问题
The above program should create a transparent stage with some text, but the stage appears opaque:
public class Test extends Application {
@Override
public void start(Stage primaryStage) {
new TextArea(); //Comment this out to enable transparency
Stage stage = new Stage();
stage.initStyle(StageStyle.TRANSPARENT);
Text text = new Text("Is this transparent?");
VBox box = new VBox();
box.getChildren().add(text);
final Scene scene = new Scene(box, 300, 250);
scene.setFill(null);
stage.setScene(scene);
stage.show();
}
}
The new TextArea() line is what breaks things - comment that out and it all works.
Creating any subclass of control (even via new Control() {};) breaks things - a Region or above does not.
This doesn't occur in Java 7 / JFX2.x.
I've created a JIRA for this since it seems a very obvious regression (https://javafx-jira.kenai.com/browse/RT-38938), but is anyone aware why this happens and thus how to work around it until a fix is provided? I've tried replicating this issue by copying the code in Control's constructor, but this seems to be fine - it's just instantiating Control itself that seems to break things.
回答1:
I remember some forum discussion on this. I think the general gist is that creating a control forces css to be applied to the layout pane, and the layout pane is getting the opaque background.
As a workaround, make the background of the layout pane transparent:
box.setStyle("-fx-background-color: transparent;");
来源：https://stackoverflow.com/questions/26278698/creating-a-control-seems-to-break-transparent-stages-on-jfx8