Min/Max Value Settings for QgsPointCloudLayer about qgis-enhancement-proposals HOT 4 OPEN

This would be a very much appreciated feature!

However, can I request that we approach this in a different way to rasters? The raster approach worked ok-ish in the single-canvas world, but since it was implemented we've now got multi-canvas and 3d canvas at play (also layout maps). And the raster approach just doesn't work well anymore for these use cases.

The issue comes from trying to update the renderer values from the calculated values during rendering. I'd much prefer to completely handle this in the renderer code alone, and omit any GUI updates of the calculated ranges.

If your use case doesn't require an updated legend text then it would be relatively easy to remove the layer renderer -> renderer widget updates and completely remove refreshRendererIfNeeded.

If this IS a requirement, then we need a different approach to handle this. I would instead go for an approach of allowing the layer renderers to report statistics collected during rendering back to the canvas. (There's already a similar mechanism used for handle errors reported by layer renderers, this could be reused with a flexible QVariantMap "calculatedRendererResults" object or similar). Then only the MAIN canvas would handle responding to the gathered statistics and updating the legend accordingly.

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@nyalldawson I think that the legend must be updated or the user won't be able to understand what's displayed, don't you think ?

If I understand what you mean, you would prefer that the logic of refreshRendererIfNeeded should be implemented the the QgsPointCloudLayerRenderer ?

For the legend update, could you indicate me where there is the mechanism that handle errors reported by layer renderers ? I don't see how I will be able to update the legend and the symbology widget.

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@nyalldawson From my understanding of QGIS, there is only one legend for each layer. How can we fix this without some major changes in code.

I think it's out of the scope of this QEP to treat the issue of multiple legend.

Is the proposed solution a No Go for you or can I start a PR ?

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I think it's out of the scope of this QEP to treat the issue of multiple legend.

That's completely fair enough. But in that case I'd ask that you omit the legend component and add the logic in the QgsPointCloudLayerRenderer class alone, and without any two-way logic to change the layer's renderer settings based on the results of rendering a particular extent.

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