The small application lens effect was the by-product of a spring break with no plans.

At that time, I was finishing programming the first version of the encoder (File Encoder Application), and I needed something catchy for the About ...

The original idea is not mine, but I implemented it based on an effect I had seen in one of those iconic DOS demos.

I decided to encapsulate the effect within a Java Swing JPanel for my project.

Everything within the panel can be magnified using a magnifying glass positioned at your chosen coordinates.

It was especially challenging to ensure that refreshing the text components, especially when modifying the selected text's location, did not adversely affect the visual appearance.

When you create the LensJPanel, the content of the JPanel is applied to the element that will undergo the magnifying effect. You can specify the radius of the magnifying glass and whether it will magnify or diminish the content.

When you have the radius and determine whether the magnifying glass will enlarge or shrink the content, a two-dimensional square matrix is created with one element for each square pixel containing the magnifying glass.
The algorithm calculates the coordinates of the corresponding source pixel in the original image for each destination pixel to determine the color when applying the transformation.
The transformation involves a simple polar coordinate transformation, which is why a magnifying lens is utilized:
A pixel is calculated from a specific position of the lens frame and is used to determine the color when the transformation is applied. The pixel will also be within the lens frame. In addition, the radius from the center of the lens to the angle for a given pixel is calculated. The "origin" pixel for the pixel we are calculating will be at the same angle, but the radius will change. The radius spans from 0% to 100% for both the “target” and “source” pixels, with 100% representing the length of the lens radius. The source pixel is calculated for each target pixel by maintaining its angle and transforming the radius using a function with a monotonically increasing derivative. This transformation occurs in the interval between 0 and 1, where f(0) equals 0 and f(1) equals 1. Here, 0 represents 0% of the lens radius, and 1 represents 100% of the lens radius. This means that the radii will take their source pixel from a smaller radius, which will expand the lens circle. Outside the circle of the lens, the transformation will be the identity, meaning the source pixel will not change.

The explanation is a bit confusing, but if you are interested in learning more about the subject, feel free to contact me.

I hope someone will find it useful :-).