GWT confirmation dialog box - gwt

Question

I'm trying to create a modal confirmation dialog box. I'd like it to work like Window.confirm(""), where I can just call it, and get a boolean response.
My trouble is I'm not sure how to do it. I'm trying to use MVP in my application. Here is the code I have so far:
public class DialogBoxPresenter implements Presenter {
public interface Display {
Label getDialogText();
Button getAffirmativeButton();
Button getCancelButton();
Widget asWidget();
public void center();
public void hide();
public void setHeader(String text);
}
private Display display;
private String header;
private String dialogText;
private String cancelButtonText;
private String affirmativeButtonText;
protected DialogBoxPresenter() {
}
public DialogBoxPresenter(Display display, String header, String dialogText, String cancelButtonText, String affirmativeButtonText) {
this.display = display;
this.header = header;
this.dialogText = dialogText;
this.cancelButtonText = cancelButtonText;
this.affirmativeButtonText = affirmativeButtonText;
bind();
}
public DialogBoxPresenter(Display display, String header, String dialogText) {
this.display = display;
this.header = header;
this.dialogText = dialogText;
this.cancelButtonText = "Cancel";
this.affirmativeButtonText = "OK";
bind();
}
private void bind() {
this.display.getDialogText().setText(dialogText);
this.display.getAffirmativeButton().setText(affirmativeButtonText);
this.display.getCancelButton().setText(cancelButtonText);
this.display.setHeader(header);
addClickHandlers();
}
private void addClickHandlers() {
this.display.getAffirmativeButton().addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
doAffirmative();
}
});
this.display.getCancelButton().addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
doCancel();
}
});
}
private void doAffirmative() {
//do something
display.hide();
}
private void doCancel() {
//do something
display.hide();
}
public void init() {
display.center();
}
#Override
public void go(HasWidgets container) {
container.clear();
container.add(display.asWidget());
}
}
and my view:
public class DialogBoxView extends DialogBox implements DialogBoxPresenter.Display {
private Label dialogText;
private Button affirmativeButton;
private Button cancelButton;
private VerticalPanel container;
public DialogBoxView() {
//init items
dialogText = new Label();
affirmativeButton = new Button();
cancelButton = new Button();
container = new VerticalPanel();
setGlassEnabled(true);
setAnimationEnabled(true);
setModal(false);
init();
}
private void init() {
//add items
container.add(dialogText);
HorizontalPanel hp = new HorizontalPanel();
hp.add(affirmativeButton);
hp.add(cancelButton);
container.add(hp);
this.add(container);
}
#Override
public Widget asWidget() {
return this;
}
#Override
public Label getDialogText() {
return dialogText;
}
#Override
public Button getAffirmativeButton() {
return affirmativeButton;
}
#Override
public Button getCancelButton() {
return cancelButton;
}
#Override
public void setHeader(String text) {
this.setText(text);
}
}

Answer 1

You're not going to be able to have it work in exactly the same way as Window.confirm(). The problem is that all of the javascript in a web page runs in a single thread. You'll notice that as long as a standard confirm dialog is open, the rest of the page goes dead. That's because the one javascript thread is blocked, waiting for confirm() to return. If you were to create a similar method for your dialog, as long as it was waiting for that method to return no user generated events would be processed and so your dialog wouldn't work. I hope that makes sense.
The best you will be able to do is similar to what the GWT library does for RPC calls -- the AsyncCallback interface. You could even reuse that interface yourself, or you might prefer to roll your own:
public interface DialogCallback {
void onOk();
void onCancel();
}
Instead of Window.confirm(String), your method signature will be more like Dialog.confirm(String,DialogCallback). Then your dialog just keeps a reference to the callback that's passed in, and where you have // do something in your code you make calls to onOk and onCancel.

Answer 2

Here is the code I have working if anyone is curious.
public class DialogBoxPresenter implements Presenter {
public interface Display {
Label getDialogText();
Button getAffirmativeButton();
Button getCancelButton();
Widget asWidget();
public void center();
public void hide();
public void setHeader(String text);
}
private Display display;
private String header;
private String dialogText;
private String cancelButtonText;
private String affirmativeButtonText;
private ConfirmDialogCallback confirmCallback;
private AlertDialogCallback alertCallback;
protected DialogBoxPresenter() {
}
public DialogBoxPresenter(Display display, String header, String dialogText, String cancelButtonText, String affirmativeButtonText, ConfirmDialogCallback callback) {
this.display = display;
this.header = header;
this.dialogText = dialogText;
this.cancelButtonText = cancelButtonText;
this.affirmativeButtonText = affirmativeButtonText;
this.confirmCallback = callback;
bind();
}
public DialogBoxPresenter(Display display, String header, String dialogText, String affirmativeButtonText, AlertDialogCallback callback) {
this.display = display;
this.header = header;
this.dialogText = dialogText;
this.affirmativeButtonText = affirmativeButtonText;
this.alertCallback = callback;
this.display.getCancelButton().setVisible(false);
bind();
}
private void bind() {
this.display.getDialogText().setText(dialogText);
this.display.getAffirmativeButton().setText(affirmativeButtonText);
this.display.getCancelButton().setText(cancelButtonText);
this.display.setHeader(header);
addClickHandlers();
}
private void addClickHandlers() {
this.display.getAffirmativeButton().addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
doAffirmative();
}
});
this.display.getCancelButton().addClickHandler(new ClickHandler() {
#Override
public void onClick(ClickEvent event) {
doCancel();
}
});
}
private void doAffirmative() {
if (confirmCallback != null) {
confirmCallback.onAffirmative();
} else {
alertCallback.onAffirmative();
}
display.hide();
}
private void doCancel() {
confirmCallback.onCancel();
display.hide();
}
public void init() {
display.center();
}
#Override
public void go(HasWidgets container) {
container.clear();
container.add(display.asWidget());
}
}
public class DialogBoxView extends DialogBox implements DialogBoxPresenter.Display {
private Label dialogText;
private Button affirmativeButton;
private Button cancelButton;
private VerticalPanel container;
public DialogBoxView() {
//init items
dialogText = new Label();
affirmativeButton = new Button();
cancelButton = new Button();
container = new VerticalPanel();
setGlassEnabled(true);
setAnimationEnabled(true);
setModal(false);
init();
}
private void init() {
//add items
container.add(dialogText);
HorizontalPanel hp = new HorizontalPanel();
hp.add(affirmativeButton);
hp.add(cancelButton);
container.add(hp);
this.add(container);
}
#Override
public Widget asWidget() {
return this;
}
#Override
public Label getDialogText() {
return dialogText;
}
#Override
public Button getAffirmativeButton() {
return affirmativeButton;
}
#Override
public Button getCancelButton() {
return cancelButton;
}
#Override
public void setHeader(String text) {
this.setText(text);
}
}
public class DialogBoxWidget implements LensooConstant {
private static DialogBoxView view = null;
private static DialogBoxPresenter presenter = null;
public static DialogBoxPresenter confirm(String header, String dialogText, String cancelButtonText, String affirmativeButtonText, ConfirmDialogCallback callback) {
view = new DialogBoxView();
presenter = new DialogBoxPresenter(view, header, dialogText, cancelButtonText, affirmativeButtonText, callback);
presenter.init();
return presenter;
}
public static DialogBoxPresenter confirm(String header, String dialogText, ConfirmDialogCallback callback) {
return DialogBoxWidget.confirm(header, dialogText, constants.cancelButton(), constants.okButton(), callback);
}
public static DialogBoxPresenter alert(String header, String dialogText, String affirmativeButtonText, AlertDialogCallback callback) {
view = new DialogBoxView();
presenter = new DialogBoxPresenter(view, header, dialogText, affirmativeButtonText, callback);
presenter.init();
return presenter;
}
public static DialogBoxPresenter alert(String header, String dialogText, AlertDialogCallback callback) {
return DialogBoxWidget.alert(header, dialogText, constants.okButton(), callback);
}
protected DialogBoxWidget() {
}
}
public interface AlertDialogCallback {
void onAffirmative();
}
public interface ConfirmDialogCallback {
void onAffirmative();
void onCancel();
}