Set vtkScalarBarActor ticks

Web
1

I’d like to be able to set the ticks for a scalar bar actor so that the min / max values on the scale always show as in the image below:

image
image200×822 15.9 KB

I see that model.ticks is set statically here:

      const scale = d3
        .scaleLinear()
        .domain([model.lastTickBounds[0], model.lastTickBounds[1]]);
      model.ticks = scale.ticks(5);
      const format = scale.tickFormat(5);
      model.tickstrings = model.ticks.map(format);

I see that the ticks property is gettable, would you all be open to making ticks settable as well? It could be exposed similar to axisTitlePixelOffset? I could open a PR for this if it seems like a reasonable thing to consider.

Thanks!

2

It needs a bit more to work. If we add a setter the ticks will still be overwritten on a window resize (which invokes the above code) so a couple approaches, one is to

  1. add a setter for ticks
  2. add a conditional where it only recomputes the ticks if range is different from model.lastTickBounds

or

  1. add an updatedTicks event that people can subscribe to and in that callback they can override the default ticks whenever they are recomputed. An example of adding an event to a class is haveVRDisplay in OpenGL\RenderWindow once that is done others can call onHaveVRDisplay to set a callback.
1 Like
3

@ken-martin thanks for the reply!

Would you consider adding another property that’s similar to the autoLayout function but for ticks instead of the legend itself?

I’m not sure I got all the piping right, but something like this:

// Sources/Rendering/Core/ScalarBarActor/index.js

function defaultGenerateTicks(publicApi, model) {
  return (helper) => {
    const scale = d3
        .scaleLinear()
        .domain([model.lastTickBounds[0], model.lastTickBounds[1]]);
      model.ticks = scale.ticks(5);
      const format = scale.tickFormat(5);
      model.tickstrings = model.ticks.map(format);
  }
}

function vtkScalarBarActorHelper(publicAPI, model) {
  // ...
  publicAPI.updateAPISpecificData = (size, camera, renderWindow) => {
    // ...
    model.generateTicks(publicAPI);
    // ...
  }
  // ...
}

function vtkScalarBarActor(publicAPI, model) {
  // ...
  publicAPI.resetTicks = () => {
    model.autoLayout = defaultGenerateTicks(publicAPI, model);
  };
  // ...
}

function defaultValues(initialValues) {
  return {
    // ...
    generateTicks: null
    // ...
  }
}

export functions extend(publicAPI, model, initialValues = {}) {
  // ...
  if (!model.generateTicks) model.generateTicks = defaultGenerateTicks(publicAPI, model);

  macro.setGet(publicAPI, model [
    // ...
    'generateTicks',
    // ...
  ])

  // ...
}
4

Basically yes. Minor tweaks

  1. (publicAPI not publicApi)

  2. model.autoLayout should be model.generateTicks in the resetTicks method

1 Like
5

Ha yes, thanks for the corrections. I will open a PR proposing this.

6

@ken-martin PR is here: feat(vtkscalarbaractor): adds generateTicks field to vtkScalarBarActor by NGimbal · Pull Request #2375 · Kitware/vtk-js · GitHub