Eventuell hilft Dir noch dies:
Ich habe meine Klasse einmal etwas umgeschrieben und JavaDoc Kommentare hinzu gefügt. Evtl. wird die so direkt nutzbar. (Dann ggf. das package umändern und einfach 1:1 nutzen.) Ist ein 08/15 Code daher ohne irgendwelche Lizenz direkt verwendbar / änderbar.
Aber ist alles noch ungetestet - habe jetzt keine Zeit gehabt, den Unit-Test anzupassen. Sollte etwas nicht funktionieren, dann bitte einmal Bescheid geben.
[CODE=java]package de.kneitzel.images;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
/**
* Helper class to scale images
*/
public class ImageScaler {
/**
* Target format to use for all generated images.
*/
private static String TARGET_FORMAT="png";
/**
* Creates a new scaled image.
* <p>
* The image is scaled with keeping the original ratio from width to height.
* <p>
* If enforceSize is false, the given size is used as a possible maximum size. The target picture might be
* smaller if the ratio height to width given is different to the ratio of the original image.
* If enforceSize is true, the new image can have a transparent arew on top/bottom or
* right/left side.
* @param originalImageBytes Bytes of the original image.
* @param width (Maximum) Width of the target image.
* @param height (Maximum) Height of the target image.
* @param enforceSize Should the size be enforced. If false, the target image will not have empty borders on top/bottom or right/left.
* @return Byte Array with the new image or null in case an error occured.
*/
public static byte[] createScaledImage(final byte[] originalImageBytes, final int width, final int height, final boolean enforceSize) {
// Validation
if (originalImageBytes == null) return null;
if (originalImageBytes.length==0) return null;
try {
// Create the image from a byte array.
BufferedImage originalImage = ImageIO.read(new ByteArrayInputStream(originalImageBytes));
return createScaledImage(originalImage, width, height, enforceSize);
} catch (Exception ex) {
return null;
}
}
/**
* Scales an image to a new size.
* <p>
* If enforceSize is false, the given size is used as a possible maximum size. The target picture might be
* smaller if the ratio height to width given is different to the ratio of the original image.
* If enforceSize is true, the new image can have a transparent arew on top/bottom or
* right/left side.
* @param originalImageBytes Bytes of the original image.
* @param width (Maximum) Width of the target image.
* @param height (Maximum) Height of the target image.
* @param enforceSize Should the size be enforced. If false, the target image will not have empty borders on top/bottom or right/left.
* @return InputStream for the new image or null if a new image couldn't be created.
*/
public static InputStream scaledImage(final byte[] originalImageBytes, final int width, final int height, final boolean enforceSize) {
// Get the scaled image.
byte[] bytes = createScaledImage(originalImageBytes, width, height, enforceSize);
// Validation of result.
if (bytes == null || bytes.length == 0) return null;
// Return new InputStream.
return new ByteArrayInputStream(bytes);
}
/**
* Creates the scaled image of a BufferedImage.
* <p>
* If enforceSize is false, the given size is used as a possible maximum size. The target picture might be
* smaller if the ratio height to width given is different to the ratio of the original image.
* If enforceSize is true, the new image can have a transparent arew on top/bottom or
* right/left side.
* @param originalImage Original image to scale.
* @param width (Maximum) Width of the target image.
* @param height (Maximum) Height of the target image.
* @param enforceSize Should the size be enforced. If false, the target image will not have empty borders on top/bottom or right/left.
* @return Byte Array with the new image or null in case an error occured.
*/
protected static byte[] createScaledImage(final BufferedImage originalImage, final int width, final int height, final boolean enforceSize) {
// Validation
if (originalImage == null) return null;
try {
// Get the scale factor.
double scaleWidth = (double) width / (double) originalImage.getWidth();
double scaleHeight = (double) height / (double) originalImage.getHeight();
double scaleFactor;
if (scaleWidth > scaleHeight) {
scaleFactor = scaleHeight;
} else {
scaleFactor = scaleWidth;
}
// Calculate target size of scaled image.
int newHeight = (int) (scaleFactor * originalImage.getHeight());
int newWidth = (int) (scaleFactor * originalImage.getWidth());
// Cooordinates of new picture and size of new picture.
int x, y, usedHeight, usedWidth;
if (enforceSize) {
usedHeight = height;
usedWidth = width;
x = (width - newWidth) / 2;
y = (height - newHeight) / 2;
} else {
x = 0;
y = 0;
usedHeight = newHeight;
usedWidth = newWidth;
}
// Scale the image
BufferedImage scaledImage = new BufferedImage(usedWidth, usedHeight, BufferedImage.TYPE_INT_ARGB);
Graphics2D graphics = scaledImage.createGraphics();
graphics.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
graphics.drawImage(originalImage, x, y, newWidth, newHeight, null);
// Get the bytes of the image
try (ByteArrayOutputStream stream = new ByteArrayOutputStream()) {
ImageIO.write(scaledImage, TARGET_FORMAT, stream);
return stream.toByteArray();
}
} catch (Exception ex) {
return null;
}
}
}[/CODE]
