我有一個可垂直滾動的 TextArea ( wrapTextis true)，我想顯示它的滾動百分比。我創建了一個這樣的監聽器：textArea.scrollTopProperty().addListener(new ChangeListener<Number>() { @Override public void changed(ObservableValue<? extends Number> observable, Number oldValue, Number newValue) { final float percentage = newValue / denominator * 100.0f; System.out.println("Scroll top: " + percentage); }});所以看起來我需要檢索一些屬性才能將其用作denominator. 任何幫助將不勝感激！謝謝。
1 回答
一只萌萌小番薯
TA貢獻1795條經驗 獲得超7個贊
您需要ScrollBar從TextArea. 訪問它的唯一方法是使用以下lookup()方法：
ScrollBar scrollBar = (ScrollBar) textArea.lookup(".scroll-bar:vertical");
請注意，這必須在屏幕上呈現后完成。TextArea
從那里，您可以設置幾個綁定到 aLabel以顯示當前滾動的百分比：
DoubleProperty scrollPercentage = new SimpleDoubleProperty();
scrollPercentage.bind(Bindings.createDoubleBinding(() -> scrollBar.valueProperty().get() * 100, scrollBar.valueProperty()));
label.textProperty().bind(Bindings.format("%,.2f", scrollPercentage));
這是一個簡單的 MCVE 來演示：
import javafx.application.Application;
import javafx.application.Platform;
import javafx.beans.binding.Bindings;
import javafx.beans.property.DoubleProperty;
import javafx.beans.property.SimpleDoubleProperty;
import javafx.geometry.Insets;
import javafx.geometry.Pos;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.ScrollBar;
import javafx.scene.control.TextArea;
import javafx.scene.layout.Priority;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class ScrollBarPercentage extends Application {
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage primaryStage) {
// Simple Interface
VBox root = new VBox(10);
root.setAlignment(Pos.CENTER);
root.setPadding(new Insets(10));
// Simple TextArea
TextArea textArea = new TextArea() {{
setWrapText(true);
setText("Lorem ipsum dolor sit amet, consectetur adipiscing elit. Donec suscipit posuere sodales. Mauris sodales velit vel sollicitudin volutpat. Sed rhoncus sodales sagittis. Duis ut congue mauris, sit amet tincidunt lacus. Mauris convallis convallis massa, in cursus nulla sollicitudin et. Etiam quis congue mi, nec tempor tellus. Praesent sed mollis ante. Curabitur fermentum volutpat massa, non dapibus tortor rutrum et. Sed lorem dui, pharetra ac lacus non, ultricies varius enim. Ut nec ante lectus. Vestibulum scelerisque vulputate facilisis. Cras commodo sapien eros, eu pellentesque massa congue vel. Aliquam urna neque, elementum iaculis justo eget, semper ullamcorper magna.\n\n" +
"Suspendisse ultricies porta auctor. Praesent ultrices lectus sed maximus ultricies. Nulla pharetra, augue in luctus fringilla, enim turpis auctor turpis, eu ullamcorper metus ligula ac nisl. Quisque accumsan tempus varius. Mauris blandit erat eget enim tempor accumsan. Nam iaculis libero a est sollicitudin, non fermentum ex viverra. Vivamus pharetra neque non augue feugiat efficitur. In hac habitasse platea dictumst. Aliquam tempor enim blandit blandit tempor. Ut porta ex sed congue maximus. Nulla non tortor est. Integer vel placerat lectus, vel tempus justo. Vestibulum ut dui sit amet mauris maximus ultricies vel in quam. Fusce suscipit volutpat magna eget ornare. Donec elementum ultricies tortor, volutpat porta enim fermentum sit amet.\n\n" +
"Aenean id erat at metus accumsan sodales. Suspendisse sed nisi iaculis, congue lectus et, efficitur nibh. Curabitur placerat erat et justo blandit porttitor. Nam mollis tempor magna, sed rutrum neque. Nunc mollis nunc posuere ex iaculis elementum. Nunc quam diam, aliquam ut ex mollis, facilisis varius ligula. Donec nec venenatis nunc, et auctor mi.");
}};
VBox.setVgrow(textArea, Priority.ALWAYS);
// Label to display percentage scrolled
Label label = new Label();
// Since the lookup will only work after the TextArea has been rendered in the Scene, we need to retrieve it later with the runLater() method
Platform.runLater(() -> {
// Get the ScrollBar from the TextArea using a lookup
ScrollBar scrollBar = (ScrollBar) textArea.lookup(".scroll-bar:vertical");
// Now create a DoubleProperty that we'll bind to our scroll value * 100
DoubleProperty scrollPercentage = new SimpleDoubleProperty();
scrollPercentage.bind(Bindings.createDoubleBinding(() -> scrollBar.valueProperty().get() * 100, scrollBar.valueProperty()));
// Bind the label to show a formatted percentage of the scrolling
label.textProperty().bind(Bindings.format("%,.2f", scrollPercentage));
});
root.getChildren().addAll(textArea, new Label("Scrolled:"), label);
// Show the stage
primaryStage.setScene(new Scene(root));
primaryStage.setTitle("Sample");
primaryStage.show();
}
}
結果：
https://i.stack.imgur.com/ngoR6.png
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