Package ej.mwt

Class Desktop

java.lang.Object

ej.microui.display.Displayable

ej.mwt.Desktop

All Implemented Interfaces:

ej.microui.event.EventHandler

public class Desktop
extends ej.microui.display.Displayable

A desktop is the top-level object that can be displayed on a Display.

It contains a widget. This widget can be a container to have a more elaborate hierarchy of widgets.

A desktop may be shown or hidden, but at most one desktop is shown per Display.

A desktop provides an animator, which can be used by the widgets to start and stop animations. When the desktop is hidden, every animation is automatically stopped.

A desktop provides a stylesheet, which is used by the widgets of the desktop in order to retrieve their style. By default, the stylesheet is a VoidStylesheet, but this can be changed at any time.

See Also:

Display

Constructor Summary

Constructors

Constructor	Description
Desktop()	Creates a new desktop.

Method Summary

Modifier and Type	Method	Description
boolean	containsWidget(Widget widget)	Returns whether or not this desktop contains the given widget.
protected EventDispatcher	createEventDispatcher()	Creates the event dispatcher which is responsible for dispatching events to the widgets.
protected RenderPolicy	createRenderPolicy()	Creates the render policy which is responsible for rendering the widgets.
Animator	getAnimator()	Gets the animator instance.
EventDispatcher	getEventDispatcher()	Gets the event dispatcher of this desktop.
Stylesheet	getStylesheet()	Gets the stylesheet instance.
Widget	getWidget()	Gets the widget attached to this desktop.
Widget	getWidgetAt(int x, int y)	Returns the child widget at the specified position.
boolean	handleEvent(int event)	Handles an event by delegating it to the event dispatcher.
boolean	isAttached()	Gets whether this desktop is attached or not.
boolean	isShown()	Checks whether the desktop is visible on the display.
protected void	onHidden()	This method is called by the system as soon as the desktop is hidden from the display.
protected void	onShown()	This method is called by the system as soon as the desktop is shown on the display.
protected void	render(ej.microui.display.GraphicsContext g)	The desktop is rendered using the given graphics context.
void	renderWidget(ej.microui.display.GraphicsContext g, Widget widget)	Renders a widget.
void	requestHide()	Hides the desktop from the display.
void	requestLayOut()	Requests a lay out of all the hierarchy of this desktop.
void	requestRender()	Requests a rendering for the entire displayable.
void	requestShow()	Shows the desktop on the display.
void	setAttached()	Sets this desktop as attached.
void	setDetached()	Sets this desktop as detached.
void	setStylesheet(Stylesheet stylesheet)	Sets the stylesheet instance.
void	setWidget(Widget widget)	Attaches a widget to this desktop.

Methods inherited from class java.lang.Object

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

Constructor Detail

Desktop

public Desktop()

Creates a new desktop.

Method Detail

createEventDispatcher

protected EventDispatcher createEventDispatcher()

Creates the event dispatcher which is responsible for dispatching events to the widgets. By default, a pointer event dispatcher is created.

Returns:

the event dispatcher.

See Also:

PointerEventDispatcher

getEventDispatcher

@Nullable
public EventDispatcher getEventDispatcher()

Gets the event dispatcher of this desktop.

Returns:

the event dispatcher of this desktop.

createRenderPolicy

protected RenderPolicy createRenderPolicy()

Creates the render policy which is responsible for rendering the widgets. By default, a default render policy is created.

Returns:

the render policy.

See Also:

DefaultRenderPolicy

setWidget

public void setWidget(@Nullable
                      Widget widget)

Attaches a widget to this desktop.

If there is already a widget on this desktop, the former is detached from the latter.

If the specified widget is null, the desktop does not hold a widget anymore.

Should be called in the display thread to avoid concurrency issues.

Parameters:

widget - the widget.

Throws:

java.lang.IllegalArgumentException - if the specified widget is already attached.

getWidget

@Nullable
public Widget getWidget()

Gets the widget attached to this desktop.

Returns:

the widget attached with this desktop or null.

requestLayOut

public void requestLayOut()

Requests a lay out of all the hierarchy of this desktop.

The lay out is done asynchronously, therefore this method returns immediately.

Nothing is done if the desktop is not shown.

Notifies its child widget that it is shown.

requestRender

public void requestRender()

Description copied from class: ej.microui.display.Displayable

Requests a rendering for the entire displayable. Calling this method may result in subsequent call to Displayable.render(GraphicsContext) on the displayable.

The call to Displayable.render(GraphicsContext) occurs asynchronously to this call. That is, this method will not block waiting for Displayable.render(GraphicsContext) to finish. After render action (after call to Displayable.render(GraphicsContext), a call to Display.flush() is synchronously performed.

This call may have no effect under certain conditions:

• if the displayable is not visible on the display (see Display.isShown(Displayable)): the request is refused.
• if the displayable is not visible on the display when the event is executed (a call to Display.requestShow(Displayable) has been performed with another displayable): the request is abandoned (this displayable is no longer the current displayable).
• if a request is already available in the events queue and if the request is called from the MicroUI pump: the request is useless because this request has been already added and cannot be executed until the end of current caller method. The request is not added into the queue.

Overrides:

requestRender in class ej.microui.display.Displayable

isShown

public boolean isShown()

Checks whether the desktop is visible on the display.

Calling this method is equivalent to calling Display.getDisplay().isShown(desktop);.

Returns:

true if the desktop is currently visible, false otherwise.

requestShow

public void requestShow()

Shows the desktop on the display.

Calling this method is equivalent to calling Display.getDisplay().requestShow(desktop);.

Throws:

java.lang.SecurityException - if a security manager exists and does not allow the caller to get the display.

requestHide

public void requestHide()

Hides the desktop from the display.

Calling this method is equivalent to calling Display.getDisplay().requestHide(desktop);.

onShown

protected void onShown()

This method is called by the system as soon as the desktop is shown on the display.

• The event dispatcher is created,
• the desktop is attached (along with its children),
• its children are shown.

Overrides:

onShown in class ej.microui.display.Displayable

See Also:

setAttached()

onHidden

protected void onHidden()

This method is called by the system as soon as the desktop is hidden from the display.

• The event dispatcher is disposed,
• the desktop is detached (along with its widget hierarchy).

Overrides:

onHidden in class ej.microui.display.Displayable

See Also:

setDetached()

setAttached

public void setAttached()

Sets this desktop as attached.

Every widget in its hierarchy is attached and a layout is performed.

See Also:

isAttached(), Widget.onAttached()

setDetached

public void setDetached()

Sets this desktop as detached.

Every widget in its hierarchy is detached.

See Also:

isAttached(), Widget.onDetached()

isAttached

public boolean isAttached()

Gets whether this desktop is attached or not.

When the desktop is attached, that means that it is ready to be displayed (shown on a display or drawn in an image).

Returns:

true if this desktop is attached, false otherwise.

handleEvent

public boolean handleEvent(int event)

Handles an event by delegating it to the event dispatcher.

Parameters:

event - the event to handle.

Returns:

true if the event is consumed, false otherwise.

See Also:

Event

renderWidget

public void renderWidget(ej.microui.display.GraphicsContext g,
                         Widget widget)

Renders a widget.

Beware that even an hidden child can be rendered by calling this method.

An assertion checks that the given widget is actually a child of this desktop.

Parameters:

g - the graphics context to use to draw the widget.

widget - the widget to render.

render

protected void render(ej.microui.display.GraphicsContext g)

The desktop is rendered using the given graphics context.

Renders its child widget entirely.

Specified by:

render in class ej.microui.display.Displayable

Parameters:

g - the graphics context of the display.

getWidgetAt

@Nullable
public Widget getWidgetAt(int x,
                          int y)

Returns the child widget at the specified position.

If this desktop does not contains(x, y), null is returned. The position is considered here as a relative position to the desktop.

Parameters:

x - x coordinate.

y - y coordinate.

Returns:

the widget at the position, null if no widget is found in this desktop hierarchy.

See Also:

Widget.getWidgetAt(int, int)

containsWidget

public boolean containsWidget(Widget widget)

Returns whether or not this desktop contains the given widget.

Parameters:

widget - the widget to check.

Returns:

true if this desktop contains the given widget, false otherwise.

See Also:

Widget.containsWidget(Widget)

getAnimator

public Animator getAnimator()

Gets the animator instance.

Returns:

the animator instance.

setStylesheet

public void setStylesheet(Stylesheet stylesheet)

Sets the stylesheet instance.

Parameters:

stylesheet - the stylesheet instance.

getStylesheet

public Stylesheet getStylesheet()

Gets the stylesheet instance.

Returns:

the stylesheet instance.