox.h>
#include <qpushbutton.h>
#include <qmultilineedit.h>
#include <qcolor.h>

int main( int argc, char **argv )
{
    QApplication a( argc, argv );

    QWidget *f = new QWidget;
    QBoxLayout *gm = new QVBoxLayout( f, 5 );

    SimpleFlow *b1 = new SimpleFlow( gm );

    b1->add( new QPushButton( "Short", f ) );
    b1->add( new QPushButton( "Longer", f ) );
    b1->add( new QPushButton( "Different text", f ) );
    b1->add( new QPushButton( "More text", f ) );
    b1->add( new QPushButton( "Even longer button text", f ) );
    QPushButton* qb = new QPushButton( "Quit", f );
    a.connect( qb, SIGNAL( clicked() ), SLOT( quit() ) );
    b1->add( qb );

    QWidget *wid = new QWidget( f );

    BorderLayout *large = new BorderLayout( wid );
    large->setSpacing( 5 );
    large->addWidget( new QPushButton( "North", wid ), BorderLayout::North );
    large->addWidget( new QPushButton( "West", wid ), BorderLayout::West );
    QMultiLineEdit* m = new QMultiLineEdit( wid );
    m->setText( "Central\nWidget" );
    large->addWidget( m, BorderLayout::Center );
    QWidget *east1 = new QPushButton( "East", wid );
    large->addWidget( east1, BorderLayout::East );
    QWidget *east2 = new QPushButton( "East 2", wid );
    large->addWidget( east2 , BorderLayout::East );
    large->addWidget( new QPushButton( "South", wid ), BorderLayout::South );
    //Left-to-right tab order looks better:
    QWidget::setTabOrder( east2, east1 );
    gm->addWidget( wid );


    wid = new QWidget( f );
    CardLayout *card = new CardLayout( wid, 10 );

    QWidget *crd = new QWidget( wid );
    crd->setBackgroundColor( Qt::red );
    card->add( crd );
    crd = new QWidget( wid );
    crd->setBackgroundColor( Qt::green );
    card->add( crd );
    crd = new QWidget( wid );
    crd->setBackgroundColor( Qt::blue );
    card->add( crd );
    crd = new QWidget( wid );
    crd->setBackgroundColor( Qt::white );
    card->add( crd );
    crd = new QWidget( wid );
    crd->setBackgroundColor( Qt::black );
    card->add( crd );
    crd = new QWidget( wid );
    crd->setBackgroundColor( Qt::yellow );
    card->add( crd );

    gm->addWidget( wid );

    QLabel* s = new QLabel( f );
    s->setText( "outermost box" );
    s->setFrameStyle( QFrame::Panel | QFrame::Sunken );
    s->setAlignment( Qt::AlignVCenter | Qt::AlignHCenter );
    gm->addWidget( s );
    a.setMainWidget( f );
    f->setCaption("Qt Example - Custom Layout");
    f->show();

    int result = a.exec();
    delete f;
    return result;
}