Report WMS scale denominators (scale hints) #70
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WMS 1.1.1 ScaleHint is converted to scale denominators as used in WMS 1.3.0 capabilities documents for consistency. Note that the test using WMS 1.1.1 currently fails due to a significant difference in the scale hints provided in the 1.1.1 and 1.3.0 test documents, presumably caused by a non-standard pixel size being used to calculate the scale hints for the 1.1.1 document (i.e. not exactly a square 0.28x0.28mm pixel as specified by the WMS 1.3.0 standard).
The StyleHint values were obviously calculated using a non-standard pixel size - this changes them to be the values produced applying the standard pixel size to the MinScaleDenom and MaxScaleDenom provided in the WMS 1.3.0 capabilities document.
This avoids floating point precision problems caused by converting ScaleHint to MinScaleDenominator and MaxScaleDenominator
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This adds support for reporting the
minScaleDenominatorandmaxScaleDenominatorfrom WMS layers in the API, which may be passed e.g. to OpenLayers to ensure that WMS calls are only made when the layer is in the visible range.The resolution values from
ScaleHintin WMS 1.1 are translated to scale denominators as used in WMS 1.3.0 using the "OGC standard pixel size".Note that the scale hints provided in the test fixture for WMS 1.1.1 were apparently not calculated using the OGC standard pixel size (my guess is around ~72dpi was used), so that I have recalculated them. Due to floating-point precision issues the test for WMS 1.1.1 also requires comparing rounded values.