| /******************************************************************************* |
| * Copyright (c) 2000, 2003 IBM Corporation and others. |
| * All rights reserved. This program and the accompanying materials |
| * are made available under the terms of the Common Public License v1.0 |
| * which accompanies this distribution, and is available at |
| * http://www.eclipse.org/legal/cpl-v10.html |
| * |
| * Contributors: |
| * IBM Corporation - initial API and implementation |
| *******************************************************************************/ |
| package org.eclipse.ui.views.properties; |
| |
| |
| /** |
| * Interface to an object which is capable of supplying properties for display by |
| * the standard property sheet page implementation (<code>PropertySheetPage</code>). |
| * <p> |
| * This interface should be implemented by clients. |
| * <code>PropertySheetPage</code> discovers the properties to display from |
| * currently selected elements. Elements that implement <code>IPropertySource</code> |
| * directly are included, as are elements that implement <code>IAdaptable</code> |
| * and have an <code>IPropertySource</code> adapter. Clients should implement |
| * this interface for any newly-defined elements that are to have properties |
| * displayable by <code>PropertySheetPage</code>. Note that in the latter case, |
| * the client will also need to register a suitable adapter factory with the |
| * platform's adapter manager (<code>Platform.getAdapterManager</code>). |
| * </p> |
| * |
| * @see org.eclipse.core.runtime.IAdaptable |
| * @see org.eclipse.core.runtime.Platform#getAdapterManager() |
| * @see org.eclipse.ui.views.properties.PropertySheetPage |
| */ |
| public interface IPropertySource { |
| |
| /** |
| * Returns a value for this property source that can be edited in a |
| * property sheet. |
| * <p> |
| * This value is used when this <code>IPropertySource</code> is appearing |
| * in the property sheet as the value of a property of some other |
| * <code>IPropertySource</code> |
| * </p> |
| * <p> |
| * This value is passed as the input to a cell editor opening on an |
| * <code>IPropertySource</code>. |
| * </p> |
| * <p> |
| * This value is also used when an <code>IPropertySource</code> is being |
| * used as the value in a <code>setPropertyValue</code> message. The reciever |
| * of the message would then typically use the editable value to update the |
| * original property source or construct a new instance. |
| * </p> |
| * <p> |
| * For example an email address which is a property source may have an |
| * editable value which is a string so that it can be edited in a text |
| * cell editor. The email address would also have a constructor or setter |
| * that takes the edited string so that an appropriate instance can be created |
| * or the original instance modified when the edited value is set. |
| * </p> |
| * <p> |
| * This behavior is important for another reason. When the property sheet is |
| * showing properties for more than one object (multiple selection), a property |
| * sheet entry will display and edit a single value (typically coming from |
| * the first selected object). After a property has been edited in a cell editor, |
| * the same value is set as the property value for all of the objects. This is |
| * fine for primitive types but otherwise all of the objects end up with a |
| * reference to the same value. Thus by creating an editable value and using it |
| * to update the state of the original property source object, one is able to |
| * edit several property source objects at once (multiple selection). |
| |
| * @return a value that can be edited |
| */ |
| public Object getEditableValue(); |
| /** |
| * Returns the list of property descriptors for this property source. |
| * The <code>getPropertyValue</code> and <code>setPropertyValue</code> methods |
| * are used to read and write the actual property values by specifying |
| * the property ids from these property descriptors. |
| * <p> |
| * Implementors should cache the descriptors as they will be asked for |
| * the descriptors with any edit/update. Since descriptors provide |
| * cell editors, returning the same descriptors if possible allows |
| * for efficient updating. |
| * </p> |
| * |
| * @return the property descriptors |
| */ |
| public IPropertyDescriptor[] getPropertyDescriptors(); |
| /** |
| * Returns the value of the property with the given id if it has one. |
| * Returns <code>null</code> if the property's value is <code>null</code> |
| * value or if this source does not have the specified property. |
| * |
| * @see #setPropertyValue |
| * |
| * @param id the id of the property being set |
| * @return the value of the property, or <code>null</code> |
| */ |
| public Object getPropertyValue(Object id); |
| /** |
| * Returns whether the value of the property with the given id has changed from |
| * its default value. Returns <code>false</code> if the notion of default value |
| * is not meaningful for the specified property, or if this source does not have |
| * the specified property. |
| * |
| * @param id the id of the property |
| * @return <code>true</code> if the value of the specified property has changed |
| * from its original default value, and <code>false</code> otherwise |
| */ |
| public boolean isPropertySet(Object id); |
| /** |
| * Resets the property with the given id to its default value if possible. |
| * Does nothing if the notion of default value is not meaningful for |
| * the specified property, or if the property's value cannot be changed, |
| * or if this source does not have the specified property. |
| * |
| * @param id the id of the property being reset |
| */ |
| public void resetPropertyValue(Object id); |
| /** |
| * Sets the property with the given id if possible. Does nothing if the |
| * property's value cannot be changed or if this source does not have the |
| * specified property. |
| * <p> |
| * In general, a property source should not directly reference the value |
| * parameter unless it is an atomic object that can be shared, such as a |
| * string. |
| * </p> |
| * <p> |
| * An important reason for this is that several property sources with |
| * compatible descriptors could be appearing in the property sheet at |
| * the same time. An editor produces a single edited value which is passed |
| * as the value parameter of this message to all the property sources. |
| * Thus to avoid a situation where all of the property sources reference |
| * the same value they should use the value parameter to create a |
| * new instance of the real value for the given property. |
| * </p> |
| * <p> |
| * There is another reason why a level of indirection is useful. The real |
| * value of property may be a type that cannot be edited with a standard cell |
| * editor. However instead of returning the real value in <code>getPropertyValue</code>, |
| * the value could be converted to a <code>String</code> which could be edited |
| * with a standard cell editor. The edited value will be passed to this method |
| * which can then turn it back into the real property value. |
| * </p> |
| * <p>Another variation on returning a value other than the real property value in |
| * <code>getPropertyValue</code> is to return a value which is an |
| * <code>IPropertySource</code> (or for which the property sheet can obtain an |
| * <code>IPropertySource</code>). In this case the value to edit is obtained from the |
| * child property source using <code>getEditableValue</code>. It is this editable value |
| * that will be passed back via this method when it has been editted |
| * </p> |
| * |
| * @see #getPropertyValue |
| * @see #getEditableValue |
| * |
| * @param id the id of the property being set |
| * @param value the new value for the property; <code>null</code> is allowed |
| */ |
| public void setPropertyValue(Object id, Object value); |
| } |
