LibPDF: Use Gfx::PathRasterizer for Adobe Type 1 font rendering

This gives much better visual results than painting the path directly.
It also has the nice side effect that Type 1 fonts will now look much
more similar to TrueType fonts, which use the same class :^)

In addition, we can now cache glyph bitmaps for repeated use.

Userland/Libraries/LibPDF/Fonts/PS1FontProgram.cpp

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
+#include <LibGfx/Font/PathRasterizer.h>
 #include <LibPDF/CommonNames.h>
 #include <LibPDF/Encoding.h>
 #include <LibPDF/Fonts/PS1FontProgram.h>
@@ -86,20 +87,61 @@ PDFErrorOr<void> PS1FontProgram::parse(ReadonlyBytes const& bytes, size_t cleart
     return parse_encrypted_portion(decrypted);
 }
 
-Gfx::Path PS1FontProgram::build_char(u32 code_point, Gfx::FloatPoint const& point, float width)
+RefPtr<Gfx::Bitmap> PS1FontProgram::rasterize_glyph(u32 code_point, float width)
 {
-    if (!m_glyph_map.contains(code_point))
+    auto path = build_char(code_point, width);
+    auto bounding_box = path.bounding_box().size();
+
+    u32 w = (u32)ceilf(bounding_box.width()) + 1;
+    u32 h = (u32)ceilf(bounding_box.height()) + 1;
+
+    Gfx::PathRasterizer rasterizer(Gfx::IntSize(w, h));
+    rasterizer.draw_path(path);
+    return rasterizer.accumulate();
+}
+
+Gfx::Path PS1FontProgram::build_char(u32 code_point, float width)
+{
+    auto maybe_glyph = m_glyph_map.get(code_point);
+    if (!maybe_glyph.has_value())
         return {};
 
-    auto glyph = m_glyph_map.get(code_point).value();
+    auto& glyph = maybe_glyph.value();
+    auto transform = glyph_transform_to_device_space(glyph, width);
+
+    // Translate such that the top-left point is at [0, 0].
+    auto bounding_box = glyph.path.bounding_box();
+    Gfx::FloatPoint translation(-bounding_box.x(), -(bounding_box.y() + bounding_box.height()));
+    transform.translate(translation);
+
+    return glyph.path.copy_transformed(transform);
+}
+
+Gfx::FloatPoint PS1FontProgram::glyph_translation(u32 code_point, float width) const
+{
+    auto maybe_glyph = m_glyph_map.get(code_point);
+    if (!maybe_glyph.has_value())
+        return {};
+
+    auto& glyph = maybe_glyph.value();
+    auto transform = glyph_transform_to_device_space(glyph, width);
+
+    // Undo the translation we applied earlier.
+    auto bounding_box = glyph.path.bounding_box();
+    Gfx::FloatPoint translation(bounding_box.x(), bounding_box.y() + bounding_box.height());
+
+    return transform.map(translation);
+}
+
+Gfx::AffineTransform PS1FontProgram::glyph_transform_to_device_space(Glyph const& glyph, float width) const
+{
     auto scale = width / (m_font_matrix.a() * glyph.width + m_font_matrix.e());
     auto transform = m_font_matrix;
 
     // Convert character space to device space.
     transform.scale(scale, -scale);
-    transform.set_translation(point);
 
-    return glyph.path.copy_transformed(transform);
+    return transform;
 }
 
 PDFErrorOr<PS1FontProgram::Glyph> PS1FontProgram::parse_glyph(ReadonlyBytes const& data, GlyphParserState& state)

Userland/Libraries/LibPDF/Fonts/PS1FontProgram.h

@@ -20,9 +20,11 @@ class PS1FontProgram : public RefCounted<PS1FontProgram> {
 public:
     PDFErrorOr<void> parse(ReadonlyBytes const&, size_t cleartext_length, size_t encrypted_length);
 
-    Gfx::Path build_char(u32 code_point, Gfx::FloatPoint const& point, float width);
+    RefPtr<Gfx::Bitmap> rasterize_glyph(u32 code_point, float width);
+    Gfx::Path build_char(u32 code_point, float width);
 
     RefPtr<Encoding> encoding() const { return m_encoding; }
+    Gfx::FloatPoint glyph_translation(u32 code_point, float width) const;
 
 private:
     struct Glyph {
@@ -46,6 +48,8 @@ private:
         Array<float, 24> postscript_stack;
     };
 
+    Gfx::AffineTransform glyph_transform_to_device_space(Glyph const&, float width) const;
+
     PDFErrorOr<Glyph> parse_glyph(ReadonlyBytes const&, GlyphParserState&);
     PDFErrorOr<void> parse_encrypted_portion(ByteBuffer const&);
     PDFErrorOr<Vector<ByteBuffer>> parse_subroutines(Reader&);

Userland/Libraries/LibPDF/Fonts/Type1Font.cpp

@@ -122,11 +122,22 @@ float Type1Font::get_char_width(u16 char_code, float) const
 
 void Type1Font::draw_glyph(Gfx::Painter& painter, Gfx::IntPoint const& point, float width, u32 code_point, Color color)
 {
-    // FIXME: Make a glyph cache
-    if (m_data.font_program) {
-        auto path = m_data.font_program->build_char(code_point, { point.x(), point.y() }, width);
-        Gfx::AntiAliasingPainter aa_painter(painter);
-        aa_painter.fill_path(path, color, Gfx::Painter::WindingRule::EvenOdd);
+    if (!m_data.font_program)
+        return;
+
+    RefPtr<Gfx::Bitmap> bitmap;
+
+    auto maybe_bitmap = m_glyph_cache.get(code_point);
+    if (maybe_bitmap.has_value()) {
+        bitmap = maybe_bitmap.value();
+    } else {
+        bitmap = m_data.font_program->rasterize_glyph(code_point, width);
+        m_glyph_cache.set(code_point, bitmap);
     }
+
+    auto translation = m_data.font_program->glyph_translation(code_point, width);
+    painter.blit_filtered(point.translated(translation.to_rounded<int>()), *bitmap, bitmap->rect(), [color](Color pixel) -> Color {
+        return pixel.multiply(color);
+    });
 }
 }

Userland/Libraries/LibPDF/Fonts/Type1Font.h

@@ -40,6 +40,7 @@ public:
 
 private:
     Data m_data;
+    HashMap<u32, RefPtr<Gfx::Bitmap>> m_glyph_cache;
 };
 
 }