Trapping events on two fields individually in blackberry - blackberry

Question

I want to trap events on two custom Fields which I had created by extending the Field class.
The events should only be touch events.
One field uses graphics.drawRect(10,10,20,20) and other field uses graphics.drawRect(50,50,20,20).
(I will not use hardcoded values, but am writing them here just for an example).
I should be able to trap the events individually; that means different events on different fields.
My code looks like:
Main screen Class:
package mypackage;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.FieldChangeListener;
import net.rim.device.api.ui.container.MainScreen;
public final class MyScreen extends MainScreen
{
CustomFieldManager cfm;
public MyScreen()
{
cfm=new CustomFieldManager();
CustomButtonField cb=new CustomButtonField(Field.FOCUSABLE,20,20,40,40);
CustomButtonField cb1=new CustomButtonField(Field.FOCUSABLE,70,70,40,40);
new CustomButtonField(cb,cb1);
cfm.add(cb);
cfm.add(cb1);
add(cfm);
}
}
Field class:
package mypackage;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.FieldChangeListener;
import net.rim.device.api.ui.Graphics;
import net.rim.device.api.ui.component.Dialog;
public class CustomButtonField extends Field {
int a,b,c,d;
CustomButtonField c1,c2;
public CustomButtonField(long style,int a,int b,int c,int d){
super(style);
this.a=a;
this.b=b;
this.c=c;
this.d=d;
}
public CustomButtonField(Object o1,Object o2){
c1=(CustomButtonField)o1;
c2=(CustomButtonField)o2;
}
public void movefirst(){
Dialog.alert("god");
}
protected void drawFocus(Graphics graphics, boolean on) {
}
protected void layout(int width, int height) {
setExtent(200, 200);
}
protected void paint(Graphics graphics) {
graphics.drawRect(a, b, c, d);
}
protected boolean navigationClick(int status, int time) {
fieldChangeNotify(0);
return true;
}
}
and manager class :
package mypackage;
import net.rim.device.api.system.Bitmap;
import net.rim.device.api.ui.Field;
import net.rim.device.api.ui.FieldChangeListener;
import net.rim.device.api.ui.Manager;
import net.rim.device.api.ui.component.Dialog;
public class CustomFieldManager extends Manager {
CustomButtonField first, second;
public CustomFieldManager() {
super(Manager.NO_HORIZONTAL_SCROLL | Manager.NO_VERTICAL_SCROLL);
}
protected void sublayout(int arg0, int arg1) {
int numberOfFields = getFieldCount();
for (int i = 0; i < numberOfFields; i++) {
// Get the field.
first = (CustomButtonField) getField(i);
setPositionChild(first, 0, 0);
layoutChild(first, 110, 110);
}
setExtent(200, 200);
}
setPositionChild(first, 50, 50);
invalidate();
}
}

Answer 1

If I understood you right, you just need to override this method:
protected boolean touchEvent(TouchEvent message)
in both custom field classes. And implement the functionality you want.

Answer 2

I think we need some clarification.
A Field in BlackBerry Java is given an 'extent' - basically a rectangle - and it paints into this area. When displayed on the screen, all 'events' in this Field's extent should be directed to that Field automatically by the framework. As far as the Field is concerned, the extent always starts at 0,0, and extends as many pixels as the Field has. In fact it is this extent that defines the size of the Field.
Now within paint, you can paint what you like for the each Field (as long as you stay inside its extent). So if you have a Field with an extent that was say 100 x 100 pixels, then you paint the left hand side of your Field red and the right hand side blue, by doing something like this:
graphics.setColor(Color.Red);
graphics.drawRect(0,0,50,100);
graphics.setColor(Color.Blue);
graohics.drawRect(50,0,100,100);
Now if you did this, you might want separately detectable areas - say the red and the blue areas. And while this is possible and you can detect it using touchEvent(), you would find it a lot easier to actually display two Fields, one all red and one all blue. Separate Fields make it a lot easier to use the standard BB methods, and in addition, also make it possible to use the trackpad to scroll round the different Fields. Remember you can't use touchevent() on non touch phones.
Anyway, with this additional information, can you please clarify your question. Do you have one Field with different areas? If you have two different Fields, remember that you are painting within each Field's extent.