On Thu, 26 Sep 2024 21:17:55 GMT, John Hendrikx <jhendr...@openjdk.org> wrote:
> This change modifies `ScrollPaneBehavior` to only consume keys that are
> targetted at it. As `KeyEvent`s are in almost all cases only intended for
> the targetted node (as visually that's where the user expects the keyboard
> input to go, as per normal UI rules) consuming key events that bubble up is
> simply incorrect. When the `ScrollPane` is focused directly (it has the
> focused border) then it is fine for it to respond to all kinds of keys.
>
> In FX controls normally there is no need to check if a `Control` is focused
> (although they probably should **all** do this) as they do not have children
> that could have received the Key Events involved, and Key Events are always
> sent to the focused Node. When `ScrollPane` was developed this was not taken
> into account, leading to it consuming keys not intended for it.
>
> This fixes several unexpected problems for custom control builders. A custom
> control normally benefits from standard navigation out of the box
> (TAB/shift+TAB) and directional keys. However, this breaks down as soon as
> this custom control is positioned within a `ScrollPane`, which is very
> surprising behavior and not at all expected. This makes it harder than
> needed for custom control developers to get the standard navigation for the
> directional keys, as they would have to specifically capture those keys
> before they reach the `ScrollPane` and trigger the correct navigation action
> themselves (for which as of this writing there is no public API).
>
> The same goes for all the other keys captured by `ScrollPane` when it does
> not have focus, although not as critical as the UP/DOWN/LEFT/RIGHT keys.
Here is a minimal working example that demonstrates the issue when people
create a custom control.
Note that the standard controls and the custom control all have directional
navigation working, except in the case where the custom control is embedded
inside a `ScrollPane`. This creates a big burden on custom control developers
as to make their control work when used in a scroll pane, they now need to
implement their own navigation...
package app;
import javafx.application.Application;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.Skin;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.HBox;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class App extends Application {
@Override
public void start(Stage primaryStage) {
GridPane gp = new GridPane(10, 10);
gp.add(new VBox(new Label("Standard Buttons in normal container"), new
HBox(5, new Button("A"), new Button("B"), new Button("C"))), 0, 0);
gp.add(new VBox(new Label("Standard Buttons in ScrollPane"), new
ScrollPane(new HBox(5, new Button("A"), new Button("B"), new Button("C")))), 1,
0);
gp.add(new VBox(new Label("Custom Buttons in normal container"), new
HBox(5, new CustomButton("A"), new CustomButton("B"), new CustomButton("C"))),
0, 1);
gp.add(new VBox(new Label("Custom Buttons in ScrollPane"), new
ScrollPane(new HBox(5, new CustomButton("A"), new CustomButton("B"), new
CustomButton("C")))), 1, 1);
Scene scene = new Scene(gp);
primaryStage.setScene(scene);
primaryStage.show();
}
static class CustomButton extends Button {
CustomButton(String title) {
super(title);
setSkin(new CustomButtonSkin(this));
}
}
static class CustomButtonSkin implements Skin<Button> {
private final Button control;
private final StackPane container;
public CustomButtonSkin(Button button) {
this.control = button;
this.container = new StackPane();
this.container.getChildren().add(new Label(button.getText()));
}
@Override
public Button getSkinnable() {
return control;
}
@Override
public Node getNode() {
return container;
}
@Override
public void dispose() {
container.getChildren().clear();
}
}
}
-------------
PR Comment: https://git.openjdk.org/jfx/pull/1582#issuecomment-2385454753
