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, 8 insertions, 2 deletions

diff --git a/source/blender/editors/interface/interface_intern.h b/source/blender/editors/interface/interface_intern.h
index e53309d43b7..4661d0816ae 100644
--- a/source/blender/editors/interface/interface_intern.h
+++ b/source/blender/editors/interface/interface_intern.h
@@ -174,7 +174,6 @@ struct uiBut {
 
   /**
    * For #uiBut.type:
-   * - UI_BTYPE_NUM:          Use to store RNA 'step' value, for dragging and click-step.
    * - UI_BTYPE_LABEL:        Use `(a1 == 1.0f)` to use a2 as a blending factor (imaginative!).
    * - UI_BTYPE_SCROLL:       Use as scroll size.
    * - UI_BTYPE_SEARCH_MENU:  Use as number or rows.
@@ -184,7 +183,6 @@ struct uiBut {
   /**
    * For #uiBut.type:
    * - UI_BTYPE_HSVCIRCLE:    Use to store the luminosity.
-   * - UI_BTYPE_NUM:          Use to store RNA 'precision' value, for dragging and click-step.
    * - UI_BTYPE_LABEL:        If `(a1 == 1.0f)` use a2 as a blending factor.
    * - UI_BTYPE_SEARCH_MENU:  Use as number or columns.
    */
@@ -276,6 +274,14 @@ struct uiBut {
   uiBlock *block;
 };
 
+/** Derived struct for #UI_BTYPE_NUM */
+typedef struct uiButNumber {
+  uiBut but;
+
+  float step_size;
+  float precision;
+} uiButNumber;
+
 /** Derived struct for #UI_BTYPE_COLOR */
 typedef struct uiButColor {
   uiBut but;