Loading image from JCR using AbstractLoader will result in adding the alpha
value as a color to generated JPGs
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Key: MGNLIMG-100
URL: http://jira.magnolia-cms.com/browse/MGNLIMG-100
Project: Magnolia Imaging Module
Issue Type: Bug
Components: image operations
Affects Versions: 2.2.1
Reporter: Christian Ringele
Assignee: Grégory Joseph
Priority: Critical
Fix For: 2.x
Attachments: AbstractLoader.java.patch, Generator.png,
OrigImage-PlacedIntoDMS.jpg, out1-works.png, out1-worksNot.jpg
Description:
Calling an image generator which uses a FromContent (extends AbstractLoader)
operation will result in wrong JPGs.
If storing PNGs it works fine. As PNGs have a alpha channel, the alpha value is
correctly applied.
Storing a JPG, it seems as the ImageIO.write() method writes the alpha value as
a color and not ignoring it as it should.
Reproduce:
1. Import the generator attached to this issue. Just containing one operation,
the load operation.
2. Add a test image to DMS.
3. execute this code with correct paths:
{code}
final ImagingModuleConfig config = (ImagingModuleConfig)
ModuleRegistry.Factory.getInstance().getModuleInstance("imaging");
final ImageGenerator generator =
config.getGenerators().get("myOperationChainBResize");
Session dmsSession = MgnlContext.getJCRSession("dms");
Node origImage = dmsSession.getNode("/test/orig");
final Content content = info.magnolia.cms.util.ContentUtil.asContent(origImage);
final ParameterProvider<Content> parameterProvider = new
ContentParameterProvider(new SimpleEqualityContentWrapper(content));
final BufferedImage bufferedImage = generator.generate(parameterProvider);
ImageIO.write(bufferedImage, "png", new
File("/Users/cringele/Documents/temp_stuff/image-test/create/out1-works.png"));
ImageIO.write(bufferedImage, "jpg", new
File("/Users/cringele/Documents/temp_stuff/image-test/create/out1-worksNot.jpg"));
{code}
You can also write the stream back into JCR, the result is the same. So for
testing much easier into a file.
Source of the problem:
info.magnolia.imaging.operations.load.AbstractLoader.apply(BufferedImage, P)
{code}
if (source != null) {
throw new ImagingException("This operation currently does not support
overlaying images");
}
final BufferedImage loaded = loadSource(filterParams);
if (loaded == null) {
throw new ImagingException("Could not load image for " + filterParams);
}
//This line is the source of the problem. Using BufferedImage.TYPE_INT_RGB
would work because it wouldn't contain any alpha channel. Of course just for
testing applicable.
final BufferedImage img = new BufferedImage(loaded.getWidth(),
loaded.getHeight(), BufferedImage.TYPE_INT_ARGB_PRE);
final Graphics2D g = img.createGraphics();
if (backgroundColor != null) {
g.setColor(backgroundColor);
g.fill(new Rectangle(0, 0, img.getWidth(), img.getHeight()));
}
g.drawImage(loaded, null, 0, 0);
// TODO would this make any difference ? g.drawRenderedImage(loaded, null);
g.dispose();
return img;
{code}
Proof of the problem source:
First possibility: Execute this code just passing back the loaded BufferedImage
{code}
if (source != null) {
throw new ImagingException("This operation currently does not support
overlaying images");
}
final BufferedImage loaded = loadSource(filterParams);
if (loaded == null) {
throw new ImagingException("Could not load image for " + filterParams);
}
return loaded;
{code}
Second possibility: Pass back the created BufferedImage (img) withour loagin
the orig image on top.
Like this you can compare alpha value in PNG to color in JPG.
{code}
if (source != null) {
throw new ImagingException("This operation currently does not support
overlaying images");
}
final BufferedImage loaded = loadSource(filterParams);
if (loaded == null) {
throw new ImagingException("Could not load image for " + filterParams);
}
final BufferedImage img = new BufferedImage(loaded.getWidth(),
loaded.getHeight(), BufferedImage.TYPE_INT_ARGB_PRE);
final Graphics2D g = img.createGraphics();
if (backgroundColor != null) {
g.setColor(backgroundColor);
g.fill(new Rectangle(0, 0, img.getWidth(), img.getHeight()));
}
//Image not loaded on top of it
//g.drawImage(loaded, null, 0, 0);
// TODO would this make any difference ? g.drawRenderedImage(loaded, null);
g.dispose();
return img;
{code}
It seems to be a known problem:
http://stackoverflow.com/questions/8410996/java-bufferedimage-saves-with-unwanted-background-color
Trying out the solution they suggest did not work.
Was not able to supply a patch with a final solution. Added a pacth as a
workaround.
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