LibPDF: Move text rendering strategy selection into SimpleFont

Seems a little neater. This excludes Type0Fonts for now, but it looks
like not much of the implementation would be shared.

No behaviour change intended.

Author: MacDue

Userland/Libraries/LibPDF/Fonts/PDFFont.h

@@ -36,10 +36,6 @@ class PDFFont : public RefCounted<PDFFont> {
 
     virtual void set_font_size(float font_size) = 0;
     virtual PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, ByteString const&, Renderer const&) = 0;
-    virtual PDFErrorOr<Gfx::FloatPoint> append_text_path(Gfx::Path&, Gfx::FloatPoint, ByteString const&, Renderer const&)
-    {
-        return Error { Error::Type::RenderingUnsupported, "append_text_path not implemented for font" };
-    }
 
     virtual WritingMode writing_mode() const { return WritingMode::Horizontal; }
 

Userland/Libraries/LibPDF/Fonts/SimpleFont.cpp

@@ -100,6 +100,36 @@ PDFErrorOr<Gfx::FloatPoint> SimpleFont::append_text_path(Gfx::Path& path, Gfx::F
 }
 
 PDFErrorOr<Gfx::FloatPoint> SimpleFont::draw_string(Gfx::Painter& painter, Gfx::FloatPoint position, ByteString const& string, Renderer const& renderer)
+{
+    auto const& text_rendering_matrix = renderer.calculate_text_rendering_matrix();
+    // Fast path: Use cached bitmap glyphs.
+    if (text_rendering_matrix.is_identity_or_translation_or_scale(Gfx::AffineTransform::AllowNegativeScaling::Yes))
+        return draw_axis_aligned_glyphs(painter, position, string, renderer);
+    // Slow path: Create a Gfx::Path for the string, transform it, then draw it. This handles arbitrary transforms.
+    if (auto end_position = draw_transformed_glyphs(painter, position, string, renderer); !end_position.is_error())
+        return end_position;
+    // Fallback to axis aligned glyphs in case `append_path` is unimplemented. This won't look correct.
+    return draw_axis_aligned_glyphs(painter, position, string, renderer);
+}
+
+PDFErrorOr<Gfx::FloatPoint> SimpleFont::draw_transformed_glyphs(Gfx::Painter& painter, Gfx::FloatPoint position, ByteString const& string, Renderer const& renderer)
+{
+    Gfx::Path text_path;
+    Gfx::AntiAliasingPainter aa_painter(painter);
+    auto horizontal_scaling = renderer.text_state().horizontal_scaling;
+    auto text_rendering_matrix = renderer.calculate_text_rendering_matrix();
+    auto end_position = TRY(append_text_path(text_path, position, string, renderer));
+    // FIXME: This is a bit janky, but the font is already scaled by `m_text_rendering_matrix.x_scale() / horizontal_scaling`,
+    // which is included in `m_text_rendering_matrix`. So, we must scale it by the reciprocal. Also, the y-axis is flipped.
+    text_path.transform(text_rendering_matrix.multiply(
+        Gfx::AffineTransform {}
+            .set_scale(1 / text_rendering_matrix.x_scale() * horizontal_scaling,
+                -1 / text_rendering_matrix.x_scale() * horizontal_scaling)));
+    Renderer::fill_path_with_style(aa_painter, text_path, renderer.state().paint_style, renderer.state().paint_alpha_constant);
+    return end_position;
+}
+
+PDFErrorOr<Gfx::FloatPoint> SimpleFont::draw_axis_aligned_glyphs(Gfx::Painter& painter, Gfx::FloatPoint position, ByteString const& string, Renderer const& renderer)
 {
     auto horizontal_scaling = renderer.text_state().horizontal_scaling;
     auto const& text_rendering_matrix = renderer.calculate_text_rendering_matrix();
@@ -110,5 +140,4 @@ PDFErrorOr<Gfx::FloatPoint> SimpleFont::draw_string(Gfx::Painter& painter, Gfx::
         return draw_glyph(painter, glyph_render_position, glyph_width, char_code, renderer);
     });
 }
-
 }

Userland/Libraries/LibPDF/Fonts/SimpleFont.h

@@ -14,12 +14,12 @@ namespace PDF {
 class SimpleFont : public PDFFont {
 public:
     PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, ByteString const&, Renderer const&) override;
-    PDFErrorOr<Gfx::FloatPoint> append_text_path(Gfx::Path&, Gfx::FloatPoint, ByteString const&, Renderer const&) override;
 
 protected:
     PDFErrorOr<void> initialize(Document* document, NonnullRefPtr<DictObject> const& dict, float font_size) override;
     virtual Optional<float> get_glyph_width(u8 char_code) const = 0;
     virtual PDFErrorOr<void> draw_glyph(Gfx::Painter& painter, Gfx::FloatPoint point, float width, u8 char_code, Renderer const&) = 0;
+
     virtual PDFErrorOr<void> append_glyph_path(Gfx::Path&, Gfx::FloatPoint, u8, Renderer const&)
     {
         return Error { Error::Type::RenderingUnsupported, "append_glyph_path not implemented for font" };
@@ -34,6 +34,10 @@ class SimpleFont : public PDFFont {
     template<typename Callback>
     PDFErrorOr<Gfx::FloatPoint> for_each_glyph_position(Gfx::FloatPoint, ByteString const&, Renderer const&, Callback callback);
 
+    PDFErrorOr<Gfx::FloatPoint> append_text_path(Gfx::Path&, Gfx::FloatPoint, ByteString const&, Renderer const&);
+    PDFErrorOr<Gfx::FloatPoint> draw_transformed_glyphs(Gfx::Painter&, Gfx::FloatPoint, ByteString const&, Renderer const&);
+    PDFErrorOr<Gfx::FloatPoint> draw_axis_aligned_glyphs(Gfx::Painter&, Gfx::FloatPoint, ByteString const&, Renderer const&);
+
     RefPtr<Encoding> m_encoding;
     RefPtr<StreamObject> m_to_unicode;
     HashMap<u8, u16> m_widths;

Userland/Libraries/LibPDF/Renderer.cpp

@@ -451,20 +451,11 @@ void Renderer::stroke_current_path()
     }
 }
 
-static void do_fill_path(Gfx::AntiAliasingPainter& painter, Gfx::Path const& path, ColorOrStyle const& style, float paint_style_opacity = 1.0f, Gfx::WindingRule winding_rule = Gfx::WindingRule::Nonzero)
-{
-    if (auto* paint_style = style.get_pointer<NonnullRefPtr<Gfx::PaintStyle>>()) {
-        painter.fill_path(path, *paint_style, paint_style_opacity, winding_rule);
-    } else {
-        painter.fill_path(path, style.get<Color>(), winding_rule);
-    }
-}
-
 void Renderer::fill_current_path(Gfx::WindingRule winding_rule)
 {
     auto path_end = m_current_path.end();
     m_current_path.close_all_subpaths();
-    do_fill_path(anti_aliasing_painter(), m_current_path, state().paint_style, state().paint_alpha_constant, winding_rule);
+    fill_path_with_style(anti_aliasing_painter(), m_current_path, state().paint_style, state().paint_alpha_constant, winding_rule);
     // .close_all_subpaths() only adds to the end of the path, so we can .trim() the path to remove any changes.
     m_current_path.trim(path_end);
 }
@@ -1380,28 +1371,7 @@ PDFErrorOr<void> Renderer::show_text(ByteString const& string)
         return Error::rendering_unsupported_error("Can't draw text because an invalid font was in use");
 
     auto start_position = Gfx::FloatPoint { 0.0f, 0.0f };
-    auto end_position = start_position;
-
-    if (m_text_rendering_matrix.is_identity_or_translation_or_scale(Gfx::AffineTransform::AllowNegativeScaling::No)) {
-        // Fast path: Use cached bitmap glyphs.
-        end_position = TRY(text_state().font->draw_string(painter(), start_position, string, *this));
-    } else {
-        Gfx::Path text_path;
-        // Slow path: Create a Gfx::Path for the string, transform it, then draw it. This handles arbitrary transforms.
-        if (auto maybe_end = text_state().font->append_text_path(text_path, start_position, string, *this); !maybe_end.is_error()) {
-            end_position = maybe_end.release_value();
-            // FIXME: This is a bit janky, but the font is already scaled by `m_text_rendering_matrix.x_scale() / horizontal_scaling`,
-            // which is included in `m_text_rendering_matrix`. So, we must scale it by the reciprocal. Also, the y-axis is flipped.
-            text_path.transform(m_text_rendering_matrix.multiply(
-                Gfx::AffineTransform {}
-                    .set_scale(1 / m_text_rendering_matrix.x_scale() * text_state().horizontal_scaling,
-                        -1 / m_text_rendering_matrix.x_scale() * text_state().horizontal_scaling)));
-            do_fill_path(anti_aliasing_painter(), text_path, state().paint_style, state().paint_alpha_constant);
-        } else {
-            // Fallback to the fast path in case `append_path` is unimplemented.
-            end_position = TRY(text_state().font->draw_string(painter(), start_position, string, *this));
-        }
-    }
+    auto end_position = TRY(text_state().font->draw_string(painter(), start_position, string, *this));
 
     // Update text matrix.
     auto delta = end_position - start_position;

Userland/Libraries/LibPDF/Renderer.h

@@ -179,6 +179,15 @@ class Renderer {
 
     bool show_hidden_text() const { return m_rendering_preferences.show_hidden_text; }
 
+    static void fill_path_with_style(Gfx::AntiAliasingPainter& painter, Gfx::Path const& path, ColorOrStyle const& style, float paint_style_opacity = 1.0f, Gfx::WindingRule winding_rule = Gfx::WindingRule::Nonzero)
+    {
+        if (auto* paint_style = style.get_pointer<NonnullRefPtr<Gfx::PaintStyle>>()) {
+            painter.fill_path(path, *paint_style, paint_style_opacity, winding_rule);
+        } else {
+            painter.fill_path(path, style.get<Color>(), winding_rule);
+        }
+    }
+
 private:
     Renderer(RefPtr<Document>, Page const&, RefPtr<Gfx::Bitmap>, Color background_color, RenderingPreferences);