how to set horizontal scroll to horizontal field manager - user-interface

Question

The following snippet contains a horizontal field manager to which five buttons are added.
1. I am unable to set horizontal scroll to the horizontal field manager because of which I am not able to access button 4 and button 5.
2. Usually we set horizontal scroll in the following manner
horizontalFieldManager =
new HorizontalFieldManager(USE_ALL_WIDTH|HorizontalFieldManager.FIELD_LEFT|HORIZONTAL_SCROLL);
but since I have added the buttons in the constructor of the horizontal field manager I am unable to use this.
3. I found this property : horizontalFieldManager.setHorizontalScroll(position);
which contains the Parameter:position where position is supposed to be the new horizontal scroll position. I tried passing the x-coordinate of the horizontal field manager but it's not working. What should i pass as the position parameter?
HorizontalFieldManager container = new HorizontalFieldManager()
{
protected void sublayout(int maxWidth, int maxHeight)
{
Field field = null;
int x = 0;
int y = 0;
int maxFieldHeight = 0;
for (int i = 0; i < getFieldCount(); i++)
{
field = getField(i);
layoutChild(field, maxWidth, maxHeight);
setPositionChild(field, x,y);
x+=field.getWidth();
if(i==0)
{
maxFieldHeight = field.getHeight(); // height set of the first button since all components have the same height
}
}
setExtent(Display.getWidth(), maxFieldHeight);
}
};
ButtonField button1 = new ButtonField("Button1");
ButtonField button2 = new ButtonField("Button2");
ButtonField button3 = new ButtonField("Button3");
ButtonField button4 = new ButtonField("Button4");
ButtonField button5 = new ButtonField("Button5");
container.add(button1);
container.add(button2);
container.add(button3);
container.add(button4);
container.add(button5);
add(container);

Answer 1

HorizontalFieldManager Constructor
If you simply change the way you call the HorizontalFieldManager constructor, from this:
HorizontalFieldManager container = new HorizontalFieldManager() {
protected void sublayout(int maxWidth, int maxHeight) {
to this:
HorizontalFieldManager container =
new HorizontalFieldManager(Manager.HORIZONTAL_SCROLL | Manager.HORIZONTAL_SCROLLBAR) {
protected void sublayout(int maxWidth, int maxHeight) {
then, you'll get the ability to scroll horizontally, and reach all five buttons.
sublayout()
In your sublayout() method, you appear to be laying out your fields just as HorizontalFieldManager would normally do. So, I don't think there's any point in adding that code. Simply do this:
HorizontalFieldManager container =
new HorizontalFieldManager(Manager.HORIZONTAL_SCROLL | Manager.HORIZONTAL_SCROLLBAR);
ButtonField button1 = new ButtonField("Button1");
/* the rest of your code is the same */
If you later want to control spacing between the buttons, do it with margins:
ButtonField button1 = new ButtonField("Button1");
button1.setMargin(10, 10, 10, 10);
ButtonField button2 = new ButtonField("Button2");
button2.setMargin(10, 10, 10, 10);
In general, it's usually not a good idea to use a HorizontalFieldManager, or a VerticalFieldManager and also override sublayout(). If you really want custom behavior there, you should probably just extend Manager directly with a subclass of your own.