Add CMake option FLTK_OPTION_PEN_SUPPORT (default: ON)

This option can be used to disable pen/tablet support if there are
build problems on a particular platform or build system (e.g. MinGW)
so users can continue to build FLTK 1.5.

Users can also choose to disable pen support if they don't need it.

CMake/options.cmake

@@ -468,6 +468,7 @@ option(FLTK_BUILD_SHARED_LIBS
 
 option(FLTK_OPTION_PRINT_SUPPORT      "allow print support"          ON)
 option(FLTK_OPTION_FILESYSTEM_SUPPORT "allow file system support"    ON)
+option(FLTK_OPTION_PEN_SUPPORT        "include Pen/Tablet support"   ON)
 
 option(FLTK_BUILD_FORMS        "Build forms compatibility library"   OFF)
 option(FLTK_BUILD_FLUID        "Build FLUID"                         ON)
@@ -481,12 +482,21 @@ else()
   option(FLTK_BUILD_TEST       "Build test/demo programs"            OFF)
 endif()
 
+
+# set variables to generate config.h or fl_config.h
+
 if(FLTK_BUILD_FORMS)
   set(FLTK_HAVE_FORMS 1)
 else()
   set(FLTK_HAVE_FORMS 0)
 endif()
 
+if(FLTK_OPTION_PEN_SUPPORT)
+  set(FLTK_HAVE_PEN_SUPPORT 1)
+else()
+  set(FLTK_HAVE_PEN_SUPPORT 0)
+endif()
+
 #######################################################################
 if(DOXYGEN_FOUND)
   option(FLTK_BUILD_HTML_DOCS "build html docs" ON)

CMakeLists.txt

@@ -397,9 +397,12 @@ fl_summary_build("Static libraries"    lib    TRUE                      "n/a")
 fl_summary_build("Shared libraries"    lib    FLTK_BUILD_SHARED_LIBS    FLTK_BUILD_SHARED_LIBS)
 fl_summary_build("The forms library"   lib    FLTK_BUILD_FORMS          FLTK_BUILD_FORMS)
 fl_summary_build("The OpenGL library"  lib    FLTK_USE_GL               FLTK_BUILD_GL)
+fl_summary_build("Pen/tablet support"  lib    FLTK_OPTION_PEN_SUPPORT   FLTK_OPTION_PEN_SUPPORT)
+
+message(STATUS "")
+
 fl_summary_build("fluid"               bin    FLTK_BUILD_FLUID          FLTK_BUILD_FLUID)
 fl_summary_build("fltk-options"        bin    FLTK_BUILD_FLTK_OPTIONS   FLTK_BUILD_FLTK_OPTIONS)
-
 fl_summary_build("Test programs"       bin/test        FLTK_BUILD_TEST        FLTK_BUILD_TEST)
 fl_summary_build("Example programs"    bin/examples    FLTK_BUILD_EXAMPLES    FLTK_BUILD_EXAMPLES)
 fl_summary_build("Screenshot programs" bin/screenshots FLTK_BUILD_SCREENSHOTS FLTK_BUILD_SCREENSHOTS)

README.CMake.txt

@@ -285,6 +285,16 @@ FLTK_OPTION_OPTIM - default EMPTY
     "-Wall -Wno-deprecated-declarations". Example:
     cmake -D FLTK_BUILD_EXAMPLES=on -D FLTK_OPTION_OPTIM="-Wall -Wextra -pedantic" ..
 
+FLTK_OPTION_PEN_SUPPORT - default ON
+    Pen support is relatively small and should be included by default, but
+    this option allows to switch it off if not needed.
+    Note: on some older systems or build platforms (notably "classic" MinGW)
+    compiling and building pen support may not be possible. As of this writing
+    (Jan. 2026) we don't use dynamic (CMake) tests to find out whether building
+    is possible or not. Instead users are encouraged to report build errors and
+    switch this option off to allow to proceed building FLTK 1.5.0.
+    Note: this option is WIP and may be removed later w/o further notice.
+
 FLTK_OPTION_PRINT_SUPPORT - default ON
     When turned off, the Fl_Printer class does nothing and the
     Fl_PostScript_File_Device class cannot be used, but the FLTK library

config.h.in

@@ -356,3 +356,17 @@
  */
 
 #cmakedefine01 HAVE_CURSOR_SHAPE
+
+
+/*
+ * FLTK_HAVE_PEN_SUPPORT
+ *
+ * Do we have pen/tablet support for the current platform?
+ * See CMake option FLTK_OPTION_PEN_SUPPORT
+ *
+ * Note: this option is "hidden" in 'config.h', i.e. it's not (yet)
+ * publicly accessibe. Move this to 'fl_config.h' to make it public.
+ *
+ */
+
+#cmakedefine FLTK_HAVE_PEN_SUPPORT 1

src/CMakeLists.txt

@@ -241,7 +241,6 @@ if(FLTK_USE_X11 AND NOT FLTK_USE_WAYLAND)
     drivers/Xlib/Fl_Xlib_Copy_Surface_Driver.cxx
     drivers/Xlib/Fl_Xlib_Image_Surface_Driver.cxx
     drivers/X11/fl_X11_platform_init.cxx
-    drivers/Base/Fl_Base_Pen_Events.cxx
     Fl_x.cxx
     fl_dnd_x.cxx
     Fl_Native_File_Chooser_FLTK.cxx
@@ -249,9 +248,9 @@ if(FLTK_USE_X11 AND NOT FLTK_USE_WAYLAND)
     Fl_get_key.cxx
   )
 
-    list(APPEND DRIVER_FILES
+  list(APPEND DRIVER_FILES
-      Fl_Native_File_Chooser_Kdialog.cxx
+    Fl_Native_File_Chooser_Kdialog.cxx
-      Fl_Native_File_Chooser_Zenity.cxx)
+    Fl_Native_File_Chooser_Zenity.cxx)
 
   if(FLTK_USE_CAIRO)
     list(APPEND DRIVER_FILES
@@ -291,7 +290,6 @@ if(FLTK_USE_X11 AND NOT FLTK_USE_WAYLAND)
     drivers/Xlib/Fl_Xlib_Copy_Surface_Driver.H
     drivers/Xlib/Fl_Xlib_Image_Surface_Driver.H
     drivers/Unix/Fl_Unix_System_Driver.H
-    drivers/Base/Fl_Base_Pen_Events.H
  )
  if(FLTK_USE_CAIRO)
    set(DRIVER_HEADER_FILES ${DRIVER_HEADER_FILES}
@@ -319,7 +317,6 @@ elseif(FLTK_USE_WAYLAND)
     drivers/Wayland/fl_wayland_clipboard_dnd.cxx
     drivers/Wayland/fl_wayland_platform_init.cxx
     drivers/Cairo/Fl_Cairo_Graphics_Driver.cxx
-    drivers/Base/Fl_Base_Pen_Events.cxx
     Fl_Native_File_Chooser_FLTK.cxx
     Fl_Native_File_Chooser_GTK.cxx
   )
@@ -351,7 +348,6 @@ elseif(FLTK_USE_WAYLAND)
     drivers/Wayland/Fl_Wayland_Copy_Surface_Driver.H
     drivers/Wayland/Fl_Wayland_Image_Surface_Driver.H
     drivers/Unix/Fl_Unix_System_Driver.H
-    drivers/Base/Fl_Base_Pen_Events.H
   )
 
 elseif(APPLE)
@@ -373,7 +369,6 @@ elseif(APPLE)
     drivers/Cocoa/Fl_Cocoa_Screen_Driver.cxx
     drivers/Posix/Fl_Posix_System_Driver.cxx
     drivers/Darwin/Fl_Darwin_System_Driver.cxx
-    drivers/Base/Fl_Base_Pen_Events.cxx
     Fl_get_key_mac.cxx
     drivers/Darwin/fl_macOS_platform_init.cxx
   )
@@ -387,7 +382,6 @@ elseif(APPLE)
     drivers/Quartz/Fl_Quartz_Copy_Surface_Driver.H
     drivers/Quartz/Fl_Font.H
     drivers/Quartz/Fl_Quartz_Image_Surface_Driver.H
-    drivers/Base/Fl_Base_Pen_Events.H
   )
 
 else()
@@ -399,7 +393,6 @@ else()
     drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
     drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx
     drivers/WinAPI/Fl_WinAPI_Printer_Driver.cxx
-    drivers/WinAPI/Fl_WinAPI_Pen_Driver.cxx
     drivers/GDI/Fl_GDI_Graphics_Driver.cxx
     drivers/GDI/Fl_GDI_Graphics_Driver_arci.cxx
     drivers/GDI/Fl_GDI_Graphics_Driver_color.cxx
@@ -410,7 +403,6 @@ else()
     drivers/GDI/Fl_GDI_Graphics_Driver_vertex.cxx
     drivers/GDI/Fl_GDI_Copy_Surface_Driver.cxx
     drivers/GDI/Fl_GDI_Image_Surface_Driver.cxx
-    drivers/Base/Fl_Base_Pen_Events.cxx
     Fl_win32.cxx
     fl_dnd_win32.cxx
     Fl_Native_File_Chooser_WIN32.cxx
@@ -425,11 +417,29 @@ else()
     drivers/GDI/Fl_Font.H
     drivers/GDI/Fl_GDI_Copy_Surface_Driver.H
     drivers/GDI/Fl_GDI_Image_Surface_Driver.H
-    drivers/Base/Fl_Base_Pen_Events.H
   )
 
+  # Optional Pen/Tablet Support
+
+  if(FLTK_OPTION_PEN_SUPPORT)
+    list(APPEND DRIVER_FILES
+      drivers/WinAPI/Fl_WinAPI_Pen_Driver.cxx
+    )
+  endif(FLTK_OPTION_PEN_SUPPORT)
+
 endif(FLTK_USE_X11 AND NOT FLTK_USE_WAYLAND)
 
+# Common Pen/Tablet Support Files
+
+if(FLTK_OPTION_PEN_SUPPORT)
+  list(APPEND DRIVER_FILES
+    drivers/Base/Fl_Base_Pen_Events.cxx
+  )
+  list(APPEND DRIVER_HEADER_FILES
+    drivers/Base/Fl_Base_Pen_Events.H
+  )
+endif(FLTK_OPTION_PEN_SUPPORT)
+
 source_group("Header Files" FILES ${HEADER_FILES})
 source_group("Private Header Files" FILES ${PRIVATE_HEADER_FILES})
 source_group("Driver Source Files" FILES ${DRIVER_FILES})
@@ -632,10 +642,14 @@ if(APPLE AND NOT FLTK_BACKEND_X11)
   set(MMFILES
     Fl_cocoa.mm
     drivers/Cocoa/Fl_Cocoa_Printer_Driver.mm
-    drivers/Cocoa/Fl_Cocoa_Pen_Events.mm
     Fl_Native_File_Chooser_MAC.mm
     Fl_MacOS_Sys_Menu_Bar.mm
   )
+  if(FLTK_OPTION_PEN_SUPPORT)
+    list(APPEND MMFILES
+      drivers/Cocoa/Fl_Cocoa_Pen_Events.mm
+    )
+  endif()
   source_group("ObjC Source Files" FILES ${MMFILES})
 else()
   set(MMFILES)

src/Fl_cocoa.mm

@@ -72,7 +72,7 @@ extern int fl_send_system_handlers(void *e);
 // converting cr lf converter function
 static void createAppleMenu(void);
 static void cocoaMouseHandler(NSEvent *theEvent);
-#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_9
+#if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_9) && defined(FLTK_HAVE_PEN_SUPPORT)
 static bool cocoaTabletHandler(NSEvent *theEvent, bool lock);
 extern bool fl_cocoa_tablet_handler(NSEvent*, Fl_Window*);
 #endif
@@ -631,7 +631,7 @@ void Fl_Cocoa_Screen_Driver::breakMacEventLoop()
            endedAtPoint:(NSPoint)screenPoint operation:(NSDragOperation)operation;
 #endif
 - (BOOL)did_view_resolution_change;
-#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_9
+#if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_9) && defined(FLTK_HAVE_PEN_SUPPORT)
 - (void)tabletProximity:(NSEvent *)theEvent;
 - (void)tabletPoint:(NSEvent *)theEvent;
 #endif
@@ -1057,6 +1057,7 @@ static void cocoaMagnifyHandler(NSEvent *theEvent)
 #endif
 }
 
+#if defined(FLTK_HAVE_PEN_SUPPORT)
 
 static bool cocoaTabletHandler(NSEvent *theEvent, bool lock)
 {
@@ -1067,6 +1068,8 @@ static bool cocoaTabletHandler(NSEvent *theEvent, bool lock)
   return ret;
 }
 
+#endif // FLTK_HAVE_PEN_SUPPORT
+
 namespace Fl {
 namespace Private {
 // Global mouse position at mouse down event
@@ -1084,6 +1087,7 @@ static void cocoaMouseHandler(NSEvent *theEvent)
 
   fl_lock_function();
 
+#if defined(FLTK_HAVE_PEN_SUPPORT)
   // Handle tablet proximity and point subevents
   if (   ([theEvent type] != NSEventTypeMouseEntered)  // does not have a subtype
       && ([theEvent type] != NSEventTypeMouseExited) ) // does not have a subtype
@@ -1098,6 +1102,7 @@ static void cocoaMouseHandler(NSEvent *theEvent)
       // else fall through into mouse event handling
     }
   }
+#endif // FLTK_HAVE_PEN_SUPPORT
 
   Fl_Window *window = (Fl_Window*)[(FLWindow*)[theEvent window] getFl_Window];
   if (!window || !window->shown() ) {
@@ -2635,7 +2640,7 @@ static FLTextInputContext* fltextinputcontext_instance = nil;
 - (void)mouseExited:(NSEvent *)theEvent {
   cocoaMouseHandler(theEvent);
 }
-#if MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_9
+#if (MAC_OS_X_VERSION_MAX_ALLOWED >= MAC_OS_X_VERSION_10_9) && defined(FLTK_HAVE_PEN_SUPPORT)
 - (void)tabletProximity:(NSEvent *)theEvent {
   cocoaTabletHandler(theEvent, true);
 }

src/Fl_grab.cxx

@@ -14,6 +14,7 @@
 //     https://www.fltk.org/bugs.php
 //
 
+#include <config.h>
 #include <FL/Fl.H>
 #include "Fl_Screen_Driver.H"
 
@@ -27,6 +28,8 @@
 
 void Fl::grab(Fl_Window *win)
 {
+#if defined(FLTK_HAVE_PEN_SUPPORT)
   Fl::Pen::release();
+#endif
   screen_driver()->grab(win);
 }

src/Fl_win32.cxx

@@ -1837,9 +1837,11 @@ content  key    keyboard layout
         return 0;
 
       default: {
+#if defined(FLTK_HAVE_PEN_SUPPORT)
         LRESULT ret = fl_win32_tablet_handler(fl_msg);
         if (ret != -1)
           return ret;
+#endif
         if (Fl::handle(0, 0))
           return 0;
         break; }

src/drivers/Wayland/fl_wayland_platform_init.cxx

@@ -145,6 +145,8 @@ Fl_Image_Surface_Driver *Fl_Image_Surface_Driver::newImageSurfaceDriver(int w, i
   return new Fl_Wayland_Image_Surface_Driver(w, h, high_res, off);
 }
 
+#if defined(FLTK_HAVE_PEN_SUPPORT)
+
 namespace Fl {
 namespace Pen {
 Driver default_driver;
@@ -152,3 +154,4 @@ Driver& driver = default_driver;
 } // namespace Pen
 } // namespace Fl
 
+#endif // FLTK_HAVE_PEN_SUPPORT

src/drivers/X11/fl_X11_platform_init.cxx

@@ -75,9 +75,11 @@ Fl_Image_Surface_Driver *Fl_Image_Surface_Driver::newImageSurfaceDriver(int w, i
   return new Fl_Xlib_Image_Surface_Driver(w, h, high_res, off);
 }
 
+#if defined(FLTK_HAVE_PEN_SUPPORT)
 namespace Fl {
 namespace Pen {
 Driver default_driver;
 Driver& driver = default_driver;
 } // namespace Pen
 } // namespace Fl
+#endif // FLTK_HAVE_PEN_SUPPORT

test/CMakeLists.txt

@@ -183,7 +183,11 @@ fl_create_example(navigation navigation.cxx fltk::fltk)
 fl_create_example(output output.cxx fltk::fltk)
 fl_create_example(overlay overlay.cxx fltk::fltk)
 fl_create_example(pack pack.cxx fltk::fltk)
-fl_create_example(penpal penpal.cxx fltk::fltk)
+
+if(FLTK_OPTION_PEN_SUPPORT)
+  fl_create_example(penpal penpal.cxx fltk::fltk)
+endif()
+
 fl_create_example(pixmap pixmap.cxx fltk::images)
 fl_create_example(pixmap_browser pixmap_browser.cxx fltk::images)
 fl_create_example(preferences preferences.fl fltk::fltk)