I have set up a background Task that waits several seconds after a given Panel/Chart become visible. That is performed by running a sleep on a background non-GUI thread and then upon waking up it runs a
Platform.runLater
to create the snapshot and image.
Before the real 'action' for saving the image occurs we can see the window come up:
While that image is rendering we have the background code that has been put to sleep by a Task. After 5000 millis that background task wakes up and launches a Platform.runLater to save the scene/pane/chart to a file.
Here is the snapshot and image code:
All this happens on a background thread via a Task submitted to a ThreadPool
Thread.sleep(5000) // Wait for images to be rendered - // they are visually confirmed to be available at about 1000 ms actually javafx.application.Platform.runLater(new Runnable() { override def run() = { // val snapShot = chart.snapshot(null) // val snapShot = scene.snapshot(null) val snapShot = pane.snapshot(null,null) ImageIO.write(SwingFXUtils.fromFXImage(snapShot, null), "jpg", new File(fileName))
As you can see (from the commented out lines) - I have confused about which object to use for creating the snapshot: all three above have been attempted:
Always the result is a Black Image. OOC I also tried changing the background color via
snapshotParameters.setFill(Color.WHITE)
That had no effect.
What is the correct procedure ?
Update I also tried a callback approach:
pane.snapshot( // Also tried scene and chart here .. new Callback[SnapshotResult, Void]() { override def call(result: SnapshotResult): Void = { ImageIO.write(SwingFXUtils.fromFXImage(result.getImage, null), "jpg", new File(fileName)) latch.countDown null } },p,null)
Likewise - still a Black Image.
Using such kinds of heuristics is rather risky. However, you didn't provide a full MCVE. If you want to do it that way, you could use a PauseTransition, snapshot any node and then save the image to a file.
import java.awt.Graphics2D; import java.awt.image.BufferedImage; import java.io.File; import java.io.IOException; import javafx.animation.PauseTransition; import javafx.application.Application; import javafx.embed.swing.SwingFXUtils; import javafx.scene.Node; import javafx.scene.Scene; import javafx.scene.SnapshotParameters; import javafx.scene.chart.LineChart; import javafx.scene.chart.NumberAxis; import javafx.scene.chart.XYChart; import javafx.scene.image.Image; import javafx.scene.image.WritableImage; import javafx.scene.layout.AnchorPane; import javafx.scene.paint.Color; import javafx.stage.Stage; import javafx.util.Duration; import javax.imageio.ImageIO; public class AutoSnapshot extends Application { private static String fileName = "c:/temp/image.jpg"; private static Color backgroundColor = Color.WHITE; @Override public void start(Stage primaryStage) { AnchorPane root = new AnchorPane(); // dummy chart final NumberAxis xAxis = new NumberAxis(); final NumberAxis yAxis = new NumberAxis(); xAxis.setLabel("Number of Month"); final LineChart<Number, Number> lineChart = new LineChart<Number, Number>(xAxis, yAxis); lineChart.setTitle("Stock Monitoring, 2010"); XYChart.Series series = new XYChart.Series(); series.setName("My portfolio"); series.getData().add(new XYChart.Data(1, 23)); series.getData().add(new XYChart.Data(2, 14)); series.getData().add(new XYChart.Data(3, 15)); series.getData().add(new XYChart.Data(4, 24)); lineChart.getData().add(series); root.getChildren().add( lineChart); Scene scene = new Scene(root, 800, 600, backgroundColor); primaryStage.setScene(scene); primaryStage.show(); Duration delay = Duration.seconds(5); PauseTransition pt = new PauseTransition(delay); pt.setOnFinished(e -> { saveSnapshot(lineChart); }); pt.play(); } public static Image createImage(Node node) { WritableImage wi; SnapshotParameters parameters = new SnapshotParameters(); parameters.setFill(backgroundColor); int imageWidth = (int) node.getBoundsInLocal().getWidth(); int imageHeight = (int) node.getBoundsInLocal().getHeight(); wi = new WritableImage(imageWidth, imageHeight); node.snapshot(parameters, wi); return wi; } private static void saveSnapshot(Node node) { Image image = createImage(node); // save image !!! has bug because of transparency (use approach below) !!! // ImageIO.write(SwingFXUtils.fromFXImage( selectedImage.getImage(), null), "jpg", file); // save image (without alpha) BufferedImage bufImageARGB = SwingFXUtils.fromFXImage(image, null); BufferedImage bufImageRGB = new BufferedImage(bufImageARGB.getWidth(), bufImageARGB.getHeight(), BufferedImage.OPAQUE); Graphics2D graphics = bufImageRGB.createGraphics(); graphics.drawImage(bufImageARGB, 0, 0, null); try { ImageIO.write(bufImageRGB, "jpg", new File(fileName)); } catch (IOException e) { e.printStackTrace(); } graphics.dispose(); System.out.println( "Image saved: " + fileName); } public static void main(String[] args) { launch(args); } }
After all that .. the answer is that "jpg" is simply not working. "png" format works fine.
