Add fl_remove_scale()/fl_restore_scale() to transiently draw without scaling factor.

This new API is a response to this message in fltk.general :
Can custom box type functions handle their own high-DPI screen scaling?

1 files changed, 19 insertions, 0 deletions

diff --git a/src/Fl_Graphics_Driver.cxx b/src/Fl_Graphics_Driver.cxx
index 2f687e151..00eaf5a15 100644
--- a/src/Fl_Graphics_Driver.cxx
+++ b/src/Fl_Graphics_Driver.cxx
@@ -626,6 +626,9 @@ void Fl_Graphics_Driver::overlay_rect(int x, int y, int w , int h) {
   loop(x, y, x+w-1, y, x+w-1, y+h-1, x, y+h-1);
 }
 
+float Fl_Graphics_Driver::remove_scale() { return 1.f;}
+
+void Fl_Graphics_Driver::restore_scale(float) { }
 
 /**
  \}
@@ -976,4 +979,20 @@ void Fl_Scalable_Graphics_Driver::draw_image_mono_unscaled(Fl_Draw_Image_Cb cb,
 
 void Fl_Scalable_Graphics_Driver::transformed_vertex0(float x, float y) {}
 
+float Fl_Scalable_Graphics_Driver::remove_scale() {
+  float s = scale();
+  if (s != 1.f) {
+    push_no_clip();
+    scale(1.f);
+  }
+  return s;
+}
+
+void Fl_Scalable_Graphics_Driver::restore_scale(float s) {
+  if (s != 1.f) {
+    scale(s);
+    pop_clip();
+  }
+}
+
 #endif