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qt3/src/kernel/qlayoutengine.cpp

323 lines
9.9 KiB

/****************************************************************************
**
** Implementation of QLayout functionality
**
** Created : 981231
**
** Copyright (C) 1998-2008 Trolltech ASA. All rights reserved.
**
** This file is part of the kernel module of the Qt GUI Toolkit.
**
** This file may be used under the terms of the GNU General
** Public License versions 2.0 or 3.0 as published by the Free
** Software Foundation and appearing in the files LICENSE.GPL2
** and LICENSE.GPL3 included in the packaging of this file.
** Alternatively you may (at your option) use any later version
** of the GNU General Public License if such license has been
** publicly approved by Trolltech ASA (or its successors, if any)
** and the KDE Free Qt Foundation.
**
** Please review the following information to ensure GNU General
** Public Licensing requirements will be met:
** http://trolltech.com/products/qt/licenses/licensing/opensource/.
** If you are unsure which license is appropriate for your use, please
** review the following information:
** http://trolltech.com/products/qt/licenses/licensing/licensingoverview
** or contact the sales department at sales@trolltech.com.
**
** This file may be used under the terms of the Q Public License as
** defined by Trolltech ASA and appearing in the file LICENSE.QPL
** included in the packaging of this file. Licensees holding valid Qt
** Commercial licenses may use this file in accordance with the Qt
** Commercial License Agreement provided with the Software.
**
** This file is provided "AS IS" with NO WARRANTY OF ANY KIND,
** INCLUDING THE WARRANTIES OF DESIGN, MERCHANTABILITY AND FITNESS FOR
** A PARTICULAR PURPOSE. Trolltech reserves all rights not granted
** herein.
**
**********************************************************************/
#include "qlayout.h"
#include "private/qlayoutengine_p.h"
#ifndef QT_NO_LAYOUT
static inline int toFixed( int i ) { return i * 256; }
static inline int fRound( int i ) {
return ( i % 256 < 128 ) ? i / 256 : 1 + i / 256;
}
/*
This is the main workhorse of the QGridLayout. It portions out
available space to the chain's children.
The calculation is done in fixed point: "fixed" variables are
scaled by a factor of 256.
If the layout runs "backwards" (i.e. RightToLeft or Up) the layout
is computed mirror-reversed, and it's the caller's responsibility
do reverse the values before use.
chain contains input and output parameters describing the geometry.
count is the count of items in the chain; pos and space give the
interval (relative to parentWidget topLeft).
*/
Q_EXPORT void qGeomCalc( QMemArray<QLayoutStruct> &chain, int start, int count,
int pos, int space, int spacer )
{
typedef int fixed;
int cHint = 0;
int cMin = 0;
int cMax = 0;
int sumStretch = 0;
int spacerCount = 0;
bool wannaGrow = FALSE; // anyone who really wants to grow?
// bool canShrink = FALSE; // anyone who could be persuaded to shrink?
int i;
for ( i = start; i < start + count; i++ ) {
chain[i].done = FALSE;
cHint += chain[i].smartSizeHint();
cMin += chain[i].minimumSize;
cMax += chain[i].maximumSize;
sumStretch += chain[i].stretch;
if ( !chain[i].empty )
spacerCount++;
wannaGrow = wannaGrow || chain[i].expansive || chain[i].stretch > 0;
}
int extraspace = 0;
if ( spacerCount )
spacerCount--; // only spacers between things
if ( space < cMin + spacerCount * spacer ) {
for ( i = start; i < start+count; i++ ) {
chain[i].size = chain[i].minimumSize;
chain[i].done = TRUE;
}
} else if ( space < cHint + spacerCount*spacer ) {
/*
Less space than smartSizeHint(), but more than minimumSize.
Currently take space equally from each, as in Qt 2.x.
Commented-out lines will give more space to stretchier
items.
*/
int n = count;
int space_left = space - spacerCount*spacer;
int overdraft = cHint - space_left;
// first give to the fixed ones:
for ( i = start; i < start + count; i++ ) {
if ( !chain[i].done
&& chain[i].minimumSize >= chain[i].smartSizeHint() ) {
chain[i].size = chain[i].smartSizeHint();
chain[i].done = TRUE;
space_left -= chain[i].smartSizeHint();
// sumStretch -= chain[i].stretch;
n--;
}
}
bool finished = n == 0;
while ( !finished ) {
finished = TRUE;
fixed fp_over = toFixed( overdraft );
fixed fp_w = 0;
for ( i = start; i < start+count; i++ ) {
if ( chain[i].done )
continue;
// if ( sumStretch <= 0 )
fp_w += fp_over / n;
// else
// fp_w += (fp_over * chain[i].stretch) / sumStretch;
int w = fRound( fp_w );
chain[i].size = chain[i].smartSizeHint() - w;
fp_w -= toFixed( w ); // give the difference to the next
if ( chain[i].size < chain[i].minimumSize ) {
chain[i].done = TRUE;
chain[i].size = chain[i].minimumSize;
finished = FALSE;
overdraft -= ( chain[i].smartSizeHint()
- chain[i].minimumSize );
// sumStretch -= chain[i].stretch;
n--;
break;
}
}
}
} else { // extra space
int n = count;
int space_left = space - spacerCount*spacer;
// first give to the fixed ones, and handle non-expansiveness
for ( i = start; i < start + count; i++ ) {
if ( !chain[i].done
&& (chain[i].maximumSize <= chain[i].smartSizeHint()
|| (wannaGrow && !chain[i].expansive && chain[i].stretch == 0)) ) {
chain[i].size = chain[i].smartSizeHint();
chain[i].done = TRUE;
space_left -= chain[i].smartSizeHint();
sumStretch -= chain[i].stretch;
n--;
}
}
extraspace = space_left;
/*
Do a trial distribution and calculate how much it is off.
If there are more deficit pixels than surplus pixels, give
the minimum size items what they need, and repeat.
Otherwise give to the maximum size items, and repeat.
Paul Olav Tvete has a wonderful mathematical proof of the
correctness of this principle, but unfortunately this
comment is too small to contain it.
*/
int surplus, deficit;
do {
surplus = deficit = 0;
fixed fp_space = toFixed( space_left );
fixed fp_w = 0;
for ( i = start; i < start+count; i++ ) {
if ( chain[i].done )
continue;
extraspace = 0;
if ( sumStretch <= 0 )
fp_w += fp_space / n;
else
fp_w += (fp_space * chain[i].stretch) / sumStretch;
int w = fRound( fp_w );
chain[i].size = w;
fp_w -= toFixed( w ); // give the difference to the next
if ( w < chain[i].smartSizeHint() ) {
deficit += chain[i].smartSizeHint() - w;
} else if ( w > chain[i].maximumSize ) {
surplus += w - chain[i].maximumSize;
}
}
if ( deficit > 0 && surplus <= deficit ) {
// give to the ones that have too little
for ( i = start; i < start+count; i++ ) {
if ( !chain[i].done &&
chain[i].size < chain[i].smartSizeHint() ) {
chain[i].size = chain[i].smartSizeHint();
chain[i].done = TRUE;
space_left -= chain[i].smartSizeHint();
sumStretch -= chain[i].stretch;
n--;
}
}
}
if ( surplus > 0 && surplus >= deficit ) {
// take from the ones that have too much
for ( i = start; i < start+count; i++ ) {
if ( !chain[i].done &&
chain[i].size > chain[i].maximumSize ) {
chain[i].size = chain[i].maximumSize;
chain[i].done = TRUE;
space_left -= chain[i].maximumSize;
sumStretch -= chain[i].stretch;
n--;
}
}
}
} while ( n > 0 && surplus != deficit );
if ( n == 0 )
extraspace = space_left;
}
/*
As a last resort, we distribute the unwanted space equally
among the spacers (counting the start and end of the chain). We
could, but don't, attempt a sub-pixel allocation of the extra
space.
*/
int extra = extraspace / ( spacerCount + 2 );
int p = pos + extra;
for ( i = start; i < start+count; i++ ) {
chain[i].pos = p;
p = p + chain[i].size;
if ( !chain[i].empty )
p += spacer+extra;
}
}
Q_EXPORT QSize qSmartMinSize( const QWidgetItem *i )
{
QWidget *w = ((QWidgetItem *)i)->widget();
QSize s( 0, 0 );
if ( w->layout() ) {
s = w->layout()->totalMinimumSize();
} else {
QSize sh;
if ( w->sizePolicy().horData() != QSizePolicy::Ignored ) {
if ( w->sizePolicy().mayShrinkHorizontally() ) {
s.setWidth( w->minimumSizeHint().width() );
} else {
sh = w->sizeHint();
s.setWidth( sh.width() );
}
}
if ( w->sizePolicy().verData() != QSizePolicy::Ignored ) {
if ( w->sizePolicy().mayShrinkVertically() ) {
s.setHeight( w->minimumSizeHint().height() );
} else {
s.setHeight( sh.isValid() ? sh.height()
: w->sizeHint().height() );
}
}
}
s = s.boundedTo( w->maximumSize() );
QSize min = w->minimumSize();
if ( min.width() > 0 )
s.setWidth( min.width() );
if ( min.height() > 0 )
s.setHeight( min.height() );
if ( i->hasHeightForWidth() && min.height() == 0 && min.width() > 0 )
s.setHeight( i->heightForWidth(s.width()) );
s = s.expandedTo( QSize(1, 1) );
return s;
}
Q_EXPORT QSize qSmartMinSize( QWidget *w )
{
QWidgetItem item( w );
return qSmartMinSize( &item );
}
Q_EXPORT QSize qSmartMaxSize( const QWidgetItem *i, int align )
{
QWidget *w = ( (QWidgetItem*)i )->widget();
if ( align & Qt::AlignHorizontal_Mask && align & Qt::AlignVertical_Mask )
return QSize( QLAYOUTSIZE_MAX, QLAYOUTSIZE_MAX );
QSize s = w->maximumSize();
if ( s.width() == QWIDGETSIZE_MAX && !(align & Qt::AlignHorizontal_Mask) )
if ( !w->sizePolicy().mayGrowHorizontally() )
s.setWidth( w->sizeHint().width() );
if ( s.height() == QWIDGETSIZE_MAX && !(align & Qt::AlignVertical_Mask) )
if ( !w->sizePolicy().mayGrowVertically() )
s.setHeight( w->sizeHint().height() );
s = s.expandedTo( w->minimumSize() );
if ( align & Qt::AlignHorizontal_Mask )
s.setWidth( QLAYOUTSIZE_MAX );
if ( align & Qt::AlignVertical_Mask )
s.setHeight( QLAYOUTSIZE_MAX );
return s;
}
Q_EXPORT QSize qSmartMaxSize( QWidget *w, int align )
{
QWidgetItem item( w );
return qSmartMaxSize( &item, align );
}
#endif // QT_NO_LAYOUT