component.java

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     */
    transient AppContext appContext;

    /**
     * Constructs a new component. Class <code>Component</code> can be
     * extended directly to create a lightweight component that does not
     * utilize an opaque native window. A lightweight component must be
     * hosted by a native container somewhere higher up in the component
     * tree (for example, by a <code>Frame</code> object).
     */
    protected Component() {
       appContext = AppContext.getAppContext();
       SunToolkit.insertTargetMapping(this, appContext);
    }

    /**
     * Construct a name for this component.  Called by getName() when the
     * name is null.
     */
    String constructComponentName() {
        return null; // For strict compliance with prior JDKs, a Component
        // that doesn't set its name should return null from
        // getName();
    }

    /**
     * Gets the name of the component.
     * @return This component's name.
     * @see    #setName
     * @since JDK1.1
     */
    public String getName() {
        if (name == null && !nameExplicitlySet) {
            synchronized (this) {
                if (name == null && !nameExplicitlySet)
                    name = constructComponentName();
            }
        }
        return name;
    }

    /**
     * Sets the name of the component to the specified string.
     * @param name  The string that is to be this
     * component's name.
     * @see #getName
     * @since JDK1.1
     */
    public void setName(String name) {
        synchronized (this) {
            this.name = name;
            nameExplicitlySet = true;
        }
    }

    /**
     * Gets the parent of this component.
     * @return The parent container of this component.
     * @since JDK1.0
     */
    public Container getParent() {
        return parent;
    }

    /**
     * Get the <code>GraphicsConfiguration</code> associated with this
     * <code>Component</code>.
     * If the <code>Component</code> has not been assigned a specific
     * <code>GraphicsConfiguration</code>,
     * the <code>GraphicsConfiguration</code> of the
     * <code>Component</code> object's top-level container is
     * returned.
     * If the <code>Component</code> has been created, but not yet added
     * to a <code>Container</code>, this method returns <code>null</code>.
     * @return the <code>GraphicsConfiguration</code> used by this
     * <code>Component</code> or <code>null</code>
     * @since 1.3
     */
    public GraphicsConfiguration getGraphicsConfiguration() {
        Frame frame = getFrame();
        return (frame != null) ? frame.getGraphicsConfiguration() : null;
    }

    /**
     * Gets the locking object for AWT component-tree and layout
     * Gets this component's locking object (the object that owns the thread
     * sychronization monitor) for AWT component-tree and layout
     * operations.
     * @return This component's locking object.
     */
    public final Object getTreeLock() {
        return LOCK;
    }

    /**
     * Gets the toolkit of this component. Note that
     * the frame that contains a component controls which
     * toolkit is used by that component. Therefore if the component
     * is moved from one frame to another, the toolkit it uses may change.
     * @return  The toolkit of this component.
     * @since JDK1.0
     */
    public Toolkit getToolkit() {
        return Toolkit.getDefaultToolkit();
    }

    /**
     * Determines whether this component is valid. A component is valid
     * when it is correctly sized and positioned within its parent
     * container and all its children are also valid. Components are
     * invalidated when they are first shown on the screen.
     * @return <code>true</code> if the component is valid; <code>false</code>
     * otherwise.
     * @see #validate
     * @see #invalidate
     * @since JDK1.0
     */
    public boolean isValid() {
        return valid;
    }

    /**
     * Determines whether this component is displayable. A component is
     * displayable when it is connected to a native screen resource.
     * <p>
     * A component is made displayable either when it is added to
     * a displayable containment hierarchy or when its containment
     * hierarchy is made displayable.
     * A containment hierarchy is made displayable when its ancestor
     * window is either packed or made visible.
     * <p>
     * A component is made undisplayable either when it is removed from
     * a displayable containment hierarchy or when its containment hierarchy
     * is made undisplayable.  A containment hierarchy is made
     * undisplayable when its ancestor window is disposed.
     *
     * @return <code>true</code> if the component is displayable;
     * <code>false</code> otherwise.
     * @see java.awt.Container#add(java.awt.Component)
     * @see java.awt.Window#pack
     * @see java.awt.Window#show
     * @see java.awt.Container#remove(java.awt.Component)
     * @see java.awt.Window#dispose
     * @since 1.2
     */
    public boolean isDisplayable() {
        return displayable;
    }

    /**
     * Determines whether this component should be visible when its
     * parent is visible. Components are
     * initially visible, with the exception of top level components such
     * as <code>Frame</code> objects.
     * @return <code>true</code> if the component is visible;
     * <code>false</code> otherwise.
     * @see #setVisible
     * @since JDK1.0
     */
    public boolean isVisible() {
        return visible;
    }

    /**
     * Determines whether this component is showing on screen. This means
     * that the component must be visible, and it must be in a container
     * that is visible and showing.
     * @return <code>true</code> if the component is showing;
     * <code>false</code> otherwise.
     * @see #setVisible
     * @since JDK1.0
     */
    public boolean isShowing() {
        Container parent = this.parent;
        return (parent != null) ? (visible && parent.isShowing()) : false;
    }

    /**
     * Determines whether this component is enabled. An enabled component
     * can respond to user input and generate events. Components are
     * enabled initially by default. A component may be enabled or disabled by
     * calling its <code>setEnabled</code> method.
     * @return <code>true</code> if the component is enabled;
     * <code>false</code> otherwise.
     * @see #setEnabled
     * @since JDK1.0
     */
    public boolean isEnabled() {
        return enabled;
    }

    /**
     * Enables or disables this component, depending on the value of the
     * parameter <code>b</code>. An enabled component can respond to user
     * input and generate events. Components are enabled initially by default.
     * @param     b   If <code>true</code>, this component is
     *            enabled; otherwise this component is disabled.
     * @see #isEnabled
     * @since JDK1.1
     */
    public void setEnabled(boolean b) {
        if (enabled && !b) {
            KeyboardFocusManager.clearMostRecentFocusOwner(this);
            synchronized (getTreeLock()) {
                enabled = false;
                if (isFocusOwner()) {
                    // Don't clear the global focus owner. If transferFocus
                    // fails, we want the focus to stay on the disabled
                    // Component so that keyboard traversal, et. al. still
                    // makes sense to the user.
                    autoTransferFocus(false);
                }
            }
        }
        enabled = b;
    }
 
    /**
     * Returns true if this component is painted to an offscreen image
     * ("buffer") that's copied to the screen later.  Component
     * subclasses that support double buffering should override this
     * method to return true if double buffering is enabled.
     *
     * @return false by default
     */
    public boolean isDoubleBuffered() {
        return false;
    }

    /**
     * Enables or disables input method support for this component. If input
     * method support is enabled and the component also processes key events,
     * incoming events are offered to
     * the current input method and will only be processed by the component or
     * dispatched to its listeners if the input method does not consume them.
     * By default, input method support is enabled.
     *
     * @param enable true to enable, false to disable
     * @see #processKeyEvent
     * @since 1.2
     */
    public void enableInputMethods(boolean enable) {
        if (enable) {
            if ((eventMask & AWTEvent.INPUT_METHODS_ENABLED_MASK) != 0)
                return;

            // If this component already has focus, then activate the
            // input method by dispatching a synthesized focus gained
            // event.
            if (isFocusOwner()) {
                InputContext inputContext = getInputContext();
                if (inputContext != null) {
                    FocusEvent focusGainedEvent =
                        new FocusEvent(this, FocusEvent.FOCUS_GAINED);
                    inputContext.dispatchEvent(focusGainedEvent);
                }
            }

            eventMask |= AWTEvent.INPUT_METHODS_ENABLED_MASK;
        } else {
            if (areInputMethodsEnabled()) {
                InputContext inputContext = getInputContext();
                if (inputContext != null) {
                    inputContext.endComposition();
                    inputContext.removeNotify(this);
                }
            }
            eventMask &= ~AWTEvent.INPUT_METHODS_ENABLED_MASK;
        }
    }

    /**
     * Shows or hides this component depending on the value of parameter
     * <code>b</code>.
     * @param b  If <code>true</code>, shows this component;
     * otherwise, hides this component.
     * @see #isVisible
     * @since JDK1.1
     */
    public void setVisible(boolean b) {
        if (b)
            show();
        else hide();
    }

    void show() {
        if (!visible) {
            synchronized (getTreeLock()) {
                visible = true;
                if (isLightweight())
                    repaint();
                if (componentListener != null ||
                    (eventMask & AWTEvent.COMPONENT_EVENT_MASK) != 0) {
                    ComponentEvent e = new ComponentEvent(this,
                            ComponentEvent.COMPONENT_SHOWN);
                    Toolkit.getEventQueue().postEvent(e);
                    //SunToolkit.postEvent(appContext, e);
                }
            }
            Container parent = this.parent;
            if (parent != null)
                parent.invalidate();
        }
    }

    void hide() {
        if (visible) {
            clearCurrentFocusCycleRootOnHide();
            clearMostRecentFocusOwnerOnHide();
            synchronized (getTreeLock()) {
                visible = false;
                if (containsFocus()) {
                    autoTransferFocus(true);
                }
                if (componentListener != null ||
                    (eventMask & AWTEvent.COMPONENT_EVENT_MASK) != 0) {
                    ComponentEvent e = new ComponentEvent(this,
                                     ComponentEvent.COMPONENT_HIDDEN);
                    Toolkit.getEventQueue().postEvent(e);
                    //SunToolkit.postEvent(appContext, e);
                }
            }
            Container parent = this.parent;
            if (parent != null) {
                parent.invalidate();
            }
        }
    }

    /**
     * Gets the foreground color of this component.
     * @return This component's foreground color. If this component does
     * not have a foreground color, the foreground color of its parent
     * is returned.
     * @see #setForeground
     * @since JDK1.0
     */
    public Color getForeground() {
        Color foreground = this.foreground;
        if (foreground != null) {
            return foreground;
        }
        Container parent = this.parent;
        return (parent != null) ? parent.getForeground() : null;
    }

    /**
     * Sets the foreground color of this component.
     * @param c The color to become this component's
     * foreground color.
     * If this parameter is null then this component will inherit
     * the foreground color of its parent.
     * @see #getForeground
     * @since JDK1.0
     */
    public void setForeground(Color c) {
	Color oldColor = foreground;
        foreground = c;

	// This is a bound property, so report the change to
	// any registered listeners.  (Cheap if there are none.)
	firePropertyChange("foreground", oldColor, c);
    }

    /**
     * Returns whether the foreground color has been explicitly set for this
     * Component. If this method returns <code>false</code>, this Component is
     * inheriting its foreground color from an ancestor.
     *
     * @return <code>true</code> if the foreground color has been explicitly
     *         set for this Component; <code>false</code> otherwise.
     * @since 1.4