3 files changed, 16 insertions, 3 deletions
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H
index 5c016ce73..ff2688bcf 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H
+++ b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.H
@@ -78,6 +78,13 @@ public:
   virtual void disable_im();
   virtual void open_display();
   virtual void offscreen_size(Fl_Offscreen off, int &width, int &height);
+  
+  virtual APP_SCALING_CAPABILITY rescalable() { return SYSTEMWIDE_APP_SCALING; }
+  virtual float scale(int n) {return scale_;}
+  virtual void scale(int n, float f) { scale_ = f;}
+  virtual float desktop_scale_factor();
+private:
+  float scale_;
 };
 
 
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
index 219c1d1d6..e9ca9d2fb 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
+++ b/src/drivers/WinAPI/Fl_WinAPI_Screen_Driver.cxx
@@ -617,6 +617,9 @@ Fl_WinAPI_Screen_Driver::read_win_rectangle(uchar *p,		// I - Pixel buffer or NU
 /** Returns the current desktop scaling factor (1.75 for example)
  */
 float Fl_WinAPI_Screen_Driver::desktop_scaling_factor() {
+#ifdef FLTK_HIDPI_SUPPORT
+  return 1;// this becomes useless if FLTK app are made DPI-aware by calling SetProcessDpiAwareness()
+#else
   // Compute the global desktop scaling factor: 1, 1.25, 1.5, 1.75, etc...
   // This factor can be set in Windows 10 by
   // "Change the size of text, apps and other items" in display settings.
@@ -636,6 +639,7 @@ float Fl_WinAPI_Screen_Driver::desktop_scaling_factor() {
   float scaling = dhr/float(hr);
   scaling = int(scaling * 100 + 0.5)/100.; // round to 2 digits after decimal point
   return scaling;
+#endif // FLTK_HIDPI_SUPPORT
 }
 
 void Fl_WinAPI_Screen_Driver::offscreen_size(Fl_Offscreen off, int &width, int &height)
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx b/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx
index eb8e13b33..1d496edff 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx
+++ b/src/drivers/WinAPI/Fl_WinAPI_Window_Driver.cxx
@@ -261,10 +261,11 @@ static HRGN bitmap2region(Fl_Image* image) {
 void Fl_WinAPI_Window_Driver::draw_begin()
 {
   if (shape_data_) {
-    if ((shape_data_->lw_ != w() || shape_data_->lh_ != h()) && shape_data_->shape_) {
+    float s = Fl::screen_driver()->scale(screen_num());
+    if ((shape_data_->lw_ != s*w() || shape_data_->lh_ != s*h()) && shape_data_->shape_) {
       // size of window has changed since last time
-      shape_data_->lw_ = w();
-      shape_data_->lh_ = h();
+      shape_data_->lw_ = s*w();
+      shape_data_->lh_ = s*h();
       Fl_Image* temp = shape_data_->shape_->copy(shape_data_->lw_, shape_data_->lh_);
       HRGN region = bitmap2region(temp);
       SetWindowRgn(fl_xid(pWindow), region, TRUE); // the system deletes the region when it's no longer needed
@@ -385,6 +386,7 @@ void Fl_WinAPI_Window_Driver::make_current() {
 #endif // USE_COLORMAP
   
   fl_graphics_driver->clip_region(0);
+fl_graphics_driver->scale(Fl::screen_driver()->scale(0));
 }
 
 void Fl_WinAPI_Window_Driver::label(const char *name,const char *iname) {