setOnKeyPressed事件无法正常工作

Question

我需要在大学中为我的项目创建一个生成类似隧道的曲线.我在Internet上找到了一些代码,允许我拖动曲线的控制点(附加到Anchor对象).

但是,我想通过按箭头键("向上"和"向下")来改变控制点Ylocation是可能的,并且它根本不起作用.我自己一直试图绝望地解决这个问题,但我找不到出路.

import javafx.application.Application;
import javafx.beans.property.DoubleProperty;
import javafx.event.EventHandler;
import javafx.scene.*;
import javafx.scene.input.KeyCode;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.BorderPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.*;
import javafx.stage.Stage;

/** Example of how a cubic curve works, drag the anchors around to change the curve. */
public class testsdfasdf extends Application {
  public static void main(String[] args) throws Exception { launch(args); }


  @Override public void start(Stage primaryStage) throws Exception {
    QuadCurve curve = createStartingCurve();


    final BorderPane root = new BorderPane();
    Scene scene = new Scene(root, 1000, 1000);

    final Anchor control2 = new Anchor(Color.GOLDENROD, curve.controlXProperty(), curve.controlYProperty());


    root.getChildren().add(curve);
    root.getChildren().add(control2);


    primaryStage.setTitle("Quadcurve Manipulation");
    primaryStage.setScene(scene);
    primaryStage.show();
  }

  private QuadCurve createStartingCurve() {
    QuadCurve curve = new QuadCurve();
    curve.setStartX(100);
    curve.setStartY(100);
    curve.setControlX(200);
    curve.setControlY(50);
    curve.setEndX(300);
    curve.setEndY(100);
    curve.setStroke(Color.BLACK);
    curve.setStrokeWidth(10);
    curve.setStrokeLineCap(StrokeLineCap.ROUND);
    curve.setFill(Color.CORNSILK.deriveColor(0, 1.2, 1, 0.6));
    return curve;
  }

  // a draggable anchor displayed around a point.
  class Anchor extends Circle { 

      Anchor(Color color, DoubleProperty x, DoubleProperty y) {
      super(x.get(), y.get(), 10);
      setFill(color.deriveColor(1, 1, 1, 0.5));

      y.bind(centerYProperty());
      enableDrag();
      changeCurve();
    }


    private void changeCurve() {
        setOnKeyPressed((event) -> { 
                System.out.println(event.getCode() == KeyCode.DOWN);
                if (event.getCode() == KeyCode.DOWN) {
                    double newY = getCenterY();
                    while (newY > 0 && newY < getScene().getHeight()) {
                        setCenterY(newY);
                        newY+=1;
                    }
                }
                else if (event.getCode() == KeyCode.UP) {
                    double newY = getCenterY();
                    while (newY > 0 && newY < getScene().getHeight()) {
                        setCenterY(newY);
                        newY-=1;
                    }
                }
        });
        setOnKeyReleased((event) -> {
                if (event.getCode() == KeyCode.DOWN) {
                }
                if (event.getCode() == KeyCode.UP) {
                }

            });
    }

    // make a node movable by dragging it around with the mouse.
    private void enableDrag() {
      setOnMousePressed(new EventHandler<MouseEvent>() {
        @Override public void handle(MouseEvent mouseEvent) {
          // record a delta distance for the drag and drop operation.
          getScene().setCursor(Cursor.MOVE);
        }
      });
      setOnMouseReleased(new EventHandler<MouseEvent>() {
        @Override public void handle(MouseEvent mouseEvent) {
          getScene().setCursor(Cursor.HAND);
        }
      });
      setOnMouseDragged(new EventHandler<MouseEvent>() {
        @Override public void handle(MouseEvent mouseEvent) {
          double newY = mouseEvent.getY();
          System.out.println(newY);
          if (newY > 0 && newY < getScene().getHeight()) {
            setCenterY(newY);
          }  
        }
      });
      setOnMouseEntered(new EventHandler<MouseEvent>() {
        @Override public void handle(MouseEvent mouseEvent) {
          if (!mouseEvent.isPrimaryButtonDown()) {
            getScene().setCursor(Cursor.HAND);
          }
        }
      });
      setOnMouseExited(new EventHandler<MouseEvent>() {
        @Override public void handle(MouseEvent mouseEvent) {
          if (!mouseEvent.isPrimaryButtonDown()) {
            getScene().setCursor(Cursor.DEFAULT);
          }
        }
      });
    }
  }  
}

也许这里的代码太多了.但这就是实际绘制曲线并使用enableDrag()函数使其可拖动的全部内容.

changeCurve()函数不起作用,这就是问题所在.

Answer 1

问题

除非重点关注,否则节点不会侦听事件.您的回声永远不会得到关注,因此,永远不会对关键事件做出反应.

解

一个简单的解决方案是在显示舞台后要求焦点.

primaryStage.show();
control2.requestFocus();

另一个解决方案是将场景绑定onKeyPressedProperty到Circle的onKeyPressedProperty.这将把场景中发生的所有按键事件绑定到圆圈.

可能有些情况下你不想这样做..

scene.onKeyPressedProperty().bind(control2.onKeyPressedProperty());

你也有一个小问题handle().没有必要while loop.您只想要setCenterY()一个小于/大于前一个值的值,具体取决于按下的键.

setOnKeyPressed((event) -> {
     if (event.getCode() == KeyCode.DOWN && getCenterY() < getScene().getHeight()){
         setCenterY(getCenterY() + 5);
     } else if (event.getCode() == KeyCode.UP && getCenterY() > 0) {
         setCenterY(getCenterY() - 5);
     }
});