StrokePatternRenderingFeaturesAvailable function

StrokePatternRenderingFeaturesAvailable loads the selected PDFium module when necessary and returns True when the optional FPDFPageObj_GetRenderedStrokePattern entry point is exported

When the export is present, GetObjectRenderedStrokePattern can rasterise the tiling pattern a path object strokes with; without it the method returns nil for every object

• The export is optional so deployments with an older pdfium.dll keep loading and rendering pages normally; only the isolated stroke-pattern rasterisation is unavailable
• A nil result from GetObjectRenderedStrokePattern is therefore ambiguous on its own; consult this function first when the distinction between "no pattern" and "no export" matters