Question

我尝试在每次释放鼠标时创建一个Path类型的新对象并将其添加到ArrayList中，以便我以后可以使用它来允许创建具有不同颜色的许多路径，这将有所帮助在创建撤消/重做。但是在事件处理程序中向ArrayList添加新元素似乎无法正常工作。

import java.util.ArrayList;
import javafx.application.Application;
import javafx.event.*;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.input.*;
import javafx.scene.paint.*;
import javafx.scene.shape.*;
import javafx.stage.Stage;

public class Source extends Application {

    public static ArrayList<Path> paths = new ArrayList<>();

    public void start(Stage stage) {
        Group root = new Group();
        Scene scene = new Scene(root, 300, 250);
        scene.setOnMouseDragged(mouseHandler);
        scene.setOnMousePressed(mouseHandler);
        scene.setOnMouseReleased(mouseHandler);
        for(int i=0; i<paths.size(); i++)
          root.getChildren().add(paths.get(i));
        stage.setScene(scene);
        stage.show();
    }

    EventHandler<MouseEvent> mouseHandler = new EventHandler<MouseEvent>() {
        Path path = new Path();
        public void handle(MouseEvent mouseEvent) {
            if(mouseEvent.getEventType() == MouseEvent.MOUSE_PRESSED){   
                path.getElements().add(new MoveTo(mouseEvent.getX(), mouseEvent.getY()));
            }
            else if(mouseEvent.getEventType() == MouseEvent.MOUSE_DRAGGED){
                path.getElements().add(new LineTo(mouseEvent.getX(), mouseEvent.getY()));
            }
            if(mouseEvent.getEventType() == mouseEvent.MOUSE_RELEASED){
                paths.add(path);  
            }   
        }
    };
}

Answer 1

尝试以下方法，

public class Source extends Application {

    public static ArrayList<Path> paths = new ArrayList<>();

    public void start(Stage stage) {
        Group root = new Group();
        Scene scene = new Scene(root, 300, 250);
        scene.setOnMouseDragged(mouseHandler);
        scene.setOnMousePressed(mouseHandler);
        scene.setOnMouseReleased(mouseHandler);
        for(int i=0; i<paths.size(); i++)
          root.getChildren().add(paths.get(i));
        stage.setScene(scene);
        stage.show();
    }

    Path path = new Path();
    EventHandler<MouseEvent> mouseHandler = new EventHandler<MouseEvent>() {
        public void handle(MouseEvent mouseEvent) {
            if(mouseEvent.getEventType() == MouseEvent.MOUSE_PRESSED){   
                path.getElements().add(new MoveTo(mouseEvent.getX(), mouseEvent.getY()));
            }
            else if(mouseEvent.getEventType() == MouseEvent.MOUSE_DRAGGED){
                path.getElements().add(new LineTo(mouseEvent.getX(), mouseEvent.getY()));
            }
            if(mouseEvent.getEventType() == mouseEvent.MOUSE_RELEASED){
                paths.add(path);
            }   
        }
    };
}

希望这有帮助！

Answer 2

public class Source extends Application {
    public static ArrayList<Path> paths = new ArrayList<>();

    public void start(Stage stage) {
        Pane root = new Pane();
        Scene scene = new Scene(root, 300, 250);

        scene.setOnMousePressed(new EventHandler<MouseEvent>() {
            public void handle(MouseEvent event) {
                Path path = new Path();
                paths.add(path);
                path.getElements().add(new MoveTo(event.getX(),event.getY()));

                scene.setOnMouseDragged(new EventHandler<MouseEvent>() {
                    public void handle(MouseEvent event) {
                        path.getElements().add(new LineTo(event.getX(),event.getY()));
                    }
                });
                root.getChildren().add(path);
            }
        });
        stage.setScene(scene);
        stage.show();
    }
}

我已经弄清楚了。：）

将元素添加到事件hundler上的arraylist

2 个答案: