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, 74 insertions, 16 deletions

diff --git a/source/blender/editors/interface/interface.c b/source/blender/editors/interface/interface.c
index d8330d62907..bbe097b5c79 100644
--- a/source/blender/editors/interface/interface.c
+++ b/source/blender/editors/interface/interface.c
@@ -622,9 +622,18 @@ void UI_block_bounds_set_explicit(uiBlock *block, int minx, int miny, int maxx,
   block->bounds_type = UI_BLOCK_BOUNDS_NONE;
 }
 
+static float ui_but_get_float_precision(uiBut *but)
+{
+  if (but->type == UI_BTYPE_NUM) {
+    return ((uiButNumber *)but)->precision;
+  }
+
+  return but->a2;
+}
+
 static int ui_but_calc_float_precision(uiBut *but, double value)
 {
-  int prec = (int)but->a2;
+  int prec = (int)ui_but_get_float_precision(but);
 
   /* first check for various special cases:
    * * If button is radians, we want additional precision (see T39861).
@@ -1737,6 +1746,24 @@ void UI_block_update_from_old(const bContext *C, uiBlock *block)
   block->oldblock = NULL;
 }
 
+#ifndef NDEBUG
+/**
+ * Extra sanity checks for invariants (debug builds only).
+ */
+static void ui_but_validate(const uiBut *but)
+{
+  /* Number buttons must have a click-step,
+   * assert instead of correcting the value to ensure the caller knows what they're doing.  */
+  if (but->type == UI_BTYPE_NUM) {
+    uiButNumber *number_but = (uiButNumber *)but;
+
+    if (ELEM(but->pointype, UI_BUT_POIN_CHAR, UI_BUT_POIN_SHORT, UI_BUT_POIN_INT)) {
+      BLI_assert((int)number_but->step_size > 0);
+    }
+  }
+}
+#endif
+
 void UI_block_end_ex(const bContext *C, uiBlock *block, const int xy[2], int r_xy[2])
 {
   wmWindow *window = CTX_wm_window(C);
@@ -1778,6 +1805,10 @@ void UI_block_end_ex(const bContext *C, uiBlock *block, const int xy[2], int r_x
       ui_but_anim_decorate_update_from_flag((uiButDecorator *)but);
     }
     ui_but_predefined_extra_operator_icons_add(but);
+
+#ifndef NDEBUG
+    ui_but_validate(but);
+#endif
   }
 
   /* handle pending stuff */
@@ -2562,7 +2593,7 @@ static void ui_get_but_string_unit(
   /* Use precision override? */
   if (float_precision == -1) {
     /* Sanity checks */
-    precision = (int)but->a2;
+    precision = (int)ui_but_get_float_precision(but);
     if (precision > UI_PRECISION_FLOAT_MAX) {
       precision = UI_PRECISION_FLOAT_MAX;
     }
@@ -3768,6 +3799,10 @@ static void ui_but_alloc_info(const eButType type,
   bool has_custom_type = true;
 
   switch (type) {
+    case UI_BTYPE_NUM:
+      alloc_size = sizeof(uiButNumber);
+      alloc_str = "uiButNumber";
+      break;
     case UI_BTYPE_COLOR:
       alloc_size = sizeof(uiButColor);
       alloc_str = "uiButColor";
@@ -3914,14 +3949,6 @@ static uiBut *ui_def_but(uiBlock *block,
                 (a1 != 0.0f && a1 != 1.0f)) == false);
   }
 
-  /* Number buttons must have a click-step,
-   * assert instead of correcting the value to ensure the caller knows what they're doing.  */
-  if ((type & BUTTYPE) == UI_BTYPE_NUM) {
-    if (ELEM((type & UI_BUT_POIN_TYPES), UI_BUT_POIN_CHAR, UI_BUT_POIN_SHORT, UI_BUT_POIN_INT)) {
-      BLI_assert((int)a1 > 0);
-    }
-  }
-
   if (type & UI_BUT_POIN_TYPES) { /* a pointer is required */
     if (poin == NULL) {
       BLI_assert(0);
@@ -4360,6 +4387,7 @@ static uiBut *ui_def_but_rna(uiBlock *block,
   uiBut *but;
   int icon = 0;
   uiMenuCreateFunc func = NULL;
+  const bool always_set_a1_a2 = ELEM(type, UI_BTYPE_NUM);
 
   if (ELEM(type, UI_BTYPE_COLOR, UI_BTYPE_HSVCIRCLE, UI_BTYPE_HSVCUBE)) {
     BLI_assert(index == -1);
@@ -4424,7 +4452,7 @@ static uiBut *ui_def_but_rna(uiBlock *block,
     tip = RNA_property_ui_description(prop);
   }
 
-  if (min == max || a1 == -1 || a2 == -1) {
+  if (min == max || a1 == -1 || a2 == -1 || always_set_a1_a2) {
     if (proptype == PROP_INT) {
       int hardmin, hardmax, softmin, softmax, step;
 
@@ -4435,10 +4463,10 @@ static uiBut *ui_def_but_rna(uiBlock *block,
         min = hardmin;
         max = hardmax;
       }
-      if (a1 == -1) {
+      if (a1 == -1 || always_set_a1_a2) {
         a1 = step;
       }
-      if (a2 == -1) {
+      if (a2 == -1 || always_set_a1_a2) {
         a2 = 0;
       }
     }
@@ -4452,10 +4480,10 @@ static uiBut *ui_def_but_rna(uiBlock *block,
         min = hardmin;
         max = hardmax;
       }
-      if (a1 == -1) {
+      if (a1 == -1 || always_set_a1_a2) {
         a1 = step;
       }
-      if (a2 == -1) {
+      if (a2 == -1 || always_set_a1_a2) {
         a2 = precision;
       }
     }
@@ -4469,6 +4497,12 @@ static uiBut *ui_def_but_rna(uiBlock *block,
   /* now create button */
   but = ui_def_but(block, type, retval, str, x, y, width, height, NULL, min, max, a1, a2, tip);
 
+  if (but->type == UI_BTYPE_NUM) {
+    /* Set default values, can be overriden later. */
+    UI_but_number_step_size_set(but, a1);
+    UI_but_number_precision_set(but, a2);
+  }
+
   but->rnapoin = *ptr;
   but->rnaprop = prop;
 
@@ -4506,7 +4540,13 @@ static uiBut *ui_def_but_rna(uiBlock *block,
 
   /* If this button uses units, calculate the step from this */
   if ((proptype == PROP_FLOAT) && ui_but_is_unit(but)) {
-    but->a1 = ui_get_but_step_unit(but, but->a1);
+    if (type == UI_BTYPE_NUM) {
+      uiButNumber *number_but = (uiButNumber *)but;
+      number_but->step_size = ui_get_but_step_unit(but, number_but->step_size);
+    }
+    else {
+      but->a1 = ui_get_but_step_unit(but, but->a1);
+    }
   }
 
   if (func) {
@@ -6707,6 +6747,24 @@ void UI_but_node_link_set(uiBut *but, bNodeSocket *socket, const float draw_colo
   rgba_float_to_uchar(but->col, draw_color);
 }
 
+void UI_but_number_step_size_set(uiBut *but, float step_size)
+{
+  uiButNumber *but_number = (uiButNumber *)but;
+  BLI_assert(but->type == UI_BTYPE_NUM);
+
+  but_number->step_size = step_size;
+  BLI_assert(step_size > 0);
+}
+
+void UI_but_number_precision_set(uiBut *but, float precision)
+{
+  uiButNumber *but_number = (uiButNumber *)but;
+  BLI_assert(but->type == UI_BTYPE_NUM);
+
+  but_number->precision = precision;
+  BLI_assert(precision > -1);
+}
+
 /**
  * push a new event onto event queue to activate the given button
  * (usually a text-field) upon entering a popup