From e92ec26771f1372a85e28f70519587487f5751e5 Mon Sep 17 00:00:00 2001
From: Rodrigo Tobar <rtobar@icrar.org>
Date: Wed, 23 Nov 2022 21:11:29 +0800
Subject: [PATCH] LibPDF: Introduce rendering preferences and show clipping
 paths

A new struct allows users to specify specific rendering preferences that
the Renderer class might use to paint some Document elements onto the
target bitmap. The first toggle allows rendering (or not) the clipping
paths on a page, which is useful for debugging.
---
 Userland/Libraries/LibPDF/Renderer.cpp | 10 +++++++---
 Userland/Libraries/LibPDF/Renderer.h   |  9 +++++++--
 2 files changed, 14 insertions(+), 5 deletions(-)

diff --git a/Userland/Libraries/LibPDF/Renderer.cpp b/Userland/Libraries/LibPDF/Renderer.cpp
index 41dee7fcd0..85bf2c59db 100644
--- a/Userland/Libraries/LibPDF/Renderer.cpp
+++ b/Userland/Libraries/LibPDF/Renderer.cpp
@@ -21,9 +21,9 @@
 
 namespace PDF {
 
-PDFErrorOr<void> Renderer::render(Document& document, Page const& page, RefPtr<Gfx::Bitmap> bitmap)
+PDFErrorOr<void> Renderer::render(Document& document, Page const& page, RefPtr<Gfx::Bitmap> bitmap, RenderingPreferences rendering_preferences)
 {
-    return Renderer(document, page, bitmap).render();
+    return Renderer(document, page, bitmap, rendering_preferences).render();
 }
 
 static void rect_path(Gfx::Path& path, float x, float y, float width, float height)
@@ -48,12 +48,13 @@ static Gfx::Path rect_path(Gfx::Rect<T> rect)
     return rect_path(rect.x(), rect.y(), rect.width(), rect.height());
 }
 
-Renderer::Renderer(RefPtr<Document> document, Page const& page, RefPtr<Gfx::Bitmap> bitmap)
+Renderer::Renderer(RefPtr<Document> document, Page const& page, RefPtr<Gfx::Bitmap> bitmap, RenderingPreferences rendering_preferences)
     : m_document(document)
     , m_bitmap(bitmap)
     , m_page(page)
     , m_painter(*bitmap)
     , m_anti_aliasing_painter(m_painter)
+    , m_rendering_preferences(rendering_preferences)
 {
     auto media_box = m_page.media_box;
 
@@ -247,6 +248,9 @@ void Renderer::begin_path_paint()
 {
     auto bounding_box = map(state().clipping_paths.current.bounding_box());
     m_painter.clear_clip_rect();
+    if (m_rendering_preferences.show_clipping_paths) {
+        m_painter.stroke_path(rect_path(bounding_box), Color::Black, 1);
+    }
     m_painter.add_clip_rect(bounding_box.to_type<int>());
 }
 
diff --git a/Userland/Libraries/LibPDF/Renderer.h b/Userland/Libraries/LibPDF/Renderer.h
index 0c0de5e155..4f0e1b0f62 100644
--- a/Userland/Libraries/LibPDF/Renderer.h
+++ b/Userland/Libraries/LibPDF/Renderer.h
@@ -84,12 +84,16 @@ struct GraphicsState {
     TextState text_state {};
 };
 
+struct RenderingPreferences {
+    bool show_clipping_paths { false };
+};
+
 class Renderer {
 public:
-    static PDFErrorOr<void> render(Document&, Page const&, RefPtr<Gfx::Bitmap>);
+    static PDFErrorOr<void> render(Document&, Page const&, RefPtr<Gfx::Bitmap>, RenderingPreferences preferences);
 
 private:
-    Renderer(RefPtr<Document>, Page const&, RefPtr<Gfx::Bitmap>);
+    Renderer(RefPtr<Document>, Page const&, RefPtr<Gfx::Bitmap>, RenderingPreferences);
 
     PDFErrorOr<void> render();
 
@@ -128,6 +132,7 @@ private:
     Page const& m_page;
     Gfx::Painter m_painter;
     Gfx::AntiAliasingPainter m_anti_aliasing_painter;
+    RenderingPreferences m_rendering_preferences;
 
     Gfx::Path m_current_path;
     Vector<GraphicsState> m_graphics_state_stack;