Function dataSample

src/processor/dataSample.ts:75–122

(seriesType: string)

};

export default function dataSample(seriesType: string): StageHandler {
    return {

        seriesType: seriesType,

        // FIXME:TS never used, so comment it
        // modifyOutputEnd: true,

        reset: function (seriesModel: SeriesModel<SeriesOption & SeriesSamplingOptionMixin>, ecModel, api) {
            const data = seriesModel.getData();
            const sampling = seriesModel.get('sampling');
            const coordSys = seriesModel.coordinateSystem;
            const count = data.count();
            // Only cartesian2d support down sampling. Disable it when there is few data.
            if (count > 10 && coordSys.type === 'cartesian2d' && sampling) {
                const baseAxis = coordSys.getBaseAxis();
                const valueAxis = coordSys.getOtherAxis(baseAxis);
                const extent = baseAxis.getExtent();
                const dpr = api.getDevicePixelRatio();
                // Coordinste system has been resized
                const size = Math.abs(extent[1] - extent[0]) * (dpr || 1);
                const rate = Math.round(count / size);

                if (isFinite(rate) && rate > 1) {
                    if (sampling === 'lttb') {
                        seriesModel.setData(data.lttbDownSample(data.mapDimension(valueAxis.dim), 1 / rate));
                    }
                    else if (sampling === 'minmax') {
                        seriesModel.setData(data.minmaxDownSample(data.mapDimension(valueAxis.dim), 1 / rate));
                    }
                    let sampler;
                    if (isString(sampling)) {
                        sampler = samplers[sampling];
                    }
                    else if (isFunction(sampling)) {
                        sampler = sampling;
                    }
                    if (sampler) {
                        // Only support sample the first dim mapped from value axis.
                        seriesModel.setData(data.downSample(
                            data.mapDimension(valueAxis.dim), 1 / rate, sampler, indexSampler
                        ));
                    }
                }
            }
        }
    };
}