Added degrees/radians conversions to math.h (same as what we'll have on master later). agx (v4) now uses fractional numbers internally, only the UI has percentages. Reformatted with 'if()', 'for()'. Temporarily backported some changes from deg2rad for consistency.

Author: kofa73

src/common/math.h

@@ -1,6 +1,6 @@
 /*
  *    This file is part of darktable,
- *    Copyright (C) 2018-2024 darktable developers.
+ *    Copyright (C) 2018-2025 darktable developers.
  *
  *    darktable is free software: you can redistribute it and/or modify
  *    it under the terms of the GNU General Public License as published by
@@ -749,9 +749,32 @@ static inline void dt_vector_sin(const dt_aligned_pixel_t arg,
     sine[c] = scaled[c] * (p[c] * (abs_scaled[c] - one[c]) + one[c]);
 }
 
-inline float deg2rad(const float degrees)
+// allows evaluating conversions involving constants at compile, e.g.:
+// const double right_angle = 90 * degrees;
+static const double degrees = M_PI / 180;
+
+// conversion factor, e.g.
+// dt_bauhaus_slider_set_factor(slider, RAD_2_DEG);
+static const double RAD_2_DEG = 180 / M_PI;
+
+static inline float deg2radf(const float deg)
+{
+  return deg * M_PI_F / 180.f;
+}
+
+static inline float rad2degf(const float radians)
+{
+  return radians / M_PI_F * 180.f;
+}
+
+static inline double deg2rad(const double deg)
+{
+  return deg * M_PI / 180.0;
+}
+
+static inline double rad2deg(const double radians)
 {
-  return degrees * M_PI_F / 180.f;
+  return radians / M_PI * 180.0;
 }
 
 // clang-format off

src/dtgtk/paint.c

@@ -21,10 +21,6 @@
 #include "gui/draw.h"
 #include <math.h>
 
-#ifndef M_PI
-#define M_PI 3.141592654
-#endif
-
 #define PREAMBLE(scaling, line_scaling, x_offset, y_offset) {  \
                   cairo_save(cr);                                                            \
                   cairo_set_line_cap(cr, CAIRO_LINE_CAP_ROUND);                              \
@@ -41,8 +37,6 @@
 
 static void _rounded_rectangle(cairo_t *cr)  // create rounded rectangle to use in other icons
 {
-  const double degrees = M_PI / 180.0;
-
   cairo_new_sub_path (cr);
   cairo_arc (cr, 0.9, 0.1, 0.1, -90 * degrees, 0 * degrees);
   cairo_arc (cr, 0.9, 0.9, 0.1, 0 * degrees, 90 * degrees);
@@ -1097,8 +1091,6 @@ void dtgtk_cairo_paint_focus_peaking(cairo_t *cr, gint x, gint y, gint w, gint h
   const double top = center - offset_h;
   const double bottom = center + offset_h;
 
-  const double degrees = M_PI / 180.0;
-
   /// north west
   cairo_move_to(cr, left, top + tick_length);
   cairo_arc (cr, left + radius, top + radius, radius, 180 * degrees, 270 * degrees);
@@ -1367,7 +1359,6 @@ void dtgtk_cairo_paint_color_harmony(cairo_t *cr, gint x, gint y, gint w, gint h
 {
   PREAMBLE(1, 1, 0.5, 0.5)
 
-  const double degrees = M_PI / 180.0;
   typedef struct
   {
     const char *name;
@@ -1460,8 +1451,6 @@ void dtgtk_cairo_paint_directory(cairo_t *cr, gint x, gint y, gint w, gint h, gi
 {
   PREAMBLE(1, 1, 0, 0);
 
-  const double degrees = M_PI / 180.0;
-
   cairo_new_sub_path (cr);
   cairo_arc (cr, 0.85, 0.35, 0.1, -90 * degrees, 0 * degrees);
   cairo_arc (cr, 0.8, 0.75, 0.1, 0 * degrees, 90 * degrees);

src/gui/gtk.c

@@ -4230,7 +4230,6 @@ void dt_gui_draw_rounded_rectangle(cairo_t *cr,
                                    const float y)
 {
   const float radius = height / 5.0f;
-  const float degrees = M_PI / 180.0;
   cairo_new_sub_path(cr);
   cairo_arc(cr, x + width - radius, y + radius, radius, -90 * degrees, 0 * degrees);
   cairo_arc(cr, x + width - radius, y + height - radius, radius, 0 * degrees, 90 * degrees);