All Downloads are FREE. Search and download functionalities are using the official Maven repository.

com.google.gwt.cell.client.Cell Maven / Gradle / Ivy

Go to download

Vaadin is a web application framework for Rich Internet Applications (RIA). Vaadin enables easy development and maintenance of fast and secure rich web applications with a stunning look and feel and a wide browser support. It features a server-side architecture with the majority of the logic running on the server. Ajax technology is used at the browser-side to ensure a rich and interactive user experience.

There is a newer version: 8.27.1
Show newest version
/*
 * Copyright 2010 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.google.gwt.cell.client;

import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.NativeEvent;
import com.google.gwt.safehtml.shared.SafeHtmlBuilder;

import java.util.Set;

/**
 * A lightweight representation of a renderable object.
 * 
 * 

* Multiple cell widgets or Columns can share a single Cell instance, but there * may be implications for certain stateful Cells. Generally, Cells are * stateless flyweights that see the world as row values/keys. If a Column * contains duplicate row values/keys, the Cell will not differentiate the value * in one row versus another. Similarly, if you use a single Cell instance in * multiple Columns, the Cells will not differentiate the values coming from one * Column versus another. *

* *

* However, some interactive Cells ({@link EditTextCell}, {@link CheckboxCell}, * {@link TextInputCell}, etc...) have a stateful "pending" state, which is a * map of row values/keys to the end user entered pending value. For example, if * an end user types a new value in a {@link TextInputCell}, the * {@link TextInputCell} maps the "pending value" and associates it with the * original row value/key. The next time the Cell Widget renders that row * value/key, the Cell renders the pending value instead. This allows * applications to refresh the Cell Widget without clearing out all of the end * user's pending changes. In subclass of {@link AbstractEditableCell}, the * pending state remains until either the original value is updated (a * successful commit), or until * {@link AbstractEditableCell#clearViewData(Object)} is called (a failed * commit). *

* *

* If you share an interactive Cell between two cell widgets (or Columns within * the same CellTable), then when the end user updates the pending value in one * widget, it will be reflected in the other widget when the other widget is * redrawn. You should base your decision on whether or not to share Cell * instances on this behavior. *

* *

*

Example

* {@example com.google.gwt.examples.cell.CellExample} *

* *

* Warning: The Cell interface may change in subtle but breaking ways as we * continuously seek to improve performance. You should always subclass {@link AbstractCell} instead * of implementing {@link Cell} directly. *

* * @param the type that this Cell represents */ public interface Cell { /** * Contains information about the context of the Cell. */ public static class Context { private final int column; private final int index; private final Object key; private final int subindex; /** * Create a new {@link Context}. * * @param index the absolute index of the value * @param column the column index of the cell, or 0 * @param key the unique key that represents the row value */ public Context(int index, int column, Object key) { this(index, column, key, 0); } /** * Create a new {@link Context}. * * @param index the absolute index of the value * @param column the column index of the cell, or 0 * @param key the unique key that represents the row value * @param subindex the child index */ public Context(int index, int column, Object key, int subindex) { this.index = index; this.column = column; this.key = key; this.subindex = subindex; } /** * Get the column index of the cell. If the view only contains a single * column, this method returns 0. * * @return the column index of the cell */ public int getColumn() { return column; } /** * Get the absolute index of the value. * * @return the index */ public int getIndex() { return index; } /** * Get the key that uniquely identifies the row object. * * @return the unique key */ public Object getKey() { return key; } /** * Get the sub index of the rendered row value. If the row value renders to * a single row element, the sub index is 0. If the row value renders to * more than one row element, the sub index may be greater than zero. */ public int getSubIndex() { return subindex; } } /** * Check if this cell depends on the selection state. * * @return true if dependent on selection, false if not */ boolean dependsOnSelection(); /** * Get the set of events that this cell consumes (see * {@link com.google.gwt.dom.client.BrowserEvents BrowserEvents} for useful * constants). The container that uses this cell should only pass these events * to * {@link #onBrowserEvent(Context, Element, Object, NativeEvent, ValueUpdater)} * when the event occurs. * *

* The returned value should not be modified, and may be an unmodifiable set. * Changes to the return value may not be reflected in the cell. *

* * @return the consumed events, or null if no events are consumed * * @see com.google.gwt.dom.client.BrowserEvents */ Set getConsumedEvents(); /** * Check if this cell handles selection. If the cell handles selection, then * its container should not automatically handle selection. * * @return true if the cell handles selection, false if not */ boolean handlesSelection(); /** * Returns true if the cell is currently editing the data identified by the * given element and key. While a cell is editing, widgets containing the cell * may choose to pass keystrokes directly to the cell rather than using them * for navigation purposes. * * @param context the {@link Context} of the cell * @param parent the parent Element * @param value the value associated with the cell * @return true if the cell is in edit mode */ boolean isEditing(Context context, Element parent, C value); /** * Handle a browser event that took place within the cell. The default * implementation returns null. * * @param context the {@link Context} of the cell * @param parent the parent Element * @param value the value associated with the cell * @param event the native browser event * @param valueUpdater a {@link ValueUpdater}, or null if not specified */ void onBrowserEvent(Context context, Element parent, C value, NativeEvent event, ValueUpdater valueUpdater); /** * Render a cell as HTML into a {@link SafeHtmlBuilder}, suitable for passing * to {@link Element#setInnerHTML(String)} on a container element. * *

* Note: If your cell contains natively focusable elements, such as buttons or * input elements, be sure to set the tabIndex to -1 so that they do not steal * focus away from the containing widget. *

* * @param context the {@link Context} of the cell * @param value the cell value to be rendered * @param sb the {@link SafeHtmlBuilder} to be written to */ void render(Context context, C value, SafeHtmlBuilder sb); /** * Reset focus on the Cell. This method is called if the cell has focus when * it is refreshed. * * @param context the {@link Context} of the cell * @param parent the parent Element * @param value the value associated with the cell * @return true if focus is taken, false if not */ boolean resetFocus(Context context, Element parent, C value); /** * This method may be used by cell containers to set the value on a single * cell directly, rather than using {@link Element#setInnerHTML(String)}. See * {@link AbstractCell#setValue(Context, Element, Object)} for a default * implementation that uses {@link #render(Context, Object, SafeHtmlBuilder)}. * * @param context the {@link Context} of the cell * @param parent the parent Element * @param value the value associated with the cell */ void setValue(Context context, Element parent, C value); }




© 2015 - 2024 Weber Informatics LLC | Privacy Policy