UI: Better split layout support for checkboxes

Makes the following layout changes possible:
{F8473498} {F8473499} {F8473502}

The next commit will contain many layout changes to make good use of
these new possibilities. The result should be more consistent, easier to
read and should give a more organized impression. Additionally, it
should be possible to replace many sub-panels with compacter layouts.

Main changes:
* Checkboxes now respect the property split layouts
* Add support for row and column headers (i.e.
  `uiLayout.column(heading="Foo")`, `uiLayout.row(heading="Bar")`). If the
  first property added to this layout doesn't insert anything into the label
  split column, the heading is inserted there. Otherwise, it's inserted as own
  item.
* Add support for manually inserting decorators for an existing item
  (`uiLayout.prop_decorator()`). That way layout creators can manually insert
  this, which was the only way I saw to support property split layouts with a
  checkbox before the actual property. {F8471883}
* Autogenerated layouts for operator properties look bad if there are only
  checkboxes (which only use half the region width). So before creating the
  layout, we iterate over visible properties and disable split layout if all
  are booleans. I think this is fine, if needed we could also add layout hints
  to operators.
* `uiTemplateOperatorPropertyButs()` now handles macros itself, the caller
  used to be responsible for this. Code that didn't handle these so far never
  used macros I think, so this change should be invisible.
* Remove manual property split layout from autogenerated operator properties
  layout.
* Padding of checkboxes is tweaked to make their label visually more connected
  to the checkboxes.
* Support split layout for menus (should work for `uiLayout.menu()`,
  `.operator_menu_enum()`, `.prop_menu_enum()`, maybe more)

Maniphest Task: https://developer.blender.org/T65965

Differential Revision: https://developer.blender.org/D7427

Reviewed by: Brecht Van Lommel, William Reynish, Pablo Vazques

1 files changed, 232 insertions, 57 deletions

diff --git a/source/blender/editors/interface/interface_layout.c b/source/blender/editors/interface/interface_layout.c
index cbea32f179a..fa962b7742d 100644
--- a/source/blender/editors/interface/interface_layout.c
+++ b/source/blender/editors/interface/interface_layout.c
@@ -135,10 +135,11 @@ enum {
 
   UI_ITEM_BOX_ITEM = 1 << 2, /* The item is "inside" a box item */
   UI_ITEM_PROP_SEP = 1 << 3,
+  UI_ITEM_INSIDE_PROP_SEP = 1 << 4,
   /* Show an icon button next to each property (to set keyframes, show status).
    * Enabled by default, depends on 'UI_ITEM_PROP_SEP'. */
-  UI_ITEM_PROP_DECORATE = 1 << 4,
-  UI_ITEM_PROP_DECORATE_NO_PAD = 1 << 5,
+  UI_ITEM_PROP_DECORATE = 1 << 5,
+  UI_ITEM_PROP_DECORATE_NO_PAD = 1 << 6,
 };
 
 typedef struct uiButtonItem {
@@ -151,8 +152,11 @@ struct uiLayout {
 
   uiLayoutRoot *root;
   bContextStore *context;
+  uiLayout *parent;
   ListBase items;
 
+  char heading[UI_MAX_NAME_STR];
+
   /** Sub layout to add child items, if not the layout itself. */
   uiLayout *child_items_layout;
 
@@ -1780,6 +1784,7 @@ static void ui_item_rna_size(uiLayout *layout,
   PropertyType type;
   PropertySubType subtype;
   int len, w = 0, h;
+  bool is_checkbox_only = false;
 
   /* arbitrary extended width by type */
   type = RNA_property_type(prop);
@@ -1791,6 +1796,10 @@ static void ui_item_rna_size(uiLayout *layout,
       name = "non-empty text";
     }
     else if (type == PROP_BOOLEAN) {
+      if (icon == ICON_NONE) {
+        /* Exception for checkboxes, they need a little less space to align nicely. */
+        is_checkbox_only = true;
+      }
       icon = ICON_DOT;
     }
     else if (type == PROP_ENUM) {
@@ -1850,6 +1859,9 @@ static void ui_item_rna_size(uiLayout *layout,
     if (type == PROP_BOOLEAN && name[0]) {
       w += UI_UNIT_X / 5;
     }
+    else if (is_checkbox_only) {
+      w -= UI_UNIT_X / 4;
+    }
     else if (type == PROP_ENUM && !icon_only) {
       w += UI_UNIT_X / 4;
     }
@@ -1863,13 +1875,62 @@ static void ui_item_rna_size(uiLayout *layout,
 }
 
 /**
+ * Find first layout ancestor (or self) with a heading set.
+ *
+ * \returns the layout to add the heading to as fallback (i.e. if it can't be placed in a split
+ *          layout). Its #uiLayout.heading member can be cleared to mark the heading as added (so
+ *          it's not added multiple times). Returns a pointer to the heading
+ */
+static uiLayout *ui_layout_heading_find(uiLayout *cur_layout)
+{
+  for (uiLayout *parent = cur_layout; parent; parent = parent->parent) {
+    if (parent->heading[0]) {
+      return parent;
+    }
+  }
+
+  return NULL;
+}
+
+static void ui_layout_heading_label_add(uiLayout *layout,
+                                        uiLayout *heading_layout,
+                                        bool right_align,
+                                        bool respect_prop_split)
+{
+  const int prev_alignment = layout->alignment;
+
+  if (right_align) {
+    uiLayoutSetAlignment(layout, UI_LAYOUT_ALIGN_RIGHT);
+  }
+
+  if (respect_prop_split) {
+    uiItemL_respect_property_split(layout, heading_layout->heading, ICON_NONE);
+  }
+  else {
+    uiItemL(layout, heading_layout->heading, ICON_NONE);
+  }
+  /* After adding the heading label, we have to mark it somehow as added, so it's not added again
+   * for other items in this layout. For now just clear it. */
+  heading_layout->heading[0] = '\0';
+
+  layout->alignment = prev_alignment;
+}
+
+/**
  * Hack to add further items in a row into the second part of the split layout, so the label part
  * keeps a fixed size.
  * \return The layout to place further items in for the split layout.
  */
 static uiLayout *ui_item_prop_split_layout_hack(uiLayout *layout_parent, uiLayout *layout_split)
 {
+  /* Tag item as using property split layout, this is inherited to children so they can get special
+   * treatment if needed. */
+  layout_parent->item.flag |= UI_ITEM_INSIDE_PROP_SEP;
+
   if (layout_parent->item.type == ITEM_LAYOUT_ROW) {
+    /* Prevent further splits within the row. */
+    uiLayoutSetPropSep(layout_parent, false);
+
     layout_parent->child_items_layout = uiLayoutRow(layout_split, true);
     return layout_parent->child_items_layout;
   }
@@ -1888,13 +1949,18 @@ void uiItemFullR(uiLayout *layout,
   uiBlock *block = layout->root->block;
   char namestr[UI_MAX_NAME_STR];
   const bool use_prop_sep = ((layout->item.flag & UI_ITEM_PROP_SEP) != 0);
-
-  /* By default 'use_prop_sep' uses a separate column for labels.
-   * This is an exception for check-boxes otherwise only the small checkbox region is clickable.
+  const bool inside_prop_sep = ((layout->item.flag & UI_ITEM_INSIDE_PROP_SEP) != 0);
+  /* Columns can define a heading to insert. If the first item added to a split layout doesn't have
+   * a label to display in the first column, the heading is inserted there. Otherwise it's inserted
+   * as a new row before the first item. */
+  uiLayout *heading_layout = ui_layout_heading_find(layout);
+  /* Although checkboxes use the split layout, they are an exception and should only place their
+   * label in the second column, to not make that almost empty.
    *
    * Keep using 'use_prop_sep' instead of disabling it entirely because
    * we need the ability to have decorators still. */
   bool use_prop_sep_split_label = use_prop_sep;
+  bool forbid_single_col = false;
 
 #ifdef UI_PROP_DECORATE
   struct {
@@ -2005,6 +2071,9 @@ void uiItemFullR(uiLayout *layout,
   if (use_prop_sep) {
     if (type == PROP_BOOLEAN && (icon == ICON_NONE) && !icon_only) {
       use_prop_sep_split_label = false;
+      /* For checkboxes we make an expection: We allow showing them in a split row even without
+       * label. It typically relates to its neighbor items, so no need for an extra label. */
+      forbid_single_col = true;
     }
   }
 #endif
@@ -2031,6 +2100,7 @@ void uiItemFullR(uiLayout *layout,
 
   /* Split the label / property. */
   uiLayout *layout_parent = layout;
+
   if (use_prop_sep) {
     uiLayout *layout_row = NULL;
 #ifdef UI_PROP_DECORATE
@@ -2041,21 +2111,28 @@ void uiItemFullR(uiLayout *layout,
     }
 #endif /* UI_PROP_DECORATE */
 
-    if ((name[0] == '\0') || (use_prop_sep_split_label == false)) {
+    if ((name[0] == '\0') && !forbid_single_col) {
       /* Ensure we get a column when text is not set. */
       layout = uiLayoutColumn(layout_row ? layout_row : layout, true);
       layout->space = 0;
+      if (heading_layout) {
+        ui_layout_heading_label_add(layout, heading_layout, false, false);
+      }
     }
     else {
       const PropertySubType subtype = RNA_property_subtype(prop);
       uiLayout *layout_split = uiLayoutSplit(
           layout_row ? layout_row : layout, UI_ITEM_PROP_SEP_DIVIDE, true);
+      bool label_added = false;
       layout_split->space = 0;
       uiLayout *layout_sub = uiLayoutColumn(layout_split, true);
       layout_sub->space = 0;
 
-      if ((index == RNA_NO_INDEX && is_array) &&
-          ((!expand && ELEM(subtype, PROP_COLOR, PROP_COLOR_GAMMA, PROP_DIRECTION)) == 0)) {
+      if (!use_prop_sep_split_label) {
+        /* Pass */
+      }
+      else if ((index == RNA_NO_INDEX && is_array) &&
+               ((!expand && ELEM(subtype, PROP_COLOR, PROP_COLOR_GAMMA, PROP_DIRECTION)) == 0)) {
         char name_with_suffix[UI_MAX_DRAW_STR + 2];
         char str[2] = {'\0'};
         for (int a = 0; a < len; a++) {
@@ -2084,6 +2161,8 @@ void uiItemFullR(uiLayout *layout,
                          "");
           but->drawflag |= UI_BUT_TEXT_RIGHT;
           but->drawflag &= ~UI_BUT_TEXT_LEFT;
+
+          label_added = true;
         }
       }
       else {
@@ -2092,13 +2171,17 @@ void uiItemFullR(uiLayout *layout,
               block, UI_BTYPE_LABEL, 0, name, 0, 0, w, UI_UNIT_Y, NULL, 0.0, 0.0, 0, 0, "");
           but->drawflag |= UI_BUT_TEXT_RIGHT;
           but->drawflag &= ~UI_BUT_TEXT_LEFT;
+
+          label_added = true;
         }
       }
 
-      if (layout_parent) {
-        layout_split = ui_item_prop_split_layout_hack(layout_parent, layout_split);
+      if (!label_added && heading_layout) {
+        ui_layout_heading_label_add(layout_sub, heading_layout, true, false);
       }
 
+      layout_split = ui_item_prop_split_layout_hack(layout_parent, layout_split);
+
       /* Watch out! We can only write into the new layout now. */
       if ((type == PROP_ENUM) && (flag & UI_ITEM_R_EXPAND)) {
         /* Expanded enums each have their own name. */
@@ -2113,7 +2196,9 @@ void uiItemFullR(uiLayout *layout,
         }
       }
       else {
-        name = "";
+        if (use_prop_sep_split_label) {
+          name = "";
+        }
         layout = uiLayoutColumn(layout_split, true);
       }
       layout->space = 0;
@@ -2132,9 +2217,20 @@ void uiItemFullR(uiLayout *layout,
 #endif /* UI_PROP_DECORATE */
   }
   /* End split. */
+  else if (heading_layout) {
+    /* Could not add heading to split layout, fallback to inserting it to the layout with the
+     * heading itself. */
+    ui_layout_heading_label_add(heading_layout, heading_layout, false, false);
+  }
 
   /* array property */
   if (index == RNA_NO_INDEX && is_array) {
+    if (inside_prop_sep) {
+      /* Within a split row, add array items to a column so they match the column layout of
+       * previous items (e.g. transform vector with lock icon for each item). */
+      layout = uiLayoutColumn(layout, true);
+    }
+
     ui_item_array(layout,
                   block,
                   name,
@@ -2214,12 +2310,6 @@ void uiItemFullR(uiLayout *layout,
     if (layout->activate_init) {
       UI_but_flag_enable(but, UI_BUT_ACTIVATE_ON_INIT);
     }
-
-    if (use_prop_sep && (use_prop_sep_split_label == false)) {
-      /* When the button uses it's own text right align it. */
-      but->drawflag |= UI_BUT_TEXT_RIGHT;
-      but->drawflag &= ~UI_BUT_TEXT_LEFT;
-    }
   }
 
   /* The resulting button may have the icon set since boolean button drawing
@@ -2242,50 +2332,21 @@ void uiItemFullR(uiLayout *layout,
 
 #ifdef UI_PROP_DECORATE
   if (ui_decorate.use_prop_decorate) {
-    const bool is_anim = RNA_property_animateable(ptr, prop);
     uiBut *but_decorate = ui_decorate.but ? ui_decorate.but->next : block->buttons.first;
+    const bool use_blank_decorator = (flag & UI_ITEM_R_FORCE_BLANK_DECORATE);
     uiLayout *layout_col = uiLayoutColumn(ui_decorate.layout, false);
     layout_col->space = 0;
     layout_col->emboss = UI_EMBOSS_NONE;
+
     int i;
     for (i = 0; i < ui_decorate.len && but_decorate; i++) {
+      PointerRNA *ptr_dec = use_blank_decorator ? NULL : &but_decorate->rnapoin;
+      PropertyRNA *prop_dec = use_blank_decorator ? NULL : but_decorate->rnaprop;
+
       /* The icons are set in 'ui_but_anim_flag' */
-      if (is_anim) {
-        but = uiDefIconBut(block,
-                           UI_BTYPE_BUT,
-                           0,
-                           ICON_DOT,
-                           0,
-                           0,
-                           UI_UNIT_X,
-                           UI_UNIT_Y,
-                           NULL,
-                           0.0,
-                           0.0,
-                           0.0,
-                           0.0,
-                           TIP_("Animate property"));
-        UI_but_func_set(but, ui_but_anim_decorate_cb, but, NULL);
-        but->flag |= UI_BUT_UNDO | UI_BUT_DRAG_LOCK;
-      }
-      else {
-        /* We may show other information here in future, for now use empty space. */
-        but = uiDefIconBut(block,
-                           UI_BTYPE_BUT,
-                           0,
-                           ICON_BLANK1,
-                           0,
-                           0,
-                           UI_UNIT_X,
-                           UI_UNIT_Y,
-                           NULL,
-                           0.0,
-                           0.0,
-                           0.0,
-                           0.0,
-                           "");
-        but->flag |= UI_BUT_DISABLED;
-      }
+      uiItemDecoratorR_prop(layout_col, ptr_dec, prop_dec, but_decorate->rnaindex);
+      but = block->buttons.last;
+
       /* Order the decorator after the button we decorate, this is used so we can always
        * do a quick lookup. */
       BLI_remlink(&block->buttons, but);
@@ -2759,6 +2820,7 @@ static uiBut *ui_item_menu(uiLayout *layout,
                            bool force_menu)
 {
   uiBlock *block = layout->root->block;
+  uiLayout *heading_layout = ui_layout_heading_find(layout);
   uiBut *but;
   int w, h;
 
@@ -2788,6 +2850,10 @@ static uiBut *ui_item_menu(uiLayout *layout,
     }
   }
 
+  if (heading_layout) {
+    ui_layout_heading_label_add(layout, heading_layout, true, true);
+  }
+
   if (name[0] && icon) {
     but = uiDefIconTextMenuBut(block, func, arg, icon, name, 0, 0, w, h, tip);
   }
@@ -2861,6 +2927,79 @@ void uiItemMContents(uiLayout *layout, const char *menuname)
   UI_menutype_draw(C, mt, layout);
 }
 
+/**
+ * Insert a decorator item for a button with the same property as \a prop.
+ * To force inserting a blank dummy element, NULL can be passed for \a ptr and \a prop.
+ */
+void uiItemDecoratorR_prop(uiLayout *layout, PointerRNA *ptr, PropertyRNA *prop, int index)
+{
+  uiBlock *block = layout->root->block;
+  const bool is_anim = ptr && prop && RNA_property_animateable(ptr, prop);
+  uiBut *but = NULL;
+  uiLayout *row;
+
+  UI_block_layout_set_current(block, layout);
+  row = uiLayoutRow(layout, false);
+  row->space = 0;
+  row->emboss = UI_EMBOSS_NONE;
+
+  if (is_anim) {
+    but = uiDefIconBut(block,
+                       UI_BTYPE_BUT,
+                       0,
+                       ICON_DOT,
+                       0,
+                       0,
+                       UI_UNIT_X,
+                       UI_UNIT_Y,
+                       NULL,
+                       0.0,
+                       0.0,
+                       0.0,
+                       0.0,
+                       TIP_("Animate property"));
+    UI_but_func_set(but, ui_but_anim_decorate_cb, but, NULL);
+    but->flag |= UI_BUT_UNDO | UI_BUT_DRAG_LOCK;
+    /* Reusing RNA search members, setting actual RNA data has many side-effects. */
+    but->rnasearchpoin = *ptr;
+    but->rnasearchprop = prop;
+    but->custom_data = POINTER_FROM_INT(index);
+  }
+  else {
+    /* We may show other information here in future, for now use empty space. */
+    but = uiDefIconBut(block,
+                       UI_BTYPE_BUT,
+                       0,
+                       ICON_BLANK1,
+                       0,
+                       0,
+                       UI_UNIT_X,
+                       UI_UNIT_Y,
+                       NULL,
+                       0.0,
+                       0.0,
+                       0.0,
+                       0.0,
+                       "");
+    but->flag |= UI_BUT_DISABLED;
+  }
+}
+
+void uiItemDecoratorR(uiLayout *layout, PointerRNA *ptr, const char *propname, int index)
+{
+  PropertyRNA *prop;
+
+  /* validate arguments */
+  prop = RNA_struct_find_property(ptr, propname);
+  if (!prop) {
+    ui_item_disabled(layout, propname);
+    RNA_warning("property not found: %s.%s", RNA_struct_identifier(ptr->type), propname);
+    return;
+  }
+
+  uiItemDecoratorR_prop(layout, ptr, prop, index);
+}
+
 /* popover */
 void uiItemPopoverPanel_ptr(
     uiLayout *layout, bContext *C, PanelType *pt, const char *name, int icon)
@@ -3017,6 +3156,7 @@ uiLayout *uiItemL_respect_property_split(uiLayout *layout, const char *text, int
 {
   if (layout->item.flag & UI_ITEM_PROP_SEP) {
     uiBlock *block = uiLayoutGetBlock(layout);
+
     uiLayout *layout_row = uiLayoutRow(layout, true);
     uiLayout *layout_split = uiLayoutSplit(layout_row, UI_ITEM_PROP_SEP_DIVIDE, true);
     uiLayout *layout_sub = uiLayoutColumn(layout_split, true);
@@ -3029,8 +3169,9 @@ uiLayout *uiItemL_respect_property_split(uiLayout *layout, const char *text, int
     layout_split = ui_item_prop_split_layout_hack(layout, layout_split);
     UI_block_layout_set_current(block, layout_split);
 
-    /* Give caller a new sub-row to place items in. */
-    return layout_row;
+    /* The decorator layout uses the row the split layout was inserted to.  */
+    uiLayout *layout_decorator = layout_row;
+    return layout_decorator;
   }
   else {
     char namestr[UI_MAX_NAME_STR];
@@ -4471,13 +4612,24 @@ static void ui_litem_init_from_parent(uiLayout *litem, uiLayout *layout, int ali
   litem->redalert = layout->redalert;
   litem->w = layout->w;
   litem->emboss = layout->emboss;
-  litem->item.flag = (layout->item.flag & (UI_ITEM_PROP_SEP | UI_ITEM_PROP_DECORATE));
+  litem->item.flag = (layout->item.flag &
+                      (UI_ITEM_PROP_SEP | UI_ITEM_PROP_DECORATE | UI_ITEM_INSIDE_PROP_SEP));
 
   if (layout->child_items_layout) {
     BLI_addtail(&layout->child_items_layout->items, litem);
+    litem->parent = layout->child_items_layout;
   }
   else {
     BLI_addtail(&layout->items, litem);
+    litem->parent = layout;
+  }
+}
+
+static void ui_layout_heading_set(uiLayout *layout, const char *heading)
+{
+  BLI_assert(layout->heading[0] == '\0');
+  if (heading) {
+    STRNCPY(layout->heading, heading);
   }
 }
 
@@ -4497,6 +4649,16 @@ uiLayout *uiLayoutRow(uiLayout *layout, bool align)
   return litem;
 }
 
+/**
+ * See #uiLayoutColumnWithHeading().
+ */
+uiLayout *uiLayoutRowWithHeading(uiLayout *layout, bool align, const char *heading)
+{
+  uiLayout *litem = uiLayoutRow(layout, align);
+  ui_layout_heading_set(litem, heading);
+  return litem;
+}
+
 uiLayout *uiLayoutColumn(uiLayout *layout, bool align)
 {
   uiLayout *litem;
@@ -4512,6 +4674,19 @@ uiLayout *uiLayoutColumn(uiLayout *layout, bool align)
   return litem;
 }
 
+/**
+ * Variant of #uiLayoutColumn() that sets a heading label for the layout if the first item is
+ * added through #uiItemFullR(). If split layout is used and the item has no string to add to the
+ * first split-column, the heading is added there instead. Otherwise the heading inserted with a
+ * new row.
+ */
+uiLayout *uiLayoutColumnWithHeading(uiLayout *layout, bool align, const char *heading)
+{
+  uiLayout *litem = uiLayoutColumn(layout, align);
+  ui_layout_heading_set(litem, heading);
+  return litem;
+}
+
 uiLayout *uiLayoutColumnFlow(uiLayout *layout, int number, bool align)
 {
   uiLayoutItemFlow *flow;