JavaFX：如何在窗格上拖动imageview

Question

有人能举一个简单的例子来说明如何设置EventHandler以在窗格（JavaFX）上拖动图像视图。对于拖动，我的意思是在图像上按下鼠标，拖动和图像应该跟随，然后释放鼠标，图像视图将停止在该位置。

Answer 1

我想通过拖放来尝试提出的解决方案。我发现它不是最佳的。

通过拖放操作，可以触发一些不必要的机制：

• 您可以将其拖动到应用程序外部
• 光标更改
• 我还有一个问题，位置增量的计算似乎与速度有关

尽管如此，如果有人感兴趣，这是我的代码：

Main.java

package sample;

import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) throws Exception{
        FXMLLoader loader = new FXMLLoader(getClass().getResource("sample.fxml"));

        Controller controller = new Controller();
        loader.setController(controller);

        Parent root = (Parent)loader.load();
        controller.InitUi();

        primaryStage.setTitle("Hello World");
        primaryStage.setScene(new Scene(root, 300, 275));
        primaryStage.show();
    }


    public static void main(String[] args) {
        launch(args);
    }
}

控制器。Java语言

package sample;

import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.scene.input.*;
import javafx.scene.layout.AnchorPane;
import javafx.scene.shape.Rectangle;

public class Controller
{
    @FXML
    private Rectangle draggable;

    private Double lastX = null;
    private Double lastY = null;

    public void InitUi()
    {
        if (this.draggable != null)
        {
            this.draggable.setOnDragOver(new EventHandler<DragEvent>()
            {
                @Override
                public void handle(DragEvent dragEvent)
                {
                    HandleMouseMovement(dragEvent.getSceneX(), dragEvent.getSceneY());
                }
            });

            this.draggable.setOnDragDetected(new EventHandler<MouseEvent>() {
                public void handle(MouseEvent event) {
                    Dragboard db = draggable.startDragAndDrop(TransferMode.ANY);
                    ClipboardContent content = new ClipboardContent();
                    content.putString("Does not matter");
                    db.setContent(content);
                    event.consume();

                    lastX = event.getSceneX();
                    lastY = event.getSceneY();
                }
            });
        }
    }

    private synchronized void HandleMouseMovement(double sceneX, double sceneY)
    {
        double deltaX = sceneX - lastX;
        double deltaY = sceneY - lastY;

        lastX = sceneX;
        lastY = sceneY;

        double currentXAnchor =AnchorPane.getLeftAnchor(this.draggable);
        double currentYAnchor =AnchorPane.getTopAnchor(this.draggable);

        AnchorPane.setLeftAnchor( this.draggable,  currentXAnchor + deltaX*1.5);
        AnchorPane.setTopAnchor(this.draggable, currentYAnchor + deltaY*1.5);
    }
}

sample.fxml

<?import javafx.scene.layout.GridPane?>

<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.shape.Rectangle?>
<GridPane xmlns:fx="http://javafx.com/fxml" alignment="center" hgap="10" vgap="10" prefHeight="500" prefWidth="500">
    <AnchorPane>
        <Rectangle fx:id="draggable" width="40" height="50" AnchorPane.topAnchor="20" AnchorPane.leftAnchor="20"/>
    </AnchorPane>
</GridPane>

Answer 2

首先阅读文档在javafx中拖放，或者您可以自己通过getMouseX和getMouseY点并更改AnchorPane中ImageView的坐标。...