Images for logos, diagramming, etc.

[mdtusz]

@etpinard @cldougl

For adding logos or other visual elements to plots that are not specifically data. A proposed interface is to add an images layout attribute:

{
  images: [{
    source: 'http://www.placekitten.com/450/450', // always kittens
    opacity: 0.8,
    layer: 'above',
    xanchor: 'center',
    yanchor: 'top',
    x: 0.5,
    y: 0,
    xref: 'paper', // default to use paper ref?
    yref: 'paper',
    width: 0.2 // smart aspect ratio preservation unless both dimensions given?
  }]
}

[etpinard]

maybe also borderwidth and bordercolor ?

[mdtusz]

Yep those can be added as well.

Regarding where to place the images - currently shapes can be in shapelayer-below or shapelayer-above. Do we create additional images-above and images-below or simply add them to the existing shapelayers? I'm hesitant to add yet more layers to the plot, but at the same time, it's nice to keep things clearly defined. Thoughts?

[etpinard]

Do we create additional images-above and images-below or simply add them to the existing shapelayers?

I'd vote for for no. Let's put images in the same layer(s) as shapes.

[etpinard]

One thing to take into consideration would be the ordering of shapes and images in those <g> layer.

I'd vote for always placing images below the shapes in a given <g> layer using d3 selection.order.