Add Fl::keyboard_screen_scaling(int) to control recognition of ctrl/+/-/0/

5 files changed, 14 insertions, 3 deletions

diff --git a/CHANGES.txt b/CHANGES.txt
index 75592e7be..83d6e33b1 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -18,6 +18,8 @@ Changes in FLTK 1.4.0					Released: ??? ?? 2019
   New Features and Extensions
 
   - (add new items here)
+  - New Fl::keyboard_screen_scaling(0) call stops recognition of ctrl/+/-/0/
+    keystrokes as scaling all windows of a screen.
   - New "Preview" switch added to the GTK native file chooser dialog
     available on the X11 platform. This requires function fl_register_images()
     to have been called.
diff --git a/FL/Fl.H b/FL/Fl.H
index e35083226..04f9b0db7 100644
--- a/FL/Fl.H
+++ b/FL/Fl.H
@@ -1037,6 +1037,7 @@ int main() {
   static float screen_scale(int n); // via screen driver
   static void screen_scale(int n, float factor); // via screen driver
   static int screen_scaling_supported();
+  static void keyboard_screen_scaling(int);
 
 /**   @} */
 
diff --git a/src/Fl.cxx b/src/Fl.cxx
index 2652ad9ff..6f2660611 100644
--- a/src/Fl.cxx
+++ b/src/Fl.cxx
@@ -2154,6 +2154,14 @@ int Fl::screen_scaling_supported() {
   return Fl::screen_driver()->rescalable();
 }
 
+/** Controls the possibilty to scale all windows by ctrl/+/-/0/ or cmd/+/-/0/.
+ This function must be called before fl_open_display() runs to be effective.
+ \param value 0 to stop recognition of ctrl/+/-/0/ (or cmd/+/-/0/ under macOS) keys as window scaling.
+ */
+void Fl::keyboard_screen_scaling(int value) {
+  Fl::screen_driver()->keyboard_screen_scaling = value;
+}
+
 // Pointers you can use to change FLTK to another language.
 // Note: Similar pointers are defined in FL/fl_ask.H and src/fl_ask.cxx
 FL_EXPORT const char* fl_local_shift = Fl::system_driver()->shift_name();
diff --git a/src/Fl_Screen_Driver.H b/src/Fl_Screen_Driver.H
index 05924812c..0b693f95b 100644
--- a/src/Fl_Screen_Driver.H
+++ b/src/Fl_Screen_Driver.H
@@ -66,11 +66,11 @@ protected:
                                       int x2, int y2, int w2, int h2);
 
 public:
+  bool keyboard_screen_scaling; // true means ctrl/+/-/0/ resize windows
   static char bg_set;
   static char bg2_set;
   static char fg_set;
 
-public:
   virtual float scale(int n) {return 1;}
   virtual void scale(int n, float f) { }
   static Fl_Screen_Driver *newScreenDriver();
diff --git a/src/Fl_Screen_Driver.cxx b/src/Fl_Screen_Driver.cxx
index c18cd40d3..eb4dce212 100644
--- a/src/Fl_Screen_Driver.cxx
+++ b/src/Fl_Screen_Driver.cxx
@@ -39,7 +39,7 @@ char Fl_Screen_Driver::fg_set = 0;
 
 
 Fl_Screen_Driver::Fl_Screen_Driver() :
-num_screens(-1), text_editor_extra_key_bindings(NULL)
+num_screens(-1), text_editor_extra_key_bindings(NULL), keyboard_screen_scaling(true)
 {
 }
 
@@ -471,7 +471,7 @@ void Fl_Screen_Driver::open_display()
     been_here = true;
     if (rescalable()) {
       use_startup_scale_factor();
-      Fl::add_handler(Fl_Screen_Driver::scale_handler);
+      if (keyboard_screen_scaling) Fl::add_handler(Fl_Screen_Driver::scale_handler);
       int mx, my;
       int ns = Fl::screen_driver()->get_mouse(mx, my);
       Fl_Graphics_Driver::default_driver().scale(scale(ns));