拍摄Javafx Textarea和WebView的快照

Question

我有以下问题：我正在编写一个像空白纸一样的程序，您可以在其中写（免费手写），插入文本，添加图像，添加PDF等...对于一个特定功能，我需要将用户添加到窗格的节点转换为图像。值得庆幸的是，Javafx节点提供了一个不错的方法：

public void snapshot(...)

但是有一个问题：当我试图制作文本对象的快照时，它们会失败。我可以拍摄快照的唯一节点是javafx.scene.text.text。以下课程失败：

javafx.scene.control.TextArea
javafx.scene.web.WebView

这是一个说明我的问题的示例：

import javafx.application.Application;
import javafx.stage.Stage;
import javafx.scene.Scene;
import javafx.scene.SnapshotParameters;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.control.TextArea;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.text.Text;
public class Main extends Application {
    @Override
    public void start(Stage primaryStage) {
        try {
            TextArea textArea = new TextArea("Lorem Ipsum is simply dummy text"
                    + " of the printing and typesetting industry. Lorem Ipsum has been n"
                    + "the industry's standard dummy text ever since the 1500s, when an n"
                    + "unknown printer took a galley of type and scrambled it to make a typen"
                    + " specimen book. It has survived not only five centuries, but also then"
                    + " leap into electronic typesetting, remaining essentially unchanged. Itn"
                    + " was popularised in the 1960s with the release of Letraset sheets containingn"
                    + " Lorem Ipsum passages, and more recently with desktop publishing software n"
                    + "like Aldus PageMaker including versions of Lorem Ipsum");
            SnapshotParameters snapshotParameters = new SnapshotParameters();
            snapshotParameters.setFill(Color.TRANSPARENT);
            Image img = textArea.snapshot(snapshotParameters, null);
            ImageView imgVw = new ImageView( img );
            System.out.printf("img.width: %s    height: %s%n", img.getWidth(), img.getHeight()); // <= width and height of the image img is 1:1! WHY?
            Pane pane = new Pane();
            pane.getChildren().addAll(imgVw);
            Scene scene = new Scene(pane, 800,800);
            pane.setMinWidth(800);
            pane.setMinHeight(800);
            pane.setMaxWidth(800);
            pane.setMaxHeight(800);
            scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());
            primaryStage.setScene(scene);
            primaryStage.show();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

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

我可以通过创建一个Javafx.scene.text.text-object来想到一个工作，然后对此进行快照。但这将失败。

预先感谢您的帮助！

Answer 1

textarea需要在拍摄之前是一个场景。在快照调用之前，将以下行添加到您的代码中，并且代码将按照您的期望工作：

Scene snapshotScene = new Scene(textArea);

快照Javadoc中提到了此要求：

注意：为了正确运行CSS和布局，节点必须 成为场景的一部分（场景可能附加到舞台上，但不需要 是）。