JavaFX TableView Filter Right Mouse Button Selection - javafx

Question

When I press the Right Mouse button on a JavaFX TreeTableView it selects the node I clicked on. I can understand why this may be desirable in most cases, however not in all cases.
I am working on an application where I have multiple columns in the tree table with one column using a canvas widget for custom graphics (waveforms). The graphics column needs to be able to be interacted with for various reasons (setting markers, zooming, etc.) with the mouse. Because of this I don't want the mouse buttons to select the row in the table (or interact with the table).
I was able filter out the click with the first mouse button by putting a addEventFilter() for MouseEvent.MOUSE_CLICKED with a event.consume(). I can then process the mouse click the way I want.
However when I right click on the cell the selection in the table changes to that row. I have tried putting event filters on the cell, the table, the row, the column, nothing seems to work to filter the right click selection change. Note the canvas widget is set to be mouse transparent.
Here is an example using the standard address book example, except I replaced the email column with a canvas widget.
package sample;
import javafx.application.Application;
import javafx.beans.property.SimpleStringProperty;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.geometry.Insets;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.control.*;
import javafx.scene.control.cell.PropertyValueFactory;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.VBox;
import javafx.scene.text.Font;
import javafx.stage.Stage;
import javafx.util.Callback;
public class Main extends Application {
private TableView<Person> table = new TableView<Person>();
private ContextMenu menu = new ContextMenu();
private final ObservableList<Person> data =
FXCollections.observableArrayList(
new Person("Jacob", "Smith", "jacob.smith#example.com"),
new Person("Isabella", "Johnson", "isabella.johnson#example.com"),
new Person("Ethan", "Williams", "ethan.williams#example.com"),
new Person("Emma", "Jones", "emma.jones#example.com"),
new Person("Michael", "Brown", "michael.brown#example.com")
);
class MyTableCell extends TableCell<Person, String> {
public MyTableCell(ContextMenu menu) {
super();
setContextMenu(menu);
}
#Override
protected void updateItem(String item, boolean empty) {
super.updateItem(item, empty);
setText(item);
setGraphic(null);
}
}
class MySpecialCell extends MyTableCell {
Canvas canvas = new Canvas(200.0, 12.0);
public MySpecialCell() {
super(null);
canvas.setMouseTransparent(true);
addEventFilter(MouseEvent.ANY, e -> e.consume());
}
#Override
protected void updateItem(String item, boolean empty) {
super.updateItem(item, empty);
setText(null);
if (! empty) {
canvas.getGraphicsContext2D().strokeText(item, 5.0, 10.0);
setGraphic(canvas);
} else {
setGraphic(null);
}
}
}
#Override
public void start(Stage stage) throws Exception{
Scene scene = new Scene(new Group());
stage.setTitle("Table View Sample");
stage.setWidth(450);
stage.setHeight(500);
final Label label = new Label("Address Book");
label.setFont(new Font("Arial", 20));
table.setEditable(true);
table.getSelectionModel().setSelectionMode(SelectionMode.MULTIPLE);
menu.getItems().add(new MenuItem("Hello World"));
Callback cellFactory = param -> new MyTableCell(menu);
TableColumn firstNameCol = new TableColumn("First Name");
firstNameCol.setMinWidth(100);
firstNameCol.setCellValueFactory(
new PropertyValueFactory<Person, String>("firstName"));
firstNameCol.setCellFactory(cellFactory);
TableColumn lastNameCol = new TableColumn("Last Name");
lastNameCol.setMinWidth(100);
lastNameCol.setCellValueFactory(
new PropertyValueFactory<Person, String>("lastName"));
lastNameCol.setCellFactory(cellFactory);
TableColumn emailCol = new TableColumn("Email");
emailCol.setMinWidth(200);
emailCol.setCellValueFactory(
new PropertyValueFactory<Person, String>("email"));
emailCol.setCellFactory(param -> new MySpecialCell());
table.setItems(data);
table.getColumns().addAll(firstNameCol, lastNameCol, emailCol);
final VBox vbox = new VBox();
vbox.setSpacing(5);
vbox.setPadding(new Insets(10, 0, 0, 10));
vbox.getChildren().addAll(label, table);
((Group) scene.getRoot()).getChildren().addAll(vbox);
stage.setScene(scene);
stage.show();
}
public static void main(String[] args) {
launch(args);
}
public static class Person {
private final SimpleStringProperty firstName;
private final SimpleStringProperty lastName;
private final SimpleStringProperty email;
private Person(String fName, String lName, String email) {
this.firstName = new SimpleStringProperty(fName);
this.lastName = new SimpleStringProperty(lName);
this.email = new SimpleStringProperty(email);
}
public String getFirstName() {
return firstName.get();
}
public void setFirstName(String fName) {
firstName.set(fName);
}
public String getLastName() {
return lastName.get();
}
public void setLastName(String fName) {
lastName.set(fName);
}
public String getEmail() {
return email.get();
}
public void setEmail(String fName) {
email.set(fName);
}
}
}
This is using Java 8u20. In this example the MyTableCell class is used for the cells in the first two columns. It adds a context menu to those columns. The MySpecialCell class is for the last column and it puts a canvas in the table with the email text in it. It also goes way overboard and filters ANY mouse event.
If you run this you will see that if you use mouse button 1 in the first two columns you can change the selection in the table. Mouse button 1 in the third column does not change selection. However Mouse button 2 (right mouse button) DOES change selection in the third column.
I want it to not change selection. Can someone give me a hint on how to prevent selection from changing when using the right mouse button in the column?
NOTE: I have tried having the canvas process the mouse input (actually not make it mouse transparent and having it filter all mouse events) and the table still changes selection on right click. For various reasons (where the data is, the fact that the canvas is actually a stack of canvas widgets, the difficulty of figuring out what node the mouse is interacting with in the table, etc) in my real application I wanted the cell to handle the mouse input.
Thanks!

Answer 1

To repeat my comments: I think the behaviour might be rather a bug than a feature - I would expect that consuming any mouseEvent would prevent the right (secondary) button just the same as the left (primary) button normal actions.
Was evaluated as a feature: the missing piece was to consume the contextMenuEvents in addition to the mouseEvents, something like
public MySpecialCell() {
super(null);
canvas.setMouseTransparent(true);
addEventFilter(MouseEvent.ANY, e -> e.consume());
// move Jonathan's code from table to cell level:
// need to consume contextMenuEvents as well
addEventFilter(ContextMenuEvent.ANY, e -> e.consume());
}
Back to disagreeing with the evaluation:
all mouse buttons should behave consistently to consuming all mouseEvents
contextMenuEvent is basically unrelated to selection, so consuming it should have no effect (in either way) on selection
The hack below might still be needed if contextMenu's triggered by keyboard on the special column are required, didn't dig further, though.
Anyway, a quick hack-around is to replace the default behaviour by a custom implementation. The collaborators
a custom TableCellBehaviour that overrides doSelect to do nothing on receiving a secondary button event
a custom TableCellSkin: that's only needed to plug-in the custom behaviour - needs to extend TableCellSkinBase (and c&p the implementation of its abstract methods from TableCellSkin) because only then we have a constructor taking our custom behaviour
let the custom TableCell create the custom skin instead of the default
Something like (note: while working, it's not properly tested):
class MySpecialCellBehavior extends TableCellBehavior {
public MySpecialCellBehavior(TableCell control) {
super(control);
}
#Override
protected void doSelect(double x, double y, MouseButton button,
int clickCount, boolean shiftDown, boolean shortcutDown) {
// do nothing on secondary button
if (button == MouseButton.SECONDARY) return;
super.doSelect(x, y, button, clickCount, shiftDown, shortcutDown);
}
}
class MySpecialCellSkin extends TableCellSkinBase {
private final TableColumn tableColumn;
public MySpecialCellSkin(TableCell tableCell) {
super(tableCell, new MySpecialCellBehavior(tableCell));
// doesn't make a difference
//consumeMouseEvents(true);
this.tableColumn = tableCell.getTableColumn();
super.init(tableCell);
}
#Override protected BooleanProperty columnVisibleProperty() {
return tableColumn.visibleProperty();
}
#Override protected ReadOnlyDoubleProperty columnWidthProperty() {
return tableColumn.widthProperty();
}
}
class MySpecialCell extends MyTableCell {
Canvas canvas = new Canvas(200.0, 12.0);
public MySpecialCell() {
super(null);
canvas.setMouseTransparent(true);
addEventFilter(MouseEvent.ANY, e -> e.consume());
}
#Override
protected void updateItem(String item, boolean empty) {
super.updateItem(item, empty);
setText(null);
if (! empty) {
canvas.getGraphicsContext2D().strokeText(item, 5.0, 10.0);
setGraphic(canvas);
} else {
setGraphic(null);
}
}
// create and return the custom skin
#Override
protected Skin<?> createDefaultSkin() {
return new MySpecialCellSkin(this);
}
}