From f5e7d62f90f5eb88afad45d56017c42835149d0c Mon Sep 17 00:00:00 2001
From: Matthias Melcher <github@matthiasm.com>
Date: Sun, 28 Dec 2025 21:37:23 +0100
Subject: Generate code block documentation using FLTK (#1353)

The Doxygen-to-pdf toolchain can not easily generate
pdf's with Japanese and Chinese characters. This patch
generates code blocks by rendering them in FLTK.
---
 documentation/CMakeLists.txt  |  4 ++++
 documentation/Doxyfile.in     |  8 +++++---
 documentation/src/unicode.dox | 10 ++++++++++
 3 files changed, 19 insertions(+), 3 deletions(-)

(limited to 'documentation')

diff --git a/documentation/CMakeLists.txt b/documentation/CMakeLists.txt
index 3dc9fbd1b..bbf8da6ae 100644
--- a/documentation/CMakeLists.txt
+++ b/documentation/CMakeLists.txt
@@ -103,6 +103,7 @@ if(FLTK_BUILD_HTML_DOCS)
 
   set(GENERATE_HTML  YES)
   set(GENERATE_LATEX NO)
+  set(EXTRA_SECTIONS "HTML_SECTIONS")
   set(LATEX_HEADER   "")
   set(DOXYFILE       "Doxyfile")
   set(LOGFILE        "${CMAKE_CURRENT_BINARY_DIR}/${DOXYFILE}_error.log")
@@ -152,6 +153,7 @@ if(FLTK_BUILD_PDF_DOCS)
 
   set(GENERATE_HTML  NO)
   set(GENERATE_LATEX YES)
+  set(EXTRA_SECTIONS "LATEX_SECTIONS")
   set(LATEX_HEADER   "${CMAKE_CURRENT_BINARY_DIR}/fltk-book.tex")
   set(DOXYFILE       "Doxybook")
   set(LOGFILE        "${CMAKE_CURRENT_BINARY_DIR}/${DOXYFILE}_error.log")
@@ -202,6 +204,7 @@ if(FLTK_BUILD_PDF_DOCS)
 
   add_custom_command(
     OUTPUT  ${CMAKE_CURRENT_BINARY_DIR}/fltk.pdf
+    COMMAND code_snapshot ${CMAKE_CURRENT_SOURCE_DIR}/src/unicode.dox
     COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/make_header
             ${DOXYGEN_EXECUTABLE}
             ${CMAKE_CURRENT_BINARY_DIR}/fltk-title.tex
@@ -220,6 +223,7 @@ if(FLTK_BUILD_PDF_DOCS)
   add_custom_target(pdf
     DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/fltk.pdf
   )
+  add_dependencies(pdf code_snapshot)
 
 endif(FLTK_BUILD_PDF_DOCS)
 
diff --git a/documentation/Doxyfile.in b/documentation/Doxyfile.in
index d1dec82db..10c277a72 100644
--- a/documentation/Doxyfile.in
+++ b/documentation/Doxyfile.in
@@ -229,7 +229,8 @@ TAB_SIZE               = 8
 # newlines (in the resulting output). You can put ^^ in the value part of an
 # alias to insert a newline as if a physical newline was in the original file.
 
-ALIASES                =
+ALIASES                = code_international{1}="@if LATEX_SECTIONS^^@image latex \1 width=\\linewidth^^@endif^^@if HTML_SECTIONS^^@code"
+ALIASES               += endcode_international="@endcode^^@endif"
 
 # This tag can be used to specify a number of word-keyword mappings (TCL only).
 # A mapping has the form "name=value". For example adding "class=itcl::class"
@@ -639,7 +640,7 @@ GENERATE_DEPRECATEDLIST= YES
 # sections, marked by \if <section_label> ... \endif and \cond <section_label>
 # ... \endcond blocks.
 
-ENABLED_SECTIONS       = @DRIVER_DOCS@
+ENABLED_SECTIONS       = @DRIVER_DOCS@ @EXTRA_SECTIONS@
 
 # The MAX_INITIALIZER_LINES tag determines the maximum number of lines that the
 # initial value of a variable or macro / define can have for it to appear in the
@@ -920,7 +921,8 @@ EXAMPLE_RECURSIVE      = NO
 # that contain images that are to be included in the documentation (see the
 # \image command).
 
-IMAGE_PATH             = @CMAKE_CURRENT_SOURCE_DIR@/src
+IMAGE_PATH             = @CMAKE_CURRENT_SOURCE_DIR@/src \
+                         @CMAKE_CURRENT_BINARY_DIR@/generated
 
 # The INPUT_FILTER tag can be used to specify a program that doxygen should
 # invoke to filter for each input file. Doxygen will invoke the filter program
diff --git a/documentation/src/unicode.dox b/documentation/src/unicode.dox
index b2eb7b872..b640e170e 100644
--- a/documentation/src/unicode.dox
+++ b/documentation/src/unicode.dox
@@ -20,6 +20,16 @@ are not yet implemented.
 
 \section unicode_quick_start Quick Start
 
+International code test for HTML and PDF:
+
+\code_international{"generated/unicode_about.png"}
+// This is a test
+// 日本語テストテキスト
+// 中文测试文本
+// Ελληνικό κείμενο δοκιμής
+\endcode_international
+
+
 For most applications, you simply need to ensure your text is UTF-8 encoded:
 
 \code
-- 
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