Can the style in ColorLayer support function callback function?

[liangyuan1]

Can the style in ColorLayer support function callback function? Currently, we have checked that each specific property supports callback. I want to dynamically modify the fill color and stroke color based on data properties, which requires multiple callbacks and is not very user-friendly. How to directly support callback function in style? After setting the property, I return a stylle object, which is more convenient to use

[AnthonyGlt]

As you said, we support for each attributes.
In the source_stream_wfs_raster.html exeample, you can see that the fill is defined by a function, isn't what you want ?

In this proposal, could you give us an example of what you're expecting.
When opening issues/MR/proposal, there are templates provided that help us to better understand and format the needs

[liangyuan1]

As you said, we support for each attributes. In the source_stream_wfs_raster.html exeample, you can see that the fill is defined by a function, isn't what you want ?

In this proposal, could you give us an example of what you're expecting. When opening issues/MR/proposal, there are templates provided that help us to better understand and format the needs

Example: source_steam-wfs_raster.html. I understand it to be either color or width, but I have a requirement: there is a water supply pipeline geojson data, and I need to render the style based on the pipeline material (color) and diameter (width). If the style callback function returns a result of an object such as:
function colorBuildings(properties) {
let color = '#FDFDFF'
let width =1
if (properties.meateri=== 'Résidentiel') {
color ='#FDFDFF';
} else if (properties.usage_1 === 'Annexe') {
color = '#C6C5B9';
}
return {
stroke: {
color: color ,
width: width ,
},
}
}
This method will be very convenient for handling the returned results

[ftoromanoff]

Thank you for using itowns.

I fell like I understand your motivation. (You want to be able to use a single callback to define a style instead of using several callbacks for each style.properties).

Unfortunatly, we decided in a technical choice, not to allow callbacks at the Style level, to limite the number of checks in order to validate the style.
But If we get others demandes in this direction (callbacks at stroke/fill/text/icon etc), we might rethink this decision.

Looking at the previous example, you can do :

function colorBuildings(properties) {
  let color = '#FDFDFF'
  if (properties.usage_1 === 'Annexe') {
    color = '#C6C5B9';
  }
  return color;
}


const style = {
  stroke: {
    color: colorBuildings,
    width: width ,
  },
}

But i guess, your real case is more complex...

[liangyuan1]

@ftoromanoff I suggest considering that my job is more focused on business. Openlayer has this method, which is very convenient for setting styles and greatly reduces development costs. Thank you

[ftoromanoff]

Hello,
Would it help if we allow the use of function to the stroke/fill/point/etc level ?

In your example this would mean being able to do:

function colorBuildings(properties) {
  let width = 1;
  let color = '#FDFDFF';
  if (properties.usage_1 === 'Annexe') {
    color = '#C6C5B9',
    width: 2,
  }
  return { color,
           width,
         };
}

const style = {
  stroke: colorBuildings
}

(And in this case it will be hard to check for the mandatory values)