Extending the GUI - Beginning Java 2 SDK - page 866

else {
g2D.draw(tempElement.getShape()); // Yes - draw to erase it
tempElement.modify(start, last); // Now modify it
}
g2D.draw(tempElement.getShape()); // and draw it
}
}
We have also updated the statements that draw an element to call the new method in the element
classes. The change to the mouseReleased() method is exactly the same as for mousePressed() so
let's go ahead and modify the if condition. The only other change we need to make is to make the
status bar respond to the TEXT element type being set. To do this we just need to make a small addition
to the definition of the setTypePane() method in the StatusBar class:
public void setTypePane(int elementType) {
String text; // Text for the type pane
switch(elementType) {
// case label as before...
case TEXT:
text = "TEXT";
break;
default:
assert false;
}
typePane.setText(text); // Set the pane text
}
How It Works
The mouseClicked() handler responds to mouse button 1 being clicked when the element type is
TEXT . This method will be called after the mouseReleased() method. Within the if statement that
determines this, we create a dialog to receive the text input by calling the static showInputDialog()
in the JOptionPane class. If you selected the Cancel button in the dialog, text will be null so in this
case we do nothing. If text is not null , we create an Element.Text object at the current cursor
position containing the text string that was entered in the dialog. We then add this to the model, as long
as it's not null . It is important to remember to reset the start and tempElement members back to
null , so as not to confuse subsequent event handling operations.
Incidentally, although there isn't a method to detect double-clicks on the mouse button, it's easy to
implement. The getClickCount() method for the MouseEvent object that is passed to
mouseClicked() returns the click count. To respond to a double-click you would write:
if(e.getClickCount() == 2) {
//Response to double-click...
}
The other event handling methods behave as before so far as the geometric elements are concerned,
and do nothing if the element type is TEXT . We can try it out.