如何在Javafx 2.0中创建可拖动节点。 [英] how to make a Draggable Node in Javafx 2.0.

问题描述

如何在Javafx 2.0中创建可拖动节点。
JavaFX专门用于GUI目的只需
我需要一些样品谢谢

how to make a Draggable Node in Javafx 2.0. The JavaFX is specially for GUI purpose only I need some sample thanks

推荐答案

Oracle提供< a href =http://docs.oracle.com/javafx/2/events/filters.htm =noreferrer>有关可拖动节点的教程。

以下是教程中的 makeDraggable 方法：

private Node makeDraggable(final Node node) {
final DragContext dragContext = new DragContext();
final Group wrapGroup = new Group(node);

wrapGroup.addEventFilter(
    MouseEvent.ANY,
    new EventHandler<MouseEvent>() {
        public void handle(final MouseEvent mouseEvent) {
            if (dragModeActiveProperty.get()) {
                // disable mouse events for all children
                mouseEvent.consume();
            }
         }
    });

wrapGroup.addEventFilter(
    MouseEvent.MOUSE_PRESSED,
    new EventHandler<MouseEvent>() {
        public void handle(final MouseEvent mouseEvent) {
            if (dragModeActiveProperty.get()) {
                // remember initial mouse cursor coordinates
                // and node position
                dragContext.mouseAnchorX = mouseEvent.getX();
                dragContext.mouseAnchorY = mouseEvent.getY();
                dragContext.initialTranslateX =
                    node.getTranslateX();
                dragContext.initialTranslateY =
                    node.getTranslateY();
            }
        }
    });

wrapGroup.addEventFilter(
    MouseEvent.MOUSE_DRAGGED,
    new EventHandler<MouseEvent>() {
        public void handle(final MouseEvent mouseEvent) {
            if (dragModeActiveProperty.get()) {
                // shift node from its initial position by delta
                // calculated from mouse cursor movement
                node.setTranslateX(
                    dragContext.initialTranslateX
                        + mouseEvent.getX()
                        - dragContext.mouseAnchorX);
                node.setTranslateY(
                    dragContext.initialTranslateY
                        + mouseEvent.getY()
                        - dragContext.mouseAnchorY);
            }
        }
    });

return wrapGroup;

}

有时你不需要过滤器和拖动上下文可以通过像示例中的各种鼠标事件一样简单地做一些事情：

Sometimes you don't need the filters and drag context and can just do something simpler by acting on various mouse events like in this example:

static class Delta { double x, y; }
// make a node movable by dragging it around with the mouse.
private void enableDrag(final Circle circle) {
final Delta dragDelta = new Delta();
circle.setOnMousePressed(new EventHandler<MouseEvent>() {
  @Override public void handle(MouseEvent mouseEvent) {
    // record a delta distance for the drag and drop operation.
    dragDelta.x = circle.getCenterX() - mouseEvent.getX();
    dragDelta.y = circle.getCenterY() - mouseEvent.getY();
    circle.getScene().setCursor(Cursor.MOVE);
  }
});
circle.setOnMouseReleased(new EventHandler<MouseEvent>() {
  @Override public void handle(MouseEvent mouseEvent) {
    circle.getScene().setCursor(Cursor.HAND);
  }
});
circle.setOnMouseDragged(new EventHandler<MouseEvent>() {
  @Override public void handle(MouseEvent mouseEvent) {
    circle.setCenterX(mouseEvent.getX() + dragDelta.x);
    circle.setCenterY(mouseEvent.getY() + dragDelta.y);
  }
});
circle.setOnMouseEntered(new EventHandler<MouseEvent>() {
  @Override public void handle(MouseEvent mouseEvent) {
    if (!mouseEvent.isPrimaryButtonDown()) {
      circle.getScene().setCursor(Cursor.HAND);
    }
  }
});
circle.setOnMouseExited(new EventHandler<MouseEvent>() {
  @Override public void handle(MouseEvent mouseEvent) {
    if (!mouseEvent.isPrimaryButtonDown()) {
      circle.getScene().setCursor(Cursor.DEFAULT);
    }
  }
});
}

用于拖动节点的相同技术也可用于拖动舞台：

The same technique for dragging nodes around can also be used to drag around stages:

static class Delta { double x, y; }
/** makes a stage draggable using a given node */
public static void makeDraggable(final Stage stage, final Node byNode) {
final Delta dragDelta = new Delta();
byNode.setOnMousePressed(new EventHandler<MouseEvent>() {
  @Override public void handle(MouseEvent mouseEvent) {
    // record a delta distance for the drag and drop operation.
    dragDelta.x = stage.getX() - mouseEvent.getScreenX();
    dragDelta.y = stage.getY() - mouseEvent.getScreenY();
    byNode.setCursor(Cursor.MOVE);
  }
});
byNode.setOnMouseReleased(new EventHandler<MouseEvent>() {
  @Override public void handle(MouseEvent mouseEvent) {
    byNode.setCursor(Cursor.HAND);
  }
});
byNode.setOnMouseDragged(new EventHandler<MouseEvent>() {
  @Override public void handle(MouseEvent mouseEvent) {
    stage.setX(mouseEvent.getScreenX() + dragDelta.x);
    stage.setY(mouseEvent.getScreenY() + dragDelta.y);
  }
});
byNode.setOnMouseEntered(new EventHandler<MouseEvent>() {
  @Override public void handle(MouseEvent mouseEvent) {
    if (!mouseEvent.isPrimaryButtonDown()) {
      byNode.setCursor(Cursor.HAND);
    }
  }
});
byNode.setOnMouseExited(new EventHandler<MouseEvent>() {
  @Override public void handle(MouseEvent mouseEvent) {
    if (!mouseEvent.isPrimaryButtonDown()) {
      byNode.setCursor(Cursor.DEFAULT);
    }
  }
});
}

拖动父节点（包含多个子节点）的示例。此示例比上面的基于圆的示例更通用，因为它不依赖于大多数节点没有的centerX / Y属性，而是在layoutX / Y上工作，这些属性可用于放置在父组或窗格中的所有节点。

Sample for dragging around a parent node (that contains multiple child nodes). This example is more generic then the circle based example from above as it does not rely on centerX/Y properties which most nodes don't have, instead it works on layoutX/Y which are available to all nodes placed in a parent Group or Pane.

import javafx.application.Application;
import javafx.scene.*;
import javafx.scene.layout.*;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.text.Text;
import javafx.scene.text.TextBoundsType;
import javafx.stage.Stage;

public class TextOnCircleWithDragging extends Application {
    private static final int W = 400;
    private static final int H = 400;
    private static final int R = 15;

    @Override
    public void start(Stage stage) {
        final StackPane circleWithText = new StackPane(
                createCircle(),
                createText()
        );
        circleWithText.relocate(
                W/2 - R/2,
                H/2 - R/2
        );

        makeDraggable(circleWithText);

        stage.setScene(
                new Scene(
                        new Pane(circleWithText),
                        W, H
                )
        );
        stage.show();
    }

    private Circle createCircle() {
        final Circle circle = new Circle(R);
        circle.setFill(Color.PALEGREEN);
        circle.relocate(0, 0);

        return circle;
    }

    private Text createText() {
        final Text text = new Text("A");
        text.setBoundsType(TextBoundsType.VISUAL);

        return text;
    }

    private void makeDraggable(Node node) {
        final Delta dragDelta = new Delta();

        node.setOnMouseEntered(me -> {
            if (!me.isPrimaryButtonDown()) {
                node.getScene().setCursor(Cursor.HAND);
            }
        });
        node.setOnMouseExited(me -> {
            if (!me.isPrimaryButtonDown()) {
                node.getScene().setCursor(Cursor.DEFAULT);
            }
        });
        node.setOnMousePressed(me -> {
            if (me.isPrimaryButtonDown()) {
                node.getScene().setCursor(Cursor.DEFAULT);
            }
            dragDelta.x = me.getX();
            dragDelta.y = me.getY();
            node.getScene().setCursor(Cursor.MOVE);
        });
        node.setOnMouseReleased(me -> {
            if (!me.isPrimaryButtonDown()) {
                node.getScene().setCursor(Cursor.DEFAULT);
            }
        });
        node.setOnMouseDragged(me -> {
            node.setLayoutX(node.getLayoutX() + me.getX() - dragDelta.x);
            node.setLayoutY(node.getLayoutY() + me.getY() - dragDelta.y);
        });
    }

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

    private class Delta {
        public double x;
        public double y;
    }
}

延迟调整

如果您看到拖动的节点滞后于光标并希望解决该问题，请参阅Xanatos的回答：

If you are seeing the dragged node lag behind the cursor and wish to address that, then see Xanatos's answer to:

• https： //stackoverflow.com/a/22695105/1155209

• https://stackoverflow.com/a/22695105/1155209

他建议你可以设置：

-Dprism.vsync=false

解决方法问题 https://bugs.openjdk.java.net/浏览/ JDK-8087922 。

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