Crop image by polygon area in Java

问题:

by using Canvas and JS I can draw a shape like this and have the x,y of each point :

Tha area can be choosen by more than 4 points, look at this link to have an idea.

I need to save and crop the image of the selected area by using the points. I can not use BufferedImage as it is just rectangular. Which lib in java I can use?

回答1:

Okay, so starting with...

I used...

BufferedImage source = ImageIO.read(new File("Example.jpg"));
GeneralPath clip = new GeneralPath();
clip.moveTo(65, 123);
clip.lineTo(241, 178);
clip.lineTo(268, 405);
clip.lineTo(145, 512);
clip.closePath();

Rectangle bounds = clip.getBounds();
BufferedImage img = new BufferedImage(bounds.width, bounds.height, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
clip.transform(AffineTransform.getTranslateInstance(-65, -123));
g2d.setClip(clip);
g2d.translate(-65, -123);
g2d.drawImage(source, 0, 0, null);
g2d.dispose();

ImageIO.write(img, "png", new File("Clipped.png"));

to generate...

Now, the image is rectangular, that's just the way it works

Now, setClip doesn't is quite rough and isn't effect by any RenderingHints, you could make use of "soft clipping" instead, which is more involved, but generates a nicer results. See this example and this exmaple for more details