LibPDF: Add basic tiled, coloured pattern rendering

Author: X-yl

Userland/Libraries/LibPDF/ColorSpace.cpp

@@ -45,7 +45,7 @@ PDFErrorOr<NonnullRefPtr<ColorSpace>> ColorSpace::create(Document* document, Non
     return Error { Error::Type::MalformedPDF, "Color space must be name or array" };
 }
 
-PDFErrorOr<NonnullRefPtr<ColorSpace>> ColorSpace::create(DeprecatedFlyString const& name, Renderer&)
+PDFErrorOr<NonnullRefPtr<ColorSpace>> ColorSpace::create(DeprecatedFlyString const& name, Renderer& renderer)
 {
     // Simple color spaces with no parameters, which can be specified directly
     if (name == CommonNames::DeviceGray)
@@ -55,7 +55,7 @@ PDFErrorOr<NonnullRefPtr<ColorSpace>> ColorSpace::create(DeprecatedFlyString con
     if (name == CommonNames::DeviceCMYK)
         return DeviceCMYKColorSpace::the();
     if (name == CommonNames::Pattern)
-        return Error::rendering_unsupported_error("Pattern color spaces not yet implemented");
+        return PatternColorSpace::create(renderer);
     VERIFY_NOT_REACHED();
 }
 
@@ -86,9 +86,6 @@ PDFErrorOr<NonnullRefPtr<ColorSpace>> ColorSpace::create(Document* document, Non
     if (color_space_name == CommonNames::Lab)
         return TRY(LabColorSpace::create(document, move(parameters)));
 
-    if (color_space_name == CommonNames::Pattern)
-        return Error::rendering_unsupported_error("Pattern color spaces not yet implemented");
-
     if (color_space_name == CommonNames::Separation)
         return TRY(SeparationColorSpace::create(document, move(parameters), renderer));
 
@@ -773,4 +770,104 @@ Vector<float> SeparationColorSpace::default_decode() const
 {
     return { 0.0f, 1.0f };
 }
+NonnullRefPtr<PatternColorSpace> PatternColorSpace::create(Renderer& renderer)
+{
+    return adopt_ref(*new PatternColorSpace(renderer));
+}
+
+PDFErrorOr<ColorOrStyle> PatternColorSpace::style(ReadonlySpan<Value> arguments) const
+{
+    VERIFY(arguments.size() >= 1);
+
+    auto resources = m_renderer.m_page.resources;
+
+    auto pattern_resource = resources->get_value(CommonNames::Pattern);
+    auto doc_pattern_dict = pattern_resource.get<NonnullRefPtr<Object>>()->cast<DictObject>();
+
+    auto const& pattern_name = arguments.last().get<NonnullRefPtr<Object>>()->cast<NameObject>()->name();
+    if (!doc_pattern_dict->contains(pattern_name))
+        return Error::malformed_error("Pattern dictionary does not contain pattern {}", pattern_name);
+
+    auto const pattern = TRY(m_renderer.m_document->resolve_to<StreamObject>(doc_pattern_dict->get_value(pattern_name)));
+
+    auto const type = pattern->dict()->get(CommonNames::Type)->get<NonnullRefPtr<Object>>()->cast<NameObject>();
+    if (type->name() != CommonNames::Pattern)
+        return Error::rendering_unsupported_error("Unsupported pattern type {}", type->name());
+
+    auto const pattern_type = pattern->dict()->get(CommonNames::PatternType)->get_u16();
+    if (pattern_type != 1)
+        return Error::rendering_unsupported_error("Unsupported pattern type {}", pattern_type);
+
+    auto const pattern_paint_type = pattern->dict()->get("PaintType")->get_u16();
+    if (pattern_paint_type != 1)
+        return Error::rendering_unsupported_error("Unsupported pattern paint type {}", pattern_paint_type);
+
+    Vector<Value> pattern_matrix;
+    if (pattern->dict()->contains(CommonNames::Matrix)) {
+        pattern_matrix = pattern->dict()->get_array(m_renderer.m_document, CommonNames::Matrix).value()->elements();
+    } else {
+        pattern_matrix = Vector { Value { 1 }, Value { 0 }, Value { 0 }, Value { 1 }, Value { 0 }, Value { 0 } };
+    }
+
+    auto pattern_bounding_box = pattern->dict()->get_array(m_renderer.m_document, "BBox").value()->elements();
+    auto pattern_transform = Gfx::AffineTransform(
+        pattern_matrix[0].to_float(),
+        pattern_matrix[1].to_float(),
+        pattern_matrix[2].to_float(),
+        pattern_matrix[3].to_float(),
+        pattern_matrix[4].to_float(),
+        pattern_matrix[5].to_float());
+
+    // To get the device space size for the bitmap, apply the pattern transform to the pattern space bounding box, and then apply the initial ctm.
+    // NB: the pattern pattern_matrix maps pattern space to the default (initial) coordinate space of the page. (i.e cannot be updated via cm).
+
+    auto initial_ctm = Gfx::AffineTransform(m_renderer.m_graphics_state_stack.first().ctm);
+    initial_ctm.set_translation(0, 0);
+    initial_ctm.set_scale(initial_ctm.x_scale(), initial_ctm.y_scale());
+
+    auto pattern_space_lower_left = Gfx::FloatPoint { pattern_bounding_box[0].to_int(), pattern_bounding_box[1].to_int() };
+    auto pattern_space_upper_right = Gfx::FloatPoint { pattern_bounding_box[2].to_int(), pattern_bounding_box[3].to_int() };
+
+    auto device_space_lower_left = initial_ctm.map(pattern_transform.map(pattern_space_lower_left));
+    auto device_space_upper_right = initial_ctm.map(pattern_transform.map(pattern_space_upper_right));
+
+    auto bitmap_width = (int)device_space_upper_right.x() - (int)device_space_lower_left.x();
+    auto bitmap_height = (int)device_space_upper_right.y() - (int)device_space_lower_left.y();
+
+    auto pattern_cell = TRY(Gfx::Bitmap::create(Gfx::BitmapFormat::BGRA8888, { bitmap_width, bitmap_height }));
+    auto page = Page(m_renderer.m_page);
+    page.media_box = Rectangle {
+        pattern_space_lower_left.x(), pattern_space_lower_left.y(),
+        pattern_space_upper_right.x(), pattern_space_upper_right.y()
+    };
+    page.crop_box = page.media_box;
+
+    auto pattern_renderer = Renderer(m_renderer.m_document, page, pattern_cell, {}, m_renderer.m_rendering_preferences);
+
+    auto operators = TRY(Parser::parse_operators(m_renderer.m_document, pattern->bytes()));
+    for (auto& op : operators)
+        TRY(pattern_renderer.handle_operator(op, resources));
+
+    auto x_steps = pattern->dict()->get("XStep").value_or(bitmap_width).to_int();
+    auto y_steps = pattern->dict()->get("YStep").value_or(bitmap_height).to_int();
+
+    auto device_space_steps = initial_ctm.map(pattern_transform.map(Gfx::IntPoint { x_steps, y_steps }));
+
+    NonnullRefPtr<Gfx::PaintStyle> style = MUST(Gfx::RepeatingBitmapPaintStyle::create(
+        *pattern_cell,
+        device_space_steps,
+        {}));
+
+    return style;
+}
+int PatternColorSpace::number_of_components() const
+{
+    // Not permitted
+    VERIFY_NOT_REACHED();
+}
+Vector<float> PatternColorSpace::default_decode() const
+{
+    // Not permitted
+    VERIFY_NOT_REACHED();
+}
 }

Userland/Libraries/LibPDF/ColorSpace.h

@@ -252,4 +252,24 @@ class SeparationColorSpace final : public ColorSpace {
     NonnullRefPtr<Function> m_tint_transform;
     Vector<Value> mutable m_tint_output_values;
 };
+
+class PatternColorSpace final : public ColorSpace {
+public:
+    static NonnullRefPtr<PatternColorSpace> create(Renderer& renderer);
+    ~PatternColorSpace() override = default;
+
+    PDFErrorOr<ColorOrStyle> style(ReadonlySpan<Value> arguments) const override;
+    int number_of_components() const override;
+    Vector<float> default_decode() const override;
+    ColorSpaceFamily const& family() const override { return ColorSpaceFamily::Pattern; }
+
+private:
+    PatternColorSpace(Renderer& renderer)
+        : m_renderer(renderer)
+    {
+    }
+
+    Renderer& m_renderer;
+};
+
 }

Userland/Libraries/LibPDF/CommonNames.h

@@ -138,8 +138,10 @@
     X(Outlines)                   \
     X(P)                          \
     X(Pages)                      \
+    X(PaintType)                  \
     X(Parent)                     \
     X(Pattern)                    \
+    X(PatternType)                \
     X(Perms)                      \
     X(Predictor)                  \
     X(Prev)                       \

Userland/Libraries/LibPDF/Renderer.cpp

@@ -616,14 +616,8 @@ RENDERER_HANDLER(set_stroking_color)
 
 RENDERER_HANDLER(set_stroking_color_extended)
 {
-    // FIXME: Handle Pattern color spaces
-    auto last_arg = args.last();
-    if (last_arg.has<NonnullRefPtr<Object>>() && last_arg.get<NonnullRefPtr<Object>>()->is<NameObject>()) {
-        dbgln("pattern space {}", last_arg.get<NonnullRefPtr<Object>>()->cast<NameObject>()->name());
-        return Error::rendering_unsupported_error("Pattern color spaces not yet implemented");
-    }
-
-    state().stroke_style = TRY(state().stroke_color_space->style(args));
+    // FIXME: Pattern color spaces might need extra resources
+    state().paint_style = TRY(state().paint_color_space->style(args));
     return {};
 }
 
@@ -635,13 +629,7 @@ RENDERER_HANDLER(set_painting_color)
 
 RENDERER_HANDLER(set_painting_color_extended)
 {
-    // FIXME: Handle Pattern color spaces
-    auto last_arg = args.last();
-    if (last_arg.has<NonnullRefPtr<Object>>() && last_arg.get<NonnullRefPtr<Object>>()->is<NameObject>()) {
-        dbgln("pattern space {}", last_arg.get<NonnullRefPtr<Object>>()->cast<NameObject>()->name());
-        return Error::rendering_unsupported_error("Pattern color spaces not yet implemented");
-    }
-
+    // FIXME: Pattern color spaces might need extra resources
     state().paint_style = TRY(state().paint_color_space->style(args));
     return {};
 }

Userland/Libraries/LibPDF/Renderer.h

@@ -97,6 +97,8 @@ struct RenderingPreferences {
 };
 
 class Renderer {
+    friend class PatternColorSpace;
+
 public:
     static PDFErrorsOr<void> render(Document&, Page const&, RefPtr<Gfx::Bitmap>, Color background_color, RenderingPreferences preferences);