Add Anchor Support for Annotations

WilliamHYZhang commented 4 years ago

Introducing the newest feature for annotations, the ability to anchor them to anything! This idea started as just to anchor text annotations, but with the help of some nifty tricks we can expand this significantly. Here's an overview of what I did in this PR:

Implement new enum, Direction. This is where we specify the north/east/south/west direction that we would like to anchor to.
Implement new protocol, Anchor. This extends Annotation to include a direction and a float buffer (space desired between the annotation and the anchor point). We also require a resolve function that will deal with the anchor directions and update the parameters of the annotation accordingly.
Have our existing Box and Text annotations also conform to Anchor. Now, we could just replace this with just conforming to Anchor as it extends Annotation, however I think that this definition is more verbose.
Update the Arrow annotation to support anchoring of any annotation that supports it. Also included an option to override the anchor and force to draw at passed coordinates if the user desires.
Update the arrow tests to support this feature- no more "guess and check" to find the locations to pass anymore!

So what does this mean for the future of annotations in SwiftPlot?

Adding annotations will be pretty straightforward. If we don't want it to support anchoring, that's fine. Otherwise, conform it to Anchor and we're good to go.
This introduces the possibility to anchor the annotations to anything we want, not just the ends of an arrow. We can pass any point we'd like to the resolve function and it will relocate itself. We can make it anchored to the origin, ends of lines in line graphs, etc... the list is endless.

Anyways, hope you guys like it. I'm definitely open to any suggestions for improvements or new ideas. Feel free to check it out.

William

WilliamHYZhang commented 4 years ago

Oooof. PR build is failing... I'll look into it.

WilliamHYZhang commented 4 years ago

Fixed, @karwa when this is merged may you rerun quartz tests when you have time? No hurry.

WilliamHYZhang commented 4 years ago

@KarthikRIyer resolved merge conflicts

WilliamHYZhang commented 4 years ago

@KarthikRIyer should be good to go.

KarthikRIyer commented 4 years ago

Looks good @WilliamHYZhang. Good job!

KarthikRIyer / swiftplot

Add Anchor Support for Annotations #100