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/**
* 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();
}
}
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