How to create unique images with Image.getInstance()?

How can I guarantee a new bitmap every time?

I need to use the GetInstance() variant that accepts raw bitmap data:

Image.getInstance(int width, int height, int components, int bpc, byte[] data);

But if I call it repeatedly, even if the bitmap data is actually different, I get the first instance back instead of a new one. This is a very good feature with, for instance, path-based fixed images but not that good for on-the-fly image generation. How can I guarantee a new bitmap every time?

Posted on StackOverflow on Nov 21, 2014 by Gábor

Please take a look at the RawImages example. In this example, I create 8 images using the method you mention, one in color space gray, three in color space RGB, four in color space CMYK:

Image gray = new Image(ImageDataFactory.create(1, 1, 1, 8, new byte[]{(byte) 0x80}, null));
gray.scaleToFit(30, 30);
Image red = new Image(ImageDataFactory.create(1, 1, 3, 8, new byte[]{(byte) 255, (byte) 0, (byte) 0}, null));
red.scaleToFit(30, 30);
Image green = new Image(ImageDataFactory.create(1, 1, 3, 8, new byte[]{(byte) 0, (byte) 255, (byte) 0}, null));
green.scaleToFit(30, 30);
Image blue = new Image(ImageDataFactory.create(1, 1, 3, 8, new byte[]{(byte) 0, (byte) 0, (byte) 255}, null));
blue.scaleToFit(30, 30);
Image cyan = new Image(ImageDataFactory.create(1, 1, 4, 8, new byte[]{(byte) 255, (byte) 0, (byte) 0, (byte) 0}, null));
cyan.scaleToFit(30, 30);
Image magenta = new Image(ImageDataFactory.create(1, 1, 4, 8, new byte[]{(byte) 0, (byte) 255, (byte) 0, (byte) 0}, null));
magenta.scaleToFit(30, 30);
Image yellow = new Image(ImageDataFactory.create(1, 1, 4, 8, new byte[]{(byte) 0, (byte) 0, (byte) 255, (byte) 0}, null));
yellow.scaleToFit(30, 30);
Image black = new Image(ImageDataFactory.create(1, 1, 4, 8, new byte[]{(byte) 0, (byte) 0, (byte) 0, (byte) 255}, null));
black.scaleToFit(30, 30);

As you can see, each image is exactly one pixel in size, and I chose different byte[] values so that I get pixels in gray, red, green, blue, cyan, magenta, yellow and black. I also scale these image to a bigger size (otherwise it would be difficult to see them).

Now I add the images like this:

doc.add(gray);
doc.add(red);
doc.add(green);
doc.add(blue);
doc.add(cyan);
doc.add(magenta);
doc.add(yellow);
doc.add(black);
doc.close();

The result does not correspond with what you claim in your question: raw_images.pdf

Raw images

There must be another error in your code, but since you don't share any code, nobody can answer your question.

Yes, I stand corrected. I used these images as soft masks and it turned out after much searching that the original images were replicated and forcing the same masks everywhere, not the on-the-fly generated masks themselves. Mea culpa and thanks.

Click How to create unique images with Image.getInstance()? if you want to see how to answer this question in iText 5.