Add support for iheatmap!()

[ConnectedSystems]

Add support for overlaying heatmaps on top of each other (adding to an existing axis).
I've also reorganised the code as discussed in #22 (comment)

Closes #24

May close #22

There are some issues - occasionally the image will tear when panning/zooming, but not sure what causes it. It may be a Makie issue.

Example using WGLMakie:

using WGLMakie
using InteractiveViz
using InteractiveViz.Demo

WGLMakie.activate!(; framerate=20)

# Example using a function
# iheatmap(mandelbrot, -2, 0.66, -1, 1)

# Example using a large in-memory array
f = iheatmap(zeros(10_000, 10_000))
iheatmap!(f, rand(10_000, 10_000); alpha=0.1)

f

I have not tested with a disk-based array/matrix - hypothetically it should work.

Note: Every now and then, a warning will be raised.

Error in window event callback
exception =

All non scalars need same length, Found lengths for each argument: (5, 3, 1), (Vector{Makie.GlyphCollection}, Vector{Point{3, Float32}}, Quaternion{Float64})

The cause of this is already known MakieOrg/Makie.jl#2473 and is not caused by/related to the changes in this PR.

[marianoarnaiz]

Hi. Thanks this is very helpful. :)
I still cannot find how to pass a new pooling function to iheatmap, any example around?

[mchitre]

Hi. Thanks this is very helpful. :) I still cannot find how to pass a new pooling function to iheatmap, any example around?

Currently the pooling functionality is not user-facing. It shouldn't be hard to make it available to the user, and I have a test implementation, but it needs some testing before I can PR it. Perhaps this weekend...

[marianoarnaiz]

Hi. Thanks this is very helpful. :) I still cannot find how to pass a new pooling function to iheatmap, any example around?

Currently the pooling functionality is not user-facing. It shouldn't be hard to make it available to the user, and I have a test implementation, but it needs some testing before I can PR it. Perhaps this weekend...

HI again.
I am sorry for the trouble. I do not mind copying the #master and making a change for myself. My data is not congruent with the current pooling. I did this for the previous version. I modded to prject for me, but the new version is quite different and I do not understand how the pooling is asing for the iheatmap. Could you let me know where is decided and I can change it.

You can see my post here

https://discourse.julialang.org/t/interactiveviz-an-interactive-visualization-toolkit-for-large-datasets/40878/27

from Mar 2023

[mchitre]

Implementation looks good to me.

My only nitpick is that your editing has now created a mix of 2-space indents and 4-space indents in the code, which is confusing. While I don't mind either option, given that the code base currently uses 2-space indents, would you mind switching to those for this project please? It'll also get rid of lots of unnecessary clutter in the diffs on this PR, making it easier to review for real code changes.

[ConnectedSystems]

Okay, standardized to two-space indentation.

[mchitre]

LGTM, thanks!