B4J Code Snippet Image to JPEG byte array with resize/quality options

Due to @Erel's comment below, I've rewritten this in pure B4X basic. The new version should work with B4A, B4J and B4i. New version (that should be used) can be found here https://www.b4x.com/android/forum/t...byte-array-with-resize-quality-options.91774/.

' Converts image to JPEG a byte array of the resulting JPEG. Ability to resize and adjust JPEG quality.
' Negative width and height values = %, such that -50 = 50% and -200 = 200%
' Positive width and height values = pixel dimensions
' If one value (either width or height) are 0, then the other value is proportionally
'  calculated from the first.
' If both width and height are 0 or -100, no resizing takes place
' If quality = -1, use Java's default quality
Sub ImageToJPEGByteArray(aImage As Image, width As Int, height As Int, quality As Int) As Byte()
   Dim jo As JavaObject = Me
   Return jo.RunMethod("imageToJPEGByteArray", Array As Object (aImage, width, height, quality))
End Sub

#if Java
import java.awt.image.BufferedImage;
import java.awt.geom.AffineTransform;
import java.awt.Graphics2D;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import java.util.Iterator;
import java.util.Locale;

import javafx.scene.image.Image;
import javafx.embed.swing.SwingFXUtils;

import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.plugins.jpeg.JPEGImageWriteParam;
import javax.imageio.stream.ImageOutputStream;

// Image resizing
// https://stackoverflow.com/a/4205711
// https://stackoverflow.com/questions/21540378/convert-javafx-image-to-bufferedimage
// https://stackoverflow.com/a/13605411
// https://www.mkyong.com/java/how-to-convert-bufferedimage-to-byte-in-java/
// JPEG quality
// https://www.b4x.com/android/forum/threads/solved-how-to-create-jpeg-output-stream.83830/#post-531280
// http://www.java2s.com/Code/Java/2D-Graphics-GUI/WritesanimagetoanoutputstreamasaJPEGfileTheJPEGqualitycanbespecifiedinpercent.htm


// Converts image to JPEG a byte array of the resulting JPEG. Ability to resize and adjust JPEG quality.
// Negative width and height values = %, such that -50 = 50% and -200 = 200%
// Positive width and height values = pixel dimensions
// If one value (either width or height) are 0, then the other value is proportionally
//  calculated from the first.
// If both width and height are 0 or -100, no resizing takes place
// If quality = -1, use Java's default quality
public static byte[] imageToJPEGByteArray(Image aImage, int width, int height, int qualityPercent) throws IOException {
   byte[] imageBytes = new byte[0];
 
   if ((qualityPercent < -1) || (qualityPercent > 100)) {
      throw new IllegalArgumentException("Quality out of bounds!");
    }
   float quality = qualityPercent / 100f;
 
   double oldWidth = aImage.getWidth();
   double oldHeight = aImage.getHeight();
   if (oldWidth == 0 || oldHeight == 0) {
       throw new IllegalArgumentException("Source image with 0 width and/or height!");
   }
 
   boolean resize = true;
   if ((width == 0 && height == 0) || (width == -100 && height == -100)) resize = false;

   BufferedImage destImage;
   if (resize) {
       double newWidth = (double) width;
       double newHeight = (double) height;
       // Calculate new dimensions
       if (newWidth < 0) newWidth = -1 * oldWidth * newWidth / 100;
       if (newHeight < 0) newHeight = -1 * oldHeight * newHeight / 100;
       if (newWidth == 0) newWidth = oldWidth * newHeight / oldHeight; 
       if (newHeight == 0) newHeight = oldHeight * newWidth / oldWidth;
       // Convert JavaFX image to BufferedImage and transform according to new dimensions
       destImage = new BufferedImage((int) newWidth, (int) newHeight, BufferedImage.TYPE_INT_RGB);
       BufferedImage srcImage = SwingFXUtils.fromFXImage(aImage, null);
       Graphics2D g = destImage.createGraphics();
       AffineTransform at = AffineTransform.getScaleInstance(newWidth/oldWidth, newHeight/oldHeight);
       g.drawRenderedImage(srcImage, at);
       g.dispose();
   } else {
       destImage = SwingFXUtils.fromFXImage(aImage, null);
   }
 
   // Output JPEG byte array
   ByteArrayOutputStream baos = new ByteArrayOutputStream();
 
   if(qualityPercent != -1) {
       // Start to create JPEG with quality option
       ImageWriter writer = null;
       Iterator iter = ImageIO.getImageWritersByFormatName("jpg");
       if (iter.hasNext()) {
         writer = (ImageWriter) iter.next();
       }
       ImageOutputStream ios = ImageIO.createImageOutputStream(baos);
       writer.setOutput(ios); 
       ImageWriteParam iwparam = new JPEGImageWriteParam(Locale.getDefault());
       iwparam.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
       iwparam.setCompressionQuality(quality);
       writer.write(null, new IIOImage(destImage, null, null), iwparam);
       ios.flush();
       writer.dispose();
       ios.close();
       // Done creating JPEG with quality option
   } else {
       // This one line below created a JPEG file without quality option
       ImageIO.write(destImage, "jpg", baos);
   }
 
   baos.flush();
   imageBytes = baos.toByteArray();
   baos.close();
 
   // Done
   return imageBytes; 
}

#End If

Example

Dim bImage As Image
bImage.Initialize(File.DirAssets, "b.png")
Dim c() As Byte = ImageToJPEGByteArray(bImage, -50, 0, 50)
'https://www.b4x.com/android/forum/threads/b4x-bytes-to-file.70111/#content
BytesToFile(File.DirApp, "b.jpg", c)

Resources used:
Image resizing
https://stackoverflow.com/a/4205711
https://stackoverflow.com/questions/21540378/convert-javafx-image-to-bufferedimage
https://stackoverflow.com/a/13605411
https://www.mkyong.com/java/how-to-convert-bufferedimage-to-byte-in-java/

JPEG quality
https://www.b4x.com/android/forum/threads/solved-how-to-create-jpeg-output-stream.83830/#post-531280
http://www.java2s.com/Code/Java/2D-Graphics-GUI/WritesanimagetoanoutputstreamasaJPEGfileTheJPEGqualitycanbespecifiedinpercent.htm

 

[Erel]

Note that with XUI library you can achieve similar results (and it works on all three platforms):

Dim bmp As B4XBitmap = img
Dim b() As Byte = ImageToBytes(bmp.Resize(200, 200, True))

ImageToBytes: https://www.b4x.com/android/forum/threads/b4x-bytes-to-file.70111/#post-445167

 

[OliverA]

Due to @Erel's comment above, I've rewritten this snippet in pure B4X basic. The new version should work with B4A, B4J and B4i. New version (that should be used) can be found here https://www.b4x.com/android/forum/t...byte-array-with-resize-quality-options.91774/.

 

[moster67]

@OliverA: Many thanks for the java-code you provided - it was a life-saver for a library I am wrapping. Thanks!