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This is a simple magnifier-type program. It shows how one can do some quite low-level operations in a portable way using Qt.
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.
Implementation:
/****************************************************************************
** $Id: qt/qmag.cpp 3.3.8 edited Jan 11 14:37 $
**
** Copyright (C) 1992-2007 Trolltech ASA. 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 <qcombobox.h>
#include <qpushbutton.h>
#include <qpixmap.h>
#include <qimage.h>
#include <qlabel.h>
#include <qfiledialog.h>
#include <qregexp.h>
#include <qapplication.h>
#include <qpainter.h>
#include <qwmatrix.h>
class MagWidget : public QWidget
{
Q_OBJECT
public:
MagWidget( QWidget *parent=0, const char *name=0 );
public slots:
void setZoom( int );
void setRefresh( int );
void save();
void multiSave();
protected:
void paintEvent( QPaintEvent * );
void mousePressEvent( QMouseEvent * );
void mouseReleaseEvent( QMouseEvent * );
void mouseMoveEvent( QMouseEvent * );
void focusOutEvent( QFocusEvent * );
void timerEvent( QTimerEvent * );
void resizeEvent( QResizeEvent * );
private:
void grabAround(QPoint pos);
void grab();
QComboBox *zoom;
QComboBox *refresh;
QPushButton *saveButton;
QPushButton *multiSaveButton;
QPushButton *quitButton;
QPixmap pm; // pixmap, magnified
QPixmap p; // pixmap
QImage image; // image of pixmap (for RGB)
QLabel *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;
QString 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 };
MagWidget::MagWidget( QWidget *parent, const char *name )
: QWidget( parent, name)
{
z = 1; // default zoom (100%)
r = 0; // default refresh (none)
#ifdef COMPLEX_GUI
int w=0, x=0, n;
zoom = new QComboBox( FALSE, this );
Q_CHECK_PTR(zoom);
zoom->insertStrList( zoomfactors, 9 );
connect( zoom, SIGNAL(activated(int)), SLOT(setZoom(int)) );
refresh = new QComboBox( FALSE, this );
Q_CHECK_PTR(refresh);
refresh->insertStrList( refreshrates, 9 );
connect( refresh, SIGNAL(activated(int)), SLOT(setRefresh(int)) );
for( n=0; n<9; n++) {
int w2 = zoom->fontMetrics().width( zoomfactors[n] );
w = QMAX(w2, w);
}
zoom->setGeometry( 2, 2, w+30, 20 );
x = w+34;
w = 0;
for( n=0; n<9; n++) {
int w2 = refresh->fontMetrics().width( refreshrates[n] );
w = QMAX(w2, w);
}
refresh->setGeometry( x, 2, w+30, 20 );
saveButton = new QPushButton( this );
Q_CHECK_PTR(saveButton);
connect( saveButton, SIGNAL(clicked()), this, SLOT(save()) );
saveButton->setText( "Save" );
saveButton->setGeometry( x+w+30+2, 2,
10+saveButton->fontMetrics().width("Save"), 20 );
multiSaveButton = new QPushButton( this );
multiSaveButton->setToggleButton(TRUE);
Q_CHECK_PTR(multiSaveButton);
connect( multiSaveButton, SIGNAL(clicked()), this, SLOT(multiSave()) );
multiSaveButton->setText( "MultiSave" );
multiSaveButton->setGeometry( saveButton->geometry().right() + 2, 2,
10+multiSaveButton->fontMetrics().width("MultiSave"), 20 );
quitButton = new QPushButton( this );
Q_CHECK_PTR(quitButton);
connect( quitButton, SIGNAL(clicked()), qApp, SLOT(quit()) );
quitButton->setText( "Quit" );
quitButton->setGeometry( multiSaveButton->geometry().right() + 2, 2,
10+quitButton->fontMetrics().width("Quit"), 20 );
#else
zoom = 0;
multiSaveButton = 0;
#endif
setRefresh(1);
setZoom(5);
rgb = new QLabel( this );
Q_CHECK_PTR( rgb );
rgb->setText( "" );
rgb->setAlignment( AlignVCenter );
rgb->resize( width(), rgb->fontMetrics().height() + 4 );
#ifdef COMPLEX_GUI
yoffset = zoom->height() // top buttons
+ 4 // space around top buttons
+ rgb->height(); // color-value text height
setMinimumSize( quitButton->pos().x(), yoffset+20 );
resize( quitButton->geometry().topRight().x() + 2, yoffset+60 );
#else
yoffset = 0;
resize(350,350);
#endif
grabx = graby = -1;
grabbing = FALSE;
setMouseTracking( TRUE ); // and do let me know what pixel I'm at, eh?
grabAround( QPoint(grabx=qApp->desktop()->width()/2, graby=qApp->desktop()->height()/2) );
}
void MagWidget::setZoom( int index )
{
if (index == 8)
z = 16;
else
z = index+1;
grab();
}
void MagWidget::setRefresh( int index )
{
r = index;
killTimers();
if (index && !grabbing)
startTimer( timer[r] );
}
void MagWidget::save()
{
if ( !p.isNull() ) {
killTimers();
QString fn = QFileDialog::getSaveFileName();
if ( !fn.isEmpty() )
p.save( fn, "BMP" );
if ( r )
startTimer( timer[r] );
}
}
void MagWidget::multiSave()
{
if ( !p.isNull() ) {
multifn = ""; // stops saving
multifn = QFileDialog::getSaveFileName();
if ( multifn.isEmpty() )
multiSaveButton->setOn(FALSE);
if ( !r )
p.save( multifn, "BMP" );
} else {
multiSaveButton->setOn(FALSE);
}
}
void 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 = (width()+z-1)/z;
h = (height()+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::desktop()->width() )
x = QApplication::desktop()->width()-w;
else if ( x < 0 )
x = 0;
if ( y + h > QApplication::desktop()->height() )
y = QApplication::desktop()->height()-h;
else if ( y < 0 )
y = 0;
p = QPixmap::grabWindow( QApplication::desktop()->winId(), x, y, w, h );
image = p.convertToImage();
QWMatrix m; // after getting it, scale it
m.scale( (double)z, (double)z );
pm = p.xForm( m );
if ( !multiSaveButton || !multiSaveButton->isOn() )
repaint( FALSE ); // and finally repaint, flicker-free
}
void MagWidget::paintEvent( QPaintEvent * )
{
if ( !pm.isNull() ) {
QPainter paint( this );
paint.drawPixmap( 0, zoom ? zoom->height()+4 : 0, pm,
0,0, width(), height()-yoffset );
}
}
void MagWidget::mousePressEvent( QMouseEvent *e )
{
if ( !grabbing ) { // prepare to grab...
grabbing = TRUE;
killTimers();
grabMouse( crossCursor );
grabx = -1;
graby = -1;
} else { // REALLY prepare to grab
grabx = mapToGlobal(e->pos()).x();
graby = mapToGlobal(e->pos()).y();
}
}
void MagWidget::mouseReleaseEvent( QMouseEvent * e )
{
if ( grabbing && grabx >= 0 && graby >= 0 ) {
grabbing = FALSE;
grabAround(e->pos());
releaseMouse();
}
}
void MagWidget::grabAround(QPoint pos)
{
int rx, ry;
rx = mapToGlobal(pos).x();
ry = mapToGlobal(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()*(height()-yoffset) &&
w*pz < QApplication::desktop()->width() &&
h*pz < QApplication::desktop()->height() )
pz++;
if ( (w*pz*h*pz - width()*(height()-yoffset)) >
(width()*(height()-yoffset) - w*(pz-1)*h*(pz-1)) )
pz--;
if ( pz < 1 )
pz = 1;
if ( pz > 8 )
pz = 8;
if ( zoom )
zoom->setCurrentItem( pz-1 );
z = pz;
grabx = QMIN(rx, grabx) + w/2;
graby = QMIN(ry, graby) + h/2;
resize( w*z, h*z+yoffset );
}
grab();
if ( r )
startTimer( timer[r] );
}
void MagWidget::mouseMoveEvent( QMouseEvent *e )
{
if ( grabbing || pm.isNull() ||
e->pos().y() > height() - (zoom ? zoom->fontMetrics().height() - 4 : 0) ||
e->pos().y() < (zoom ? zoom->height()+4 : 4) ) {
rgb->setText( "" );
} else {
int x,y;
x = e->pos().x() / z;
y = (e->pos().y() - ( zoom ? zoom->height() : 0 ) - 4) / z;
QString pixelinfo;
if ( image.valid(x,y) )
{
QRgb px = image.pixel(x,y);
pixelinfo.sprintf(" %3d,%3d,%3d #%02x%02x%02x",
qRed(px), qGreen(px), qBlue(px),
qRed(px), qGreen(px), qBlue(px));
}
QString label;
label.sprintf( "x=%d, y=%d %s",
x+grabx, y+graby, (const char*)pixelinfo );
rgb->setText( label );
}
}
void MagWidget::focusOutEvent( QFocusEvent * )
{
rgb->setText( "" );
}
void MagWidget::timerEvent( QTimerEvent * )
{
grab();
/*
if ( multiSaveButton->isOn() && !multifn.isEmpty() ) {
QRegExp num("[0-9][0-9]*");
int start;
int len;
if ((start=num.match(multifn,0,&len))>=0)
multifn.replace(num,
QString().setNum(multifn.mid(start,len).toInt()+1)
);
p.save( multifn, "BMP" );
}
*/
}
void MagWidget::resizeEvent( QResizeEvent * )
{
rgb->setGeometry( 0, height() - rgb->height(), width(), rgb->height() );
grab();
}
#include "qmag.moc"
int main( int argc, char **argv )
{
QApplication a( argc, argv );
MagWidget m;
a.setMainWidget( &m );
m.show();
return a.exec();
}
See also Examples.
| Copyright © 2007 Trolltech | Trademarks | Qt 3.3.8
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