Not possible to set colorMap for IDW layers

[raitisbe]

Colormap seems to be always hardcoded to jet and changing the getColor function on IDW source class object doesn't seem to have any effect since moving to ES6, since it's a local variable in olsourceIDW function.

Would be good if var getColor = function (v) { could be exposed as a public variable in the olsourceIDW class.

[raitisbe]

Currently we managed to set the custom color map by overriding the whole computeImage function. Not sure its thee right way to go though.

  const clrMap = this.generateColormap('copper')
  const getColor = (v) => {
      const black = [0, 0, 0, 255];
      if (isNaN(v)) {
        return black;
      }
      if (v > 99) {
        v = 99;
      }
      if (v < 0) {
        v = 0;
      }
      v = Math.floor(v);
      return clrMap[v];
    };
  super.computeImage = (e) => {
      const pts = e.data.pts;
      const width = e.data.width;
      const height = e.data.height;
      const imageData = new Uint8ClampedArray(width * height * 4);
      // Compute image
      let x, y;
      for (y = 0; y < height; y++) {
        for (x = 0; x < width; x++) {
          let t = 0,
            b = 0;
          for (let i = 0; i < pts.length; ++i) {
            const dx = x - pts[i][0];
            const dy = y - pts[i][1];
            const d = dx * dx + dy * dy;

            // Inverse distance weighting - Shepard's method
            if (d === 0) {
              b = 1;
              t = pts[i][2];
              break;
            }
            const inv = 1 / (d * d);
            t += inv * pts[i][2];
            b += inv;
          }
          // Set color
          const color = getColor(t / b);
          // Convert to RGB
          const pos = (y * width + x) * 4;
          imageData[pos] = color[0];
          imageData[pos + 1] = color[1];
          imageData[pos + 2] = color[2];
          imageData[pos + 3] = color[3];
        }
      }
      return {type: 'image', data: imageData, width: width, height: height};
    }

[Viglino]

You're right... I've encapsulated the getColor method to make it accessible with worker...
I'll have to find a trick to handle it as a parameter...

[Viglino]

I added a getColor parameter to let you override the default color function when creating IDW.
You can also add lib functions when using workers.
See doc http://viglino.github.io/ol-ext/doc/doc-pages/ol.source.IDW.html
and example source : https://github.com/Viglino/ol-ext/blob/master/examples/layer/map.layer.idw.html#L113

[raitisbe]

How about possibility to change the color map for an existing ol.source.IDW object instance?

[Viglino]

If you're not using worker, you just have to set the getColor method.

idwSource.getColor = function(v) { return [r,g,b,a] } 

If you're using worker it's a little bit more difficult...

[raitisbe]

Thanks, works great. I'm not using worker.