Pete's Place

Let's assume that you have a text field to which you want to apply special effects. One of the most popular effects is to make the field behave like a hyperlink: blue in color, underlined, and, most importantly, having the mouse cursor change to the historical "hand".
Applying the color and underline are straightforward Forms development features, but the mouse cursor is another matter entirely. Ever since Forms became "webified", the ability to natively capture mouse-over events has disappeared because the traffic required for the server to track mouse movement is huge. However, PJCs run on the client, so we can employ them to implement mouse over effects. Oracle has provided a Hyperlink Bean in its demo package, but the drawback of the Hyperlink bean is that it takes too long to load, so having a decent number of them in a Form (say, 10 - 20) causes the Form load time to go through the roof.
However, if you write a class that extends the Forms text field, you can apply that class to select fields using the Implementation Class in the Properties Page, and the load time (so long as you don't do extravent things in the constructor) is the same as a regular text field.
Now, take that and apply it to ANY forms object. Write a class that extends the button object to implement "rollover" effects. Or how about extending text fields so that they scroll their text like a ticker tape? Or image objects that load new images every x seconds?

Anyway, here's one implementation I came up with. This text field extension underlines the text and does the following on mouseover: turns the cursor into a hand, makes the font bold, changes the font color to red, changes the background color to gray. You can easily add Property IDs to control the behavior. This concept and most of the code was taken from the Oracle demo ModCursor:


import java.awt.Graphics;
import java.awt.Color;
import java.awt.FontMetrics;
import java.awt.Font;
import oracle.forms.ui.VTextField;
import oracle.forms.properties.ID;
import oracle.forms.handler.IHandler;

public Hotlink()
{
super();
}

public void init(IHandler h)
{
super.init(h);

stdCursor = this.getCursor();

this.addMouseListener(new MouseAdapter()
{
public void mouseEntered(MouseEvent me)
{
if(getTextLength() > 0)
{
((VTextField)me.getSource()).setForeground(Color.red);
((VTextField)me.getSource()).setBackground(Color.lightGray);
setFont(stdFont.deriveFont(Font.BOLD));
setCursor(new Cursor(Cursor.HAND_CURSOR));
}
}
public void mouseExited(MouseEvent me)
{
if(getTextLength() > 0)
{
((VTextField)me.getSource()).setForeground(stdForeColor);
((VTextField)me.getSource()).setBackground(stdBackColor);
setFont(stdFont);
setCursor(stdCursor);
}
}
});
}

public void paint(Graphics g)
{
super.paint(g);
if (this.getTextLength() > 0)
{
FontMetrics metrics = getFontMetrics(getFont());
int strWidth = metrics.stringWidth(getText());
int yoffset = (int)(metrics.getHeight() * 0.95);
g.drawLine(0, yoffset, strWidth, yoffset);
}
}

public boolean setProperty(ID pid, Object value)
{
if(pid.getName().equals("FOREGROUND")) this.stdForeColor = (Color)value;
else if(pid.getName().equals("BACKGROUND")) this.stdBackColor = (Color)value;
else if(pid.getName().equals("FONT")) this.stdFont = (Font)value;
return super.setProperty(pid, value);
}
}