LibPDF: Refactor parsing of ColorSpaces

ColorSpaces can be specified in two ways: with a stream as operands of
the color space operations (CS/cs), or as a separate PDF object, which
is then referred to by other means (e.g., from Image XObjects and other
entities). These two modes of addressing a ColorSpace are slightly
different and need to be addressed separately. However, the current
implementation embedded the full logic of the first case in the routine
that created ColorSpace objects.

This commit refactors the creation of ColorSpace to support both cases.
First, a new ColorSpaceFamily class encapsulates the static aspects of a
family, like its name or whether color space construction never requires
parameters. Then we define the supported ColorSpaceFamily objects.

On top of this also sit a breakage on how ColorSpaces are created. Two
methods are now offered: one only providing construction of no-argument
color spaces (and thus taking a simple name), and another taking an
ArrayObject, hence used to create ColorSpaces requiring arguments.

Finally, on top of *that* two ways to get a color space in the Renderer
are made available: the first creates a ColorSpace with a name and a
Resources dictionary, and another takes an Object. These model the two
addressing modes described above.

4 files changed, 97 insertions, 34 deletions

diff --git a/Userland/Libraries/LibPDF/ColorSpace.cpp b/Userland/Libraries/LibPDF/ColorSpace.cpp
index d9b87a0dc9..943f9b96fb 100644
--- a/Userland/Libraries/LibPDF/ColorSpace.cpp
+++ b/Userland/Libraries/LibPDF/ColorSpace.cpp
@@ -11,7 +11,23 @@
 
 namespace PDF {
 
-PDFErrorOr<NonnullRefPtr<ColorSpace>> ColorSpace::create(Document* document, FlyString const& name, NonnullRefPtr<DictObject> resources)
+#define ENUMERATE(name, ever_needs_parameters) \
+    ColorSpaceFamily ColorSpaceFamily::name { #name, ever_needs_parameters };
+ENUMERATE_COLOR_SPACE_FAMILIES(ENUMERATE);
+#undef ENUMERATE
+
+PDFErrorOr<ColorSpaceFamily> ColorSpaceFamily::get(FlyString const& family_name)
+{
+#define ENUMERATE(f_name, ever_needs_parameters) \
+    if (family_name == f_name.name()) {          \
+        return ColorSpaceFamily::f_name;         \
+    }
+    ENUMERATE_COLOR_SPACE_FAMILIES(ENUMERATE)
+#undef ENUMERATE
+    return Error(Error::Type::MalformedPDF, DeprecatedString::formatted("Unknown ColorSpace family {}", family_name));
+}
+
+PDFErrorOr<NonnullRefPtr<ColorSpace>> ColorSpace::create(FlyString const& name)
 {
     // Simple color spaces with no parameters, which can be specified directly
     if (name == CommonNames::DeviceGray)
@@ -22,14 +38,11 @@ PDFErrorOr<NonnullRefPtr<ColorSpace>> ColorSpace::create(Document* document, Fly
         return DeviceCMYKColorSpace::the();
     if (name == CommonNames::Pattern)
         TODO();
+    VERIFY_NOT_REACHED();
+}
 
-    // The color space is a complex color space with parameters that resides in
-    // the resource dictionary
-    auto color_space_resource_dict = TRY(resources->get_dict(document, CommonNames::ColorSpace));
-    if (!color_space_resource_dict->contains(name))
-        TODO();
-
-    auto color_space_array = TRY(color_space_resource_dict->get_array(document, name));
+PDFErrorOr<NonnullRefPtr<ColorSpace>> ColorSpace::create(Document* document, NonnullRefPtr<ArrayObject> color_space_array)
+{
     auto color_space_name = TRY(color_space_array->get_name_at(document, 0))->name();
 
     Vector<Value> parameters;
@@ -41,7 +54,7 @@ PDFErrorOr<NonnullRefPtr<ColorSpace>> ColorSpace::create(Document* document, Fly
         return TRY(CalRGBColorSpace::create(document, move(parameters)));
 
     if (color_space_name == CommonNames::ICCBased)
-        return TRY(ICCBasedColorSpace::create(document, resources, move(parameters)));
+        return TRY(ICCBasedColorSpace::create(document, move(parameters)));
 
     dbgln("Unknown color space: {}", color_space_name);
     TODO();
@@ -261,7 +274,7 @@ Color CalRGBColorSpace::color(Vector<Value> const& arguments) const
     return Color(red, green, blue);
 }
 
-PDFErrorOr<NonnullRefPtr<ColorSpace>> ICCBasedColorSpace::create(Document* document, NonnullRefPtr<DictObject> resources, Vector<Value>&& parameters)
+PDFErrorOr<NonnullRefPtr<ColorSpace>> ICCBasedColorSpace::create(Document* document, Vector<Value>&& parameters)
 {
     if (parameters.is_empty())
         return Error { Error::Type::MalformedPDF, "ICCBased color space expected one parameter" };
@@ -283,11 +296,16 @@ PDFErrorOr<NonnullRefPtr<ColorSpace>> ICCBasedColorSpace::create(Document* docum
             name = CommonNames::DeviceCMYK;
         else
             VERIFY_NOT_REACHED();
-    } else {
-        name = TRY(dict->get_name(document, CommonNames::Alternate))->name();
+        return ColorSpace::create(name);
     }
 
-    return TRY(ColorSpace::create(document, name, resources));
+    auto alternate_color_space_object = MUST(dict->get_object(document, CommonNames::Alternate));
+    if (alternate_color_space_object->is<NameObject>()) {
+        return ColorSpace::create(alternate_color_space_object->cast<NameObject>()->name());
+    }
+
+    dbgln("Alternate color spaces in array format not supported yet ");
+    TODO();
 }
 
 Color ICCBasedColorSpace::color(Vector<Value> const&) const
diff --git a/Userland/Libraries/LibPDF/ColorSpace.h b/Userland/Libraries/LibPDF/ColorSpace.h
index 60eaf79ff8..ab1e8c4da5 100644
--- a/Userland/Libraries/LibPDF/ColorSpace.h
+++ b/Userland/Libraries/LibPDF/ColorSpace.h
@@ -10,30 +10,51 @@
 #include <LibGfx/Color.h>
 #include <LibPDF/Value.h>
 
-#define ENUMERATE_COLOR_SPACES(V) \
-    V(DeviceGray)                 \
-    V(DeviceRGB)                  \
-    V(DeviceCMYK)                 \
-    V(CalGray)                    \
-    V(CalRGB)                     \
-    V(Lab)                        \
-    V(ICCBased)                   \
-    V(Indexed)                    \
-    V(Pattern)                    \
-    V(Separation)                 \
-    V(DeviceN)
+#define ENUMERATE_COLOR_SPACE_FAMILIES(V) \
+    V(DeviceGray, true)                   \
+    V(DeviceRGB, true)                    \
+    V(DeviceCMYK, true)                   \
+    V(CalGray, false)                     \
+    V(CalRGB, false)                      \
+    V(Lab, false)                         \
+    V(ICCBased, false)                    \
+    V(Indexed, false)                     \
+    V(Pattern, false)                     \
+    V(Separation, false)                  \
+    V(DeviceN, false)
 
 namespace PDF {
 
-struct Page;
+class ColorSpaceFamily {
+public:
+    ColorSpaceFamily(FlyString name, bool never_needs_paramaters_p)
+        : m_name(move(name))
+        , m_never_needs_parameters(never_needs_paramaters_p)
+    {
+    }
+
+    FlyString name() const { return m_name; };
+    bool never_needs_parameters() const { return m_never_needs_parameters; };
+    static PDFErrorOr<ColorSpaceFamily> get(FlyString const&);
+
+#define ENUMERATE(name, ever_needs_parameters) static ColorSpaceFamily name;
+    ENUMERATE_COLOR_SPACE_FAMILIES(ENUMERATE)
+#undef ENUMERATE
+
+private:
+    FlyString m_name;
+    bool m_never_needs_parameters;
+};
 
 class ColorSpace : public RefCounted<ColorSpace> {
 public:
-    static PDFErrorOr<NonnullRefPtr<ColorSpace>> create(Document*, FlyString const& name, NonnullRefPtr<DictObject> resources);
+    static PDFErrorOr<NonnullRefPtr<ColorSpace>> create(FlyString const&);
+    static PDFErrorOr<NonnullRefPtr<ColorSpace>> create(Document*, NonnullRefPtr<ArrayObject>);
 
     virtual ~ColorSpace() = default;
 
     virtual Color color(Vector<Value> const& arguments) const = 0;
+    virtual ColorSpaceFamily const& family() const = 0;
 };
 
 class DeviceGrayColorSpace final : public ColorSpace {
@@ -43,6 +64,7 @@ public:
     ~DeviceGrayColorSpace() override = default;
 
     Color color(Vector<Value> const& arguments) const override;
+    ColorSpaceFamily const& family() const override { return ColorSpaceFamily::DeviceGray; }
 
 private:
     DeviceGrayColorSpace() = default;
@@ -55,6 +77,7 @@ public:
     ~DeviceRGBColorSpace() override = default;
 
     Color color(Vector<Value> const& arguments) const override;
+    ColorSpaceFamily const& family() const override { return ColorSpaceFamily::DeviceRGB; }
 
 private:
     DeviceRGBColorSpace() = default;
@@ -67,6 +90,7 @@ public:
     ~DeviceCMYKColorSpace() override = default;
 
     Color color(Vector<Value> const& arguments) const override;
+    ColorSpaceFamily const& family() const override { return ColorSpaceFamily::DeviceCMYK; }
 
 private:
     DeviceCMYKColorSpace() = default;
@@ -79,6 +103,7 @@ public:
     ~CalRGBColorSpace() override = default;
 
     Color color(Vector<Value> const& arguments) const override;
+    ColorSpaceFamily const& family() const override { return ColorSpaceFamily::CalRGB; }
 
 private:
     CalRGBColorSpace() = default;
@@ -91,11 +116,12 @@ private:
 
 class ICCBasedColorSpace final : public ColorSpace {
 public:
-    static PDFErrorOr<NonnullRefPtr<ColorSpace>> create(Document*, NonnullRefPtr<DictObject> resources, Vector<Value>&& parameters);
+    static PDFErrorOr<NonnullRefPtr<ColorSpace>> create(Document*, Vector<Value>&& parameters);
 
     ~ICCBasedColorSpace() override = default;
 
     Color color(Vector<Value> const& arguments) const override;
+    ColorSpaceFamily const& family() const override { return ColorSpaceFamily::ICCBased; }
 
 private:
     ICCBasedColorSpace() = delete;
diff --git a/Userland/Libraries/LibPDF/Renderer.cpp b/Userland/Libraries/LibPDF/Renderer.cpp
index e80d6213d1..0fde4418ed 100644
--- a/Userland/Libraries/LibPDF/Renderer.cpp
+++ b/Userland/Libraries/LibPDF/Renderer.cpp
@@ -523,14 +523,14 @@ RENDERER_TODO(type3_font_set_glyph_width_and_bbox)
 
 RENDERER_HANDLER(set_stroking_space)
 {
-    state().stroke_color_space = TRY(get_color_space(args[0], extra_resources.value_or(m_page.resources)));
+    state().stroke_color_space = TRY(get_color_space_from_resources(args[0], extra_resources.value_or(m_page.resources)));
     VERIFY(state().stroke_color_space);
     return {};
 }
 
 RENDERER_HANDLER(set_painting_space)
 {
-    state().paint_color_space = TRY(get_color_space(args[0], extra_resources.value_or(m_page.resources)));
+    state().paint_color_space = TRY(get_color_space_from_resources(args[0], extra_resources.value_or(m_page.resources)));
     VERIFY(state().paint_color_space);
     return {};
 }
@@ -759,10 +759,28 @@ void Renderer::show_text(DeprecatedString const& string)
     m_text_matrix.translate(delta_x / text_rendering_matrix.x_scale(), 0.0f);
 }
 
-PDFErrorOr<NonnullRefPtr<ColorSpace>> Renderer::get_color_space(Value const& value, NonnullRefPtr<DictObject> resources)
+PDFErrorOr<NonnullRefPtr<ColorSpace>> Renderer::get_color_space_from_resources(Value const& value, NonnullRefPtr<DictObject> resources)
 {
-    auto name = value.get<NonnullRefPtr<Object>>()->cast<NameObject>()->name();
-    return TRY(ColorSpace::create(m_document, name, resources));
+    auto color_space_name = value.get<NonnullRefPtr<Object>>()->cast<NameObject>()->name();
+    auto maybe_color_space_family = ColorSpaceFamily::get(color_space_name);
+    if (!maybe_color_space_family.is_error()) {
+        auto color_space_family = maybe_color_space_family.release_value();
+        if (color_space_family.never_needs_parameters()) {
+            return ColorSpace::create(color_space_name);
+        }
+    }
+    auto color_space_resource_dict = TRY(resources->get_dict(m_document, CommonNames::ColorSpace));
+    auto color_space_array = TRY(color_space_resource_dict->get_array(m_document, color_space_name));
+    return ColorSpace::create(m_document, color_space_array);
+}
+
+PDFErrorOr<NonnullRefPtr<ColorSpace>> Renderer::get_color_space_from_document(NonnullRefPtr<Object> color_space_object)
+{
+    // Pattern cannot be a name in these cases
+    if (color_space_object->is<NameObject>()) {
+        return ColorSpace::create(color_space_object->cast<NameObject>()->name());
+    }
+    return ColorSpace::create(m_document, color_space_object->cast<ArrayObject>());
 }
 
 Gfx::AffineTransform const& Renderer::calculate_text_rendering_matrix()
diff --git a/Userland/Libraries/LibPDF/Renderer.h b/Userland/Libraries/LibPDF/Renderer.h
index 9ca5cab815..762c2207c8 100644
--- a/Userland/Libraries/LibPDF/Renderer.h
+++ b/Userland/Libraries/LibPDF/Renderer.h
@@ -109,7 +109,8 @@ private:
     void end_path_paint();
     PDFErrorOr<void> set_graphics_state_from_dict(NonnullRefPtr<DictObject>);
     void show_text(DeprecatedString const&);
-    PDFErrorOr<NonnullRefPtr<ColorSpace>> get_color_space(Value const&, NonnullRefPtr<DictObject>);
+    PDFErrorOr<NonnullRefPtr<ColorSpace>> get_color_space_from_resources(Value const&, NonnullRefPtr<DictObject>);
+    PDFErrorOr<NonnullRefPtr<ColorSpace>> get_color_space_from_document(NonnullRefPtr<Object>);
 
     ALWAYS_INLINE GraphicsState const& state() const { return m_graphics_state_stack.last(); }
     ALWAYS_INLINE GraphicsState& state() { return m_graphics_state_stack.last(); }