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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * 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
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package javafx.scene.control;

import java.lang.ref.WeakReference;
import java.util.Optional;

import javafx.beans.InvalidationListener;
import javafx.beans.property.BooleanProperty;
import javafx.beans.property.ObjectProperty;
import javafx.beans.property.ReadOnlyBooleanProperty;
import javafx.beans.property.ReadOnlyDoubleProperty;
import javafx.beans.property.SimpleObjectProperty;
import javafx.beans.property.StringProperty;
import javafx.collections.ListChangeListener;
import javafx.css.PseudoClass;
import javafx.event.Event;
import javafx.event.EventDispatchChain;
import javafx.event.EventHandler;
import javafx.event.EventTarget;
import javafx.scene.Node;
import javafx.scene.control.ButtonBar.ButtonData;
import javafx.stage.Modality;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
import javafx.stage.Window;
import javafx.util.Callback;

import com.sun.javafx.event.EventHandlerManager;

/**
 * A Dialog in JavaFX wraps a {@link DialogPane} and provides the necessary API
 * to present it to end users. In JavaFX 8u40, this essentially means that the
 * {@link DialogPane} is shown to users inside a {@link Stage}, but future releases
 * may offer alternative options (such as 'lightweight' or 'internal' dialogs).
 * This API therefore is intentionally ignorant of the underlying implementation, 
 * and attempts to present a common API for all possible implementations.
 * 
 * 

The Dialog class has a single generic type, R, which is used to represent * the type of the {@link #resultProperty() result} property (and also, how to * convert from {@link ButtonType} to R, through the use of the * {@link #resultConverterProperty() result converter} {@link Callback}). * *

Critical note: It is critical that all developers who choose * to create their own dialogs by extending the Dialog class understand the * importance of the {@link #resultConverterProperty() result converter} property. * A result converter must always be set, whenever the R type is not * {@link Void} or {@link ButtonType}. If this is not heeded, developers will find * that they get ClassCastExceptions in their code, for failure to convert from * {@link ButtonType} via the {@link #resultConverterProperty() result converter}. * *

It is likely that most developers would be better served using either the * {@link Alert} class (for pre-defined, notification-style alerts), or either of * the two pre-built dialogs ({@link TextInputDialog} and {@link ChoiceDialog}), * depending on their needs. * *

Once a Dialog is instantiated, the next step is to configure it. Almost * all properties on Dialog are not related to the content of the Dialog, the * only exceptions are {@link #contentTextProperty()}, * {@link #headerTextProperty()}, and {@link #graphicProperty()}, and these * properties are simply forwarding API onto the respective properties on the * {@link DialogPane} stored in the {@link #dialogPaneProperty() dialog pane} * property. These three properties are forwarded from DialogPane for developer * convenience. For developers wanting to configure their dialog, they will in many * cases be required to use code along the lines of * {@code dialog.getDialogPane().setExpandableContent(node)}. * *

After configuring these properties, all that remains is to consider whether * the buttons (created using {@link ButtonType} and the * {@link DialogPane#createButton(ButtonType)} method) are fully configured. * Developers will quickly find that the amount of configurability offered * via the {@link ButtonType} class is minimal. This is intentional, but does not * mean that developers can not modify the buttons created by the {@link ButtonType} * that have been specified. To do this, developers simply call the * {@link DialogPane#lookupButton(ButtonType)} method with the ButtonType * (assuming it has already been set in the {@link DialogPane#getButtonTypes()} * list. The returned Node is typically of type {@link Button}, but this depends * on if the {@link DialogPane#createButton(ButtonType)} method has been overridden. A * typical approach is therefore along the following lines: * *

{@code ButtonType loginButtonType = new ButtonType("Login", ButtonData.OK_DONE);
 * Dialog dialog = new Dialog<>();
 * dialog.getDialogPane().getButtonTypes().add(loginButtonType);
 * boolean disabled = false; // computed based on content of text fields, for example
 * dialog.getDialogPane().lookupButton(loginButtonType).setDisable(disabled);}
* *

Once a Dialog is instantiated and fully configured, the next step is to * show it. More often than not, dialogs are shown in a modal and blocking * fashion. 'Modal' means that the dialog prevents user interaction with the * owning application whilst it is showing, and 'blocking' means that code * execution stops at the point in which the dialog is shown. This means that * you can show a dialog, await the user response, and then continue running the * code that directly follows the show call, giving developers the ability to * immediately deal with the user input from the dialog (if relevant). * *

JavaFX dialogs are modal by default (you can change this via the * {@link #initModality(javafx.stage.Modality)} API). To specify whether you want * blocking or non-blocking dialogs, developers simply choose to call * {@link #showAndWait()} or {@link #show()} (respectively). By default most * developers should choose to use {@link #showAndWait()}, given the ease of * coding in these situations. Shown below is three code snippets, showing three * equally valid ways of showing a dialog: * *

Option 1: The 'traditional' approach *

{@code Optional result = dialog.showAndWait();
 * if (result.isPresent() && result.get() == ButtonType.OK) {
 *     formatSystem();
 * }}
* *

Option 2: The traditional + Optional approach *

{@code dialog.showAndWait().ifPresent(response -> {
 *     if (response == ButtonType.OK) {
 *         formatSystem();
 *     }
 * });}
* *

Option 3: The fully lambda approach *

{@code dialog.showAndWait()
 *      .filter(response -> response == ButtonType.OK)
 *      .ifPresent(response -> formatSystem());}
* *

There is no better or worse option of the three listed above, so developers * are encouraged to work to their own style preferences. The purpose of showing * the above is to help introduce developers to the {@link Optional} API, which * is new in Java 8 and may be foreign to many developers. * *

It is important to understand what happens when a Dialog is closed, and * also how a Dialog can be closed, especially in abnormal closing situations * (such as when the 'X' button is clicked in a dialogs title bar, or when * operating system specific keyboard shortcuts (such as alt-F4 on Windows) * are entered). Fortunately, the outcome is well-defined in these situations, * and can be best summarised in the following bullet points: * *

    *
  • JavaFX dialogs can only be closed 'abnormally' (as defined above) in * two situations: *
      *
    1. When the dialog only has one button, or *
    2. When the dialog has multiple buttons, as long as one of them has * a {@link ButtonType} whose {@link ButtonData} is of type * {@link ButtonData#CANCEL_CLOSE}. *
    *
  • In all other situations, the dialog will refuse to respond to all * close requests, remaining open until the user clicks on one of the available * buttons in the {@link DialogPane} area of the dialog. *
  • If a dialog is closed abnormally, and if the dialog contains a button * which has a {@link ButtonData} of {@link ButtonData#CANCEL_CLOSE}, * the dialog will attempt to set the {@link #resultProperty() result} property * to whatever value is returned from calling the * {@link #resultConverterProperty() result converter} with the first matching * {@link ButtonType}. *
  • If for any reason the result converter returns null, or if the dialog * is closed when on one non-cancel button is present, the * {@link #resultProperty() result} property will be null, and the * {@link #showAndWait()} method will return {@link Optional#empty()}. This * later point means that, if you use either of option 2 or option 3 (as * presented earlier in this class documentation), the * {@link Optional#ifPresent(java.util.function.Consumer)} lambda will never * be called, and code will continue executing as if the dialog had not * returned any value at all. *
* * @param The return type of the dialog, via the * {@link #resultProperty() result} property. * @see Alert * @see TextInputDialog * @see ChoiceDialog * @since JavaFX 8u40 */ public class Dialog implements EventTarget { /************************************************************************** * * Static fields * **************************************************************************/ /************************************************************************** * * Static methods * **************************************************************************/ /************************************************************************** * * Private fields * **************************************************************************/ private final FXDialog dialog; private boolean isClosing; /************************************************************************** * * Constructors * **************************************************************************/ /** * Creates a dialog without a specified owner. */ public Dialog() { this.dialog = new HeavyweightDialog(this); setDialogPane(new DialogPane()); initModality(Modality.APPLICATION_MODAL); } /************************************************************************** * * Abstract methods * **************************************************************************/ /************************************************************************** * * Public API * **************************************************************************/ /** * Shows the dialog but does not wait for a user response (in other words, * this brings up a non-blocking dialog). Users of this API must either * poll the {@link #resultProperty() result property}, or else add a listener * to the result property to be informed of when it is set. */ public final void show() { Event.fireEvent(this, new DialogEvent(this, DialogEvent.DIALOG_SHOWING)); dialog.setDialogPane(getDialogPane()); dialog.sizeToScene(); Node root = dialog.getRoot(); root.pseudoClassStateChanged(HEADER_PSEUDO_CLASS, getDialogPane().hasHeader()); root.pseudoClassStateChanged(NO_HEADER_PSEUDO_CLASS, !getDialogPane().hasHeader()); dialog.show(); Event.fireEvent(this, new DialogEvent(this, DialogEvent.DIALOG_SHOWN)); } /** * Shows the dialog and waits for the user response (in other words, brings * up a blocking dialog, with the returned value the users input). * * @return An {@link Optional} that contains the {@link #resultProperty() result}. * Refer to the {@link Dialog} class documentation for more detail. */ public final Optional showAndWait() { Event.fireEvent(this, new DialogEvent(this, DialogEvent.DIALOG_SHOWING)); final DialogPane dialogPane = getDialogPane(); dialog.setDialogPane(dialogPane); dialog.sizeToScene(); Node root = dialog.getRoot(); root.pseudoClassStateChanged(HEADER_PSEUDO_CLASS, getDialogPane().hasHeader()); root.pseudoClassStateChanged(NO_HEADER_PSEUDO_CLASS, !getDialogPane().hasHeader()); // this is slightly odd - we fire the SHOWN event before the show() // call, so that users get the event before the dialog blocks Event.fireEvent(this, new DialogEvent(this, DialogEvent.DIALOG_SHOWN)); dialog.showAndWait(); return Optional.ofNullable(getResult()); } /** * Hides the dialog. */ public final void close() { if (isClosing) return; isClosing = true; final R result = getResult(); // if the result is null and we do not have permission to close the // dialog, then we cancel the close request before any events are // even fired if (result == null && ! dialog.requestPermissionToClose(this)) { isClosing = false; return; } // This code is called just before close, and ONLY in cases where the // dialog was closed abnormally (as represented by closeWasNormal). // In these cases, and where the dialog had a cancel button, we call // into the result converter to see what to do. This is used primarily // to handle the requirement that the X button has the same result as // clicking the cancel button. // TODO we used to discern between normal and abnormal closures of the // stage, but this was not resilient enough. For now, we no longer check // in the code below whether the close was normal or not, but depending // on how things work out, this may need to change if (result == null) { ButtonType cancelButton = null; for (ButtonType button : getDialogPane().getButtonTypes()) { if (button.getButtonData() == ButtonData.CANCEL_CLOSE) { cancelButton = button; break; } } impl_setResultAndClose(cancelButton, false); } // start normal closing process Event.fireEvent(this, new DialogEvent(this, DialogEvent.DIALOG_HIDING)); DialogEvent closeRequestEvent = new DialogEvent(this, DialogEvent.DIALOG_CLOSE_REQUEST); Event.fireEvent(this, closeRequestEvent); if (closeRequestEvent.isConsumed()) { isClosing = false; return; } dialog.close(); Event.fireEvent(this, new DialogEvent(this, DialogEvent.DIALOG_HIDDEN)); isClosing = false; } /** * closes the dialog. */ public final void hide() { close(); } /** * Specifies the modality for this dialog. This must be done prior to making * the dialog visible. The modality is one of: Modality.NONE, * Modality.WINDOW_MODAL, or Modality.APPLICATION_MODAL. * * @param modality the modality for this dialog. * * @throws IllegalStateException if this property is set after the dialog * has ever been made visible. * * @defaultValue Modality.APPLICATION_MODAL */ public final void initModality(Modality modality) { dialog.initModality(modality); } /** * Retrieves the modality attribute for this dialog. * * @return the modality. */ public final Modality getModality() { return dialog.getModality(); } /** * Specifies the style for this dialog. This must be done prior to making * the dialog visible. The style is one of: StageStyle.DECORATED, * StageStyle.UNDECORATED, StageStyle.TRANSPARENT, StageStyle.UTILITY, * or StageStyle.UNIFIED. * * @param style the style for this dialog. * * @throws IllegalStateException if this property is set after the dialog * has ever been made visible. * * @defaultValue StageStyle.DECORATED */ public final void initStyle(StageStyle style) { dialog.initStyle(style); } /** * Specifies the owner {@link Window} for this dialog, or null for a top-level, * unowned dialog. This must be done prior to making the dialog visible. * * @param window the owner {@link Window} for this dialog. * * @throws IllegalStateException if this property is set after the dialog * has ever been made visible. * * @defaultValue null */ public final void initOwner(Window window) { dialog.initOwner(window); } /** * Retrieves the owner Window for this dialog, or null for an unowned dialog. * * @return the owner Window. */ public final Window getOwner() { return dialog.getOwner(); } /************************************************************************** * * Properties * **************************************************************************/ // --- dialog Pane /** * The root node of the dialog, the {@link DialogPane} contains all visual * elements shown in the dialog. As such, it is possible to completely adjust * the display of the dialog by modifying the existing dialog pane or creating * a new one. */ private ObjectProperty dialogPane = new SimpleObjectProperty(this, "dialogPane", new DialogPane()) { final InvalidationListener expandedListener = o -> { DialogPane dialogPane = getDialogPane(); if (dialogPane == null) return; final Node content = dialogPane.getExpandableContent(); final boolean isExpanded = content == null ? false : content.isVisible(); setResizable(isExpanded); Dialog.this.dialog.sizeToScene(); }; final InvalidationListener headerListener = o -> { final Node root = Dialog.this.dialog.getRoot(); if (root == null) return; final boolean hasHeader = getDialogPane().hasHeader(); root.pseudoClassStateChanged(HEADER_PSEUDO_CLASS, hasHeader); root.pseudoClassStateChanged(NO_HEADER_PSEUDO_CLASS, !hasHeader); }; WeakReference dialogPaneRef = new WeakReference<>(null); protected void invalidated() { DialogPane oldDialogPane = dialogPaneRef.get(); if (oldDialogPane != null) { // clean up oldDialogPane.expandedProperty().removeListener(expandedListener); oldDialogPane.headerProperty().removeListener(headerListener); oldDialogPane.headerTextProperty().removeListener(headerListener); oldDialogPane.setDialog(null); } final DialogPane newDialogPane = getDialogPane(); if (newDialogPane != null) { newDialogPane.setDialog(Dialog.this); // if the buttons change, we dynamically update the dialog newDialogPane.getButtonTypes().addListener((ListChangeListener) c -> { newDialogPane.requestLayout(); }); newDialogPane.expandedProperty().addListener(expandedListener); newDialogPane.headerProperty().addListener(headerListener); newDialogPane.headerTextProperty().addListener(headerListener); newDialogPane.requestLayout(); } // push the new dialog down into the implementation for rendering dialog.setDialogPane(newDialogPane); dialogPaneRef = new WeakReference(newDialogPane); } }; public final ObjectProperty dialogPaneProperty() { return dialogPane; } public final DialogPane getDialogPane() { return dialogPane.get(); } public final void setDialogPane(DialogPane value) { dialogPane.set(value); } // --- content text (forwarded from DialogPane) /** * A property representing the content text for the dialog pane. The content text * is lower precedence than the {@link DialogPane#contentProperty() content node}, meaning * that if both the content node and the contentText properties are set, the * content text will not be displayed in a default DialogPane instance. */ public final StringProperty contentTextProperty() { return getDialogPane().contentTextProperty(); } /** * Returns the currently-set content text for this DialogPane. */ public final String getContentText() { return getDialogPane().getContentText(); } /** * Sets the string to show in the dialog content area. Note that the content text * is lower precedence than the {@link DialogPane#contentProperty() content node}, meaning * that if both the content node and the contentText properties are set, the * content text will not be displayed in a default DialogPane instance. */ public final void setContentText(String contentText) { getDialogPane().setContentText(contentText); } // --- header text (forwarded from DialogPane) /** * A property representing the header text for the dialog pane. The header text * is lower precedence than the {@link DialogPane#headerProperty() header node}, meaning * that if both the header node and the headerText properties are set, the * header text will not be displayed in a default DialogPane instance. */ public final StringProperty headerTextProperty() { return getDialogPane().headerTextProperty(); } /** * Returns the currently-set header text for this DialogPane. */ public final String getHeaderText() { return getDialogPane().getHeaderText(); } /** * Sets the string to show in the dialog header area. Note that the header text * is lower precedence than the {@link DialogPane#headerProperty() header node}, meaning * that if both the header node and the headerText properties are set, the * header text will not be displayed in a default DialogPane instance. */ public final void setHeaderText(String headerText) { getDialogPane().setHeaderText(headerText); } // --- graphic (forwarded from DialogPane) /** * The dialog graphic, presented either in the header, if one is showing, or * to the left of the {@link DialogPane#contentProperty() content}. * * @return An ObjectProperty wrapping the current graphic. */ public final ObjectProperty graphicProperty() { return getDialogPane().graphicProperty(); } public final Node getGraphic() { return getDialogPane().getGraphic(); } /** * Sets the dialog graphic, which will be displayed either in the header, if * one is showing, or to the left of the {@link DialogPane#contentProperty() content}. * * @param graphic * The new dialog graphic, or null if no graphic should be shown. */ public final void setGraphic(Node graphic) { getDialogPane().setGraphic(graphic); } // --- result private final ObjectProperty resultProperty = new SimpleObjectProperty() { protected void invalidated() { close(); } }; /** * A property representing what has been returned from the dialog. A result * is generated through the {@link #resultConverterProperty() result converter}, * which is intended to convert from the {@link ButtonType} that the user * clicked on into a value of type R. Refer to the {@link Dialog} class * JavaDoc for more details. */ public final ObjectProperty resultProperty() { return resultProperty; } public final R getResult() { return resultProperty().get(); } public final void setResult(R value) { this.resultProperty().set(value); } // --- result converter private final ObjectProperty> resultConverterProperty = new SimpleObjectProperty<>(this, "resultConverter"); /** * API to convert the {@link ButtonType} that the user clicked on into a * result that can be returned via the {@link #resultProperty() result} * property. This is necessary as {@link ButtonType} represents the visual * button within the dialog, and do not know how to map themselves to a valid * result - that is a requirement of the dialog implementation by making use * of the result converter. In some cases, the result type of a Dialog * subclass is ButtonType (which means that the result converter can be null), * but in some cases (where the result type, R, is not ButtonType or Void), * this callback must be specified. */ public final ObjectProperty> resultConverterProperty() { return resultConverterProperty; } public final Callback getResultConverter() { return resultConverterProperty().get(); } public final void setResultConverter(Callback value) { this.resultConverterProperty().set(value); } // --- showing /** * Represents whether the dialog is currently showing. */ public final ReadOnlyBooleanProperty showingProperty() { return dialog.showingProperty(); } /** * Returns whether or not the dialog is showing. * * @return true if dialog is showing. */ public final boolean isShowing() { return showingProperty().get(); } // --- resizable /** * Represents whether the dialog is resizable. */ public final BooleanProperty resizableProperty() { return dialog.resizableProperty(); } /** * Returns whether or not the dialog is resizable. * * @return true if dialog is resizable. */ public final boolean isResizable() { return resizableProperty().get(); } /** * Sets whether the dialog can be resized by the user. * Resizable dialogs can also be maximized ( maximize button * becomes visible) * * @param resizable true if dialog should be resizable. */ public final void setResizable(boolean resizable) { resizableProperty().set(resizable); } // --- width /** * Property representing the width of the dialog. */ public final ReadOnlyDoubleProperty widthProperty() { return dialog.widthProperty(); } /** * Returns the width of the dialog. */ public final double getWidth() { return widthProperty().get(); } /** * Sets the width of the dialog. */ public final void setWidth(double width) { dialog.setWidth(width); } // --- height /** * Property representing the height of the dialog. */ public final ReadOnlyDoubleProperty heightProperty() { return dialog.heightProperty(); } /** * Returns the height of the dialog. */ public final double getHeight() { return heightProperty().get(); } /** * Sets the height of the dialog. */ public final void setHeight(double height) { dialog.setHeight(height); } // --- title /** * Return the titleProperty of the dialog. */ public final StringProperty titleProperty(){ return this.dialog.titleProperty(); } /** * Return the title of the dialog. */ public final String getTitle(){ return this.dialog.titleProperty().get(); } /** * Change the Title of the dialog. * @param title */ public final void setTitle(String title){ this.dialog.titleProperty().set(title); } // --- x public final double getX() { return dialog.getX(); } public final void setX(double x) { dialog.setX(x); } /** * The horizontal location of this {@code Dialog}. Changing this attribute * will move the {@code Dialog} horizontally. */ public final ReadOnlyDoubleProperty xProperty() { return dialog.xProperty(); } // --- y public final double getY() { return dialog.getY(); } public final void setY(double y) { dialog.setY(y); } /** * The vertical location of this {@code Dialog}. Changing this attribute * will move the {@code Dialog} vertically. */ public final ReadOnlyDoubleProperty yProperty() { return dialog.yProperty(); } /*************************************************************************** * * Events * **************************************************************************/ private final EventHandlerManager eventHandlerManager = new EventHandlerManager(this); /** {@inheritDoc} */ @Override public EventDispatchChain buildEventDispatchChain(EventDispatchChain tail) { return tail.prepend(eventHandlerManager); } /** * Called just prior to the Dialog being shown. */ private ObjectProperty> onShowing; public final void setOnShowing(EventHandler value) { onShowingProperty().set(value); } public final EventHandler getOnShowing() { return onShowing == null ? null : onShowing.get(); } public final ObjectProperty> onShowingProperty() { if (onShowing == null) { onShowing = new SimpleObjectProperty>(this, "onShowing") { @Override protected void invalidated() { eventHandlerManager.setEventHandler(DialogEvent.DIALOG_SHOWING, get()); } }; } return onShowing; } /** * Called just after the Dialog is shown. */ private ObjectProperty> onShown; public final void setOnShown(EventHandler value) { onShownProperty().set(value); } public final EventHandler getOnShown() { return onShown == null ? null : onShown.get(); } public final ObjectProperty> onShownProperty() { if (onShown == null) { onShown = new SimpleObjectProperty>(this, "onShown") { @Override protected void invalidated() { eventHandlerManager.setEventHandler(DialogEvent.DIALOG_SHOWN, get()); } }; } return onShown; } /** * Called just prior to the Dialog being hidden. */ private ObjectProperty> onHiding; public final void setOnHiding(EventHandler value) { onHidingProperty().set(value); } public final EventHandler getOnHiding() { return onHiding == null ? null : onHiding.get(); } public final ObjectProperty> onHidingProperty() { if (onHiding == null) { onHiding = new SimpleObjectProperty>(this, "onHiding") { @Override protected void invalidated() { eventHandlerManager.setEventHandler(DialogEvent.DIALOG_HIDING, get()); } }; } return onHiding; } /** * Called just after the Dialog has been hidden. * When the {@code Dialog} is hidden, this event handler is invoked allowing * the developer to clean up resources or perform other tasks when the * {@link Alert} is closed. */ private ObjectProperty> onHidden; public final void setOnHidden(EventHandler value) { onHiddenProperty().set(value); } public final EventHandler getOnHidden() { return onHidden == null ? null : onHidden.get(); } public final ObjectProperty> onHiddenProperty() { if (onHidden == null) { onHidden = new SimpleObjectProperty>(this, "onHidden") { @Override protected void invalidated() { eventHandlerManager.setEventHandler(DialogEvent.DIALOG_HIDDEN, get()); } }; } return onHidden; } /** * Called when there is an external request to close this {@code Dialog}. * The installed event handler can prevent dialog closing by consuming the * received event. */ private ObjectProperty> onCloseRequest; public final void setOnCloseRequest(EventHandler value) { onCloseRequestProperty().set(value); } public final EventHandler getOnCloseRequest() { return (onCloseRequest != null) ? onCloseRequest.get() : null; } public final ObjectProperty> onCloseRequestProperty() { if (onCloseRequest == null) { onCloseRequest = new SimpleObjectProperty>(this, "onCloseRequest") { @Override protected void invalidated() { eventHandlerManager.setEventHandler(DialogEvent.DIALOG_CLOSE_REQUEST, get()); } }; } return onCloseRequest; } /*************************************************************************** * * Private implementation * **************************************************************************/ // This code is called both in the normal and in the abnormal case (i.e. // both when a button is clicked and when the user forces a window closed // with keyboard OS-specific shortchuts or OS-native titlebar buttons). @SuppressWarnings("unchecked") void impl_setResultAndClose(ButtonType cmd, boolean close) { Callback resultConverter = getResultConverter(); R priorResultValue = getResult(); R newResultValue = null; if (resultConverter == null) { // The choice to cast cmd to R here was a conscious decision, taking // into account the choices available to us. Firstly, to summarise the // issue, at this point here we have a null result converter, and no // idea how to convert the given ButtonType to R. Our options are: // // 1) We could throw an exception here, but this requires that all // developers who create a dialog set a result converter (at least // setResultConverter(buttonType -> (R) buttonType)). This is // non-intuitive and depends on the developer reading documentation. // // 2) We could set a default result converter in the resultConverter // property that does the identity conversion. This saves people from // having to set a default result converter, but it is a little odd // that the result converter is non-null by default. // // 3) We can cast the button type here, which is what we do. This means // that the result converter is null by default. // // In the case of option 1), developers will receive a NPE when the // dialog is closed, regardless of how it was closed. In the case of // option 2) and 3), the user unfortunately receives a ClassCastException // in their code. This is unfortunate as it is not immediately obvious // why the ClassCastException occurred, and how to resolve it. However, // we decided to take this later approach as it prevents the issue of // requiring all custom dialog developers from having to supply their // own result converters. newResultValue = (R) cmd; } else { newResultValue = resultConverter.call(cmd); } setResult(newResultValue); // fix for the case where we set the same result as what // was already set. We should still close the dialog, but // we need to special-case it here, as the result property // won't fire any event if the value won't change. if (close && priorResultValue == newResultValue) { close(); } } /*************************************************************************** * * Stylesheet Handling * **************************************************************************/ private static final PseudoClass HEADER_PSEUDO_CLASS = PseudoClass.getPseudoClass("header"); //$NON-NLS-1$ private static final PseudoClass NO_HEADER_PSEUDO_CLASS = PseudoClass.getPseudoClass("no-header"); //$NON-NLS-1$ }




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