doc: update doxygen configuration

doc/CMakeLists.txt

@@ -157,9 +157,27 @@ if(DOXYGEN_FOUND)
   list(APPEND CMAKE_DOXYGEN_HTML_FILES "${CMAKE_CURRENT_SOURCE_DIR}/tutorial-utils.js")
   string(REPLACE ";" " \\\n" CMAKE_DOXYGEN_HTML_FILES "${CMAKE_DOXYGEN_HTML_FILES}")
 
+  set(OPENCV_DOCS_DOT_PATH "" CACHE PATH "Doxygen/DOT_PATH value")
+  set(CMAKECONFIG_DOT_PATH "${OPENCV_DOCS_DOT_PATH}")
+
+  set(OPENCV_DOCS_HAVE_DOT "NO" CACHE BOOL "Doxygen: build extra diagrams")
+  set(CMAKECONFIG_HAVE_DOT "${OPENCV_DOCS_HAVE_DOT}")
+
+  # 'png' is good enough for compatibility (but requires +50% storage space)
+  set(OPENCV_DOCS_DOT_IMAGE_FORMAT "svg" CACHE STRING "Doxygen/DOT_IMAGE_FORMAT value")
+  set(CMAKECONFIG_DOT_IMAGE_FORMAT "${OPENCV_DOCS_DOT_IMAGE_FORMAT}")
+
+  # Doxygen 1.8.16 fix: https://github.com/doxygen/doxygen/pull/6870
+  # NO is needed here: https://github.com/opencv/opencv/pull/16039
+  set(OPENCV_DOCS_INTERACTIVE_SVG "NO" CACHE BOOL "Doxygen/INTERACTIVE_SVG value")
+  set(CMAKECONFIG_INTERACTIVE_SVG "${OPENCV_DOCS_INTERACTIVE_SVG}")
+
+  set(OPENCV_DOCS_DOXYFILE_IN "Doxyfile.in" CACHE PATH "Doxygen configuration template file (Doxyfile.in)")
+  set(OPENCV_DOCS_DOXYGEN_LAYOUT "DoxygenLayout.xml" CACHE PATH "Doxygen layout file (.xml)")
+
   # writing file
-  configure_file(DoxygenLayout.xml DoxygenLayout.xml @ONLY)
-  configure_file(Doxyfile.in ${doxyfile} @ONLY)
+  configure_file("${OPENCV_DOCS_DOXYGEN_LAYOUT}" DoxygenLayout.xml @ONLY)
+  configure_file("${OPENCV_DOCS_DOXYFILE_IN}" ${doxyfile} @ONLY)
   configure_file(root.markdown.in ${rootfile} @ONLY)
 
   # js tutorial assets

doc/Doxyfile.in

@@ -264,7 +264,7 @@ EXTERNAL_PAGES         = YES
 CLASS_DIAGRAMS         = YES
 DIA_PATH               =
 HIDE_UNDOC_RELATIONS   = NO
-HAVE_DOT               = NO
+HAVE_DOT               = @CMAKECONFIG_HAVE_DOT@
 DOT_NUM_THREADS        = 0
 DOT_FONTNAME           = Helvetica
 DOT_FONTSIZE           = 10
@@ -281,9 +281,9 @@ CALL_GRAPH             = YES
 CALLER_GRAPH           = NO
 GRAPHICAL_HIERARCHY    = YES
 DIRECTORY_GRAPH        = YES
-DOT_IMAGE_FORMAT       = svg
-INTERACTIVE_SVG        = YES
-DOT_PATH               =
+DOT_IMAGE_FORMAT       = @CMAKECONFIG_DOT_IMAGE_FORMAT@
+INTERACTIVE_SVG        = @CMAKECONFIG_INTERACTIVE_SVG@
+DOT_PATH               = @CMAKECONFIG_DOT_PATH@
 DOTFILE_DIRS           =
 MSCFILE_DIRS           =
 DIAFILE_DIRS           =