按下键时JavaFX imageView旋转

Question

Basically, I want to rotate an ImageView by 90 degrees when the user hits R on the keyboard.

@FXML
private Image arrow;
@FXML
private ImageView arrowDirection;


@FXML
public void arrowRotation(KeyEvent keyEvent)
{
    if(keyEvent.getCode() == KeyCode.R)
    arrowDirection.setRotate(90);
}

Answer 1

Your question is a bit unspecific, so I assumed that you want an EventHandler that is added to the pane in which the image view rests, and that you want to set it in the Controller. This is my solution:

import java.net.URL;
import java.util.ResourceBundle;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.Scene;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.input.KeyCode;
import javafx.scene.input.KeyEvent;
import javafx.scene.layout.Pane;

public class FXMLDocumentController implements Initializable {

    @FXML
    Pane pane;

    @FXML
    ImageView imgView;

    public void arrowRotation(KeyEvent event){
        if(event.getCode().equals(KeyCode.R))
            imgView.setRotate(90);
    }

    @Override
    public void initialize(URL url, ResourceBundle rb) {
        Image img = new Image("https://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/Javafx-layout-classes.svg/1000px-Javafx-layout-classes.svg.png");
        imgView.setImage(img);
        pane.sceneProperty().addListener(new ChangeListener<Scene>() {
            @Override
            public void changed(ObservableValue<? extends Scene> observable, Scene oldValue, Scene newValue) {
                if(newValue != null){
                    pane.requestFocus();
                }
            }
        });
        pane.setOnKeyPressed(new EventHandler<KeyEvent>() {
            @Override
            public void handle(KeyEvent event) {
                arrowRotation(event);
            }
        });

    }    

}

Of course, this needs an FXML that holds an ImageView inside of a Pane, but that can easily be adjusted to fit your needs. The function that performs the rotation works pretty much like you thought, but I would compare using equals whenever possible. I added a listener to the sceneProperty of the pane to let the pane request the focus once the whole thing is loaded and the scene is set. This means that pressing a key will actually trigger KeyEventHandlers that are registered on the pane. Registering the EventHandler is straight forward again. Hope that helps :)