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Show Image
This example reads and displays an image in any supported image format (GIF, BMP, PPM, XMP, etc.).
Header file:
/**************************************************************************** ** $Id: qt/showimg.h 3.0.5 edited Oct 12 2001 $ ** ** 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 char *fileName ); 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 ); const char* 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 3.0.5 edited Oct 12 2001 $ ** ** 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 ) 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(); 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 char *fileName ) { filename = fileName; bool ok = FALSE; if ( filename ) { 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 3.0.5 edited Oct 12 2001 $ ** ** 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 © 2002 Trolltech | Trademarks | Qt version 3.0.5
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