From 9e502dcfe41bcee2d3e99442657d4a8a2af97b48 Mon Sep 17 00:00:00 2001
From: Nico Weber <thakis@chromium.org>
Date: Fri, 1 Mar 2024 11:13:58 -0500
Subject: [PATCH] LibPDF: Honor writing mode in TJ operator as well

---
 Userland/Libraries/LibPDF/Fonts/PDFFont.h   | 7 +++++++
 Userland/Libraries/LibPDF/Fonts/Type0Font.h | 6 +-----
 Userland/Libraries/LibPDF/Renderer.cpp      | 5 ++++-
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/Userland/Libraries/LibPDF/Fonts/PDFFont.h b/Userland/Libraries/LibPDF/Fonts/PDFFont.h
index f1b2f84c1a..07c29b75cc 100644
--- a/Userland/Libraries/LibPDF/Fonts/PDFFont.h
+++ b/Userland/Libraries/LibPDF/Fonts/PDFFont.h
@@ -20,6 +20,11 @@ class Renderer;
 // these tables in some cases. Skip reading these tables.
 constexpr u32 pdf_skipped_opentype_tables = OpenType::FontOptions::SkipTables::Name | OpenType::FontOptions::SkipTables::Hmtx | OpenType::FontOptions::SkipTables::OS2;
 
+enum class WritingMode {
+    Horizontal,
+    Vertical,
+};
+
 class PDFFont : public RefCounted<PDFFont> {
 public:
     static PDFErrorOr<NonnullRefPtr<PDFFont>> create(Document*, NonnullRefPtr<DictObject> const&, float font_size);
@@ -29,6 +34,8 @@ public:
     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 WritingMode writing_mode() const { return WritingMode::Horizontal; }
+
     // TABLE 5.20 Font flags
     bool is_fixed_pitch() const { return m_flags & (1 << (1 - 1)); }
     bool is_serif() const { return m_flags & (1 << (2 - 1)); }
diff --git a/Userland/Libraries/LibPDF/Fonts/Type0Font.h b/Userland/Libraries/LibPDF/Fonts/Type0Font.h
index ebdca2c341..59a19732ec 100644
--- a/Userland/Libraries/LibPDF/Fonts/Type0Font.h
+++ b/Userland/Libraries/LibPDF/Fonts/Type0Font.h
@@ -27,11 +27,6 @@ public:
     virtual u32 next() = 0;
 };
 
-enum class WritingMode {
-    Horizontal,
-    Vertical,
-};
-
 class Type0CMap {
 public:
     virtual ~Type0CMap() = default;
@@ -58,6 +53,7 @@ public:
 
     void set_font_size(float font_size) override;
     PDFErrorOr<Gfx::FloatPoint> draw_string(Gfx::Painter&, Gfx::FloatPoint, ByteString const&, Renderer const&) override;
+    WritingMode writing_mode() const override { return m_cmap->writing_mode(); }
 
     DeprecatedFlyString base_font_name() const { return m_base_font_name; }
 
diff --git a/Userland/Libraries/LibPDF/Renderer.cpp b/Userland/Libraries/LibPDF/Renderer.cpp
index 6c69bb10e1..4502b725e6 100644
--- a/Userland/Libraries/LibPDF/Renderer.cpp
+++ b/Userland/Libraries/LibPDF/Renderer.cpp
@@ -598,7 +598,10 @@ RENDERER_HANDLER(text_show_string_array)
     for (auto& element : elements) {
         if (element.has_number()) {
             float shift = element.to_float() / 1000.0f;
-            m_text_matrix.translate(-shift * text_state().font_size * text_state().horizontal_scaling, 0.0f);
+            if (text_state().font->writing_mode() == WritingMode::Horizontal)
+                m_text_matrix.translate(-shift * text_state().font_size * text_state().horizontal_scaling, 0.0f);
+            else
+                m_text_matrix.translate(0.0f, -shift * text_state().font_size);
             m_text_rendering_matrix_is_dirty = true;
         } else {
             auto str = element.get<NonnullRefPtr<Object>>()->cast<StringObject>()->string();