Vector layer can hide layer symbology when conditional styling used #222
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In some uses of conditional styling, styling is applied to feature values in a way that each feature is included and matches one style, similar to a pie chart. In such situations, including a style for the entire layer in a legend is unnecessary. This adds a "hideLayer" property to legend configuration in vector layers and to legend display HTML. When added to a vector/GeoJSON layer's legend configuration and set to true, the symbology for the layer (but not its conditional styling) is omitted in the legends.
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Do you have an example of this behavior or a description on how to reproduce? |
I think it's easiest to show the difference :) Our use case is for the CleanBC app. The Ministry EVCS layer uses conditional styling to set the colour of a feature based on the stall type. Each feature is one of the two stall types we conditionally style for, but we still show a style for the layer itself, which seems redundant:
With this change, and a change to CleanBC to add "hideLayer": true to the layer's legend config, we modify the legend display to make more sense:
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Thanks for the explanation and pictures! My recommendation would be to never show the swatch for the layer when conditional styling is present. If you want to be able to show the default style for the layer, it is common practice to display a 'default' entry below the entries for conditional styles. You could have config to show/hide this default symbol and a 'label' property or something like that so you can configure what text to display instead of 'default'. This is a more typical approach for web maps. Also, the layer name needs some whitespace to the left. |
Thanks for this suggestion. I like the idea of making things more consistent by always omitting legend styling for a layer's name when the layer has conditional styling. Do you happen to have a link or two handy where this style of legend appears? I don't have much reference for this style. I think I'd like to get more feedback from others (especially UX advice from Jeffrey) about this approach also. I agree that it would be good to be able to configure "default" labeling. |
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The following link has a legend with an 'Other' entry which is analogous to the 'default'. |
* Documentation is updated for vector/GeoJSON layer * Legend swatches are now always omitted when conditional styling is used * Property "includeOtherLegendWithDefaultStyling" is added to legend configuration in the vector layer. When set to true, an "Other" legend is added for the layer and the swatch is styled with the default styling. * Legend tool CSS is updated to add padding
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Here is what legends look like after changes in the latest commit. The new "includeOtherLegendWithDefaultStyling" legend property has been set to true for layer "Electric Charging Stations in BC".
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src/smk/layer/layer-vector.js
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| @@ -24,7 +24,8 @@ include.module( 'layer.layer-vector-js', [ 'layer.layer-js' ], function () { | |||
| const legendData = []; | |||
| legendData.push({ | |||
| title: self.config.legend && self.config.legend.title || self.config.title, | |||
| style: self.config.style | |||
| style: self.config.style, | |||
| hasConditionalStyling: self.config.conditionalStyles || false | |||
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While JavaScript allows the assignment of an object or a boolean to the same variable, it is not good practice. I'd suggest assigning true/false or assigning the object/undefined to hasConditionalStyling.
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My choice would be true/false as you never actually access the object properties.
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I'm checking for the existence of the "conditionalStyles" property in config, but yes, it is kind of dumb to actually assign it when it's present :) . I'll update this to do a better check of existence.
docs/configuration/layers/vector.md
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| Set the shape of the legend swatch. "line" is the default. | ||
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| `"includeOtherLegendWithDefaultStyling": Boolean` |
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On further thought, I think I will reverse this to something like "hideOtherLegendWithDefaultStyling". I think we should include the default styling as a ... default :) . I think most uses of conditional styling will want to include the default, and I want to favour inclusion.
In some uses of conditional styling, styling is applied to feature values in a way that each feature is included and matches one style, similar to a pie chart. In such situations, including a style for the entire layer in a legend is unnecessary.
This adds a "hideLayer" property to legend configuration in vector layers and to legend display HTML. When added to a vector/GeoJSON layer's legend configuration and set to true, the symbology for the layer (but not its conditional styling) is omitted in the legends.