UI Code Quality: Use derived struct for number buttons

For the man rationale behind this design, see 49f088e2d093. Further,
this removes users of uiBut.a1/uiBut.a2, which is a very ugly design
choice (hard to reason about).

Note that I had to do rather ugly, specific exceptions for the number
buttons in `ui_def_but_rna()`. But once all users of a1/a2 are removed,
this special handling shouldn't be needed anymore.
I also had to move a sanity check out of the button definition. It's now
moved into a new debug only sanity checking function executed when
finishing the layout definition (block end).

1 files changed, 18 insertions, 8 deletions

diff --git a/source/blender/editors/interface/interface_handlers.c b/source/blender/editors/interface/interface_handlers.c
index 83cbdeff0d8..a4042ab8265 100644
--- a/source/blender/editors/interface/interface_handlers.c
+++ b/source/blender/editors/interface/interface_handlers.c
@@ -3896,12 +3896,14 @@ static void ui_numedit_begin(uiBut *but, uiHandleButtonData *data)
     softrange = softmax - softmin;
 
     if ((but->type == UI_BTYPE_NUM) && (ui_but_is_cursor_warp(but) == false)) {
+      uiButNumber *number_but = (uiButNumber *)but;
       /* Use a minimum so we have a predictable range,
        * otherwise some float buttons get a large range. */
       const float value_step_float_min = 0.1f;
       const bool is_float = ui_but_is_float(but);
-      const double value_step = is_float ? (double)(but->a1 * UI_PRECISION_FLOAT_SCALE) :
-                                           (int)but->a1;
+      const double value_step = is_float ?
+                                    (double)(number_but->step_size * UI_PRECISION_FLOAT_SCALE) :
+                                    (int)number_but->step_size;
       const float drag_map_softrange_max = UI_DRAG_MAP_SOFT_RANGE_PIXEL_MAX * UI_DPI_FAC;
       const float softrange_max = min_ff(
           softrange,
@@ -4699,13 +4701,14 @@ static float ui_numedit_apply_snap(int temp,
   return temp;
 }
 
-static bool ui_numedit_but_NUM(uiBut *but,
+static bool ui_numedit_but_NUM(uiButNumber *number_but,
                                uiHandleButtonData *data,
                                int mx,
                                const bool is_motion,
                                const enum eSnapType snap,
                                float fac)
 {
+  uiBut *but = &number_but->but;
   float deler, tempf;
   int lvalue, temp;
   bool changed = false;
@@ -4724,7 +4727,7 @@ static bool ui_numedit_but_NUM(uiBut *but,
     /* Mouse location isn't screen clamped to the screen so use a linear mapping
      * 2px == 1-int, or 1px == 1-ClickStep */
     if (is_float) {
-      fac *= 0.01f * but->a1;
+      fac *= 0.01f * number_but->step_size;
       tempf = (float)data->startvalue + ((float)(mx - data->dragstartx) * fac);
       tempf = ui_numedit_apply_snapf(but, tempf, softmin, softmax, snap);
 
@@ -4927,6 +4930,7 @@ static void ui_numedit_set_active(uiBut *but)
 static int ui_do_but_NUM(
     bContext *C, uiBlock *block, uiBut *but, uiHandleButtonData *data, const wmEvent *event)
 {
+  uiButNumber *number_but = (uiButNumber *)but;
   int click = 0;
   int retval = WM_UI_HANDLER_CONTINUE;
 
@@ -4936,6 +4940,8 @@ static int ui_do_but_NUM(
   /* mouse location kept at screen pixel coords */
   const int screen_mx = event->x;
 
+  BLI_assert(but->type == UI_BTYPE_NUM);
+
   ui_window_to_block(data->region, block, &mx, &my);
   ui_numedit_set_active(but);
 
@@ -5028,8 +5034,12 @@ static int ui_do_but_NUM(
         fac /= 10.0f;
       }
 
-      if (ui_numedit_but_NUM(
-              but, data, (ui_but_is_cursor_warp(but) ? screen_mx : mx), is_motion, snap, fac)) {
+      if (ui_numedit_but_NUM(number_but,
+                             data,
+                             (ui_but_is_cursor_warp(but) ? screen_mx : mx),
+                             is_motion,
+                             snap,
+                             fac)) {
         ui_numedit_apply(C, block, but, data);
       }
 #ifdef USE_DRAG_MULTINUM
@@ -5060,7 +5070,7 @@ static int ui_do_but_NUM(
       if (but->drawflag & (UI_BUT_ACTIVE_LEFT | UI_BUT_ACTIVE_RIGHT)) {
         button_activate_state(C, but, BUTTON_STATE_NUM_EDITING);
 
-        const int value_step = (int)but->a1;
+        const int value_step = (int)number_but->step_size;
         BLI_assert(value_step > 0);
         const int softmin = round_fl_to_int_clamp(but->softmin);
         const int softmax = round_fl_to_int_clamp(but->softmax);
@@ -5084,7 +5094,7 @@ static int ui_do_but_NUM(
       if (but->drawflag & (UI_BUT_ACTIVE_LEFT | UI_BUT_ACTIVE_RIGHT)) {
         button_activate_state(C, but, BUTTON_STATE_NUM_EDITING);
 
-        const double value_step = (double)but->a1 * UI_PRECISION_FLOAT_SCALE;
+        const double value_step = (double)number_but->step_size * UI_PRECISION_FLOAT_SCALE;
         BLI_assert(value_step > 0.0f);
         const double value_test = (but->drawflag & UI_BUT_ACTIVE_LEFT) ?
                                       (double)max_ff(but->softmin,