Package ej.mwt

Class 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

      All Methods Instance Methods Concrete Methods 
      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()  
      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, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

    • Constructor Detail

      • Desktop

        public Desktop()
        Creates a new desktop.

    • Method Detail

      • getEventDispatcher

        @Nullable
public EventDispatcher getEventDispatcher()
        Gets the event dispatcher of this desktop.
        Returns:
        the event dispatcher of this desktop.

      • 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 layout is done asynchronously, therefore this method returns immediately. To execute some code just after the layout is done, this code could be wrapped in a Runnable and executed asynchronously with MicroUI.callSerially(Runnable).

        Nothing is done if the desktop is not shown.

        Notifies its child widget that it is shown.

      • requestRender

        public void requestRender()
        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);.

        This method returns immediately and the desktop is shown asynchronously in the MicroUI thread. To execute some code just after the show is done, this code could be wrapped in a Runnable and executed asynchronously with MicroUI.callSerially(Runnable).

        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);.

        This method returns immediately and the desktop is hidden asynchronously in the MicroUI thread. To execute some code just after the hide is done, this code could be wrapped in a Runnable and executed asynchronously with MicroUI.callSerially(Runnable).

      • 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.

      • 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.