JavaFX : Canvas to Image in non GUI Thread - image

Question

I have to visualize lot of data (real-time) and I am using JavaFX 2.2. So I have decided to "pre-visualize" data before they are inserted into GUI thread.
In my opinion the fastest way to do it (with antialliasing etc.) is let some NON GUI thread to generate image/bitmap and then put in GUI thread (so the UI is still responsive for user).
But I can't find way how to conver Canvas to Image and then use:
Image imageToDraw = convert_tmpCanvasToImage(tmpCanvas);
Platform.runLater(new Runnable() {
#Override
public void run() {
canvas.getGraphicsContext2D().drawImage(imageToDraw, data.offsetX, data.offsetY);
}
});
Thx for some usable answers. :-)
btw: I have made test app to show my problem.
package canvasandthreads02;
import java.util.Random;
import javafx.application.Application;
import javafx.application.Platform;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.control.Button;
import javafx.scene.image.Image;
import javafx.scene.layout.AnchorPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
public class CanvasAndThreads02 extends Application {
#Override
public void start(Stage primaryStage) {
Button btn = new Button();
btn.setText("Paint");
final AnchorPane root = new AnchorPane();
final Canvas canvas = new Canvas(900, 800);
canvas.setLayoutX(50);
canvas.setLayoutY(50);
root.getChildren().add(canvas);
root.getChildren().add(btn);
Scene scene = new Scene(root, 900, 800);
primaryStage.setTitle("Painting in JavaFX");
primaryStage.setScene(scene);
primaryStage.show();
btn.setOnAction(new EventHandler<ActionEvent>() {
#Override
public void handle(ActionEvent event) {
System.out.println("Start painting");
/**
* Start Thread where some data will be visualized
*/
new Thread(new PainterThread(canvas, new DataToPaint())).start();
}
});
}
private class PainterThread implements Runnable{
private final DataToPaint data;
private final Canvas canvas;
public PainterThread(Canvas canvas, DataToPaint data){
this.canvas = canvas;
this.data = data;
}
#Override
public void run() {
long currentTimeMillis = System.currentTimeMillis();
Canvas tmpCanvas = new Canvas(data.width, data.height);
GraphicsContext graphicsContext2D = tmpCanvas.getGraphicsContext2D();
graphicsContext2D.setFill(data.color;);
for (int i = 0; i < data.height; i++) {
for (int j = 0; j < data.width; j++) {
graphicsContext2D.fillRect(j, i, 1, 1); //draw 1x1 rectangle
}
}
/**
* And now I need still in this Thread convert tmpCanvas to Image,
* or use some other method to put result to Main GIU Thread using Platform.runLater(...);
*/
final Image imageToDraw = convert_tmpCanvasToImage(tmpCanvas);
System.out.println("Canvas painting: " + (System.currentTimeMillis()-currentTimeMillis));
Platform.runLater(new Runnable() {
#Override
public void run() {
//Start painting\n Canvas painting: 430 \n Time to convert:62
//long currentTimeMillis1 = System.currentTimeMillis();
//Image imageToDraw = tmpCanvas.snapshot(null, null);
//System.out.println("Time to convert:" + (System.currentTimeMillis()-currentTimeMillis1));
canvas.getGraphicsContext2D().drawImage(imageToDraw, data.offsetX, data.offsetY);
}
});
}
}
private class DataToPaint{
double offsetX = 0;
double offsetY = 0;
Color color;
int width = 500;
int height = 250;
public DataToPaint(){
Random rand = new Random();
color = new Color(rand.nextDouble(), rand.nextDouble(), rand.nextDouble(), rand.nextDouble());
offsetX = rand.nextDouble() * 20;
offsetY = rand.nextDouble() * 20;
}
}
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
launch(args);
}
}

Answer 1

use Canvas' snapshot(...) method to create a WritableImage from the Canvas' content. ^^
Works fine for me.

Answer 2

I know this is a really old question, but just for anyone who cares:
There is now a second version of canvas.snapshot that takes a callback and works asynchronously!
public void snapshot(Callback<SnapshotResult,Void> callback,
SnapshotParameters params,
WritableImage image)