javafx.scene.control.ComboBox Maven / Gradle / Ivy
Show all versions of openjfx-78-backport Show documentation
/*
* Copyright (c) 2010, 2013, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javafx.scene.control;
import javafx.collections.WeakListChangeListener;
import com.sun.javafx.scene.control.skin.ComboBoxListViewSkin;
import javafx.beans.InvalidationListener;
import javafx.beans.Observable;
import javafx.beans.property.*;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.beans.value.WeakChangeListener;
import javafx.collections.FXCollections;
import javafx.collections.ListChangeListener;
import javafx.collections.ObservableList;
import javafx.scene.Node;
import javafx.util.Callback;
import javafx.util.StringConverter;
/**
* An implementation of the {@link ComboBoxBase} abstract class for the most common
* form of ComboBox, where a popup list is shown to users providing them with
* a choice that they may select from. For more information around the general
* concepts and API of ComboBox, refer to the {@link ComboBoxBase} class
* documentation.
*
* On top of ComboBoxBase, the ComboBox class introduces additional API. Most
* importantly, it adds an {@link #itemsProperty() items} property that works in
* much the same way as the ListView {@link ListView#itemsProperty() items}
* property. In other words, it is the content of the items list that is displayed
* to users when they click on the ComboBox button.
*
*
By default, when the popup list is showing, the maximum number of rows
* visible is 10, but this can be changed by modifying the
* {@link #visibleRowCountProperty() visibleRowCount} property. If the number of
* items in the ComboBox is less than the value of visibleRowCount,
* then the items size will be used instead so that the popup list is not
* exceedingly long.
*
*
As with ListView, it is possible to modify the
* {@link javafx.scene.control.SelectionModel selection model} that is used,
* although this is likely to be rarely changed. This is because the ComboBox
* enforces the need for a {@link javafx.scene.control.SingleSelectionModel}
* instance, and it is not likely that there is much need for alternate
* implementations. Nonetheless, the option is there should use cases be found
* for switching the selection model.
*
*
As the ComboBox internally renders content with a ListView, API exists in
* the ComboBox class to allow for a custom cell factory to be set. For more
* information on cell factories, refer to the {@link Cell} and {@link ListCell}
* classes. It is important to note that if a cell factory is set on a ComboBox,
* cells will only be used in the ListView that shows when the ComboBox is
* clicked. If you also want to customize the rendering of the 'button' area
* of the ComboBox, you can set a custom {@link ListCell} instance in the
* {@link #buttonCellProperty() button cell} property. One way of doing this
* is with the following code (note the use of {@code setButtonCell}:
*
*
* {@code
* Callback, ListCell> cellFactory = ...;
* ComboBox comboBox = new ComboBox();
* comboBox.setItems(items);
* comboBox.setButtonCell(cellFactory.call(null));
* comboBox.setCellFactory(cellFactory);}
*
* Because a ComboBox can be {@link #editableProperty() editable}, and the
* default means of allowing user input is via a {@link TextField}, a
* {@link #converterProperty() string converter} property is provided to allow
* for developers to specify how to translate a users string into an object of
* type T, such that the {@link #valueProperty() value} property may contain it.
* By default the converter simply returns the String input as the user typed it,
* which therefore assumes that the type of the editable ComboBox is String. If
* a different type is specified and the ComboBox is to be editable, it is
* necessary to specify a custom {@link StringConverter}.
*
*
A warning about inserting Nodes into the ComboBox items list
* ComboBox allows for the items list to contain elements of any type, including
* {@link Node} instances. Putting nodes into
* the items list is strongly not recommended. This is because
* the default {@link #cellFactoryProperty() cell factory} simply inserts Node
* items directly into the cell, including in the ComboBox 'button' area too.
* Because the scenegraph only allows for Nodes to be in one place at a time,
* this means that when an item is selected it becomes removed from the ComboBox
* list, and becomes visible in the button area. When selection changes the
* previously selected item returns to the list and the new selection is removed.
*
* The recommended approach, rather than inserting Node instances into the
* items list, is to put the relevant information into the ComboBox, and then
* provide a custom {@link #cellFactoryProperty() cell factory}. For example,
* rather than use the following code:
*
*
* {@code
* ComboBox cmb = new ComboBox();
* cmb.getItems().addAll(
* new Rectangle(10, 10, Color.RED),
* new Rectangle(10, 10, Color.GREEN),
* new Rectangle(10, 10, Color.BLUE));}
*
* You should do the following:
*
*
* ComboBox<Color> cmb = new ComboBox<Color>();
* cmb.getItems().addAll(
* Color.RED,
* Color.GREEN,
* Color.BLUE);
*
* cmb.setCellFactory(new Callback<ListView<Color>, ListCell<Color>>() {
* @Override public ListCell<Color> call(ListView<Color> p) {
* return new ListCell<Color>() {
* private final Rectangle rectangle;
* {
* setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
* rectangle = new Rectangle(10, 10);
* }
*
* @Override protected void updateItem(Color item, boolean empty) {
* super.updateItem(item, empty);
*
* if (item == null || empty) {
* setGraphic(null);
* } else {
* rectangle.setFill(item);
* setGraphic(rectangle);
* }
* }
* };
* }
*});
*
* Admittedly the above approach is far more verbose, but it offers the
* required functionality without encountering the scenegraph constraints.
*
* @see ComboBoxBase
* @see Cell
* @see ListCell
* @see StringConverter
* @since JavaFX 2.1
*/
public class ComboBox extends ComboBoxBase {
/***************************************************************************
* *
* Static properties and methods *
* *
**************************************************************************/
private static StringConverter defaultStringConverter() {
return new StringConverter() {
@Override public String toString(T t) {
return t == null ? null : t.toString();
}
@Override public T fromString(String string) {
return (T) string;
}
};
}
/***************************************************************************
* *
* Constructors *
* *
**************************************************************************/
/**
* Creates a default ComboBox instance with an empty
* {@link #itemsProperty() items} list and default
* {@link #selectionModelProperty() selection model}.
*/
public ComboBox() {
this(FXCollections.observableArrayList());
}
/**
* Creates a default ComboBox instance with the provided items list and
* a default {@link #selectionModelProperty() selection model}.
*/
public ComboBox(ObservableList items) {
getStyleClass().add(DEFAULT_STYLE_CLASS);
setItems(items);
setSelectionModel(new ComboBoxSelectionModel(this));
// listen to the value property input by the user, and if the value is
// set to something that exists in the items list, we should update the
// selection model to indicate that this is the selected item
valueProperty().addListener(new ChangeListener() {
@Override public void changed(ObservableValue ov, T t, T t1) {
if (getItems() == null) return;
SelectionModel sm = getSelectionModel();
int index = getItems().indexOf(t1);
if (index == -1) {
sm.setSelectedItem(t1);
} else {
// we must compare the value here with the currently selected
// item. If they are different, we overwrite the selection
// properties to reflect the new value.
// We do this as there can be circumstances where there are
// multiple instances of a value in the ComboBox items list,
// and if we don't check here we may change the selection
// mistakenly because the indexOf above will return the first
// instance always, and selection may be on the second or
// later instances. This is RT-19227.
T selectedItem = sm.getSelectedItem();
if (selectedItem == null || ! selectedItem.equals(getValue())) {
sm.clearAndSelect(index);
}
}
}
});
editableProperty().addListener(new InvalidationListener() {
@Override public void invalidated(Observable o) {
// when editable changes, we reset the selection / value states
getSelectionModel().clearSelection();
}
});
}
/***************************************************************************
* *
* Properties *
* *
**************************************************************************/
// --- items
/**
* The list of items to show within the ComboBox popup.
*/
private ObjectProperty> items = new SimpleObjectProperty>(this, "items") {
@Override protected void invalidated() {
// FIXME temporary fix for RT-15793. This will need to be
// properly fixed when time permits
if (getSelectionModel() instanceof ComboBoxSelectionModel) {
((ComboBoxSelectionModel)getSelectionModel()).updateItemsObserver(null, getItems());
}
if (getSkin() instanceof ComboBoxListViewSkin) {
ComboBoxListViewSkin skin = (ComboBoxListViewSkin) getSkin();
skin.updateListViewItems();
}
}
};
public final void setItems(ObservableList value) { itemsProperty().set(value); }
public final ObservableList getItems() {return items.get(); }
public ObjectProperty> itemsProperty() { return items; }
// --- string converter
/**
* Converts the user-typed input (when the ComboBox is
* {@link #editableProperty() editable}) to an object of type T, such that
* the input may be retrieved via the {@link #valueProperty() value} property.
*/
public ObjectProperty> converterProperty() { return converter; }
private ObjectProperty> converter =
new SimpleObjectProperty>(this, "converter", ComboBox.defaultStringConverter());
public final void setConverter(StringConverter value) { converterProperty().set(value); }
public final StringConverter getConverter() {return converterProperty().get(); }
// --- cell factory
/**
* Providing a custom cell factory allows for complete customization of the
* rendering of items in the ComboBox. Refer to the {@link Cell} javadoc
* for more information on cell factories.
*/
private ObjectProperty, ListCell>> cellFactory =
new SimpleObjectProperty, ListCell>>(this, "cellFactory");
public final void setCellFactory(Callback, ListCell> value) { cellFactoryProperty().set(value); }
public final Callback, ListCell> getCellFactory() {return cellFactoryProperty().get(); }
public ObjectProperty, ListCell>> cellFactoryProperty() { return cellFactory; }
// --- button cell
/**
* The button cell is used to render what is shown in the ComboBox 'button'
* area. If a cell is set here, it does not change the rendering of the
* ComboBox popup list - that rendering is controlled via the
* {@link #cellFactoryProperty() cell factory} API.
* @since JavaFX 2.2
*/
public ObjectProperty> buttonCellProperty() { return buttonCell; }
private ObjectProperty> buttonCell =
new SimpleObjectProperty>(this, "buttonCell");
public final void setButtonCell(ListCell value) { buttonCellProperty().set(value); }
public final ListCell getButtonCell() {return buttonCellProperty().get(); }
// --- Selection Model
/**
* The selection model for the ComboBox. A ComboBox only supports
* single selection.
*/
private ObjectProperty> selectionModel = new SimpleObjectProperty>(this, "selectionModel") {
private SingleSelectionModel oldSM = null;
@Override protected void invalidated() {
if (oldSM != null) {
oldSM.selectedItemProperty().removeListener(selectedItemListener);
}
SingleSelectionModel sm = get();
oldSM = sm;
if (sm != null) {
sm.selectedItemProperty().addListener(selectedItemListener);
}
}
};
public final void setSelectionModel(SingleSelectionModel value) { selectionModel.set(value); }
public final SingleSelectionModel getSelectionModel() { return selectionModel.get(); }
public final ObjectProperty> selectionModelProperty() { return selectionModel; }
// --- Visible Row Count
/**
* The maximum number of rows to be visible in the ComboBox popup when it is
* showing. By default this value is 10, but this can be changed to increase
* or decrease the height of the popup.
*/
private IntegerProperty visibleRowCount
= new SimpleIntegerProperty(this, "visibleRowCount", 10);
public final void setVisibleRowCount(int value) { visibleRowCount.set(value); }
public final int getVisibleRowCount() { return visibleRowCount.get(); }
public final IntegerProperty visibleRowCountProperty() { return visibleRowCount; }
// --- Editor
private TextField textField;
/**
* The editor for the ComboBox. The editor is null if the ComboBox is not
* {@link #editableProperty() editable}.
* @since JavaFX 2.2
*/
private ReadOnlyObjectWrapper editor;
public final TextField getEditor() {
return editorProperty().get();
}
public final ReadOnlyObjectProperty editorProperty() {
if (editor == null) {
editor = new ReadOnlyObjectWrapper(this, "editor");
textField = new TextField();
editor.set(textField);
}
return editor.getReadOnlyProperty();
}
// --- Placeholder Node
private ObjectProperty placeholder;
/**
* This Node is shown to the user when the ComboBox has no content to show.
* The placeholder node is shown in the ComboBox popup area
* when the items list is null or empty. This is different than the
* {@link #emptyTextProperty() emptyText} property, which is shown in the
* ComboBox Button / TextField area when there is no user-input value.
* @since JavaFX 8.0
*/
public final ObjectProperty placeholderProperty() {
if (placeholder == null) {
placeholder = new SimpleObjectProperty(this, "placeholder");
}
return placeholder;
}
public final void setPlaceholder(Node value) {
placeholderProperty().set(value);
}
public final Node getPlaceholder() {
return placeholder == null ? null : placeholder.get();
}
/***************************************************************************
* *
* Methods *
* *
**************************************************************************/
/** {@inheritDoc} */
@Override protected Skin createDefaultSkin() {
return new ComboBoxListViewSkin(this);
}
/***************************************************************************
* *
* Callbacks and Events *
* *
**************************************************************************/
// Listen to changes in the selectedItem property of the SelectionModel.
// When it changes, set the selectedItem in the value property.
private ChangeListener selectedItemListener = new ChangeListener() {
@Override public void changed(ObservableValue ov, T t, T t1) {
if (wasSetAllCalled && t1 == null) {
// no-op: fix for RT-22572 where the developer was completely
// replacing all items in the ComboBox, and expecting the
// selection (and ComboBox.value) to remain set. If this isn't
// here, we would updateValue(null).
// Additional fix for RT-22937: adding the '&& t1 == null'.
// Without this, there would be circumstances where the user
// selecting a new value from the ComboBox would end up in here,
// when we really should go into the updateValue(t1) call below.
// We should only ever go into this clause if t1 is null.
wasSetAllCalled = false;
} else {
updateValue(t1);
}
}
};
/***************************************************************************
* *
* Private methods *
* *
**************************************************************************/
private void updateValue(T newValue) {
if (! valueProperty().isBound()) {
setValue(newValue);
}
}
/***************************************************************************
* *
* Stylesheet Handling *
* *
**************************************************************************/
private static final String DEFAULT_STYLE_CLASS = "combo-box";
private boolean wasSetAllCalled = false;
private int previousItemCount = -1;
// package for testing
static class ComboBoxSelectionModel extends SingleSelectionModel {
private final ComboBox comboBox;
public ComboBoxSelectionModel(final ComboBox cb) {
if (cb == null) {
throw new NullPointerException("ComboBox can not be null");
}
this.comboBox = cb;
selectedIndexProperty().addListener(new InvalidationListener() {
@Override public void invalidated(Observable valueModel) {
// we used to lazily retrieve the selected item, but now we just
// do it when the selection changes.
setSelectedItem(getModelItem(getSelectedIndex()));
}
});
/*
* The following two listeners are used in conjunction with
* SelectionModel.select(T obj) to allow for a developer to select
* an item that is not actually in the data model. When this occurs,
* we actively try to find an index that matches this object, going
* so far as to actually watch for all changes to the items list,
* rechecking each time.
*/
this.comboBox.itemsProperty().addListener(weakItemsObserver);
if (comboBox.getItems() != null) {
this.comboBox.getItems().addListener(weakItemsContentObserver);
}
}
// watching for changes to the items list content
private final ListChangeListener itemsContentObserver = new ListChangeListener() {
@Override public void onChanged(Change c) {
if (comboBox.getItems() == null || comboBox.getItems().isEmpty()) {
setSelectedIndex(-1);
} else if (getSelectedIndex() == -1 && getSelectedItem() != null) {
int newIndex = comboBox.getItems().indexOf(getSelectedItem());
if (newIndex != -1) {
setSelectedIndex(newIndex);
}
}
while (c.next()) {
comboBox.wasSetAllCalled = comboBox.previousItemCount == c.getRemovedSize();
if (c.getFrom() <= getSelectedIndex() && getSelectedIndex()!= -1 && (c.wasAdded() || c.wasRemoved())) {
int shift = c.wasAdded() ? c.getAddedSize() : -c.getRemovedSize();
clearAndSelect(getSelectedIndex() + shift);
}
}
comboBox.previousItemCount = getItemCount();
}
};
// watching for changes to the items list
private final ChangeListener> itemsObserver = new ChangeListener>() {
@Override
public void changed(ObservableValue> valueModel,
ObservableList oldList, ObservableList newList) {
updateItemsObserver(oldList, newList);
}
};
private WeakListChangeListener weakItemsContentObserver =
new WeakListChangeListener(itemsContentObserver);
private WeakChangeListener> weakItemsObserver =
new WeakChangeListener>(itemsObserver);
private void updateItemsObserver(ObservableList oldList, ObservableList newList) {
// update listeners
if (oldList != null) {
oldList.removeListener(weakItemsContentObserver);
}
if (newList != null) {
newList.addListener(weakItemsContentObserver);
}
// when the items list totally changes, we should clear out
// the selection and focus
setSelectedIndex(-1);
}
// API Implementation
@Override protected T getModelItem(int index) {
final ObservableList items = comboBox.getItems();
if (items == null) return null;
if (index < 0 || index >= items.size()) return null;
return items.get(index);
}
@Override protected int getItemCount() {
final ObservableList items = comboBox.getItems();
return items == null ? 0 : items.size();
}
}
}