Java tutorial
/******************************************************************************* * Copyright (c) 2012-2016 Codenvy, S.A. * All rights reserved. This program and the accompanying materials * are made available under the terms of the Eclipse Public License v1.0 * which accompanies this distribution, and is available at * http://www.eclipse.org/legal/epl-v10.html * * Contributors: * Codenvy, S.A. - initial API and implementation *******************************************************************************/ package org.eclipse.che.ide.ui.listbox; import com.google.gwt.core.client.GWT; import com.google.gwt.dom.client.Document; import com.google.gwt.dom.client.Element; import com.google.gwt.dom.client.InputElement; import com.google.gwt.dom.client.LabelElement; import com.google.gwt.dom.client.NodeList; import com.google.gwt.event.dom.client.BlurEvent; import com.google.gwt.event.dom.client.BlurHandler; import com.google.gwt.event.dom.client.ChangeEvent; import com.google.gwt.event.dom.client.ChangeHandler; import com.google.gwt.event.dom.client.HasChangeHandlers; import com.google.gwt.event.dom.client.MouseDownEvent; import com.google.gwt.event.dom.client.MouseDownHandler; import com.google.gwt.event.dom.client.MouseUpEvent; import com.google.gwt.event.dom.client.MouseUpHandler; import com.google.gwt.event.shared.HandlerRegistration; import com.google.gwt.user.client.ui.FlowPanel; import com.google.gwt.user.client.ui.FocusWidget; import com.google.gwt.user.client.ui.RadioButton; import com.google.gwt.user.client.ui.RootPanel; /** * Custom list box widget for use instead of com.google.gwt.user.client.ui.ListBox which based on select tag. * * @author Oleksii Orel */ public class CustomListBox extends FocusWidget implements HasChangeHandlers { private static final CustomListBoxResources RESOURCES = GWT.create(CustomListBoxResources.class); static { RESOURCES.getCSS().ensureInjected(); } private final LabelElement currentItemLabel = Document.get().createLabelElement(); private final FlowPanel optionsPanel = new FlowPanel(); private final String optionsGroupName = "listBox-" + Document.get().createUniqueId(); private int dropDownSize = 6; private int selectedIndex = -1; private int defaultSelectedIndex = -1; private boolean isActive = false; public static CustomListBox wrap(Element element) { // Assert that the element is attached. assert Document.get().getBody().isOrHasChild(element); CustomListBox customListBox = new CustomListBox(element); // Mark it attached and remember it for cleanup. customListBox.onAttach(); RootPanel.detachOnWindowClose(customListBox); return customListBox; } /** * Creates an empty custom list box. */ public CustomListBox() { super(Document.get().createDivElement()); Element listBoxElement = getElement(); listBoxElement.appendChild(currentItemLabel); listBoxElement.appendChild(optionsPanel.getElement()); listBoxElement.appendChild(RESOURCES.arrow().getSvg().getElement()); optionsPanel.setVisible(false); addDomHandler(new BlurHandler() { @Override public void onBlur(BlurEvent event) { optionsPanel.setVisible(false); isActive = false; } }, BlurEvent.getType()); addDomHandler(new MouseDownHandler() { @Override public void onMouseDown(MouseDownEvent event) { //Update isActive state. It actually when we lose onBlur event in the parent widget. isActive = isActive(getElement()); if (!isActive) { optionsPanel.setVisible(true); } } }, MouseDownEvent.getType()); addDomHandler(new MouseUpHandler() { @Override public void onMouseUp(MouseUpEvent event) { if (isActive) { optionsPanel.setVisible(!optionsPanel.isVisible()); } else { isActive = true; } } }, MouseUpEvent.getType()); addChangeHandler(new ChangeHandler() { @Override public void onChange(ChangeEvent event) { selectedIndex = -1; NodeList<Element> selectionElements = optionsPanel.getElement().getElementsByTagName("input"); for (int pos = 0; pos < selectionElements.getLength(); pos++) { InputElement inputElement = (InputElement) selectionElements.getItem(pos); if (inputElement.isChecked()) { //update currentItemLabel currentItemLabel.setInnerText(getItemText(pos)); selectedIndex = pos; break; } } if (selectedIndex == -1) { currentItemLabel.setInnerText(""); } } }); setStyleName(RESOURCES.getCSS().listBox()); } /** * This constructor may be used by subclasses to explicitly use an existing element. * * @param element * the element to be used */ protected CustomListBox(Element element) { super(element); } private InputElement getListItemElement(int index) { final Element optionElement = (Element) optionsPanel.getElement().getChild(index); return (InputElement) optionElement.getElementsByTagName("input").getItem(0); } /** * Adds an ChangeHandler. * * @param handler * the change handler */ public HandlerRegistration addChangeHandler(ChangeHandler handler) { return addDomHandler(handler, ChangeEvent.getType()); } /** * Adds an item to the list box. * * @param item * the text of the item to be added */ public void addItem(String item) { this.insertItem(item); } /** * Adds an item to the list box, specifying an initial value for the item. * * @param item * the text of the item to be added * @param value * the item's value, to be submitted if it is part of a * {@link com.google.gwt.user.client.ui.FormPanel}; cannot be <code>null</code> */ public void addItem(String item, String value) { this.insertItem(item, value); } /** * Removes all items from the list box. */ public void clear() { selectedIndex = -1; currentItemLabel.setInnerText(""); optionsPanel.getElement().removeAllChildren(); } /** * Gets the number of items present in the list box. * * @return the number of items */ public int getItemCount() { return optionsPanel.getElement().getChildCount(); } /** * Gets the text associated with the item at the specified index. * * @param index * the index of the item whose text is to be retrieved * @return the text associated with the item * @throws IndexOutOfBoundsException * if the index is out of range */ public String getItemText(int index) { checkIndex(index); final Element optionElement = (Element) optionsPanel.getElement().getChild(index); final LabelElement labelElement = (LabelElement) optionElement.getElementsByTagName("label").getItem(0); return labelElement.getInnerText(); } /** * Gets the text for currently selected item. If multiple items are selected, * this method will return the text of the first selected item. * * @return the text for selected item, or {@code null} if none is selected */ public String getSelectedItemText() { int index = getSelectedIndex(); return index == -1 ? null : getItemText(index); } /** * Gets the currently-selected item. * * @return the selected index, or <code>-1</code> if none is selected */ public int getSelectedIndex() { return selectedIndex; } /** * Gets the value associated with the item at a given index. * * @param index * the index of the item to be retrieved * @return the item's associated value * @throws IndexOutOfBoundsException * if the index is out of range */ public String getValue(int index) { checkIndex(index); final Element optionElement = (Element) optionsPanel.getElement().getChild(index); final InputElement inputElement = (InputElement) optionElement.getElementsByTagName("input").getItem(0); return inputElement.getValue(); } /** * Gets the value for currently selected item. * * @return the value for selected item, or {@code null} if none is selected */ public String getValue() { int index = getSelectedIndex(); return index == -1 ? null : getValue(index); } /** * Inserts an item into the custom list box. * * @param item * the text of the item to be inserted */ public void insertItem(String item) { this.insertItem(item, item); } /** * Inserts an item into the list box. * * @param item * the text of the item to be inserted. * @param value * the item's value. */ public void insertItem(String item, String value) { //create new widget final RadioButton radioButton = new RadioButton(optionsGroupName, item); //remove the default gwt-RadioButton style radioButton.removeStyleName("gwt-RadioButton"); //set value final InputElement inputElement = (InputElement) radioButton.getElement().getElementsByTagName("input") .getItem(0); inputElement.removeAttribute("tabindex"); inputElement.setAttribute("value", value); //set default state if (defaultSelectedIndex > -1 && optionsPanel.getElement().getChildCount() == defaultSelectedIndex) { inputElement.setChecked(true); currentItemLabel.setInnerText(item); } //add to widget optionsPanel.add(radioButton); } /** * Sets custom height inside widget as height and line-height properties. * * @param height */ public void setHeight(String height) { this.getElement().getStyle().setProperty("height", height); currentItemLabel.getStyle().setProperty("lineHeight", height); optionsPanel.getElement().getStyle().setProperty("lineHeight", height); optionsPanel.getElement().getStyle().setProperty("maxHeight", "calc(" + dropDownSize + "*" + height + ")"); } /** * Sets dropdown part size. * * @param dropDownSize * @throws IndexOutOfBoundsException * if the index is out of range */ public void setSize(int dropDownSize) { if (dropDownSize < 1 || dropDownSize > 99) { throw new IndexOutOfBoundsException(); } this.dropDownSize = dropDownSize; } /** * Determines whether an individual list item is selected. * * @param index * the index of the item to be tested * @return <code>true</code> if the item is selected * @throws IndexOutOfBoundsException * if the index is out of range */ public boolean isItemSelected(int index) { checkIndex(index); return selectedIndex == index; } /** * Removes the item at the specified index. * * @param index * the index of the item to be removed * @throws IndexOutOfBoundsException * if the index is out of range */ public void removeItem(int index) { checkIndex(index); if (index == selectedIndex) { currentItemLabel.setInnerText(""); selectedIndex = -1; } optionsPanel.getElement().removeChild(optionsPanel.getElement().getChild(index)); } /** * Sets whether an individual list item is selected. * * @param index * the index of the item to be selected or unselected * @param selected * <code>true</code> to select the item */ public void setItemSelected(int index, boolean selected) { if (index < 0 || index >= getItemCount()) { return; } if (selected) { selectedIndex = index; currentItemLabel.setInnerText(getItemText(index)); } final InputElement inputElement = getListItemElement(index); inputElement.setChecked(selected); } /** * Sets the text associated with the item at a given index. * * @param index * the index of the item to be set * @param text * the item's new text * @throws IndexOutOfBoundsException * if the index is out of range */ public void setItemText(int index, String text) { checkIndex(index); final Element optionElement = (Element) optionsPanel.getElement().getChild(index); final LabelElement labelElement = (LabelElement) optionElement.getElementsByTagName("label").getItem(0); labelElement.setInnerText(text); if (selectedIndex == index) { currentItemLabel.setInnerText(text); } } /** * Sets the currently selected index. * * @param index * the index of the item to be selected */ public void setSelectedIndex(int index) { if (index < 0) { return; } //set default index if not added options yet if (index >= getItemCount()) { defaultSelectedIndex = index; return; } selectedIndex = index; currentItemLabel.setInnerText(getItemText(index)); InputElement inputElement = getListItemElement(index); inputElement.setChecked(true); } /** * Selects an item with given text. * * @param text * text of an item to be selected */ public void select(String text) { // uncheck previous value if (selectedIndex >= 0) { InputElement inputElement = getListItemElement(selectedIndex); inputElement.setChecked(false); } // find and select a new one if (text != null) { for (int i = 0; i < getItemCount(); i++) { if (text.equals(getItemText(i))) { setSelectedIndex(i); return; } } } // clear the selection selectedIndex = -1; currentItemLabel.setInnerText(""); } /** * Sets the value associated with the item at a given index. * * @param index * the index of the item to be set * @param value * the item's new value * @throws IndexOutOfBoundsException * if the index is out of range */ public void setValue(int index, String value) { checkIndex(index); final InputElement inputElement = getListItemElement(index); inputElement.setValue(value); } /** * @see com.google.gwt.user.client.ui.UIObject#onEnsureDebugId(String) */ @Override protected void onEnsureDebugId(String baseID) { super.onEnsureDebugId(baseID); } private void checkIndex(int index) { if (index < 0 || index >= getItemCount()) { throw new IndexOutOfBoundsException(); } } /** * Check isActive status. */ private native boolean isActive(Element element) /*-{ var activeElement = $doc.activeElement; return activeElement.isEqualNode(element); }-*/; }