Java tutorial
/* * Copyright 2010 bufferings[at]gmail.com * * 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 bufferings.ktr.wjr.client.ui.widget; import static bufferings.ktr.wjr.client.ui.widget.JQueryUI.*; import static bufferings.ktr.wjr.shared.util.Preconditions.*; import java.util.ArrayList; import java.util.List; import com.google.gwt.core.client.GWT; import com.google.gwt.event.dom.client.ClickEvent; import com.google.gwt.event.dom.client.ClickHandler; import com.google.gwt.event.dom.client.HasClickHandlers; import com.google.gwt.event.dom.client.KeyCodes; import com.google.gwt.event.shared.HandlerRegistration; import com.google.gwt.resources.client.ClientBundle; import com.google.gwt.resources.client.CssResource; import com.google.gwt.user.client.DOM; import com.google.gwt.user.client.Element; import com.google.gwt.user.client.Event; import com.google.gwt.user.client.ui.Composite; import com.google.gwt.user.client.ui.FlowPanel; import com.google.gwt.user.client.ui.FocusPanel; import com.google.gwt.user.client.ui.Label; import com.google.gwt.user.client.ui.Widget; /** * The simple list box with JQueryUI theme. * * @author bufferings[at]gmail.com */ public class WjrListBox extends Composite { protected static final int OTHER_KEY_DOWN = 63233; protected static final int OTHER_KEY_UP = 63232; /** * The resource client bundle for the WjrListBox. * * @author bufferings[at]gmail.com */ protected interface Resources extends ClientBundle { Resources INSTANCE = GWT.create(Resources.class); /** * The css resource. * * @return The css resource. */ @Source("WjrListBox.css") Css css(); } /** * CssResource used in the WjrListBox. * * @author bufferings[at]gmail.com */ protected interface Css extends CssResource { String itemStyle(); } /** * Hoverable and clickable label. * * @author bufferings[at]gmail.com */ protected static class HoverableAndClickableLabel extends Label implements HasClickHandlers { /** * Constructs the HoverableAndClickableLabel. */ public HoverableAndClickableLabel() { sinkEvents(Event.ONMOUSEOVER | Event.ONMOUSEOUT); } /** * {@inheritDoc} */ public void onBrowserEvent(Event event) { super.onBrowserEvent(event); switch (DOM.eventGetType(event)) { case Event.ONMOUSEOVER: if (getTitle().length() > 0) {// Title is never null, it's only empty // when not set. addStyleName(UI_STATE_HOVER); } break; case Event.ONMOUSEOUT: removeStyleName(UI_STATE_HOVER); break; } } /** * {@inheritDoc} */ @Override public HandlerRegistration addClickHandler(ClickHandler handler) { return addDomHandler(handler, ClickEvent.getType()); } } /** * The main panel. */ protected FlowPanel mainPanel; /** * The row items. */ protected List<Label> children = new ArrayList<Label>(); /** * The current selected row item. */ protected Widget curSelection; /** * For controling key events. */ protected boolean lastWasKeyDown; /** * The panel to get focus. */ protected FocusPanel focusPanel; /** * Constructs the WjrListBox. */ public WjrListBox() { Resources.INSTANCE.css().ensureInjected(); mainPanel = new FlowPanel(); focusPanel = new WjrNoBorderFocusPanel(mainPanel); initWidget(focusPanel); sinkEvents(Event.ONMOUSEDOWN | Event.ONCLICK | Event.KEYEVENTS); } /** * Sets the tab index. * * @param index * The tab index. */ public void setTabIndex(int index) { focusPanel.setTabIndex(index); } /** * Adds the item. * * @param item * The item to add. * @throws NullPointerException * If the item parameter is null. */ public void addItem(String item) { checkNotNull(item, "The item parameter is null."); Label label = new HoverableAndClickableLabel(); label.setStyleName(Resources.INSTANCE.css().itemStyle()); // Use trimedItem not to show prefix tab on the tooltip. String trimedItem = item.trim(); label.setTitle(trimedItem); if (trimedItem.length() == 0) { // Allows to show empty line. label.getElement().setInnerHTML(" "); } else { // HTML element is escaped. label.setText(item); } mainPanel.add(label); } /** * Clears the all items. */ public void clear() { mainPanel.clear(); } /** * {@inheritDoc} */ @Override public void onBrowserEvent(Event event) { int eventType = DOM.eventGetType(event); switch (eventType) { case Event.ONKEYDOWN: if (curSelection == null) { if (mainPanel.getWidgetCount() > 0) { setSelection(mainPanel.getWidget(0)); } super.onBrowserEvent(event); return; } } switch (eventType) { case Event.ONKEYDOWN: case Event.ONKEYPRESS: case Event.ONKEYUP: if (DOM.eventGetAltKey(event) || DOM.eventGetMetaKey(event)) { super.onBrowserEvent(event); return; } } switch (eventType) { case Event.ONMOUSEDOWN: { if ((DOM.eventGetCurrentTarget(event) == getElement()) && (event.getButton() == Event.BUTTON_LEFT)) { elementClicked(DOM.eventGetTarget(event)); } break; } case Event.ONKEYDOWN: { keyboardNavigation(event); lastWasKeyDown = true; break; } case Event.ONKEYPRESS: { if (!lastWasKeyDown) { keyboardNavigation(event); } lastWasKeyDown = false; break; } case Event.ONKEYUP: { lastWasKeyDown = false; break; } } switch (eventType) { case Event.ONKEYDOWN: case Event.ONKEYUP: { if (isArrowKey(DOM.eventGetKeyCode(event))) { DOM.eventCancelBubble(event, true); DOM.eventPreventDefault(event); return; } } } super.onBrowserEvent(event); } /** * Sets the selected item. * * @param item * The item to select. */ protected void setSelection(Widget item) { if (curSelection != null) { curSelection.setStyleName(Resources.INSTANCE.css().itemStyle()); } curSelection = item; if (curSelection != null) { curSelection.setStyleName(join(Resources.INSTANCE.css().itemStyle(), UI_STATE_HIGHLIGHT)); DOMUtil.scrollTopIntoView(curSelection.getElement()); } } private boolean elementClicked(Element hElem) { ArrayList<Element> chain = new ArrayList<Element>(); collectElementChain(chain, getElement(), hElem); Widget item = findItemByChain(chain, 0); if (item != null) { setSelection(item); return true; } return false; } private void collectElementChain(ArrayList<Element> chain, Element hRoot, Element hElem) { if ((hElem == null) || (hElem == hRoot)) { return; } collectElementChain(chain, hRoot, DOM.getParent(hElem)); chain.add(hElem); } private Widget findItemByChain(ArrayList<Element> chain, int idx) { if (idx == chain.size()) { return null; } Element hCurElem = chain.get(idx); for (int i = 0, n = mainPanel.getWidgetCount(); i < n; ++i) { Widget child = mainPanel.getWidget(i); if (child.getElement() == hCurElem) { return child; } } return findItemByChain(chain, idx + 1); } private void keyboardNavigation(Event event) { int code = DOM.eventGetKeyCode(event); switch (standardizeKeycode(code)) { case KeyCodes.KEY_UP: moveSelectionUp(curSelection); break; case KeyCodes.KEY_DOWN: moveSelectionDown(curSelection); break; default: return; } } private void moveSelectionDown(Widget sel) { int idx = mainPanel.getWidgetIndex(sel); if (idx < mainPanel.getWidgetCount() - 1) { setSelection(mainPanel.getWidget(idx + 1)); } } private void moveSelectionUp(Widget sel) { int idx = mainPanel.getWidgetIndex(sel); if (idx > 0) { setSelection(mainPanel.getWidget(idx - 1)); } } private boolean isArrowKey(int code) { switch (code) { case OTHER_KEY_DOWN: case OTHER_KEY_UP: case KeyCodes.KEY_DOWN: case KeyCodes.KEY_UP: return true; default: return false; } } private int standardizeKeycode(int code) { switch (code) { case OTHER_KEY_DOWN: code = KeyCodes.KEY_DOWN; break; case OTHER_KEY_UP: code = KeyCodes.KEY_UP; break; } return code; } }