UI: Add shortcuts for modifier panels

The shortcuts act on the modifier with its panel under the mouse.
The following shortcuts are enabled by default:
  - Remove modifier: X, Delete
  - Apply modifier: Ctrl A
  - Duplicate modifier: Shift D
More shortcuts can be added in the keymap.

Each panel can now store a custom data RNA pointer, and a new
function is added to get the custom data for the panel under the
cursor. This custom data could be used to refactor the "List Panel
System" to generalize it and integrate it further with RNA.

The same functionality will be added  in further commits where it
applies to constraints, grease pencil modifiers, and effects.

Differential Revision: https://developer.blender.org/D8031

3 files changed, 121 insertions, 19 deletions

diff --git a/source/blender/editors/interface/interface_layout.c b/source/blender/editors/interface/interface_layout.c
index 6aefef197df..771e9383b8a 100644
--- a/source/blender/editors/interface/interface_layout.c
+++ b/source/blender/editors/interface/interface_layout.c
@@ -5576,6 +5576,7 @@ static void ui_paneltype_draw_impl(bContext *C, PanelType *pt, uiLayout *layout,
   panel->layout = layout;
   pt->draw(C, panel);
   panel->layout = NULL;
+  BLI_assert(panel->runtime.custom_data_ptr = NULL);
 
   MEM_freeN(panel);
 
diff --git a/source/blender/editors/interface/interface_panel.c b/source/blender/editors/interface/interface_panel.c
index 9ff678df0db..4bf88c76857 100644
--- a/source/blender/editors/interface/interface_panel.c
+++ b/source/blender/editors/interface/interface_panel.c
@@ -245,20 +245,25 @@ static bool panels_need_realign(ScrArea *area, ARegion *region, Panel **r_panel_
 
 /********* Functions for instanced panels. ***********/
 
-static Panel *UI_panel_add_instanced_ex(
-    ScrArea *area, ARegion *region, ListBase *panels, PanelType *panel_type, int list_index)
+static Panel *UI_panel_add_instanced_ex(ScrArea *area,
+                                        ARegion *region,
+                                        ListBase *panels,
+                                        PanelType *panel_type,
+                                        int list_index,
+                                        PointerRNA *custom_data)
 {
   Panel *panel = MEM_callocN(sizeof(Panel), "instanced panel");
   panel->type = panel_type;
   BLI_strncpy(panel->panelname, panel_type->idname, sizeof(panel->panelname));
 
   panel->runtime.list_index = list_index;
+  panel->runtime.custom_data_ptr = custom_data;
 
   /* Add the panel's children too. Although they aren't instanced panels, we can still use this
    * function to create them, as UI_panel_begin does other things we don't need to do. */
   LISTBASE_FOREACH (LinkData *, child, &panel_type->children) {
     PanelType *child_type = child->data;
-    UI_panel_add_instanced_ex(area, region, &panel->children, child_type, list_index);
+    UI_panel_add_instanced_ex(area, region, &panel->children, child_type, list_index, custom_data);
   }
 
   /* Make sure the panel is added to the end of the display-order as well. This is needed for
@@ -283,8 +288,12 @@ static Panel *UI_panel_add_instanced_ex(
  * Called in situations where panels need to be added dynamically rather than having only one panel
  * corresponding to each PanelType.
  */
-Panel *UI_panel_add_instanced(
-    ScrArea *area, ARegion *region, ListBase *panels, char *panel_idname, int list_index)
+Panel *UI_panel_add_instanced(ScrArea *area,
+                              ARegion *region,
+                              ListBase *panels,
+                              char *panel_idname,
+                              int list_index,
+                              PointerRNA *custom_data)
 {
   ARegionType *region_type = region->type;
 
@@ -296,7 +305,7 @@ Panel *UI_panel_add_instanced(
     return NULL;
   }
 
-  return UI_panel_add_instanced_ex(area, region, panels, panel_type, list_index);
+  return UI_panel_add_instanced_ex(area, region, panels, panel_type, list_index, custom_data);
 }
 
 /**
@@ -332,7 +341,8 @@ static void panel_free_block(ARegion *region, Panel *panel)
 }
 
 /**
- * Free a panel and it's children.
+ * Free a panel and it's children. Custom data is shared by the panel and its children
+ * and is freed by #UI_panels_free_instanced.
  *
  * \note The only panels that should need to be deleted at runtime are panels with the
  * #PNL_INSTANCED flag set.
@@ -369,6 +379,13 @@ void UI_panels_free_instanced(bContext *C, ARegion *region)
       if (C != NULL && panel->activedata != NULL) {
         panel_activate_state(C, panel, PANEL_STATE_EXIT);
       }
+
+      /* Free panel's custom data. */
+      if (panel->runtime.custom_data_ptr != NULL) {
+        MEM_freeN(panel->runtime.custom_data_ptr);
+      }
+
+      /* Free the panel and its subpanels. */
       panel_delete(region, &region->panels, panel);
     }
   }
@@ -2886,6 +2903,56 @@ int ui_handler_panel_region(bContext *C,
   return retval;
 }
 
+static void ui_panel_custom_data_set_recursive(Panel *panel, PointerRNA *custom_data)
+{
+  panel->runtime.custom_data_ptr = custom_data;
+
+  LISTBASE_FOREACH (Panel *, child_panel, &panel->children) {
+    ui_panel_custom_data_set_recursive(child_panel, custom_data);
+  }
+}
+
+void UI_panel_custom_data_set(Panel *panel, PointerRNA *custom_data)
+{
+  BLI_assert(panel->type != NULL);
+
+  /* Free the old custom data, which should be shared among all of the panel's subpanels. */
+  if (panel->runtime.custom_data_ptr != NULL) {
+    MEM_freeN(panel->runtime.custom_data_ptr);
+  }
+
+  ui_panel_custom_data_set_recursive(panel, custom_data);
+}
+
+PointerRNA *UI_region_panel_custom_data_under_cursor(const bContext *C, const wmEvent *event)
+{
+  ARegion *region = CTX_wm_region(C);
+
+  Panel *panel = NULL;
+  LISTBASE_FOREACH (uiBlock *, block, &region->uiblocks) {
+    panel = block->panel;
+    if (panel == NULL) {
+      continue;
+    }
+
+    int mx = event->x;
+    int my = event->y;
+    ui_window_to_block(region, block, &mx, &my);
+    int mouse_state = ui_panel_mouse_state_get(block, panel, mx, my);
+    if (ELEM(mouse_state, PANEL_MOUSE_INSIDE_CONTENT, PANEL_MOUSE_INSIDE_HEADER)) {
+      break;
+    }
+  }
+
+  if (panel == NULL) {
+    return NULL;
+  }
+
+  PointerRNA *customdata = panel->runtime.custom_data_ptr;
+
+  return customdata;
+}
+
 /**************** window level modal panel interaction **************/
 
 /* note, this is modal handler and should not swallow events for animation */
diff --git a/source/blender/editors/interface/interface_templates.c b/source/blender/editors/interface/interface_templates.c
index c22eb097761..5a5b501e21e 100644
--- a/source/blender/editors/interface/interface_templates.c
+++ b/source/blender/editors/interface/interface_templates.c
@@ -1873,14 +1873,22 @@ void uiTemplateModifiers(uiLayout *UNUSED(layout), bContext *C)
     ModifierData *md = modifiers->first;
     for (int i = 0; md; i++, md = md->next) {
       const ModifierTypeInfo *mti = BKE_modifier_get_info(md->type);
-      if (mti->panelRegister) {
-        char panel_idname[MAX_NAME];
-        modifier_panel_id(md, panel_idname);
+      if (mti->panelRegister == NULL) {
+        continue;
+      }
 
-        Panel *new_panel = UI_panel_add_instanced(sa, region, &region->panels, panel_idname, i);
-        if (new_panel != NULL) {
-          UI_panel_set_expand_from_list_data(C, new_panel);
-        }
+      char panel_idname[MAX_NAME];
+      modifier_panel_id(md, panel_idname);
+
+      /* Create custom data RNA pointer. */
+      PointerRNA *md_ptr = MEM_mallocN(sizeof(PointerRNA), "panel customdata");
+      RNA_pointer_create(&ob->id, &RNA_Modifier, md, md_ptr);
+
+      Panel *new_panel = UI_panel_add_instanced(
+          sa, region, &region->panels, panel_idname, i, md_ptr);
+
+      if (new_panel != NULL) {
+        UI_panel_set_expand_from_list_data(C, new_panel);
       }
     }
   }
@@ -1890,6 +1898,27 @@ void uiTemplateModifiers(uiLayout *UNUSED(layout), bContext *C)
       if ((panel->type != NULL) && (panel->type->flag & PNL_INSTANCED))
         UI_panel_set_expand_from_list_data(C, panel);
     }
+
+    /* Assuming there's only one group of instanced panels, update the custom data pointers. */
+    Panel *panel = region->panels.first;
+    LISTBASE_FOREACH (ModifierData *, md, modifiers) {
+      const ModifierTypeInfo *mti = BKE_modifier_get_info(md->type);
+      if (mti->panelRegister == NULL) {
+        continue;
+      }
+
+      /* Move to the next instanced panel corresponding to the next modifier. */
+      while ((panel->type == NULL) || !(panel->type->flag & PNL_INSTANCED)) {
+        panel = panel->next;
+        BLI_assert(panel != NULL); /* There shouldn't be fewer panels than modifiers with UIs. */
+      }
+
+      PointerRNA *md_ptr = MEM_mallocN(sizeof(PointerRNA), "panel customdata");
+      RNA_pointer_create(&ob->id, &RNA_Modifier, md, md_ptr);
+      UI_panel_custom_data_set(panel, md_ptr);
+
+      panel = panel->next;
+    }
   }
 }
 
@@ -2026,9 +2055,11 @@ void uiTemplateConstraints(uiLayout *UNUSED(layout), bContext *C, bool use_bone_
       char panel_idname[MAX_NAME];
       panel_id_func(con, panel_idname);
 
-      Panel *new_panel = UI_panel_add_instanced(sa, region, &region->panels, panel_idname, i);
+      Panel *new_panel = UI_panel_add_instanced(
+          sa, region, &region->panels, panel_idname, i, NULL);
       if (new_panel) {
-        /* Set the list panel functionality function pointers since we don't do it with python. */
+        /* Set the list panel functionality function pointers since we don't do it with
+         * python. */
         new_panel->type->set_list_data_expand_flag = set_constraint_expand_flag;
         new_panel->type->get_list_data_expand_flag = get_constraint_expand_flag;
         new_panel->type->reorder = constraint_reorder;
@@ -2082,7 +2113,8 @@ void uiTemplateGpencilModifiers(uiLayout *UNUSED(layout), bContext *C)
         char panel_idname[MAX_NAME];
         gpencil_modifier_panel_id(md, panel_idname);
 
-        Panel *new_panel = UI_panel_add_instanced(sa, region, &region->panels, panel_idname, i);
+        Panel *new_panel = UI_panel_add_instanced(
+            sa, region, &region->panels, panel_idname, i, NULL);
         if (new_panel != NULL) {
           UI_panel_set_expand_from_list_data(C, new_panel);
         }
@@ -2107,7 +2139,8 @@ void uiTemplateGpencilModifiers(uiLayout *UNUSED(layout), bContext *C)
 /* -------------------------------------------------------------------- */
 /** \name ShaderFx Template
  *
- *  Template for building the panel layout for the active object's grease pencil shader effects.
+ *  Template for building the panel layout for the active object's grease pencil shader
+ * effects.
  * \{ */
 
 /**
@@ -2138,7 +2171,8 @@ void uiTemplateShaderFx(uiLayout *UNUSED(layout), bContext *C)
       char panel_idname[MAX_NAME];
       shaderfx_panel_id(fx, panel_idname);
 
-      Panel *new_panel = UI_panel_add_instanced(sa, region, &region->panels, panel_idname, i);
+      Panel *new_panel = UI_panel_add_instanced(
+          sa, region, &region->panels, panel_idname, i, NULL);
       if (new_panel != NULL) {
         UI_panel_set_expand_from_list_data(C, new_panel);
       }