/** * A class that lets the user draw with the mouse. The * window knows how to redraw itself. */ import org.kde.qt.*; public class ScribbleWindow extends QWidget { public static final int COLOR_MENU_ID_BLACK = 0; public static final int COLOR_MENU_ID_RED = 1; public static final int COLOR_MENU_ID_BLUE = 2; public static final int COLOR_MENU_ID_GREEN = 3; public static final int COLOR_MENU_ID_YELLOW = 4; private QMenuBar _menubar; private QPopupMenu _filemenu; private QPopupMenu _colormenu; private QPopupMenu _helpmenu; private QScrollView _scrollview; private ScribbleArea _scribblearea; public class ScribbleArea extends QWidget { private QPoint _last; private QColor _currentcolor; private QPixmap _buffer; private QPopupMenu _popupmenu; /** * The constructor. Initializes the member variables. */ ScribbleArea() { // initialize member variables _buffer = new QPixmap(); _last = new QPoint(); _currentcolor = black(); // don't blank the window before repainting setBackgroundMode( NoBackground ); // create a pop-up menu _popupmenu = new QPopupMenu(); _popupmenu.insertItem( "&Clear", this, SLOT( "slotClearArea()" ) ); } /** * This slot sets the curren color for the scribble area. It will be * connected with the colorChanged( QColor ) signal from the * ScribbleWindow. */ public void setColor( QColor new_color ) { _currentcolor = new_color; } /** * This slot clears the drawing area by filling the off-screen buffer with * white and copying it over to the window. */ public void slotClearArea() { // fill the off screen buffer with plain white _buffer.fill( white() ); // and copy it over to the window bitBlt( this, 0, 0, _buffer ); } /** * This method does the actual loading. It relies on QPixmap (and the * underlying I/O machinery) to determine the filetype. */ public void slotLoad( String filename ) { if ( !_buffer.load( filename ) ) QMessageBox.warning( null, "Load error", "Could not load file" ); repaint(); // refresh the window } /** * This method does the actual saving. We hard-code the file type as * BMP. Unix users might want to replace this with something like XPM. */ public void slotSave( String filename ) { if( !_buffer.save( filename, "BMP" ) ) QMessageBox.warning( null, "Save error", "Could not save file" ); } /** * This method is called whenever the user presses the * mouse over the window. It just records the position of the mouse * at the time of the click. */ protected void mousePressEvent(QMouseEvent event) { if ( event.button() == RightButton ) _popupmenu.exec( QCursor.pos() ); else { _last = event.pos(); // retrieve the coordinates from the event } } /** * The method is called whenever the usr moves the mouse * while the mouse button is pressed. If we had called * setMouseTracking(true) before, the method would also be called * when the mouse was moved with any button pressed. We know that * we haven't, and thus don't have to check whether any buttons are * pressed. */ protected void mouseMoveEvent(QMouseEvent event) { // create a QPainter object for drawing onto the window QPainter windowpainter = new QPainter(); // and another QPainter object for drawing int an off-screen pixmap QPainter bufferpainter = new QPainter(); // start painting windowpainter.begin( this ); // this painter paints onto the window bufferpainter.begin( _buffer ); // and this one paints in the buffer // set a standard pen with the currently selected color windowpainter.setPen( _currentcolor ); bufferpainter.setPen( _currentcolor ); // draw a line in both the window and the buffer windowpainter.drawLine( _last, event.pos() ); bufferpainter.drawLine( _last, event.pos() ); // done with painting windowpainter.end(); bufferpainter.end(); // remember the current mouse position _last = event.pos(); } /** * This method is called whenever the widget needs * painting, for example when it has been obscured and then revealed again. */ protected void paintEvent(QPaintEvent event) { bitBlt(this, 0, 0, _buffer); } /** * This method get called whenever the widget needs * painting, for example, when it has been obscured and then revealed again. */ protected void resizeEvent(QResizeEvent event) { QPixmap save = new QPixmap( _buffer ); _buffer.resize( event.size() ); _buffer.fill( white() ); bitBlt( _buffer, 0, 0, save ); } } ScribbleWindow() { /* The next lines build the menu bar. We first create the menus * one by one, then add them to the menu bar. */ _filemenu = new QPopupMenu(); // create a file menu _filemenu.insertItem( "&Load", this, SLOT( "slotLoad()" ) ); _filemenu.insertItem( "&Save", this, SLOT( "slotSave()" ) ); _filemenu.insertSeparator(); _filemenu.insertItem( "&Quit", qApp(), SLOT( "quit()" ) ); _colormenu = new QPopupMenu(); // create a color menu _colormenu.insertItem( "B&lack", COLOR_MENU_ID_BLACK); _colormenu.insertItem( "&Red", COLOR_MENU_ID_RED); _colormenu.insertItem( "&Blue", COLOR_MENU_ID_BLUE); _colormenu.insertItem( "&Green", COLOR_MENU_ID_GREEN); _colormenu.insertItem( "&Yellow", COLOR_MENU_ID_YELLOW); QObject.connect( _colormenu, SIGNAL( "activated( int )" ), this, SLOT( "slotColorMenu( int )" ) ); _helpmenu = new QPopupMenu(); // create a help menu _helpmenu.insertItem( "&About QtScribble", this, SLOT( "slotAbout()" ) ); _helpmenu.insertItem( "&About Qt", this, SLOT( "slotAboutQt()" ) ); _menubar = new QMenuBar( this, "" ); // create a menu bar _menubar.insertItem( "&File", _filemenu ); _menubar.insertItem( "&Color", _colormenu ); _menubar.insertItem( "&Help", _helpmenu ); /* We create a QScrollView and a ScribbleArea. The ScribbleArea will * be managed by the scroll view.*/ _scrollview = new QScrollView( this ); _scrollview.setGeometry( 0, _menubar.height(), width(), height() - _menubar.height() ); _scribblearea = new ScribbleArea(); _scribblearea.setGeometry( 0, 0, 1000, 1000 ); _scrollview.addChild( _scribblearea ); QObject.connect( this, SIGNAL( "colorChanged( QColor )" ), _scribblearea, SLOT( "setColor( QColor )" ) ); QObject.connect( this, SIGNAL( "save( String )" ), _scribblearea, SLOT( "slotSave( String )" ) ); QObject.connect( this, SIGNAL( "load(String)" ), _scribblearea, SLOT( "slotLoad( String )" ) ); } protected void resizeEvent( QResizeEvent event ) { /* When the whole window is resized, we have to rearrange the geometry * in the ScribbleWindow as well. Note that the ScribbleArea does not need * to be changed. */ _scrollview.setGeometry( 0, _menubar.height(), width(), height() - _menubar.height() ); } private void slotAbout() { QMessageBox.information( this, "About QtScribble 5", "This is the Scribble 5 application\n" + "Copyright 1998 by Mathias Kalle Dalheimer\n" ); } private void slotAboutQt() { QMessageBox.aboutQt( this, "About Qt" ); } private void slotColorMenu( int item ) { switch( item ) { case COLOR_MENU_ID_BLACK: emit("colorChanged", black()); break; case COLOR_MENU_ID_RED: emit("colorChanged", darkRed()); break; case COLOR_MENU_ID_BLUE: emit("colorChanged", darkBlue()); break; case COLOR_MENU_ID_GREEN: emit("colorChanged", darkGreen()); break; case COLOR_MENU_ID_YELLOW: emit("colorChanged", yellow()); break; } } /** * This is the slot for the menu item File/Load. It opens a * QFileDialog to ask the user for a filename, then emits a save() * signal with the filename as parameter. */ private void slotLoad() { /* Open a file dialog for loading. The default directory is the * current directory, the filter *.bmp. */ String filename = QFileDialog.getOpenFileName( ".", "*.bmp", this ); if ( !filename.equals("") ) emit("load", filename); } /** * This is the slot for the menu item File/Load. It opens a * QFileDialog to ask the user for a filename, then emits a save() * signal with the filename as parameter. */ private void slotSave() { /* Open a file dialog for saving. The default directory is the * current directory, the filter *.bmp. */ String filename = QFileDialog.getSaveFileName( ".", "*.bmp", this ); if ( !filename.equals("") ) emit("save", filename); } public static void main(String[] args) { QApplication myapp = new QApplication(args); ScribbleWindow mywidget = new ScribbleWindow(); mywidget.setGeometry(50, 500, 400, 400); myapp.setMainWidget(mywidget); mywidget.show(); myapp.exec(); return; } static { qtjava.initialize(); } }