Captures web pages to image files using JavaFX WebView and ImageIO

WebViewCaptureDemo.java

import javafx.animation.PauseTransition;
import javafx.application.Application;
import javafx.beans.value.*;
import javafx.embed.swing.SwingFXUtils;
import javafx.event.*;
import javafx.geometry.Bounds;
import javafx.scene.Scene;
import javafx.scene.control.*;
import javafx.scene.image.*;
import javafx.scene.layout.*;
import javafx.scene.web.WebView;
import javafx.stage.Stage;
import javafx.util.Duration;
import javafx.util.converter.NumberStringConverter;

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

public class WebViewCaptureDemo extends Application {
  private static final String HOME_LOC = "http://docs.oracle.com/javafx/2/get_started/animation.htm";

  private WebView webView;

  private File captureFile = new File("cap.png");

  public static void main(String[] args) { Application.launch(WebViewCaptureDemo.class); }

  @Override public void start(Stage stage) throws Exception {
    webView = new WebView();
    webView.setPrefSize(1000, 8000);

    final TextField location = new TextField();
    location.setOnAction(new EventHandler<ActionEvent>() {
      @Override public void handle(ActionEvent event) {
        if (!location.getText().startsWith("http")) {
          location.setText("http://" + location.getText());
        }
        webView.getEngine().load(location.getText());
      }
    });
    webView.getEngine().locationProperty().addListener(new ChangeListener<String>() {
      @Override
      public void changed(ObservableValue<? extends String> observable, String oldLocation, String newLocation) {
        location.setText(newLocation);
      }
    });

    ScrollPane webViewScroll = new ScrollPane();
    webViewScroll.setContent(webView);
    webViewScroll.setPrefSize(800, 300);

    final Button capture = new Button("Capture");

    final ProgressIndicator progress = new ProgressIndicator();
    progress.setVisible(false);

    final TextField prefWidth  = new TextField("1000");
    final TextField prefHeight = new TextField("8000");

    HBox controls = new HBox(10);
    controls.getChildren().addAll(capture, progress, prefWidth, prefHeight);

    final ImageView imageView = new ImageView();
    ScrollPane imageViewScroll = makeScrollable(imageView);
    imageViewScroll.setPrefSize(800, 300);

    final PauseTransition pt = new PauseTransition();
    pt.setDuration(Duration.millis(500));
    pt.setOnFinished(new EventHandler<ActionEvent>() {
      @Override
      public void handle(ActionEvent actionEvent) {
        WritableImage image = webView.snapshot(null, null);
        BufferedImage bufferedImage = SwingFXUtils.fromFXImage(image, null);
        try {
          ImageIO.write(bufferedImage, "png", captureFile);
          imageView.setImage(new Image(captureFile.toURI().toURL().toExternalForm()));
          System.out.println("Captured WebView to: " + captureFile.getAbsoluteFile());
          progress.setVisible(false);
          capture.setDisable(false);
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    });

    capture.setOnAction(new EventHandler<ActionEvent>() {
      @Override
      public void handle(ActionEvent actionEvent) {
        NumberStringConverter converter = new NumberStringConverter();
        double W = converter.fromString(prefWidth.getText()).doubleValue();
        double H = converter.fromString(prefHeight.getText()).doubleValue();

        // ensure that the capture size has a reasonable min size and is within the limits of what JavaFX is capable of processing.
        if (W < 100) {
          W = 100;
          prefWidth.setText("100");
        }

        if (W > 2000) {
          W = 2000;
          prefWidth.setText("2000");
        }

        if (H < 100) {
          H = 100;
          prefHeight.setText("100");
        }

        if (H > 16000) {
          H = 16000;
          prefHeight.setText("16000");
        }

        webView.setPrefWidth(W);
        webView.setPrefHeight(H);

        pt.play();
        capture.setDisable(true);
        progress.setVisible(true);
      }
    });

    webView.getEngine().load(HOME_LOC);

    VBox layout = new VBox(10);
    layout.setStyle("-fx-padding: 10; -fx-background-color: cornsilk;");
    layout.getChildren().setAll(
        location,
        webViewScroll,
        controls,
        imageViewScroll,
        new Label("Capture File: " + captureFile.getAbsolutePath())
    );
    VBox.setVgrow(imageViewScroll, Priority.ALWAYS);

    stage.setScene(new Scene(layout));
    stage.show();
  }

  private ScrollPane makeScrollable(final ImageView imageView) {
    final ScrollPane scroll = new ScrollPane();
    final StackPane centeredImageView = new StackPane();

    centeredImageView.getChildren().add(imageView);
    scroll.viewportBoundsProperty().addListener(new ChangeListener<Bounds>() {
      @Override public void changed(ObservableValue<? extends Bounds> ov, Bounds oldBounds, Bounds bounds) {
        centeredImageView.setPrefSize(
          Math.max(imageView.prefWidth(bounds.getHeight()), bounds.getWidth()),
          Math.max(imageView.prefHeight(bounds.getWidth()), bounds.getHeight())
        );
      }
    });
    scroll.setContent(centeredImageView);

    return scroll;
  }

}