Save image without having to use awt

Question

There\'s an old bug in JavaFX which prevents you to save images properly using

ImageIO.write(SwingFXUtils.fromFXImage( wi, null), \"jpg\", new File( fileNam         


        

Answer 1

I've done a bit more reasearch and made an example showing the wrong handling of some methods:

import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.IntBuffer;
import java.util.Arrays;
import java.util.logging.Level;
import java.util.logging.Logger;
import javafx.application.Application;
import javafx.embed.swing.SwingFXUtils;
import javafx.scene.Scene;
import javafx.scene.SnapshotParameters;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.SplitPane;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.image.PixelReader;
import javafx.scene.image.PixelWriter;
import javafx.scene.image.WritableImage;
import javafx.scene.image.WritablePixelFormat;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import javax.imageio.ImageIO;

public class WritableImageDemo extends Application {

  private Image src;
  private int width;
  private int height;
  ImageView srcView;
  ImageView srcView2;
  ImageView srcView3;

  @Override
  public void start(Stage primaryStage) {
    primaryStage.setTitle("Image");

    src = new Image("http://www.gnu.org/graphics/gnu-head.jpg");
    width = (int) src.getWidth();
    height = (int) src.getHeight();

    srcView = new ImageView(src);
    srcView2 = new ImageView();
    srcView3 = new ImageView();

    ScrollPane scrollPane = new ScrollPane();
    ScrollPane scrollPane2 = new ScrollPane();
    ScrollPane scrollPane3 = new ScrollPane();

    scrollPane.setContent(srcView);
    scrollPane2.setContent(srcView2);
    scrollPane3.setContent(srcView3);

    SplitPane root = new SplitPane(scrollPane, scrollPane2, scrollPane3);

    primaryStage.setScene(new Scene(root, 800, 600));
    primaryStage.show();

    srcView2.setImage(writeToFile());
  }

  private WritableImage writeToFile() {
    WritableImage insert = new WritableImage(width, height);
    WritableImage newimage = new WritableImage(width, height);

    SnapshotParameters parameters = new SnapshotParameters();
    parameters.setFill(Color.TRANSPARENT);
    // make a snapshot
    srcView.snapshot(parameters, insert);

    PixelReader reader = insert.getPixelReader();
    PixelWriter writer = newimage.getPixelWriter();
    WritablePixelFormat<IntBuffer> format = WritablePixelFormat.getIntArgbInstance();

    System.out.println("WritablePixelFormat.getType(): " + format.getType());
    // the following normally creates an exact copy of the original
    for (int x = 0; x < width; x++) {
      for (int y = 0; y < height; y++) {
        int recWidth = 1;
        int recHeight = 1;

        int[] buffer = new int[recWidth * recHeight];
        reader.getPixels(x, y, recWidth, recHeight, format, buffer, 0, recWidth);

        int alpha = 0;
        int red = 0;
        int green = 0;
        int blue = 0;

        for (int color : buffer) {
          alpha += (color >>> 24);
          red += (color >>> 16 & 0xFF);
          green += (color >>> 8 & 0xFF);
          blue += (color & 0xFF);
        }
        alpha = alpha / recWidth / recHeight;
        red = red / recWidth / recHeight;
        green = green / recWidth / recHeight;
        blue = blue / recWidth / recHeight;

        int color = (alpha << 24) + (red << 16) + (green << 8) + blue;
        Arrays.fill(buffer, color);

        writer.setPixels(x, y, recWidth, recHeight, format, buffer, 0, recWidth);
      }

    }
    System.out.println("Reader Type: " + reader.getPixelFormat().getType());
    System.out.println("Writer Type: " + writer.getPixelFormat().getType());

    try {
      BufferedImage bf = SwingFXUtils.fromFXImage(newimage, null);
      ImageIO.write(bf, "jpg", new File("C:\\temp\\test1.jpg"));
    } catch (IOException ex) {
      Logger.getLogger(WritableImageDemo.class.getName()).
              log(Level.SEVERE, null, ex);
    }
    try {
      Image img = new Image(new FileInputStream(new File("C:\\temp\\test1.jpg")));
      srcView3.setImage(img);
    } catch (IOException ex) {
      Logger.getLogger(WritableImageDemo.class.getName()).log(Level.SEVERE, null, ex);
    }
    return newimage;
  }

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

If I run this code, I'll get this result. Showing in the left, the original read image, in middle the copied from the method and in the right the created one by the SwingFXUtils.fromFXImage method. So, this is to me a bug!

Update

On new comment at the bug:

It's probably not relevant to the problem in thie JIRA, but the following is a bug in your program:

srcView.snapshot(parameters, insert); 

You must not rely on snapshot actually using the passed in image. It will if it can, but for correctness you need to use the return value of the method. For example:

insert = srcView.snapshot(parameters, insert);

and they have scheduled the bug fix for version 9.