维帝博客 - JavaFX透明窗口

## 背景说明

今天在写自己的桌面小工具时，做了一个后台运行的周期性任务，想着每次任务完成时在桌面右下角显示一个文字提示。最终做出来Demo效果如下图，点击”显示提示”按钮，桌面右下角用绿色透明显示”显示提示信息成功!”字样。

![](https://veddy-blog.oss-accelerate.aliyuncs.com/assets/images/article/2022020816561701944b7d9a944775bae49cb7758c1167/transparent-stage.png)

## 实现分析

这里我是新创建了一个Stage，然后将一个Text放到VBox中，进儿放到Stage的Scene中。那么这里就有几个要点：

1) Stage要没有窗口装饰

```java
stage.initStyle(StageStyle.TRANSPARENT);
```

2) Scene要透明

```java
scene.setFill(null);
```

3) VBox要透明

```java
box.setStyle("-fx-background:transparent;");
```

4) Text要设置字体和颜色

```java
text.setFont(new Font(20));
text.setFill(Color.GREEN);
```

5) Stage要居桌面右下角

```java
Rectangle2D primaryScreenBounds = Screen.getPrimary().getVisualBounds();
stage.setX(primaryScreenBounds.getWidth() - width);
stage.setY(primaryScreenBounds.getHeight() - height);
```

## Demo完整代码

```java
import javafx.application.Application;
import javafx.application.Platform;
import javafx.concurrent.Task;
import javafx.event.ActionEvent;
import javafx.geometry.Rectangle2D;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.layout.StackPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.stage.Screen;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
/**
 *
 * @author Alan
 */
public class TransparentStage extends Application {
    @Override
    public void start(Stage primaryStage) {
        Button btn = new Button();
        btn.setText("显示提示");
        btn.setOnAction((ActionEvent event) -> {
            Text text = new Text("显示提示信息成功!");
            text.setFont(new Font(20));
            text.setFill(Color.GREEN);
            VBox box = new VBox();
            box.getChildren().add(text);
            box.setStyle("-fx-background:transparent;");
            final int width = 200;
            final int height = 50;
            final Scene scene = new Scene(box, width, height);
            scene.setFill(null);
            final Stage stage = new Stage();
            stage.initStyle(StageStyle.TRANSPARENT);
            stage.setScene(scene);
            Rectangle2D primaryScreenBounds = Screen.getPrimary().getVisualBounds();
            stage.setX(primaryScreenBounds.getWidth() - width);
            stage.setY(primaryScreenBounds.getHeight() - height);
            stage.show();
            Task t = new Task() {
                @Override
                protected Object call() throws Exception {
                    Thread.sleep(1000);
                    Platform.runLater(stage::close);
                    return "";
                }
            };
            new Thread(t).start();
        });
        StackPane root = new StackPane();
        root.getChildren().add(btn);
        Scene scene = new Scene(root, 300, 250);
        primaryStage.setTitle("Hello World!");
        primaryStage.setScene(scene);
        primaryStage.show();
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }
}
```