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<td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QMag</h1>
<p>
This is a simple magnifier-type program. It shows how one can do
some quite low-level operations in a portable way using Qt.
<p> Run it, click in the magnifier window, then click where you want to
magnify or drag out a rectangle. Two combo boxes let you select
amplification and refresh frequency, a text label tells you the color
of the pixel the cursor is on, and a button lets you save the
magnified area as a .bmp file.
<p> <hr>
<p> Implementation:
<p> <pre>/****************************************************************************
** $Id: qt/qmag.cpp 3.0.2 edited Oct 12 12:18 $
**
** Copyright (C) 1992-2000 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 <<a href="qcombobox-h.html">qcombobox.h</a>>
#include <<a href="qpushbutton-h.html">qpushbutton.h</a>>
#include <<a href="qpixmap-h.html">qpixmap.h</a>>
#include <<a href="qimage-h.html">qimage.h</a>>
#include <<a href="qlabel-h.html">qlabel.h</a>>
#include <<a href="qfiledialog-h.html">qfiledialog.h</a>>
#include <<a href="qregexp-h.html">qregexp.h</a>>
#include <<a href="qapplication-h.html">qapplication.h</a>>
#include <<a href="qpainter-h.html">qpainter.h</a>>
#include <<a href="qwmatrix-h.html">qwmatrix.h</a>>
class MagWidget : public <a href="qwidget.html">QWidget</a>
{
<a href="metaobjects.html#Q_OBJECT">Q_OBJECT</a>
public:
MagWidget( <a href="qwidget.html">QWidget</a> *parent=0, const char *name=0 );
public slots:
void setZoom( int );
void setRefresh( int );
void save();
void multiSave();
protected:
void paintEvent( <a href="qpaintevent.html">QPaintEvent</a> * );
void mousePressEvent( <a href="qmouseevent.html">QMouseEvent</a> * );
void mouseReleaseEvent( <a href="qmouseevent.html">QMouseEvent</a> * );
void mouseMoveEvent( <a href="qmouseevent.html">QMouseEvent</a> * );
void focusOutEvent( <a href="qfocusevent.html">QFocusEvent</a> * );
void timerEvent( <a href="qtimerevent.html">QTimerEvent</a> * );
void resizeEvent( <a href="qresizeevent.html">QResizeEvent</a> * );
private:
void grabAround(QPoint pos);
void grab();
<a href="qcombobox.html">QComboBox</a> *zoom;
<a href="qcombobox.html">QComboBox</a> *refresh;
<a href="qpushbutton.html">QPushButton</a> *saveButton;
<a href="qpushbutton.html">QPushButton</a> *multiSaveButton;
<a href="qpushbutton.html">QPushButton</a> *quitButton;
<a href="qpixmap.html">QPixmap</a> pm; // pixmap, magnified
<a href="qpixmap.html">QPixmap</a> p; // pixmap
<a href="qimage.html">QImage</a> image; // image of pixmap (for RGB)
<a href="qlabel.html">QLabel</a> *rgb;
int yoffset; // pixels in addition to the actual picture
int z; // magnification factor
int r; // autorefresh rate (index into refreshrates)
bool grabbing; // TRUE if qmag is currently grabbing
int grabx, graby;
<a href="qstring.html">QString</a> multifn; // filename for multisave
};
#ifdef COMPLEX_GUI
static const char *zoomfactors[] = {
"100%", "200%", "300%", "400%", "500%",
"600%", "700%", "800%", "1600%", 0 };
static const char *refreshrates[] = {
"No autorefresh", "50 per second", "4 per second", "3 per second", "2 per second",
"Every second", "Every two seconds", "Every three seconds",
"Every five seconds", "Every ten seconds", 0 };
#endif
static const int timer[] = {
0, 20, 250, 333, 500, 1000, 2000, 3000, 5000, 10000 };
<a name="f262"></a>MagWidget::MagWidget( <a href="qwidget.html">QWidget</a> *parent, const char *name )
: <a href="qwidget.html">QWidget</a>( parent, name)
{
z = 1; // default zoom (100%)
r = 0; // default refresh (none)
#ifdef COMPLEX_GUI
int w=0, x=0, n;
zoom = new <a href="qcombobox.html">QComboBox</a>( FALSE, this );
<a href="qapplication.html#Q_CHECK_PTR">Q_CHECK_PTR</a>(zoom);
<a name="x693"></a> zoom-><a href="qcombobox.html#insertStrList">insertStrList</a>( zoomfactors, 9 );
<a name="x692"></a> <a href="qobject.html#connect">connect</a>( zoom, SIGNAL(<a href="qcombobox.html#activated">activated</a>(int)), SLOT(setZoom(int)) );
refresh = new <a href="qcombobox.html">QComboBox</a>( FALSE, this );
<a href="qapplication.html#Q_CHECK_PTR">Q_CHECK_PTR</a>(refresh);
refresh-><a href="qcombobox.html#insertStrList">insertStrList</a>( refreshrates, 9 );
<a href="qobject.html#connect">connect</a>( refresh, SIGNAL(<a href="qcombobox.html#activated">activated</a>(int)), SLOT(setRefresh(int)) );
for( n=0; n<9; n++) {
<a name="x716"></a> int w2 = zoom-><a href="qwidget.html#fontMetrics">fontMetrics</a>().width( zoomfactors[n] );
w = QMAX(w2, w);
}
<a name="x726"></a> zoom-><a href="qwidget.html#setGeometry">setGeometry</a>( 2, 2, w+30, 20 );
x = w+34;
w = 0;
for( n=0; n<9; n++) {
int w2 = refresh-><a href="qwidget.html#fontMetrics">fontMetrics</a>().width( refreshrates[n] );
w = QMAX(w2, w);
}
refresh-><a href="qwidget.html#setGeometry">setGeometry</a>( x, 2, w+30, 20 );
saveButton = new <a href="qpushbutton.html">QPushButton</a>( this );
<a href="qapplication.html#Q_CHECK_PTR">Q_CHECK_PTR</a>(saveButton);
<a href="qobject.html#connect">connect</a>( saveButton, SIGNAL(<a href="qbutton.html#clicked">clicked</a>()), this, SLOT(save()) );
<a name="x691"></a> saveButton-><a href="qbutton.html#setText">setText</a>( "Save" );
saveButton-><a href="qwidget.html#setGeometry">setGeometry</a>( x+w+30+2, 2,
10+saveButton-><a href="qwidget.html#fontMetrics">fontMetrics</a>().width("Save"), 20 );
multiSaveButton = new <a href="qpushbutton.html">QPushButton</a>( this );
<a name="x709"></a> multiSaveButton-><a href="qpushbutton.html#setToggleButton">setToggleButton</a>(TRUE);
<a href="qapplication.html#Q_CHECK_PTR">Q_CHECK_PTR</a>(multiSaveButton);
<a href="qobject.html#connect">connect</a>( multiSaveButton, SIGNAL(<a href="qbutton.html#clicked">clicked</a>()), this, SLOT(multiSave()) );
multiSaveButton-><a href="qbutton.html#setText">setText</a>( "MultiSave" );
<a name="x717"></a> multiSaveButton-><a href="qwidget.html#setGeometry">setGeometry</a>( saveButton-><a href="qwidget.html#geometry">geometry</a>().right() + 2, 2,
10+multiSaveButton-><a href="qwidget.html#fontMetrics">fontMetrics</a>().width("MultiSave"), 20 );
quitButton = new <a href="qpushbutton.html">QPushButton</a>( this );
<a href="qapplication.html#Q_CHECK_PTR">Q_CHECK_PTR</a>(quitButton);
<a href="qobject.html#connect">connect</a>( quitButton, SIGNAL(<a href="qbutton.html#clicked">clicked</a>()), qApp, SLOT(<a href="qapplication.html#quit">quit</a>()) );
quitButton-><a href="qbutton.html#setText">setText</a>( "Quit" );
quitButton-><a href="qwidget.html#setGeometry">setGeometry</a>( multiSaveButton-><a href="qwidget.html#geometry">geometry</a>().right() + 2, 2,
10+quitButton-><a href="qwidget.html#fontMetrics">fontMetrics</a>().width("Quit"), 20 );
#else
zoom = 0;
multiSaveButton = 0;
#endif
setRefresh(1);
setZoom(5);
rgb = new <a href="qlabel.html">QLabel</a>( this );
<a href="qapplication.html#Q_CHECK_PTR">Q_CHECK_PTR</a>( rgb );
<a name="x699"></a> rgb-><a href="qlabel.html#setText">setText</a>( "" );
rgb-><a href="qlabel.html#setAlignment">setAlignment</a>( AlignVCenter );
rgb-><a href="qwidget.html#resize">resize</a>( <a href="qwidget.html#width">width</a>(), rgb-><a href="qwidget.html#fontMetrics">fontMetrics</a>().height() + 4 );
#ifdef COMPLEX_GUI
<a name="x718"></a> yoffset = zoom-><a href="qwidget.html#height">height</a>() // top buttons
+ 4 // space around top buttons
+ rgb-><a href="qwidget.html#height">height</a>(); // color-value text height
<a name="x723"></a> <a href="qwidget.html#setMinimumSize">setMinimumSize</a>( quitButton-><a href="qwidget.html#pos">pos</a>().x(), yoffset+20 );
<a href="qwidget.html#resize">resize</a>( quitButton-><a href="qwidget.html#geometry">geometry</a>().topRight().x() + 2, yoffset+60 );
#else
yoffset = 0;
<a href="qwidget.html#resize">resize</a>(350,350);
#endif
grabx = graby = -1;
grabbing = FALSE;
<a href="qwidget.html#setMouseTracking">setMouseTracking</a>( TRUE ); // and do let me know what pixel I'm at, eh?
<a name="x685"></a> grabAround( QPoint(grabx=qApp-><a href="qapplication.html#desktop">desktop</a>()->width()/2, graby=qApp-><a href="qapplication.html#desktop">desktop</a>()->height()/2) );
}
void <a name="f263"></a>MagWidget::setZoom( int index )
{
if (index == 8)
z = 16;
else
z = index+1;
grab();
}
void <a name="f264"></a>MagWidget::setRefresh( int index )
{
r = index;
<a href="qobject.html#killTimers">killTimers</a>();
if (index && !grabbing)
<a href="qobject.html#startTimer">startTimer</a>( timer[r] );
}
void <a name="f265"></a>MagWidget::save()
{
<a name="x705"></a> if ( !p.<a href="qpixmap.html#isNull">isNull</a>() ) {
<a href="qobject.html#killTimers">killTimers</a>();
<a name="x695"></a> <a href="qstring.html">QString</a> fn = QFileDialog::<a href="qfiledialog.html#getSaveFileName">getSaveFileName</a>();
<a name="x711"></a> if ( !fn.<a href="qstring.html#isEmpty">isEmpty</a>() )
<a name="x706"></a> p.<a href="qpixmap.html#save">save</a>( fn, "BMP" );
if ( r )
<a href="qobject.html#startTimer">startTimer</a>( timer[r] );
}
}
void <a name="f266"></a>MagWidget::multiSave()
{
if ( !p.<a href="qpixmap.html#isNull">isNull</a>() ) {
multifn = ""; // stops saving
multifn = QFileDialog::<a href="qfiledialog.html#getSaveFileName">getSaveFileName</a>();
if ( multifn.<a href="qstring.html#isEmpty">isEmpty</a>() )
<a name="x708"></a> multiSaveButton-><a href="qpushbutton.html#setOn">setOn</a>(FALSE);
if ( !r )
p.<a href="qpixmap.html#save">save</a>( multifn, "BMP" );
} else {
multiSaveButton-><a href="qpushbutton.html#setOn">setOn</a>(FALSE);
}
}
void <a name="f267"></a>MagWidget::grab()
{
if ( !isVisible() )
return; // don't eat resources when iconified
if ( grabx < 0 || graby < 0 )
return; // don't grab until the user has said to
int x,y, w,h;
w = (<a href="qwidget.html#width">width</a>()+z-1)/z;
h = (<a href="qwidget.html#height">height</a>()+z-1-yoffset)/z;
if ( w<1 || h<1 )
return; // don't ask too much from the window system :)
x = grabx-w/2; // find a suitable position to grab from
y = graby-h/2;
if ( x + w > QApplication::<a href="qapplication.html#desktop">desktop</a>()->width() )
x = QApplication::<a href="qapplication.html#desktop">desktop</a>()->width()-w;
else if ( x < 0 )
x = 0;
if ( y + h > QApplication::<a href="qapplication.html#desktop">desktop</a>()->height() )
y = QApplication::<a href="qapplication.html#desktop">desktop</a>()->height()-h;
else if ( y < 0 )
y = 0;
<a name="x704"></a> p = QPixmap::<a href="qpixmap.html#grabWindow">grabWindow</a>( QApplication::<a href="qapplication.html#desktop">desktop</a>()->winId(), x, y, w, h );
<a name="x703"></a> image = p.<a href="qpixmap.html#convertToImage">convertToImage</a>();
<a href="qwmatrix.html">QWMatrix</a> m; // after getting it, scale it
<a name="x728"></a> m.<a href="qwmatrix.html#scale">scale</a>( (double)z, (double)z );
<a name="x707"></a> pm = p.<a href="qpixmap.html#xForm">xForm</a>( m );
<a name="x690"></a> if ( !multiSaveButton || !multiSaveButton-><a href="qbutton.html#isOn">isOn</a>() )
<a href="qwidget.html#repaint">repaint</a>( FALSE ); // and finally repaint, flicker-free
}
<a name="x722"></a>void MagWidget::<a href="qwidget.html#paintEvent">paintEvent</a>( <a href="qpaintevent.html">QPaintEvent</a> * )
{
if ( !pm.<a href="qpixmap.html#isNull">isNull</a>() ) {
<a href="qpainter.html">QPainter</a> paint( this );
paint.<a href="qpainter.html#drawPixmap">drawPixmap</a>( 0, zoom ? zoom-><a href="qwidget.html#height">height</a>()+4 : 0, pm,
0,0, width(), height()-yoffset );
}
}
<a name="x720"></a>void MagWidget::<a href="qwidget.html#mousePressEvent">mousePressEvent</a>( <a href="qmouseevent.html">QMouseEvent</a> *e )
{
if ( !grabbing ) { // prepare to grab...
grabbing = TRUE;
<a href="qobject.html#killTimers">killTimers</a>();
<a href="qwidget.html#grabMouse">grabMouse</a>( crossCursor );
grabx = -1;
graby = -1;
} else { // REALLY prepare to grab
<a name="x700"></a> grabx = <a href="qwidget.html#mapToGlobal">mapToGlobal</a>(e-><a href="qmouseevent.html#pos">pos</a>()).x();
graby = <a href="qwidget.html#mapToGlobal">mapToGlobal</a>(e-><a href="qmouseevent.html#pos">pos</a>()).y();
}
}
<a name="x721"></a>void MagWidget::<a href="qwidget.html#mouseReleaseEvent">mouseReleaseEvent</a>( <a href="qmouseevent.html">QMouseEvent</a> * e )
{
if ( grabbing && grabx >= 0 && graby >= 0 ) {
grabbing = FALSE;
grabAround(e-><a href="qmouseevent.html#pos">pos</a>());
<a href="qwidget.html#releaseMouse">releaseMouse</a>();
}
}
void <a name="f268"></a>MagWidget::grabAround(QPoint pos)
{
int rx, ry;
rx = <a href="qwidget.html#mapToGlobal">mapToGlobal</a>(pos).x();
ry = <a href="qwidget.html#mapToGlobal">mapToGlobal</a>(pos).y();
int w = QABS(rx-grabx);
int h = QABS(ry-graby);
if ( w > 10 && h > 10 ) {
int pz;
pz = 1;
while ( w*pz*h*pz < width()*(<a href="qwidget.html#height">height</a>()-yoffset) &&
w*pz < QApplication::<a href="qapplication.html#desktop">desktop</a>()->width() &&
h*pz < QApplication::<a href="qapplication.html#desktop">desktop</a>()->height() )
pz++;
if ( (w*pz*h*pz - width()*(<a href="qwidget.html#height">height</a>()-yoffset)) >
(<a href="qwidget.html#width">width</a>()*(<a href="qwidget.html#height">height</a>()-yoffset) - w*(pz-1)*h*(pz-1)) )
pz--;
if ( pz < 1 )
pz = 1;
if ( pz > 8 )
pz = 8;
if ( zoom )
<a name="x694"></a> zoom-><a href="qcombobox.html#setCurrentItem">setCurrentItem</a>( pz-1 );
z = pz;
grabx = QMIN(rx, grabx) + w/2;
graby = QMIN(ry, graby) + h/2;
<a href="qwidget.html#resize">resize</a>( w*z, h*z+yoffset );
}
grab();
if ( r )
<a href="qobject.html#startTimer">startTimer</a>( timer[r] );
}
<a name="x719"></a>void MagWidget::<a href="qwidget.html#mouseMoveEvent">mouseMoveEvent</a>( <a href="qmouseevent.html">QMouseEvent</a> *e )
{
if ( grabbing || pm.<a href="qpixmap.html#isNull">isNull</a>() ||
e-><a href="qmouseevent.html#pos">pos</a>().y() > height() - (zoom ? zoom-><a href="qwidget.html#fontMetrics">fontMetrics</a>().height() - 4 : 0) ||
e-><a href="qmouseevent.html#pos">pos</a>().y() < (zoom ? zoom-><a href="qwidget.html#height">height</a>()+4 : 4) ) {
rgb-><a href="qlabel.html#setText">setText</a>( "" );
} else {
int x,y;
x = e-><a href="qmouseevent.html#pos">pos</a>().x() / z;
y = (e-><a href="qmouseevent.html#pos">pos</a>().y() - ( zoom ? zoom-><a href="qwidget.html#height">height</a>() : 0 ) - 4) / z;
<a href="qstring.html">QString</a> pixelinfo;
<a name="x697"></a> if ( image.<a href="qimage.html#valid">valid</a>(x,y) )
{
<a name="x696"></a> QRgb px = image.<a href="qimage.html#pixel">pixel</a>(x,y);
<a name="x714"></a> pixelinfo.<a href="qstring.html#sprintf">sprintf</a>(" %3d,%3d,%3d #%02x%02x%02x",
<a href="qcolor.html#qRed">qRed</a>(px), qGreen(px), qBlue(px),
<a href="qcolor.html#qRed">qRed</a>(px), qGreen(px), qBlue(px));
}
<a href="qstring.html">QString</a> label;
label.<a href="qstring.html#sprintf">sprintf</a>( "x=%d, y=%d %s",
x+grabx, y+graby, (const char*)pixelinfo );
rgb-><a href="qlabel.html#setText">setText</a>( label );
}
}
<a name="x715"></a>void MagWidget::<a href="qwidget.html#focusOutEvent">focusOutEvent</a>( <a href="qfocusevent.html">QFocusEvent</a> * )
{
rgb-><a href="qlabel.html#setText">setText</a>( "" );
}
<a name="x701"></a>void MagWidget::<a href="qobject.html#timerEvent">timerEvent</a>( <a href="qtimerevent.html">QTimerEvent</a> * )
{
grab();
/*
if ( multiSaveButton-><a href="qbutton.html#isOn">isOn</a>() && !multifn.<a href="qstring.html#isEmpty">isEmpty</a>() ) {
<a href="qregexp.html">QRegExp</a> num("[0-9][0-9]*");
int start;
int len;
<a name="x710"></a> if ((start=num.<a href="qregexp.html#match">match</a>(multifn,0,&len))>=0)
<a name="x713"></a> multifn.<a href="qstring.html#replace">replace</a>(num,
<a name="x712"></a> QString().setNum(multifn.<a href="qstring.html#mid">mid</a>(start,len).toInt()+1)
);
p.<a href="qpixmap.html#save">save</a>( multifn, "BMP" );
}
*/
}
<a name="x725"></a>void MagWidget::<a href="qwidget.html#resizeEvent">resizeEvent</a>( <a href="qresizeevent.html">QResizeEvent</a> * )
{
rgb-><a href="qwidget.html#setGeometry">setGeometry</a>( 0, height() - rgb-><a href="qwidget.html#height">height</a>(), width(), rgb-><a href="qwidget.html#height">height</a>() );
grab();
}
#include "qmag.moc"
int main( int argc, char **argv )
{
<a href="qapplication.html">QApplication</a> a( argc, argv );
MagWidget m;
a.<a href="qapplication.html#setMainWidget">setMainWidget</a>( &m );
m.<a href="qwidget.html#show">show</a>();
return a.<a href="qapplication.html#exec">exec</a>();
}
</pre>
<p>See also <a href="examples.html">Examples</a>.
<!-- eof -->
<p><address><hr><div align=center>
<table width=100% cellspacing=0 border=0><tr>
<td>Copyright © 2001
<a href="http://www.trolltech.com">Trolltech</a><td><a href="http://www.trolltech.com/trademarks.html">Trademarks</a>
<td align=right><div align=right>Qt version 3.0.2</div>
</table></div></address></body>
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