java - 如何在javafx中保存选定的图像？

Question

like this blank image is saving

 import java.io.File;
    import java.io.IOException;
    import javafx.application.Application;
    import javafx.embed.swing.SwingFXUtils;
    import javafx.event.EventHandler;
    import javafx.scene.Scene;
    import javafx.scene.SnapshotParameters;
    import javafx.scene.effect.Light.Point;
    import javafx.scene.image.WritableImage;
    import javafx.scene.input.KeyCode;
    import javafx.scene.input.KeyEvent;
    import javafx.scene.layout.Pane;
    import javafx.scene.paint.Color;
    import javafx.scene.shape.Rectangle;
    import javafx.scene.web.WebEngine;
    import javafx.scene.web.WebView;
    import javafx.stage.Stage;
    import javax.imageio.ImageIO;

public class JavaFxSelectPlay extends Application {

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

    @Override
    public void start(Stage primaryStage) throws Exception {
        Pane root = new Pane();
        WebView wv = new WebView();
        WebEngine Img = wv.getEngine();
        Img.load("https://app.leadlock.pro/upload/69/1019/images/welcome.jpeg");
        final Rectangle selection = new Rectangle();
        final Point anchor = new Point();

        wv.setOnMousePressed(event -> {
            anchor.setX(event.getX());
            anchor.setY(event.getY());
            selection.setX(event.getX());
            selection.setY(event.getY());
            selection.setFill(null); // transparent 
            selection.setStroke(Color.BLACK); // border
            selection.getStrokeDashArray().add(10.0);
         root.getChildren().add(selection);
        });

        wv.setOnMouseDragged(event -> {
            selection.setWidth(Math.abs(event.getX() - anchor.getX()));
            selection.setHeight(Math.abs(event.getY() - anchor.getY()));
            selection.setX(Math.min(anchor.getX(), event.getX()));
            selection.setY(Math.min(anchor.getY(), event.getY()));
        });

        wv.setOnMouseReleased(event -> {
            // Do what you want with selection's properties here
            System.out.printf("X: %.2f, Y: %.2f, Width: %.2f, Height: %.2f%n", 
                    selection.getX(), selection.getY(), selection.getWidth(), selection.getHeight());
          //  root.getChildren().remove(selection);
           // selection.setWidth(0);
          //  selection.setHeight(0);
        });
          wv.addEventFilter(KeyEvent.KEY_RELEASED, (KeyEvent e1) -> {
            if (e1.getCode() == KeyCode.SPACE ) {
     selection.setFill(Color.WHITE); // transparent 
            }
            });
          wv.setOnKeyPressed(new EventHandler<KeyEvent>() {
 public void handle(final KeyEvent keyEvent) {
   if (keyEvent.getCode() == KeyCode.F5) {
    System.out.println("F5 pressed");
    //Stop letting it do anything else
   // WritableImage croppedImage = selection.snapshot(null, null);


           WritableImage image = selection.snapshot(new SnapshotParameters(), null);

    // TODO: probably use a file chooser here
     File file = new File("C:/temp/snapshot.jpg");

    try {
        ImageIO.write(SwingFXUtils.fromFXImage(image, null), "jpg", file);
    } catch (IOException e) {
        // TODO: handle exception here
    }
}
            System.out.println("snapshot saved: " );
   }
 });

        root.getChildren().add(wv);
        Scene scene = new Scene(root, 300, 200);
        primaryStage.setScene(scene);
        primaryStage.setTitle("Primary Stage");
        primaryStage.show();
    }
 }

我尝试过这段代码，它运行良好，但是保存的图像是以白色保存的，它没有保存原始选定的图像，所以我该怎么做，请帮助我需要保存选定的图像，我已经做了白色，但是不是白色，而是所选的图像，所以请告诉我该怎么做以及我做错了什么。

Answer 1

这里似乎发生了两件事。

首先，您可能想要拍摄根的快照并使用选择矩形来指定快照的哪一部分，而不是拍摄用于标记选择的矩形的快照采取。所以，不要写

        WritableImage image = selection.snapshot(new SnapshotParameters(), null);

尝试写作

        SnapshotParameters params = new SnapshotParameters();
        params.setViewport(
            new Rectangle2D(
                selection.getX(),
                selection.getY(),
                selection.getWidth(),
                selection.getHeight()));

        root.getChildren().remove(selection);
        WritableImage image = root.snapshot(params, null);

我还从根中删除了矩形，以便它不会出现在输出图像中。

发生的第二件事是图像变成粉红色。这似乎是 existing issue which is supposed to have been fixed in Java 8但我仍然可以在 Java 8 update 152 中重现它。调整我链接到的问题中的代码，您必须替换该行

            ImageIO.write(SwingFXUtils.fromFXImage(image, null), "jpg", file);

与

            BufferedImage bufferedImage = SwingFXUtils.fromFXImage(image, null);
            BufferedImage imageRGB = new BufferedImage(
                bufferedImage.getWidth(), bufferedImage.getHeight(), BufferedImage.OPAQUE);
            Graphics2D graphics = imageRGB.createGraphics();
            graphics.drawImage(bufferedImage, 0, 0, null);
            ImageIO.write(imageRGB, "jpg", file);