java - 在 JavaFX 中绘制节点

Question

我试图通过创建用户去过的地方的踪迹来跟踪用户的 Activity 。我已经弄清楚了该程序的大部分方面，但我仍然困惑于如何保持用户在 Pane 上的移动。

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.text.Text;
import javafx.stage.Stage;

public class DrawLines extends Application {
  @Override 
  public void start(Stage primaryStage) {

    Pane pane = new Pane();
    Text text = new Text(150, 150, ".");

    pane.getChildren().add(text);
    text.setOnKeyPressed(e -> {          
      switch (e.getCode()) {
        case DOWN: text.setY(text.getY() + 10); break;
        case UP:  text.setY(text.getY() - 10); break;
        case LEFT: text.setX(text.getX() - 10); break;
        case RIGHT: text.setX(text.getX() + 10); break;
        default: 
          if (Character.isLetterOrDigit(e.getText().charAt(0)))
            text.setText(e.getText());
      }
    });

    // Create a scene and place the pane in the stage
    Scene scene = new Scene(pane, 300, 300);
    primaryStage.setTitle("Draw a Line!"); 
    primaryStage.setScene(scene); 
    primaryStage.show(); 

    text.requestFocus(); 
  }

Answer 1

您需要创建一个新的文本并将其添加到每次用户移动的 Pane 中。只需创建一个新方法来处理此问题并为每个用户移动调用它即可。

private void leaveTrail(Pane pane, Text text){
    Text newText = new Text(text.getText());
    pane.getChildren().add(newText);
    newText.setY(text.getY());
    newText.setX(text.getX());
}

一个完整的工作示例:

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.text.Text;
import javafx.stage.Stage;

public class DrawLines extends Application {

    @Override
    public void start(Stage primaryStage) {

        Pane pane = new Pane();
        Text text = new Text(150, 150, ".");

        pane.getChildren().add(text);
        text.setOnKeyPressed(e -> {
            switch (e.getCode()) {
                case DOWN:
                    leaveTrail(pane, text);
                    text.setY(text.getY() + 10);
                    break;
                case UP:
                    leaveTrail(pane, text);
                    text.setY(text.getY() - 10);
                    break;
                case LEFT:
                    leaveTrail(pane, text);
                    text.setX(text.getX() - 10);
                    break;
                case RIGHT:
                    leaveTrail(pane, text);
                    text.setX(text.getX() + 10);
                    break;
                default:
                    if (Character.isLetterOrDigit(e.getText().charAt(0)))
                        text.setText(e.getText());
            }
        });

        // Create a scene and place the pane in the stage
        Scene scene = new Scene(pane, 300, 300);
        primaryStage.setTitle("Draw a Line!");
        primaryStage.setScene(scene);
        primaryStage.show();
        text.requestFocus();
    }

    private void leaveTrail(Pane pane, Text text){
        Text newText = new Text(text.getText());
        pane.getChildren().add(newText);
        newText.setY(text.getY());
        newText.setX(text.getX());
    }
    public static void main(String[] args) {
        launch(args);
    }
}

示例图像