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LibPDF: Implement SeparationColorSpace

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Requires PDF::Function, which isn't implemented yet, so this has
no visual effect yet.
This commit is contained in:
Nico Weber 2023-11-04 21:02:28 +01:00 • committed by Andreas Kling
parent 9204252d02
commit b78ea81de5
3 changed files with 68 additions and 8 deletions
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64
Userland/Libraries/LibPDF/ColorSpace.cpp
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@ -688,16 +688,70 @@ Vector<float> IndexedColorSpace::default_decode() const
return { 0.0, static_cast<float>(m_hival) };
}
PDFErrorOr<NonnullRefPtr<SeparationColorSpace>> SeparationColorSpace::create(Document*, Vector<Value>&&)
PDFErrorOr<NonnullRefPtr<SeparationColorSpace>> SeparationColorSpace::create(Document* document, Vector<Value>&& parameters)
{
auto color_space = adopt_ref(*new SeparationColorSpace());
// FIXME: Implement.
if (parameters.size() != 3)
return Error { Error::Type::MalformedPDF, "Separation color space expected three parameters" };
// "The name parameter is a name object specifying the name of the colorant that this Separation color space
// is intended to represent (or one of the special names All or None; see below)"
auto param0 = TRY(document->resolve(parameters[0]));
if (!param0.has<NonnullRefPtr<Object>>())
return Error { Error::Type::MalformedPDF, "Separation color space expects object for first arg" };
auto name_object = param0.get<NonnullRefPtr<Object>>();
if (!name_object->is<NameObject>())
return Error { Error::Type::MalformedPDF, "Separation color space expects name object for first arg" };
auto name = name_object->cast<NameObject>()->name();
// "The alternateSpace parameter must be an array or name object that identifies the alternate color space,
// which can be any device or CIE-based color space but not another special color space
// (Pattern, Indexed, Separation, or DeviceN)."
auto param1 = TRY(document->resolve(parameters[1]));
if (!param1.has<NonnullRefPtr<Object>>())
return Error { Error::Type::MalformedPDF, "Separation color space expects object for second arg" };
auto alternate_space_object = param1.get<NonnullRefPtr<Object>>();
auto alternate_space = TRY(ColorSpace::create(document, alternate_space_object));
auto family = alternate_space->family();
if (family.name() == ColorSpaceFamily::Pattern.name() || family.name() == ColorSpaceFamily::Indexed.name() || family.name() == ColorSpaceFamily::Separation.name() || family.name() == ColorSpaceFamily::DeviceN.name())
return Error { Error::Type::MalformedPDF, "Separation color space has invalid alternate color space" };
// "The tintTransform parameter must be a function"
auto param2 = TRY(document->resolve(parameters[2]));
if (!param2.has<NonnullRefPtr<Object>>())
return Error { Error::Type::MalformedPDF, "Separation color space expects object for third arg" };
auto tint_transform_object = param2.get<NonnullRefPtr<Object>>();
auto tint_transform = TRY(Function::create(document, tint_transform_object));
auto color_space = adopt_ref(*new SeparationColorSpace(move(alternate_space), move(tint_transform)));
color_space->m_name = move(name);
return color_space;
}
PDFErrorOr<Color> SeparationColorSpace::color(ReadonlySpan<Value>) const
SeparationColorSpace::SeparationColorSpace(NonnullRefPtr<ColorSpace> alternate_space, NonnullRefPtr<Function> tint_transform)
: m_alternate_space(move(alternate_space))
, m_tint_transform(move(tint_transform))
{
return Error::rendering_unsupported_error("Separation color spaces not yet implemented");
}
PDFErrorOr<Color> SeparationColorSpace::color(ReadonlySpan<Value> arguments) const
{
// "For an additive device such as a computer display, a Separation color space never applies a process colorant directly;
// it always reverts to the alternate color space as described below."
// "During subsequent painting operations, an application calls [the tint] function to transform a tint value into
// color component values in the alternate color space."
// FIXME: Does this need handling for the special colorant names "All" and "None"?
// FIXME: When drawing to a printer, do something else.
VERIFY(arguments.size() == 1);
auto a = arguments[0].to_float();
auto tint_output = TRY(m_tint_transform->evaluate(ReadonlySpan<float> { &a, 1 }));
m_tint_output_values.resize(tint_output.size());
for (size_t i = 0; i < tint_output.size(); ++i)
m_tint_output_values[i] = tint_output[i];
return m_alternate_space->color(m_tint_output_values);
}
Vector<float> SeparationColorSpace::default_decode() const