com.yospace.yae.yogi
Class FocusManager

java.lang.Object
  |
  +--com.yospace.yae.yogi.FocusManager

Direct Known Subclasses:

StandardFocusManager, StandardFocusManager

public abstract class FocusManager

extends java.lang.Object

Base class of FocusManagers in the YoGI system. UIs will subclass this: the UIManager provides a reference to the current FocusManager

The FocusManager has the responsibility of pre-filtering all events and deciding whether to use them for changing the current focus (ie "tabbing") or for other high-level purpose (in the sense of the "MSWindows" button or ALT-Tab on PCs).

It can also search for targets other than the current focus. If, for instance, the event is a keystroke indicating that we should scroll up, then we may search for next scrollable parent from the current focus.

It is also the FocusManager's responsibility to ensure that scrollers and layered windows are adjusted where possible so that the focussed item stays on screen.

Field Summary

protected YogiRootWindow

rootWindow The root window component that is to be managed.

Constructor Summary

FocusManager()

Method Summary

abstract boolean	processKeyEvent(int keyCode, int eventType) This method receives all keypad events from the low-level event system, and is expected to pick out and act upon focus-traversal commands and other significant focus controls.
abstract boolean	processPointerEvent(int x, int y, int eventType) This method receives pointer events from the low-level event system.
void	setRootWindow(YogiRootWindow rootWindow) Sets the root window component that is to be managed.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

rootWindow

protected YogiRootWindow rootWindow

The root window component that is to be managed.

See Also:

setRootWindow(YogiRootWindow)

Constructor Detail

FocusManager

public FocusManager()

Method Detail

setRootWindow

public void setRootWindow(YogiRootWindow rootWindow)

Sets the root window component that is to be managed. This can only be set once.

Parameters:

rootWindow - the root window component to be managed.

Throws:

IllegalStateException - if the root window has already been set.

processKeyEvent

public abstract boolean processKeyEvent(int keyCode,
                                        int eventType)

This method receives all keypad events from the low-level event system, and is expected to pick out and act upon focus-traversal commands and other significant focus controls. If the focus is moved, it is expected that the focus manager will ensure that the focus is still visible. It should pass events to the current focussed component's keyPressed, keyRepeated or keyReleased methods, as appropriate, and also pass them to its UI delegate's processKeyEvent method. It may choose to pass events elsewhere (such as to the component's containers, as per AWT 1.0), but this is UI dependent. It should take account of the enablement, context-enablement and visibility of the components.

Parameters:

keyCode - the keycode of the key that was pressed, according to MIDP Canvas.

eventType - a key event type, one of KEY_PRESSED, KEY_REPEATED or KEY_RELEASED.

processPointerEvent

public abstract boolean processPointerEvent(int x,
                                            int y,
                                            int eventType)

This method receives pointer events from the low-level event system. It is responsible for assigning the component under a pointer-press to be the current focus, and It should pass events to the current focussed component's pointerPressed, pointerDragged or pointerReleased methods, as appropriate, and also pass them to its UI delegate's processPointerEvent method. It may choose to pass events elsewhere (such as to the component's containers, as per AWT 1.0), but this is UI dependent. It should take account of the enablement, context-enablement and visibility of the components.

Parameters:

x - the x-coordinate of the pointer event, in global canvas coordinates

y - the y-coordinate of the pointer event, in global canvas coordinates

eventType - a key event type, one of POINTER_PRESSED, POINTER_DRAGGED or POINTER_RELEASED.