danielvoogsgerd/icon-finder-rs

This project has not even entered alpha yet. It might soon though

icon-finder-rs's Issues

Add README / Documentation

Some of the specifications are inlined as documentation in the project. This is still quite raw and needs some documentation for this specific implementation. I'm still doubting whether I should just include the spec wherever it's relevant under a separate heading.

Add Unittests

Threshold behaviour according to spec makes no sense

The Problem

According to the spec we have a function to determine distance and a function to determine an exact match. For the types fixed and scalable that is no problem. But taking a good look at threshold things, start to get weird.

The pseudocode for both functions below:

Inside DirectoryMatchesSize(subdir, iconsize, iconscale) we find:

  if Type is Threshold
    return Size - Threshold <= iconsize <= Size + Threshold

Inside DirectorySizeDistance(subdir, iconsize, iconscale) we find:

if Type is Threshold
    if iconsize*iconscale < (Size - Threshold)*Scale
        return MinSize*Scale - iconsize*iconscale
    if iconsize*iconsize > (Size + Threshold)*Scale
        return iconsize*iconsize - MaxSize*Scale
    return 0

The problem is with the DirectorySizeDistance(...) function. The two if-statements use the Threshold, but the return uses MaxSize and MinSize.

This leads to this kind of behaviour.

theme_dir = {
    "min_size": 256,
    "max_size": 768,
    "size": 512,
    "scale": 1,
    "threshold": 128
}

Of course negative distance does not make all that much sense.

Luckilly the spec gives us a hint.

Table 2. Per-Directory Keys

Key	Description	Value Type	Required	Type
MaxSize	Specifies the maximum (unscaled) size that the icons in this directory can be scaled to. Defaults to the value of Size if not present.	integer	NO	Scalable
MinSize	Specifies the minimum (unscaled) size that the icons in this directory can be scaled to. Defaults to the value of Size if not present.	integer	NO	Scalable
Threshold	The icons in this directory can be used if the size differ at most this much from the desired (unscaled) size. Defaults to 2 if not present.	integer	NO	Threshold

On one hand this would imply that the variables MaxSize and MinSize are not applicable for the icon type Threshold, but if that were the case, why is it in the pseudocode?

Solution

Solution 1

Replacing DirectorySizeDistance(...) with the following logic

if Type is Threshold
    if iconsize*iconscale < (Size - Threshold)*Scale
        return Size*Scale - iconsize*iconscale
    if iconsize*iconsize > (Size + Threshold)*Scale
        return iconsize*iconsize - Size*Scale
    return 0

yields the following result

This makes more sense.

Solution 2

Another solution is replacing DirectorySizeDistance(...) with something more along the lines of the behaviour of scaled. The logic for this would be:

if Type is Threshold
    if iconsize*iconscale < (Size - Threshold)*Scale
        return Size*Scale - iconsize*iconscale - Threshold
    if iconsize*iconsize > (Size + Threshold)*Scale
        return iconsize*iconsize - Size*Scale - Threshold
    return 0

and this yield the following result