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LibPDF: Implement StitchingFunction::evaluate()

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This commit is contained in:
Nico Weber 2023-11-10 13:10:14 +01:00 • committed by Andreas Kling
parent ba34ddeb21
commit b23ed86889
1 changed files with 28 additions and 2 deletions
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30
Userland/Libraries/LibPDF/Function.cpp
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@ -208,9 +208,35 @@ StitchingFunction::create(Document* document, Vector<Bound> domain, Optional<Vec
return function;
}
PDFErrorOr<ReadonlySpan<float>> StitchingFunction::evaluate(ReadonlySpan<float>) const
PDFErrorOr<ReadonlySpan<float>> StitchingFunction::evaluate(ReadonlySpan<float> xs) const
{
return Error(Error::Type::RenderingUnsupported, "StitchingFunction not yet implemented"_string);
if (xs.size() != 1)
return Error { Error::Type::MalformedPDF, "Function argument size does not match domain size" };
float x = clamp(xs[0], m_domain.lower, m_domain.upper);
// FIXME: binary search
size_t i = 0;
for (; i < m_bounds.size(); ++i) {
if (x < m_bounds[i])
break;
}
float left_bound = i == 0 ? m_domain.lower : m_bounds[i - 1];
float right_bound = i == m_bounds.size() ? m_domain.upper : m_bounds[i];
auto interpolate = [](float x, float x_min, float x_max, float y_min, float y_max) {
return y_min + (x - x_min) * (y_max - y_min) / (x_max - x_min);
};
x = interpolate(x, left_bound, right_bound, m_encode[i].lower, m_encode[i].upper);
auto result = TRY(m_functions[i]->evaluate({ &x, 1 }));
if (!m_range.has_value())
return result;
if (result.size() != m_range.value().size())
return Error { Error::Type::MalformedPDF, "Function stitching result size does not match range size" };
for (size_t i = 0; i < result.size(); ++i)
m_result[i] = clamp(result[i], m_range.value()[i].lower, m_range.value()[i].upper);
return m_result;
}
class PostScriptCalculatorFunction final : public Function {