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This example reads and displays an image in any supported image format (GIF, BMP, PPM, XMP, etc.).
Header file:
/****************************************************************************
** $Id: qt/showimg.h 3.1.2 edited Jan 22 15:20 $
**
** 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.
**
*****************************************************************************/
#ifndef SHOWIMG_H
#define SHOWIMG_H
#include <qwidget.h>
#include <qimage.h>
class QLabel;
class QMenuBar;
class QPopupMenu;
class ImageViewer : public QWidget
{
Q_OBJECT
public:
ImageViewer( QWidget *parent=0, const char *name=0, int wFlags=0 );
~ImageViewer();
bool loadImage( const QString& );
protected:
void paintEvent( QPaintEvent * );
void resizeEvent( QResizeEvent * );
void mousePressEvent( QMouseEvent * );
void mouseReleaseEvent( QMouseEvent * );
void mouseMoveEvent( QMouseEvent * );
private:
void scale();
int conversion_flags;
bool smooth() const;
bool useColorContext() const;
int alloc_context;
bool convertEvent( QMouseEvent* e, int& x, int& y );
QString filename;
QImage image; // the loaded image
QPixmap pm; // the converted pixmap
QPixmap pmScaled; // the scaled pixmap
QMenuBar *menubar;
QPopupMenu *file;
QPopupMenu *saveimage;
QPopupMenu *savepixmap;
QPopupMenu *edit;
QPopupMenu *options;
QWidget *helpmsg;
QLabel *status;
int si, sp, ac, co, mo, fd, bd, // Menu item ids
td, ta, ba, fa, au, ad, dd,
ss, cc, t1, t8, t32;
void updateStatus();
void setMenuItemFlags();
bool reconvertImage();
int pickx, picky;
int clickx, clicky;
bool may_be_other;
static ImageViewer* other;
void setImage(const QImage& newimage);
private slots:
void to1Bit();
void to8Bit();
void to32Bit();
void toBitDepth(int);
void copy();
void paste();
void hFlip();
void vFlip();
void rot180();
void editText();
void newWindow();
void openFile();
void saveImage(int);
void savePixmap(int);
void giveHelp();
void doOption(int);
void copyFrom(ImageViewer*);
};
#endif // SHOWIMG_H
Implementation:
/****************************************************************************
** $Id: qt/showimg.cpp 3.1.2 edited Jan 22 15:28 $
**
** 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 "showimg.h"
#include "imagetexteditor.h"
#include <qmenubar.h>
#include <qfiledialog.h>
#include <qmessagebox.h>
#include <qpopupmenu.h>
#include <qlabel.h>
#include <qpainter.h>
#include <qapplication.h>
#include <qclipboard.h>
/*
In the constructor, we just pass the standard parameters on to
QWidget.
The menu uses a single slot to simplify the process of adding
more items to the options menu.
*/
ImageViewer::ImageViewer( QWidget *parent, const char *name, int wFlags )
: QWidget( parent, name, wFlags ),
conversion_flags( PreferDither ),
filename( 0 ),
helpmsg( 0 )
{
pickx = -1;
picky = -1;
clickx = -1;
clicky = -1;
alloc_context = 0;
menubar = new QMenuBar(this);
menubar->setSeparator( QMenuBar::InWindowsStyle );
QStrList fmt = QImage::outputFormats();
saveimage = new QPopupMenu( menubar );
savepixmap = new QPopupMenu( menubar );
for (const char* f = fmt.first(); f; f = fmt.next()) {
saveimage->insertItem( f );
savepixmap->insertItem( f );
}
connect( saveimage, SIGNAL(activated(int)), this, SLOT(saveImage(int)) );
connect( savepixmap, SIGNAL(activated(int)), this, SLOT(savePixmap(int)) );
file = new QPopupMenu( menubar );
menubar->insertItem( "&File", file );
file->insertItem( "&New window", this, SLOT(newWindow()), CTRL+Key_N );
file->insertItem( "&Open...", this, SLOT(openFile()), CTRL+Key_O );
si = file->insertItem( "Save image", saveimage );
sp = file->insertItem( "Save pixmap", savepixmap );
file->insertSeparator();
file->insertItem( "E&xit", qApp, SLOT(quit()), CTRL+Key_Q );
edit = new QPopupMenu( menubar );
menubar->insertItem( "&Edit", edit );
edit->insertItem("&Copy", this, SLOT(copy()), CTRL+Key_C);
edit->insertItem("&Paste", this, SLOT(paste()), CTRL+Key_V);
edit->insertSeparator();
edit->insertItem("&Horizontal flip", this, SLOT(hFlip()), ALT+Key_H);
edit->insertItem("&Vertical flip", this, SLOT(vFlip()), ALT+Key_V);
edit->insertItem("&Rotate 180", this, SLOT(rot180()), ALT+Key_R);
edit->insertSeparator();
edit->insertItem("&Text...", this, SLOT(editText()));
edit->insertSeparator();
t1 = edit->insertItem( "Convert to &1 bit", this, SLOT(to1Bit()) );
t8 = edit->insertItem( "Convert to &8 bit", this, SLOT(to8Bit()) );
t32 = edit->insertItem( "Convert to &32 bit", this, SLOT(to32Bit()) );
options = new QPopupMenu( menubar );
menubar->insertItem( "&Options", options );
ac = options->insertItem( "AutoColor" );
co = options->insertItem( "ColorOnly" );
mo = options->insertItem( "MonoOnly" );
options->insertSeparator();
fd = options->insertItem( "DiffuseDither" );
bd = options->insertItem( "OrderedDither" );
td = options->insertItem( "ThresholdDither" );
options->insertSeparator();
ta = options->insertItem( "ThresholdAlphaDither" );
ba = options->insertItem( "OrderedAlphaDither" );
fa = options->insertItem( "DiffuseAlphaDither" );
options->insertSeparator();
ad = options->insertItem( "PreferDither" );
dd = options->insertItem( "AvoidDither" );
options->insertSeparator();
ss = options->insertItem( "Smooth scaling" );
cc = options->insertItem( "Use color context" );
if ( QApplication::colorSpec() == QApplication::ManyColor )
options->setItemEnabled( cc, FALSE );
options->setCheckable( TRUE );
setMenuItemFlags();
menubar->insertSeparator();
QPopupMenu* help = new QPopupMenu( menubar );
menubar->insertItem( "&Help", help );
help->insertItem( "Help!", this, SLOT(giveHelp()), CTRL+Key_H );
connect( options, SIGNAL(activated(int)), this, SLOT(doOption(int)) );
status = new QLabel(this);
status->setFrameStyle( QFrame::WinPanel | QFrame::Sunken );
status->setFixedHeight( fontMetrics().height() + 4 );
setMouseTracking( TRUE );
}
ImageViewer::~ImageViewer()
{
if ( alloc_context )
QColor::destroyAllocContext( alloc_context );
if ( other == this )
other = 0;
}
/*
This function modifies the conversion_flags when an options menu item
is selected, then ensures all menu items are up to date, and reconverts
the image if possibly necessary.
*/
void ImageViewer::doOption(int item)
{
if ( item == ss || item == cc ) {
// Toggle
bool newbool = !options->isItemChecked(item);
options->setItemChecked(item, newbool);
// And reconvert...
reconvertImage();
repaint(image.hasAlphaBuffer()); // show image in widget
return;
}
if ( options->isItemChecked( item ) ) return; // They are all radio buttons
int ocf = conversion_flags;
if ( item == ac ) {
conversion_flags = ( conversion_flags & ~ColorMode_Mask ) | AutoColor;
} else if ( item == co ) {
conversion_flags = ( conversion_flags & ~ColorMode_Mask ) | ColorOnly;
} else if ( item == mo ) {
conversion_flags = ( conversion_flags & ~ColorMode_Mask ) | MonoOnly;
} else if ( item == fd ) {
conversion_flags = ( conversion_flags & ~Dither_Mask ) | DiffuseDither;
} else if ( item == bd ) {
conversion_flags = ( conversion_flags & ~Dither_Mask ) | OrderedDither;
} else if ( item == td ) {
conversion_flags = ( conversion_flags & ~Dither_Mask ) | ThresholdDither;
} else if ( item == ta ) {
conversion_flags = ( conversion_flags & ~AlphaDither_Mask ) | ThresholdAlphaDither;
} else if ( item == fa ) {
conversion_flags = ( conversion_flags & ~AlphaDither_Mask ) | DiffuseAlphaDither;
} else if ( item == ba ) {
conversion_flags = ( conversion_flags & ~AlphaDither_Mask ) | OrderedAlphaDither;
} else if ( item == ad ) {
conversion_flags = ( conversion_flags & ~DitherMode_Mask ) | PreferDither;
} else if ( item == dd ) {
conversion_flags = ( conversion_flags & ~DitherMode_Mask ) | AvoidDither;
}
if ( ocf != conversion_flags ) {
setMenuItemFlags();
// And reconvert...
reconvertImage();
repaint(image.hasAlphaBuffer()); // show image in widget
}
}
/*
Set the options menu to reflect the conversion_flags value.
*/
void ImageViewer::setMenuItemFlags()
{
// File
bool valid_image = pm.size() != QSize( 0, 0 );
file->setItemEnabled( si, valid_image );
file->setItemEnabled( sp, valid_image );
// Edit
edit->setItemEnabled( t1, image.depth() != 1 );
edit->setItemEnabled( t8, image.depth() != 8 );
edit->setItemEnabled( t32, image.depth() != 32 );
// Options
bool may_need_color_dithering =
!valid_image
|| image.depth() == 32 && QPixmap::defaultDepth() < 24;
bool may_need_dithering = may_need_color_dithering
|| image.depth() > 1 && options->isItemChecked(mo)
|| image.depth() > 1 && QPixmap::defaultDepth() == 1;
bool has_alpha_mask = !valid_image || image.hasAlphaBuffer();
options->setItemEnabled( fd, may_need_dithering );
options->setItemEnabled( bd, may_need_dithering );
options->setItemEnabled( td, may_need_dithering );
options->setItemEnabled( ta, has_alpha_mask );
options->setItemEnabled( fa, has_alpha_mask );
options->setItemEnabled( ba, has_alpha_mask );
options->setItemEnabled( ad, may_need_color_dithering );
options->setItemEnabled( dd, may_need_color_dithering );
options->setItemChecked( ac, (conversion_flags & ColorMode_Mask) == AutoColor );
options->setItemChecked( co, (conversion_flags & ColorMode_Mask) == ColorOnly );
options->setItemChecked( mo, (conversion_flags & ColorMode_Mask) == MonoOnly );
options->setItemChecked( fd, (conversion_flags & Dither_Mask) == DiffuseDither );
options->setItemChecked( bd, (conversion_flags & Dither_Mask) == OrderedDither );
options->setItemChecked( td, (conversion_flags & Dither_Mask) == ThresholdDither );
options->setItemChecked( ta, (conversion_flags & AlphaDither_Mask) == ThresholdAlphaDither );
options->setItemChecked( fa, (conversion_flags & AlphaDither_Mask) == DiffuseAlphaDither );
options->setItemChecked( ba, (conversion_flags & AlphaDither_Mask) == OrderedAlphaDither );
options->setItemChecked( ad, (conversion_flags & DitherMode_Mask) == PreferDither );
options->setItemChecked( dd, (conversion_flags & DitherMode_Mask) == AvoidDither );
}
void ImageViewer::updateStatus()
{
if ( pm.size() == QSize( 0, 0 ) ) {
if ( !filename.isEmpty() )
status->setText("Could not load image");
else
status->setText("No image - select Open from File menu.");
} else {
QString message, moremsg;
message.sprintf("%dx%d", image.width(), image.height());
if ( pm.size() != pmScaled.size() ) {
moremsg.sprintf(" [%dx%d]", pmScaled.width(),
pmScaled.height());
message += moremsg;
}
moremsg.sprintf(", %d bits ", image.depth());
message += moremsg;
if (image.valid(pickx,picky)) {
moremsg.sprintf("(%d,%d)=#%0*x ",
pickx, picky,
image.hasAlphaBuffer() ? 8 : 6,
image.pixel(pickx,picky));
message += moremsg;
}
if ( image.numColors() > 0 ) {
if (image.valid(pickx,picky)) {
moremsg.sprintf(", %d/%d colors", image.pixelIndex(pickx,picky),
image.numColors());
} else {
moremsg.sprintf(", %d colors", image.numColors());
}
message += moremsg;
}
if ( image.hasAlphaBuffer() ) {
if ( image.depth() == 8 ) {
int i;
bool alpha[256];
int nalpha=0;
for (i=0; i<256; i++)
alpha[i] = FALSE;
for (i=0; i<image.numColors(); i++) {
int alevel = image.color(i) >> 24;
if (!alpha[alevel]) {
alpha[alevel] = TRUE;
nalpha++;
}
}
moremsg.sprintf(", %d alpha levels", nalpha);
} else {
// Too many pixels to bother counting.
moremsg = ", 8-bit alpha channel";
}
message += moremsg;
}
status->setText(message);
}
}
/*
This function saves the image.
*/
void ImageViewer::saveImage( int item )
{
const char* fmt = saveimage->text(item);
QString savefilename = QFileDialog::getSaveFileName(QString::null, QString::null,
this, filename);
if ( !savefilename.isEmpty() )
if ( !image.save( savefilename, fmt ) )
QMessageBox::warning( this, "Save failed", "Error saving file" );
}
/*
This function saves the converted image.
*/
void ImageViewer::savePixmap( int item )
{
const char* fmt = savepixmap->text(item);
QString savefilename = QFileDialog::getSaveFileName(QString::null,
QString::null, this, filename);
if ( !savefilename.isEmpty() )
if ( !pmScaled.save( savefilename, fmt ) )
QMessageBox::warning( this, "Save failed", "Error saving file" );
}
void ImageViewer::newWindow()
{
ImageViewer* that = new ImageViewer(0, "new window", WDestructiveClose);
that->options->setItemChecked( that->cc, useColorContext() );
that->show();
}
/*
This function is the slot for processing the Open menu item.
*/
void ImageViewer::openFile()
{
QString newfilename = QFileDialog::getOpenFileName( QString::null,
QString::null,
this );
if ( !newfilename.isEmpty() ) {
loadImage( newfilename ) ;
repaint(); // show image in widget
}
}
/*
This function loads an image from a file and resizes the widget to
exactly fit the image size. If the file was not found or the image
format was unknown it will resize the widget to fit the errorText
message (see above) displayed in the current font.
Returns TRUE if the image was successfully loaded.
*/
bool ImageViewer::loadImage( const QString& fileName )
{
filename = fileName;
bool ok = FALSE;
if ( !filename.isEmpty() ) {
QApplication::setOverrideCursor( waitCursor ); // this might take time
ok = image.load(filename, 0);
pickx = -1;
clickx = -1;
if ( ok )
ok = reconvertImage();
if ( ok ) {
setCaption( filename ); // set window caption
int w = pm.width();
int h = pm.height();
const int reasonable_width = 128;
if ( w < reasonable_width ) {
// Integer scale up to something reasonable
int multiply = ( reasonable_width + w - 1 ) / w;
w *= multiply;
h *= multiply;
}
h += menubar->heightForWidth(w) + status->height();
resize( w, h ); // we resize to fit image
} else {
pm.resize(0,0); // couldn't load image
update();
}
QApplication::restoreOverrideCursor(); // restore original cursor
}
updateStatus();
setMenuItemFlags();
return ok;
}
bool ImageViewer::reconvertImage()
{
bool success = FALSE;
if ( image.isNull() ) return FALSE;
if ( alloc_context ) {
QColor::destroyAllocContext( alloc_context );
alloc_context = 0;
}
if ( useColorContext() ) {
alloc_context = QColor::enterAllocContext();
// Clear the image to hide flickering palette
QPainter painter(this);
painter.eraseRect(0, menubar->heightForWidth( width() ), width(), height());
}
QApplication::setOverrideCursor( waitCursor ); // this might take time
if ( pm.convertFromImage(image, conversion_flags) )
{
pmScaled = QPixmap();
scale();
resize( width(), height() );
success = TRUE; // load successful
} else {
pm.resize(0,0); // couldn't load image
}
updateStatus();
setMenuItemFlags();
QApplication::restoreOverrideCursor(); // restore original cursor
if ( useColorContext() )
QColor::leaveAllocContext();
return success; // TRUE if loaded OK
}
bool ImageViewer::smooth() const
{
return options->isItemChecked(ss);
}
bool ImageViewer::useColorContext() const
{
return options->isItemChecked(cc);
}
/*
This functions scales the pixmap in the member variable "pm" to fit the
widget size and puts the resulting pixmap in the member variable "pmScaled".
*/
void ImageViewer::scale()
{
int h = height() - menubar->heightForWidth( width() ) - status->height();
if ( image.isNull() ) return;
QApplication::setOverrideCursor( waitCursor ); // this might take time
if ( width() == pm.width() && h == pm.height() )
{ // no need to scale if widget
pmScaled = pm; // size equals pixmap size
} else {
if (smooth()) {
pmScaled.convertFromImage(image.smoothScale(width(), h),
conversion_flags);
} else {
QWMatrix m; // transformation matrix
m.scale(((double)width())/pm.width(),// define scale factors
((double)h)/pm.height());
pmScaled = pm.xForm( m ); // create scaled pixmap
}
}
QApplication::restoreOverrideCursor(); // restore original cursor
}
/*
The resize event handler, if a valid pixmap was loaded it will call
scale() to fit the pixmap to the new widget size.
*/
void ImageViewer::resizeEvent( QResizeEvent * )
{
status->setGeometry(0, height() - status->height(),
width(), status->height());
if ( pm.size() == QSize( 0, 0 ) ) // we couldn't load the image
return;
int h = height() - menubar->heightForWidth( width() ) - status->height();
if ( width() != pmScaled.width() || h != pmScaled.height())
{ // if new size,
scale(); // scale pmScaled to window
updateStatus();
}
if ( image.hasAlphaBuffer() )
erase();
}
bool ImageViewer::convertEvent( QMouseEvent* e, int& x, int& y)
{
if ( pm.size() != QSize( 0, 0 ) ) {
int h = height() - menubar->heightForWidth( width() ) - status->height();
int nx = e->x() * image.width() / width();
int ny = (e->y()-menubar->heightForWidth( width() )) * image.height() / h;
if (nx != x || ny != y ) {
x = nx;
y = ny;
updateStatus();
return TRUE;
}
}
return FALSE;
}
void ImageViewer::mousePressEvent( QMouseEvent *e )
{
may_be_other = convertEvent(e, clickx, clicky);
}
void ImageViewer::mouseReleaseEvent( QMouseEvent * )
{
if ( may_be_other )
other = this;
}
/*
Record the pixel position of interest.
*/
void ImageViewer::mouseMoveEvent( QMouseEvent *e )
{
if (convertEvent(e,pickx,picky)) {
updateStatus();
if ((e->state()&LeftButton)) {
may_be_other = FALSE;
if ( clickx >= 0 && other) {
copyFrom(other);
}
}
}
}
/*
Draws the portion of the scaled pixmap that needs to be updated or prints
an error message if no legal pixmap has been loaded.
*/
void ImageViewer::paintEvent( QPaintEvent *e )
{
if ( pm.size() != QSize( 0, 0 ) ) { // is an image loaded?
QPainter painter(this);
painter.setClipRect(e->rect());
painter.drawPixmap(0, menubar->heightForWidth( width() ), pmScaled);
}
}
/*
Explain anything that might be confusing.
*/
void ImageViewer::giveHelp()
{
if (!helpmsg) {
QString helptext =
"<b>Usage:</b> <tt>showimg [-m] <i>filename ...</i></tt>"
"<blockquote>"
"<tt>-m</tt> - use <i>ManyColor</i> color spec"
"</blockquote>"
"<p>Supported input formats:"
"<blockquote>";
helptext += QImage::inputFormatList().join(", ");
helptext += "</blockquote>";
helpmsg = new QMessageBox( "Help", helptext,
QMessageBox::Information, QMessageBox::Ok, 0, 0, 0, 0, FALSE );
}
helpmsg->show();
helpmsg->raise();
}
void ImageViewer::copyFrom(ImageViewer* s)
{
if ( clickx >= 0 ) {
int dx = clickx;
int dy = clicky;
int sx = s->clickx;
int sy = s->clicky;
int sw = QABS(clickx - pickx)+1;
int sh = QABS(clicky - picky)+1;
if ( clickx > pickx ) {
dx = pickx;
sx -= sw-1;
}
if ( clicky > picky ) {
dy = picky;
sy -= sh-1;
}
bitBlt( &image, dx, dy, &s->image, sx, sy, sw, sh );
reconvertImage();
repaint( image.hasAlphaBuffer() );
}
}
ImageViewer* ImageViewer::other = 0;
void ImageViewer::hFlip()
{
setImage(image.mirror(TRUE,FALSE));
}
void ImageViewer::vFlip()
{
setImage(image.mirror(FALSE,TRUE));
}
void ImageViewer::rot180()
{
setImage(image.mirror(TRUE,TRUE));
}
void ImageViewer::copy()
{
#ifndef QT_NO_MIMECLIPBOARD
QApplication::clipboard()->setImage(image); // Less information loss
#endif
}
void ImageViewer::paste()
{
#ifndef QT_NO_MIMECLIPBOARD
QImage p = QApplication::clipboard()->image();
if ( !p.isNull() ) {
filename = "pasted";
setImage(p);
}
#endif
}
void ImageViewer::setImage(const QImage& newimage)
{
image = newimage;
pickx = -1;
clickx = -1;
setCaption( filename ); // set window caption
int w = image.width();
int h = image.height();
if ( !w )
return;
const int reasonable_width = 128;
if ( w < reasonable_width ) {
// Integer scale up to something reasonable
int multiply = ( reasonable_width + w - 1 ) / w;
w *= multiply;
h *= multiply;
}
h += menubar->heightForWidth(w) + status->height();
resize( w, h ); // we resize to fit image
reconvertImage();
repaint( image.hasAlphaBuffer() );
updateStatus();
setMenuItemFlags();
}
void ImageViewer::editText()
{
ImageTextEditor editor(image,this);
editor.exec();
}
void ImageViewer::to1Bit()
{
toBitDepth(1);
}
void ImageViewer::to8Bit()
{
toBitDepth(8);
}
void ImageViewer::to32Bit()
{
toBitDepth(32);
}
void ImageViewer::toBitDepth(int d)
{
image = image.convertDepth(d);
reconvertImage();
repaint( image.hasAlphaBuffer() );
}
Main:
/****************************************************************************
** $Id: qt/main.cpp 3.1.2 edited Nov 8 10:35 $
**
** 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 "showimg.h"
#include "imagefip.h"
#include <qapplication.h>
#include <qimage.h>
int main( int argc, char **argv )
{
if ( argc > 1 && QString(argv[1]) == "-m" ) {
QApplication::setColorSpec( QApplication::ManyColor );
argc--;
argv++;
}
else if ( argc > 1 && QString(argv[1]) == "-n" ) {
QApplication::setColorSpec( QApplication::NormalColor );
argc--;
argv++;
}
else {
QApplication::setColorSpec( QApplication::CustomColor );
}
QApplication::setFont( QFont("Helvetica", 12) );
QApplication a( argc, argv );
ImageIconProvider iip;
QFileDialog::setIconProvider( &iip );
if ( argc <= 1 ) {
// Create a window which looks after its own existence.
ImageViewer *w =
new ImageViewer(0, "new window", Qt::WDestructiveClose | Qt::WResizeNoErase );
w->setCaption("Qt Example - Image Viewer");
w->show();
} else {
for ( int i=1; i<argc; i++ ) {
// Create a window which looks after its own existence.
ImageViewer *w =
new ImageViewer(0, argv[i], Qt::WDestructiveClose | Qt::WResizeNoErase );
w->setCaption("Qt Example - Image Viewer");
w->loadImage( argv[i] );
w->show();
}
}
QObject::connect(qApp, SIGNAL(lastWindowClosed()), qApp, SLOT(quit()));
return a.exec();
}
See also Examples.
| Copyright © 2003 Trolltech | Trademarks | Qt version 3.1.2
|