Java: Rilevamento formato immagine, ridimensionamento (scala) e salvataggio come JPEG

Question

Questo è il codice che ho, funziona davvero, non perfettamente ma lo fa, il problema è che le miniature ridimensionate non si incollano sul rettangolo bianco disegnato, rompendo le proporzioni delle immagini, ecco il codice, qualcuno potrebbe suggerirmi una soluzione per questo, per favore?

Grazie

import java.awt.Color; 
import java.awt.Graphics2D; 
import java.awt.Image; 
import java.awt.RenderingHints; 
import java.awt.geom.Rectangle2D; 
import java.awt.image.BufferedImage; 
import java.io.BufferedInputStream; 
import java.io.ByteArrayInputStream; 
import java.io.ByteArrayOutputStream; 
import java.io.IOException; 
import java.io.InputStream; 

import javax.imageio.ImageIO; 

import org.apache.commons.logging.Log; 
import org.apache.commons.logging.LogFactory; 

public class ImageScalerImageIoImpl implements ImageScaler { 

private static final String OUTPUT_FORMAT_ID = "jpeg"; 

// Re-scaling image 
public byte[] scaleImage(byte[] originalImage, int targetWidth, 
    int targetHeight) { 

    try { 
    InputStream imageStream = new BufferedInputStream(
    new ByteArrayInputStream(originalImage)); 
    Image image = (Image) ImageIO.read(imageStream); 

    int thumbWidth = targetWidth; 
    int thumbHeight = targetHeight; 

    // Make sure the aspect ratio is maintained, so the image is not skewed 
     double thumbRatio = (double)thumbWidth/(double)thumbHeight; 
     int imageWidth = image.getWidth(null); 
     int imageHeight = image.getHeight(null); 
     double imageRatio = (double)imageWidth/(double)imageHeight; 
     if (thumbRatio < imageRatio) { 
      thumbHeight = (int)(thumbWidth/imageRatio); 
     } else { 
      thumbWidth = (int)(thumbHeight * imageRatio); 
     } 

    // Draw the scaled image 
    BufferedImage thumbImage = new BufferedImage(thumbWidth, 
    thumbHeight, BufferedImage.TYPE_INT_RGB); 
    System.out.println("Thumb width Buffered: " + thumbWidth + " || Thumb height Buffered: " + thumbHeight); 

    Graphics2D graphics2D = thumbImage.createGraphics(); 
    // Use of BILNEAR filtering to enable smooth scaling 
    graphics2D.setRenderingHint(RenderingHints.KEY_INTERPOLATION, 
    RenderingHints.VALUE_INTERPOLATION_BILINEAR); 
    // graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null); 

    // White Background 
    graphics2D.setPaint(Color.WHITE); 
    graphics2D.fill(new Rectangle2D.Double(0, 0, targetWidth, 
    targetHeight)); 
    graphics2D.fillRect(0, 0, targetWidth, targetHeight); 

    System.out.println("Target width: " + targetWidth + " || Target height: " + targetHeight); 

    // insert the resized thumbnail between X and Y of the image 
    graphics2D.drawImage(image, 0, 0, thumbWidth, thumbHeight, null); 

    System.out.println("Thumb width: " + thumbWidth + " || Thumb height: " + thumbHeight); 

    // Write the scaled image to the outputstream 
    ByteArrayOutputStream out = new ByteArrayOutputStream(); 
    ImageIO.write(thumbImage, OUTPUT_FORMAT_ID, out); 
    return out.toByteArray(); 

    } catch (IOException ioe) { 
    throw new ImageResizingException(ioe); 
    } 
} 

} 

Answer 1

Si può facilmente scalare l'immagine utilizzando Image s' getScaledInstance metodo:

BufferedImage img = ImageIO.read(new File("image.jpg")); 
int scaleX = (int) (img.getWidth() * 0.5); 
int scaleY = (int) (img.getHeight() * 0.5); 

Image newImg = img.getScaledInstance(scaleX, scaleY, Image.SCALE_SMOOTH); 

Una volta che hai ottenuto la tua scala Image è possibile 'convertire' nuovamente in a BufferedImage come descritto here.

Infine, utilizzare la classe ImageIO per scrivere il file BufferedImage in un file.