preferencedialog.java

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	 */
	public void setErrorMessage(String newErrorMessage) {
		if (newErrorMessage == null) {
			messageArea.clearErrorMessage();
		} else {
			messageArea.updateText(newErrorMessage, IMessageProvider.ERROR);
		}
	}

	/**
	 * Save the last known tree width.
	 * 
	 * @param width
	 *            the width.
	 */
	private void setLastTreeWidth(int width) {
		lastTreeWidth = width;
	}

	/**
	 * Set the message text. If the message line currently displays an error,
	 * the message is stored and will be shown after a call to clearErrorMessage
	 * <p>
	 * Shortcut for <code>setMessage(newMessage, NONE)</code>
	 * </p>
	 * 
	 * @param newMessage
	 *            the message, or <code>null</code> to clear the message
	 */
	public void setMessage(String newMessage) {
		setMessage(newMessage, IMessageProvider.NONE);
	}

	/**
	 * Sets the message for this dialog with an indication of what type of
	 * message it is.
	 * <p>
	 * The valid message types are one of <code>NONE</code>,
	 * <code>INFORMATION</code>,<code>WARNING</code>, or
	 * <code>ERROR</code>.
	 * </p>
	 * <p>
	 * Note that for backward compatibility, a message of type
	 * <code>ERROR</code> is different than an error message (set using
	 * <code>setErrorMessage</code>). An error message overrides the current
	 * message until the error message is cleared. This method replaces the
	 * current message and does not affect the error message.
	 * </p>
	 * 
	 * @param newMessage
	 *            the message, or <code>null</code> to clear the message
	 * @param newType
	 *            the message type
	 * @since 2.0
	 */
	public void setMessage(String newMessage, int newType) {
		messageArea.updateText(newMessage, newType);
	}

	/**
	 * Sets the minimum page size.
	 * 
	 * @param minWidth
	 *            the minimum page width
	 * @param minHeight
	 *            the minimum page height
	 * @see #setMinimumPageSize(Point)
	 */
	public void setMinimumPageSize(int minWidth, int minHeight) {
		minimumPageSize.x = minWidth;
		minimumPageSize.y = minHeight;
	}

	/**
	 * Sets the minimum page size.
	 * 
	 * @param size
	 *            the page size encoded as <code>new Point(width,height)</code>
	 * @see #setMinimumPageSize(int,int)
	 */
	public void setMinimumPageSize(Point size) {
		minimumPageSize.x = size.x;
		minimumPageSize.y = size.y;
	}

	/**
	 * Sets the preference store for this preference dialog.
	 * 
	 * @param store
	 *            the preference store
	 * @see #getPreferenceStore
	 */
	public void setPreferenceStore(IPreferenceStore store) {
		Assert.isNotNull(store);
		preferenceStore = store;
	}

	/**
	 * Save the currently selected node.
	 */
	private void setSelectedNode() {
		String storeValue = null;
		IStructuredSelection selection = (IStructuredSelection) getTreeViewer().getSelection();
		if (selection.size() == 1) {
			IPreferenceNode node = (IPreferenceNode) selection.getFirstElement();
			storeValue = node.getId();
		}
		setSelectedNodePreference(storeValue);
	}

	/**
	 * Sets the name of the selected item preference. Public equivalent to
	 * <code>setSelectedNodePreference</code>.
	 * 
	 * @param pageId
	 *            The identifier for the page
	 * @since 3.0
	 */
	public void setSelectedNode(String pageId) {
		setSelectedNodePreference(pageId);
	}

	/**
	 * Sets the name of the selected item preference.
	 * 
	 * @param pageId
	 *            The identifier for the page
	 */
	protected void setSelectedNodePreference(String pageId) {
		lastPreferenceId = pageId;
	}

	/**
	 * Changes the shell size to the given size, ensuring that it is no larger
	 * than the display bounds.
	 * 
	 * @param width
	 *            the shell width
	 * @param height
	 *            the shell height
	 */
	private void setShellSize(int width, int height) {
		Rectangle preferred = getShell().getBounds();
		preferred.width = width;
		preferred.height = height;
		getShell().setBounds(getConstrainedShellBounds(preferred));
	}

	/**
	 * Shows the preference page corresponding to the given preference node.
	 * Does nothing if that page is already current.
	 * 
	 * @param node
	 *            the preference node, or <code>null</code> if none
	 * @return <code>true</code> if the page flip was successful, and
	 *         <code>false</code> is unsuccessful
	 */
	protected boolean showPage(IPreferenceNode node) {
		if (node == null) {
			return false;
		}
		// Create the page if nessessary
		if (node.getPage() == null) {
			createPage(node);
		}
		if (node.getPage() == null) {
			return false;
		}
		IPreferencePage newPage = getPage(node);
		if (newPage == currentPage) {
			return true;
		}
		if (currentPage != null) {
			if (!currentPage.okToLeave()) {
				return false;
			}
		}
		IPreferencePage oldPage = currentPage;
		currentPage = newPage;
		// Set the new page's container
		currentPage.setContainer(this);
		// Ensure that the page control has been created
		// (this allows lazy page control creation)
		if (currentPage.getControl() == null) {
			final boolean[] failed = { false };
			SafeRunnable.run(new ISafeRunnable() {
				public void handleException(Throwable e) {
					failed[0] = true;
				}

				public void run() {
					createPageControl(currentPage, pageContainer);
				}
			});
			if (failed[0]) {
				return false;
			}
			// the page is responsible for ensuring the created control is
			// accessable
			// via getControl.
			Assert.isNotNull(currentPage.getControl());
		}
		// Force calculation of the page's description label because
		// label can be wrapped.
		final Point[] size = new Point[1];
		final Point failed = new Point(-1, -1);
		SafeRunnable.run(new ISafeRunnable() {
			public void handleException(Throwable e) {
				size[0] = failed;
			}

			public void run() {
				size[0] = currentPage.computeSize();
			}
		});
		if (size[0].equals(failed)) {
			return false;
		}
		Point contentSize = size[0];
		// Do we need resizing. Computation not needed if the
		// first page is inserted since computing the dialog's
		// size is done by calling dialog.open().
		// Also prevent auto resize if the user has manually resized
		Shell shell = getShell();
		Point shellSize = shell.getSize();
		if (oldPage != null) {
			Rectangle rect = pageContainer.getClientArea();
			Point containerSize = new Point(rect.width, rect.height);
			int hdiff = contentSize.x - containerSize.x;
			int vdiff = contentSize.y - containerSize.y;
			if ((hdiff > 0 || vdiff > 0) && shellSize.equals(lastShellSize)) {
					hdiff = Math.max(0, hdiff);
					vdiff = Math.max(0, vdiff);
					setShellSize(shellSize.x + hdiff, shellSize.y + vdiff);
					lastShellSize = shell.getSize();
					if (currentPage.getControl().getSize().x == 0) {
						currentPage.getControl().setSize(containerSize);
					}
				
			} else {
				currentPage.setSize(containerSize);
			}
		}
		// Ensure that all other pages are invisible
		// (including ones that triggered an exception during
		// their creation).
		Control[] children = pageContainer.getChildren();
		Control currentControl = currentPage.getControl();
		for (int i = 0; i < children.length; i++) {
			if (children[i] != currentControl) {
				children[i].setVisible(false);
			}
		}
		// Make the new page visible
		currentPage.setVisible(true);
		if (oldPage != null) {
			oldPage.setVisible(false);
		}
		// update the dialog controls
		update();
		return true;
	}

	/**
	 * Create the page for the node.
	 * @param node
	 * 
	 * @since 3.1
	 */
	protected void createPage(IPreferenceNode node) {
		node.createPage();
	}

	/**
	 * Get the page for the node.
	 * @param node
	 * @return IPreferencePage
	 * 
	 * @since 3.1
	 */
	protected IPreferencePage getPage(IPreferenceNode node) {
		return node.getPage();
	}

	/**
	 * Shows the "Page Flipping abort" dialog.
	 */
	void showPageFlippingAbortDialog() {
		MessageDialog.openError(getShell(), JFaceResources
				.getString("AbortPageFlippingDialog.title"), //$NON-NLS-1$
				JFaceResources.getString("AbortPageFlippingDialog.message")); //$NON-NLS-1$
	}

	/**
	 * Updates this dialog's controls to reflect the current page.
	 */
	protected void update() {
		// Update the title bar
		updateTitle();
		// Update the message line
		updateMessage();
		// Update the buttons
		updateButtons();
		//Saved the selected node in the preferences
		setSelectedNode();
		firePageChanged(new PageChangedEvent(this, getCurrentPage()));
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.preference.IPreferencePageContainer#updateButtons()
	 */
	public void updateButtons() {
		okButton.setEnabled(isCurrentPageValid());
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.preference.IPreferencePageContainer#updateMessage()
	 */
	public void updateMessage() {
		String message = null;
		String errorMessage = null;
		if(currentPage != null){
			message = currentPage.getMessage();
			errorMessage = currentPage.getErrorMessage();
		}
		int messageType = IMessageProvider.NONE;
		if (message != null && currentPage instanceof IMessageProvider) {
			messageType = ((IMessageProvider) currentPage).getMessageType();
		}

		if (errorMessage == null){
			if (showingError) {
				// we were previously showing an error
				showingError = false;
			}
		}
		else {
			message = errorMessage;
			messageType = IMessageProvider.ERROR;
			if (!showingError) {
				// we were not previously showing an error
				showingError = true;
			}
		}  
		messageArea.updateText(message,messageType);
	}

	/*
	 * (non-Javadoc)
	 * 
	 * @see org.eclipse.jface.preference.IPreferencePageContainer#updateTitle()
	 */
	public void updateTitle() {
		if(currentPage == null) {
			return;
		}
		messageArea.showTitle(currentPage.getTitle(), currentPage.getImage());
	}

	/**
	 * Update the tree to use the specified <code>Font</code>.
	 * 
	 * @param dialogFont
	 *            the <code>Font</code> to use.
	 * @since 3.0
	 */
	protected void updateTreeFont(Font dialogFont) {
		getTreeViewer().getControl().setFont(dialogFont);
	}

	/**
	 * Returns the currentPage.
	 * @return IPreferencePage
	 * @since 3.1
	 */
	protected IPreferencePage getCurrentPage() {
		return currentPage;
	}

	/**
	 * Sets the current page.
	 * @param currentPage
	 * 
	 * @since 3.1
	 */
	protected void setCurrentPage(IPreferencePage currentPage) {
		this.currentPage = currentPage;
	}

	/**
	 * Set the treeViewer.
	 * @param treeViewer
	 * 
	 * @since 3.1
	 */
	protected void setTreeViewer(TreeViewer treeViewer) {
		this.treeViewer = treeViewer;
	}

	/**
	 * Get the composite that is showing the page.
	 *
	 * @return Composite.
	 * 
	 * @since 3.1
	 */
	protected Composite getPageContainer() {
		return this.pageContainer;
	}

	/**
	 * Set the composite that is showing the page.
	 * @param pageContainer Composite
	 * 
	 * @since 3.1
	 */
	protected void setPageContainer(Composite pageContainer) {
		this.pageContainer = pageContainer;
	}
	/**
	 * Create the page control for the supplied page.
	 * 
	 * @param page - the preference page to be shown
	 * @param parent - the composite to parent the page
	 * 
	 * @since 3.1
	 */
	protected void createPageControl(IPreferencePage page, Composite parent) {
		page.createControl(parent);
	}
	
	/**
	 * @see org.eclipse.jface.dialogs.IPageChangeProvider#getSelectedPage()
	 * 
	 * @since 3.1
	 */
	public Object getSelectedPage() {
			return getCurrentPage();
		}
	
	/**
	 * @see org.eclipse.jface.dialogs.IPageChangeProvider#addPageChangedListener(org.eclipse.jface.dialogs.IPageChangedListener)
	 * @since 3.1
	 */
	public void addPageChangedListener(IPageChangedListener listener) {
		pageChangedListeners.add(listener);
	}
	
	/**
	 * @see org.eclipse.jface.dialogs.IPageChangeProvider#removePageChangedListener(org.eclipse.jface.dialogs.IPageChangedListener)
	 * @since 3.1
	 */
	public void removePageChangedListener(IPageChangedListener listener) {
		pageChangedListeners.remove(listener);
		
	}

	/**
     * Notifies any selection changed listeners that the selected page
     * has changed.
     * Only listeners registered at the time this method is called are notified.
     *
     * @param event a selection changed event
     *
     * @see IPageChangedListener#pageChanged
     * 
     * @since 3.1
     */
    protected void firePageChanged(final PageChangedEvent event) {
        Object[] listeners = pageChangedListeners.getListeners();
        for (int i = 0; i < listeners.length; i++) {
            final IPageChangedListener l = (IPageChangedListener) listeners[i];
            SafeRunnable.run(new SafeRunnable() {
                public void run() {
                    l.pageChanged(event);
                }
            });
        }
    }	
}