com.google.gwt.user.client.ui.ListBox Maven / Gradle / Ivy
/*
* Copyright 2008 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.user.client.ui;
import com.google.gwt.dom.client.Document;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.OptionElement;
import com.google.gwt.dom.client.SelectElement;
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.shared.HandlerRegistration;
import com.google.gwt.i18n.client.HasDirection.Direction;
import com.google.gwt.i18n.shared.BidiFormatter;
import com.google.gwt.i18n.shared.DirectionEstimator;
import com.google.gwt.i18n.shared.HasDirectionEstimator;
import com.google.gwt.i18n.shared.WordCountDirectionEstimator;
/**
* A widget that presents a list of choices to the user, either as a list box or
* as a drop-down list.
*
*
* 
*
*
* CSS Style Rules
*
* - .gwt-ListBox { }
*
*
*
*
Example
* {@example com.google.gwt.examples.ListBoxExample}
*
*
*
*
Built-in Bidi Text Support
* This widget is capable of automatically adjusting its direction according to
* its content. This feature is controlled by {@link #setDirectionEstimator},
* and is off by default.
*
*
* Use in UiBinder Templates
*
* The items of a ListBox element are laid out in <g:item> elements.
* Each item contains text that will be added to the list of available
* items that will be shown, either in the drop down or list. (Note that
* the tags of the item elements are not capitalized. This is meant to
* signal that the item is not a runtime object, and so cannot have a
* ui:field attribute.) It is also possible to explicitly
* specify item's value using value attribute as shown below.
*
* For example:
*
*
* <g:ListBox>
* <g:item>
* first
* </g:item>
* <g:item value='2'>
* second
* </g:item>
* </g:ListBox>
*
*
*
Important usage note
* Subclasses should neither read nor write option text directly from the
* option elements created by this class, since such text may need to be wrapped
* in Unicode bidi formatting characters. They can use the getOptionText and/or
* setOptionText methods for this purpose instead.
*/
@SuppressWarnings("deprecation")
public class ListBox extends FocusWidget implements SourcesChangeEvents,
HasChangeHandlers, HasName, HasDirectionEstimator {
public static final DirectionEstimator DEFAULT_DIRECTION_ESTIMATOR =
WordCountDirectionEstimator.get();
private static final String BIDI_ATTR_NAME = "bidiwrapped";
private static final int INSERT_AT_END = -1;
/**
* Creates a ListBox widget that wraps an existing <select> element.
*
* This element must already be attached to the document. If the element is
* removed from the document, you must call
* {@link RootPanel#detachNow(Widget)}.
*
* @param element the element to be wrapped
* @return list box
*/
public static ListBox wrap(Element element) {
// Assert that the element is attached.
assert Document.get().getBody().isOrHasChild(element);
ListBox listBox = new ListBox(element);
// Mark it attached and remember it for cleanup.
listBox.onAttach();
RootPanel.detachOnWindowClose(listBox);
return listBox;
}
private DirectionEstimator estimator;
/**
* Creates an empty list box in single selection mode.
*/
public ListBox() {
this(false);
}
/**
* Creates an empty list box. The preferred way to enable multiple selections
* is to use this constructor rather than {@link #setMultipleSelect(boolean)}.
*
* @param isMultipleSelect specifies if multiple selection is enabled
*/
public ListBox(boolean isMultipleSelect) {
super(Document.get().createSelectElement(isMultipleSelect));
setStyleName("gwt-ListBox");
}
/**
* This constructor may be used by subclasses to explicitly use an existing
* element. This element must be a <select> element.
*
* @param element the element to be used
*/
protected ListBox(Element element) {
super(element);
SelectElement.as(element);
}
public HandlerRegistration addChangeHandler(ChangeHandler handler) {
return addDomHandler(handler, ChangeEvent.getType());
}
/**
* @deprecated Use {@link #addChangeHandler} instead
*/
@Deprecated
public void addChangeListener(ChangeListener listener) {
ListenerWrapper.WrappedChangeListener.add(this, listener);
}
/**
* Adds an item to the list box. This method has the same effect as
*
*
* addItem(item, item)
*
*
* @param item the text of the item to be added
*/
public void addItem(String item) {
insertItem(item, INSERT_AT_END);
}
/**
* Adds an item to the list box, specifying its direction. This method has the
* same effect as
*
*
* addItem(item, dir, item)
*
*
* @param item the text of the item to be added
* @param dir the item's direction
*/
public void addItem(String item, Direction dir) {
insertItem(item, dir, INSERT_AT_END);
}
/**
* 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 FormPanel}; cannot be null
*/
public void addItem(String item, String value) {
insertItem(item, value, INSERT_AT_END);
}
/**
* Adds an item to the list box, specifying its direction and an initial value
* for the item.
*
* @param item the text of the item to be added
* @param dir the item's direction
* @param value the item's value, to be submitted if it is part of a
* {@link FormPanel}; cannot be null
*/
public void addItem(String item, Direction dir, String value) {
insertItem(item, dir, value, INSERT_AT_END);
}
/**
* Removes all items from the list box.
*/
public void clear() {
getSelectElement().clear();
}
public DirectionEstimator getDirectionEstimator() {
return estimator;
}
/**
* Gets the number of items present in the list box.
*
* @return the number of items
*/
public int getItemCount() {
return getSelectElement().getOptions().getLength();
}
/**
* 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);
return getOptionText(getSelectElement().getOptions().getItem(index));
}
public String getName() {
return getSelectElement().getName();
}
/**
* Gets the currently-selected item. If multiple items are selected, this
* method will return the first selected item ({@link #isItemSelected(int)}
* can be used to query individual items).
*
* @return the selected index, or -1 if none is selected
*/
public int getSelectedIndex() {
return getSelectElement().getSelectedIndex();
}
/**
* 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);
return getSelectElement().getOptions().getItem(index).getValue();
}
/**
* Gets the number of items that are visible. If only one item is visible,
* then the box will be displayed as a drop-down list.
*
* @return the visible item count
*/
public int getVisibleItemCount() {
return getSelectElement().getSize();
}
/**
* Inserts an item into the list box. Has the same effect as
*
*
* insertItem(item, item, index)
*
*
* @param item the text of the item to be inserted
* @param index the index at which to insert it
*/
public void insertItem(String item, int index) {
insertItem(item, item, index);
}
/**
* Inserts an item into the list box, specifying its direction. Has the same
* effect as
*
*
* insertItem(item, dir, item, index)
*
*
* @param item the text of the item to be inserted
* @param dir the item's direction
* @param index the index at which to insert it
*/
public void insertItem(String item, Direction dir, int index) {
insertItem(item, dir, item, index);
}
/**
* Inserts an item into the list box, specifying an initial value for the
* item. Has the same effect as
*
*
* insertItem(item, null, value, index)
*
*
* @param item the text of the item to be inserted
* @param value the item's value, to be submitted if it is part of a
* {@link FormPanel}.
* @param index the index at which to insert it
*/
public void insertItem(String item, String value, int index) {
insertItem(item, null, value, index);
}
/**
* Inserts an item into the list box, specifying its direction and an initial
* value for the item. If the index is less than zero, or greater than or
* equal to the length of the list, then the item will be appended to the end
* of the list.
*
* @param item the text of the item to be inserted
* @param dir the item's direction. If {@code null}, the item is displayed in
* the widget's overall direction, or, if a direction estimator has
* been set, in the item's estimated direction.
* @param value the item's value, to be submitted if it is part of a
* {@link FormPanel}.
* @param index the index at which to insert it
*/
public void insertItem(String item, Direction dir, String value, int index) {
SelectElement select = getSelectElement();
OptionElement option = Document.get().createOptionElement();
setOptionText(option, item, dir);
option.setValue(value);
int itemCount = select.getLength();
if (index < 0 || index > itemCount) {
index = itemCount;
}
if (index == itemCount) {
select.add(option, null);
} else {
OptionElement before = select.getOptions().getItem(index);
select.add(option, before);
}
}
/**
* Determines whether an individual list item is selected.
*
* @param index the index of the item to be tested
* @return true if the item is selected
* @throws IndexOutOfBoundsException if the index is out of range
*/
public boolean isItemSelected(int index) {
checkIndex(index);
return getSelectElement().getOptions().getItem(index).isSelected();
}
/**
* Gets whether this list allows multiple selection.
*
* @return true if multiple selection is allowed
*/
public boolean isMultipleSelect() {
return getSelectElement().isMultiple();
}
/**
* @deprecated Use the {@link HandlerRegistration#removeHandler}
* method on the object returned by {@link #addChangeHandler} instead
*/
@Deprecated
public void removeChangeListener(ChangeListener listener) {
ListenerWrapper.WrappedChangeListener.remove(this, listener);
}
/**
* 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);
getSelectElement().remove(index);
}
/**
* {@inheritDoc}
* See note at
* {@link #setDirectionEstimator(com.google.gwt.i18n.shared.DirectionEstimator)}
*/
public void setDirectionEstimator(boolean enabled) {
setDirectionEstimator(enabled ? DEFAULT_DIRECTION_ESTIMATOR : null);
}
/**
* {@inheritDoc}
* Note: this does not affect the direction of already-existing content.
*/
public void setDirectionEstimator(DirectionEstimator directionEstimator) {
estimator = directionEstimator;
}
/**
* Sets whether an individual list item is selected.
*
*
* Note that setting the selection programmatically does not cause
* the {@link ChangeHandler#onChange(ChangeEvent)} event to be fired.
*
*
* @param index the index of the item to be selected or unselected
* @param selected true to select the item
* @throws IndexOutOfBoundsException if the index is out of range
*/
public void setItemSelected(int index, boolean selected) {
checkIndex(index);
getSelectElement().getOptions().getItem(index).setSelected(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) {
setItemText(index, text, null);
}
/**
* 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
* @param dir the item's direction.
* @throws IndexOutOfBoundsException if the index is out of range
*/
public void setItemText(int index, String text, Direction dir) {
checkIndex(index);
if (text == null) {
throw new NullPointerException("Cannot set an option to have null text");
}
setOptionText(getSelectElement().getOptions().getItem(index), text, dir);
}
/**
* Sets whether this list allows multiple selections. NOTE: The preferred
* way of enabling multiple selections in a list box is by using the
* {@link #ListBox(boolean)} constructor. Using this method can spuriously
* fail on Internet Explorer 6.0.
*
* @param multiple true to allow multiple selections
* @deprecated use {@link #ListBox(boolean)} instead
*/
@Deprecated
public void setMultipleSelect(boolean multiple) {
getSelectElement().setMultiple(multiple);
}
public void setName(String name) {
getSelectElement().setName(name);
}
/**
* Sets the currently selected index.
*
* After calling this method, only the specified item in the list will remain
* selected. For a ListBox with multiple selection enabled, see
* {@link #setItemSelected(int, boolean)} to select multiple items at a time.
*
*
* Note that setting the selected index programmatically does not
* cause the {@link ChangeHandler#onChange(ChangeEvent)} event to be fired.
*
*
* @param index the index of the item to be selected
*/
public void setSelectedIndex(int index) {
getSelectElement().setSelectedIndex(index);
}
/**
* Sets the value associated with the item at a given index. This value can be
* used for any purpose, but is also what is passed to the server when the
* list box is submitted as part of a {@link FormPanel}.
*
* @param index the index of the item to be set
* @param value the item's new value; cannot be null
* @throws IndexOutOfBoundsException if the index is out of range
*/
public void setValue(int index, String value) {
checkIndex(index);
getSelectElement().getOptions().getItem(index).setValue(value);
}
/**
* Sets the number of items that are visible. If only one item is visible,
* then the box will be displayed as a drop-down list.
*
* @param visibleItems the visible item count
*/
public void setVisibleItemCount(int visibleItems) {
getSelectElement().setSize(visibleItems);
}
/**
* Retrieves the text of an option element. If the text was set by
* {@link #setOptionText} and was wrapped with Unicode bidi formatting
* characters, also removes those additional formatting characters.
*
* @param option an option element
* @return the element's text
*/
protected String getOptionText(OptionElement option) {
String text = option.getText();
if (option.hasAttribute(BIDI_ATTR_NAME) && text.length() > 1) {
text = text.substring(1, text.length() - 1);
}
return text;
}
/**
* Affected Elements:
*
* - -item# = the option at the specified index.
*
*
* @see UIObject#onEnsureDebugId(String)
*/
@Override
protected void onEnsureDebugId(String baseID) {
super.onEnsureDebugId(baseID);
// Set the id of each option
int numItems = getItemCount();
for (int i = 0; i < numItems; i++) {
ensureDebugId(getSelectElement().getOptions().getItem(i), baseID, "item"
+ i);
}
}
/**
* Sets the text of an option element. If the direction of the text is
* opposite to the page's direction, also wraps it with Unicode bidi
* formatting characters to prevent garbling, and indicates that this was done
* by setting the option's BIDI_ATTR_NAME custom attribute.
*
* @param option an option element
* @param text text to be set to the element
* @param dir the text's direction. If {@code null} and direction estimation
* is turned off, direction is ignored.
*/
protected void setOptionText(OptionElement option, String text,
Direction dir) {
if (dir == null && estimator != null) {
dir = estimator.estimateDirection(text);
}
if (dir == null) {
option.setText(text);
option.removeAttribute(BIDI_ATTR_NAME);
} else {
String formattedText =
BidiFormatter.getInstanceForCurrentLocale().unicodeWrapWithKnownDir(
dir, text, false /* isHtml */, false /* dirReset */);
option.setText(formattedText);
if (formattedText.length() > text.length()) {
option.setAttribute(BIDI_ATTR_NAME, "");
} else {
option.removeAttribute(BIDI_ATTR_NAME);
}
}
}
private void checkIndex(int index) {
if (index < 0 || index >= getItemCount()) {
throw new IndexOutOfBoundsException();
}
}
private SelectElement getSelectElement() {
return getElement().cast();
}
}