add drawable kerning

[tiptop96]

Hey, this is more a question than a PR so far.

We are adding text to an image using the following code:

image.draw(
    new DrawableGravity(Gravity.Center),
    new DrawableGravity(Gravity.South),
    new DrawableFont("OurCustomFont"),
    new DrawableFontPointSize(100),
    new DrawableFillColor(new MagickColor("white")),
    new DrawableText(0, 190, formatText(titleText))
);

However we have a need to set the text kerning which is not possible.

To work around this we implemented our own DrawableKerning as below, but we figured it might make more sense to get it into the library then keeping it to ourselves.

This is just a draft to give you an idea of what we were going for, we assume it might need tests and more work.

Please let us know if you think this might be a good addition to the lib! 🥳

[dlemstra]

This would of course be a good addition to the library. I am adding this step by step based on what I think people would need but I am always happy when a PR comes with something that someone needs. And this is the exact same implementation that I would do when I would add this myself. One tiny remark.... all methods are sorted alphabetically so could you please change that? And this of course needs a test. Maybe something where you check if a pixel has the background color or check if the pixel has the drawing color And do this with two tests, one where you don't set the kerning and one where you do but in both situations you check the same pixel.

p.s. You can run just your own test with npm run test kerning (this matches the filename drawable-kerning.spec.ts)

[tiptop96]

Awesome, thanks for the feedback!

We sorted the methods and gave out best shot at adding a test. 🥳

[dlemstra]

Code looks fine to me and I will merge this if the tests run successfully.

Would it help you if I would publish a new release or are you planning to add more functionality? Or can I wait with the next release?

[dlemstra]

Whoops 😁 You added a new new file so we should add this to the index. I keep forgetting this myself also so I made this part of the build. You can update the index with the following command: npm run update-index.

[hannanilsson]

Hi! We have updated the index now. We are in no hurry to get a new release, we currently have a working workaround in our project with basically the same code that we added in the PR. We will extend our use of image magick in August, so we might come back with more ideas then. 😄