Extending the GUI - Beginning Java - page 1097

if(buttonState == MouseEvent.BUTTON1) {
g2D = (Graphics2D)getGraphics(); // Get graphics context
g2D.setXORMode(getBackground()); // Set XOR mode

}

}

Directory "Sketcher 7 with element context menus"

This just adds an if statement that calls the showContextMenu() method as the condition. This method
displays the appropriate menu depending on whether there is a highlighted element, and returns true
when it displays a menu and false otherwise. You can add a definition for this to the MouseHandler
class:

private boolean showContextMenu(MouseEvent e) {
if(e.isPopupTrigger()){
if(last != null) { // If mouse was dragged

start = last; // show popup at last

cursor position
}
if(highlightElement == null) { // If there is no

highlighted element
// Show the popup menu from the app window
theApp.getWindow().getPopup().show(SketcherView.this,
start.x, start.y);
} else { // Otherwise...
// Show the element operations context menu
elementPopup.show(SketcherView.this, start.x, start.y);

}
return true;

}
return false;

}

Directory "Sketcher 7 with element context menus"

The mouseReleased() method makes use of this method, too:

public void mouseReleased(MouseEvent e) {
if(showContextMenu(e)) {
start = last = null;
return;

}