Java tutorial
/* * Copyright 2010 Google Inc. * Copyright (C) 2011 University of Washington * * 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 org.opendatakit.common.web.client; import com.google.gwt.cell.client.AbstractEditableCell; import com.google.gwt.cell.client.ValueUpdater; import com.google.gwt.dom.client.Element; import com.google.gwt.dom.client.InputElement; import com.google.gwt.dom.client.NativeEvent; import com.google.gwt.event.dom.client.KeyCodes; import com.google.gwt.safehtml.shared.SafeHtml; import com.google.gwt.safehtml.shared.SafeHtmlBuilder; import com.google.gwt.safehtml.shared.SafeHtmlUtils; /** * This is a simple checkbox -- it is copied from CheckboxCell GWT 2.3.0 * and the functionality to support radio buttons (SelectionManager) has * been removed. This checkbox supports validation of the selection choice, * visibility of the control, and the enabled/disabled state of the checkbox. * If all of the predicates are null (any or all of them can be), this * behaves as a CheckboxCell not managed by a SelectionManager. * * @author mitchellsundt@gmail.com * * @param <T> */ public class UIEnabledValidatingCheckboxCell<T> extends AbstractEditableCell<Boolean, Boolean> { /** * An html string representation of a checked input box. */ private static final SafeHtml INPUT_CHECKED = SafeHtmlUtils .fromSafeConstant("<input type=\"checkbox\" tabindex=\"-1\" checked/>"); /** * An html string representation of a disabled checked input box. */ private static final SafeHtml INPUT_DISABLED_CHECKED = SafeHtmlUtils .fromSafeConstant("<input type=\"checkbox\" tabindex=\"-1\" checked disabled/>"); /** * An html string representation of an unchecked input box. */ private static final SafeHtml INPUT_UNCHECKED = SafeHtmlUtils .fromSafeConstant("<input type=\"checkbox\" tabindex=\"-1\"/>"); /** * An html string representation of an disabled unchecked input box. */ private static final SafeHtml INPUT_DISABLED_UNCHECKED = SafeHtmlUtils .fromSafeConstant("<input type=\"checkbox\" tabindex=\"-1\" disabled/>"); private final BooleanValidationPredicate<T> validationPredicate; private final UIEnabledPredicate<T> isEnabledPredicate; private final UIVisiblePredicate<T> isVisiblePredicate; /** * Construct a new {@link UIEnabledValidatingCheckboxCell}. */ public UIEnabledValidatingCheckboxCell(BooleanValidationPredicate<T> validationPredicate, UIVisiblePredicate<T> isVisiblePredicate) { this(validationPredicate, isVisiblePredicate, null); } public UIEnabledValidatingCheckboxCell(BooleanValidationPredicate<T> validationPredicate, UIEnabledPredicate<T> isEnabledPredicate) { this(validationPredicate, null, isEnabledPredicate); } /** * Construct a new {@link UIEnabledValidatingCheckboxCell}. * * @param validationPredicate * true if the supplied value is OK (will reset to the inverse if fails). * If null, will the supplied value is always be accepted. * @param isVisiblePredicate * true if the cell should be visible. If null, always visible. * @param isEnabledPredicate * true if the cell should be enabled. If null, always enabled. */ public UIEnabledValidatingCheckboxCell(BooleanValidationPredicate<T> validationPredicate, UIVisiblePredicate<T> isVisiblePredicate, UIEnabledPredicate<T> isEnabledPredicate) { super("change", "keydown"); this.validationPredicate = validationPredicate; this.isVisiblePredicate = isVisiblePredicate; this.isEnabledPredicate = isEnabledPredicate; } @Override public boolean dependsOnSelection() { return false; } @Override public boolean handlesSelection() { return false; } @Override public boolean isEditing(Context context, Element parent, Boolean value) { // A checkbox is never in "edit mode". There is no intermediate state // between checked and unchecked. return false; } @SuppressWarnings("unchecked") @Override public void onBrowserEvent(Context context, Element parent, Boolean value, NativeEvent event, ValueUpdater<Boolean> valueUpdater) { String type = event.getType(); boolean enterPressed = "keydown".equals(type) && event.getKeyCode() == KeyCodes.KEY_ENTER; if ("change".equals(type) || enterPressed) { InputElement input = parent.getFirstChild().cast(); Boolean isChecked = input.isChecked(); Object key = context.getKey(); if (isEnabledPredicate != null && !isEnabledPredicate.isEnabled((T) key)) { // disabled checkbox -- no changes! return; } /* * Toggle the value if the enter key was pressed; this brings * the key-press event path in line with a mouse-click event path. */ if (enterPressed) { isChecked = !isChecked; input.setChecked(isChecked); } /* * See if this is a valid action for this checkbox. */ boolean changed = true; if (validationPredicate != null && !validationPredicate.isValid(isChecked, (T) key)) { isChecked = !isChecked; changed = false; } /* * Save the new value. */ if (value != isChecked) { setViewData(context.getKey(), isChecked); } else { clearViewData(context.getKey()); } // redraw our parent with the value we ended up with... SafeHtmlBuilder sb = new SafeHtmlBuilder(); render(context, isChecked, sb); parent.setInnerHTML(sb.toSafeHtml().asString()); // apparently the element never gains focus... if (changed) { // do value-change action... if (valueUpdater != null) { valueUpdater.update(isChecked); } } } } @SuppressWarnings("unchecked") @Override public void render(Context context, Boolean value, SafeHtmlBuilder sb) { // Get the view data. Object key = context.getKey(); Boolean viewData = getViewData(key); if (viewData != null && viewData.equals(value)) { clearViewData(key); viewData = null; } if (isVisiblePredicate == null || isVisiblePredicate.isVisible((T) key)) { if (value != null && ((viewData != null) ? viewData : value)) { if (isEnabledPredicate == null || isEnabledPredicate.isEnabled((T) key)) { sb.append(INPUT_CHECKED); } else { sb.append(INPUT_DISABLED_CHECKED); } } else { if (isEnabledPredicate == null || isEnabledPredicate.isEnabled((T) key)) { sb.append(INPUT_UNCHECKED); } else { sb.append(INPUT_DISABLED_UNCHECKED); } } } } }