JavaFX 2.2:挂钩滑块拖放事件 [英] JavaFX 2.2: Hooking Slider Drag n Drop Events

问题描述

我正在尝试捕捉 JavaFX 上的事件 滑块 尤其是表示拖动停止并被释放的滑块.起初我使用 valueProperty 和这样的模拟代码

I am trying to catch the events on the JavaFX Slider especially the one which indicates that the drag stopped and was released. At first I used the valueProperty with mock-up code like this

slider.valueProperty().addListener(new ChangeListener<Number>() {
    @Override
    public void changed(ObservableValue<? extends Number> ov, Number oldValue, Number newValue) {
        log.fine(newValue.toString());
    }
});

但是这样更新太频繁了.所以我在 SceneBuilder 和 API 中进行了搜索，发现了一些有趣的东西，比如

but with this it update too often. So I searched within SceneBuilder and the API and found some interessting like

slider.setOnMouseDragReleased(new EventHandler<MouseDragEvent>() {
    @Override
    public void handle(MouseDragEvent event) {
        System.out.println("setOnMouseDragReleased");
    }
});

但他们永远不会被解雇.只有一些像 setOnMouseReleased 我得到了一些输出，但是这例如对于标签等 whole 节点的计数.

but they never get fired. There only some like setOnMouseReleased I get some output, but this for example count for the whole Node like the labels etc.

所以我的问题是，这是知道值不再变化的正确钩子(如果可能在释放鼠标后，如拖放手势)，也许还有一个小例子来查看它的界面工作.

推荐答案

为滑块的valueChangingProperty 了解滑块的值何时发生变化，并对值更改采取任何您想要的操作.

Add a change listener to the slider's valueChangingProperty to know when the slider's value is changing, and take whatever action you want on the value change.

下面的示例将在滑块开始更改时记录滑块的值，并在结束更改时再次记录.

The sample below will log the slider's value when it starts to change and again when it finishes changing.

import javafx.application.Application;
import javafx.beans.value.*;
import javafx.geometry.*;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.layout.*;
import javafx.stage.Stage;

public class SliderChangeLog extends Application {
    private final ListView<String> startLog = new ListView<>();
    private final ListView<String> endLog   = new ListView<>();

    @Override public void start(Stage stage) throws Exception {
        Pane logsPane = createLogsPane();
        Slider slider = createMonitoredSlider();

        VBox layout = new VBox(10);
        layout.setAlignment(Pos.CENTER);
        layout.setPadding(new Insets(10));
        layout.getChildren().setAll(
                slider,
                logsPane
        );
        VBox.setVgrow(logsPane, Priority.ALWAYS);

        stage.setTitle("Slider Value Change Logger");
        stage.setScene(new Scene(layout));
        stage.show();
    }

    private Slider createMonitoredSlider() {
        final Slider slider = new Slider(0, 1, 0.5);
        slider.setMajorTickUnit(0.5);
        slider.setMinorTickCount(0);
        slider.setShowTickMarks(true);
        slider.setShowTickLabels(true);
        slider.setMinHeight(Slider.USE_PREF_SIZE);

        slider.valueChangingProperty().addListener(new ChangeListener<Boolean>() {
            @Override
            public void changed(
                    ObservableValue<? extends Boolean> observableValue,
                    Boolean wasChanging,
                    Boolean changing) {
                String valueString = String.format("%1$.3f", slider.getValue());

                if (changing) {
                    startLog.getItems().add(
                            valueString
                    );
                } else {
                    endLog.getItems().add(
                            valueString
                    );
                }
            }
        });
        return slider;
    }

    private HBox createLogsPane() {
        HBox logs = new HBox(10);
        logs.getChildren().addAll(
                createLabeledLog("Start", startLog),
                createLabeledLog("End",   endLog)
        );
        return logs;
    }

    public Pane createLabeledLog(String logName, ListView<String> log) {
        Label label = new Label(logName);
        label.setLabelFor(log);

        VBox logPane = new VBox(5);
        logPane.getChildren().setAll(
                label,
                log
        );

        logPane.setAlignment(Pos.TOP_LEFT);

        return logPane;
    }

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

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