UI: Ctrl+Tab and Ctrl+Shift+Tab to cycle through space context "tabs"

In User Preferences, Properties Editor and toolshelf, Ctrl+Tab and Ctrl+Shift+Tab now activates the next or previous space context (or category in case of toolshelf tabs), respectively.

For Properties Editor such functionality was completely missing, only toolshelf allowed cycling using ctrl+mousewheel (or only mousewheel while hovering tab region). Ctrl+Tab and Ctrl+Shift+Tab are common web browser shortcuts, so they're a reasonable choice to go with.
Reaching the first/last item doesn't cause the cycling to stop, we continue at the other end of the list then. (I didn't add this to Ctrl+Mousewheel toggling in toolshelf since I wanted to keep its behavior unchanged.)

We could get rid of (Ctrl+)Mousewheel cycling in toolshelf, but this may break user habits.

The cycling happens using a new operator, UI_OT_space_context_cycle, for toolshelf tabs it's hardcoded in panel handling code though.
Generalized rna_property_enum_step a bit and moved it to rna_access.c to allow external reuse.

Reviewed By: venomgfx
Differential Revision: https://developer.blender.org/D2189

1 files changed, 50 insertions, 26 deletions

diff --git a/source/blender/editors/interface/interface_panel.c b/source/blender/editors/interface/interface_panel.c
index 79961eae79d..c131bcb8e14 100644
--- a/source/blender/editors/interface/interface_panel.c
+++ b/source/blender/editors/interface/interface_panel.c
@@ -1841,6 +1841,52 @@ void UI_panel_category_draw_all(ARegion *ar, const char *category_id_active)
 #undef USE_FLAT_INACTIVE
 }
 
+static int ui_handle_panel_category_cycling(const wmEvent *event, ARegion *ar, const uiBut *active_but)
+{
+	const bool is_mousewheel = ELEM(event->type, WHEELUPMOUSE, WHEELDOWNMOUSE);
+	const bool inside_tabregion = (event->mval[0] < ((PanelCategoryDyn *)ar->panels_category.first)->rect.xmax);
+
+	/* if mouse is inside non-tab region, ctrl key is required */
+	if (is_mousewheel && !event->ctrl && !inside_tabregion)
+		return WM_UI_HANDLER_CONTINUE;
+
+
+	if (active_but && ui_but_supports_cycling(active_but)) {
+		/* skip - exception to make cycling buttons
+		 * using ctrl+mousewheel work in tabbed regions */
+	}
+	else {
+		const char *category = UI_panel_category_active_get(ar, false);
+		if (LIKELY(category)) {
+			PanelCategoryDyn *pc_dyn = UI_panel_category_find(ar, category);
+			if (LIKELY(pc_dyn)) {
+				if (is_mousewheel) {
+					/* we can probably get rid of this and only allow ctrl+tabbing */
+					pc_dyn = (event->type == WHEELDOWNMOUSE) ? pc_dyn->next : pc_dyn->prev;
+				}
+				else {
+					const bool backwards = event->shift;
+					pc_dyn = backwards ? pc_dyn->prev : pc_dyn->next;
+					if (!pc_dyn) {
+						/* proper cyclic behavior, back to first/last category (only used for ctrl+tab) */
+						pc_dyn = backwards ? ar->panels_category.last : ar->panels_category.first;
+					}
+				}
+
+				if (pc_dyn) {
+					/* intentionally don't reset scroll in this case,
+					 * this allows for quick browsing between tabs */
+					UI_panel_category_active_set(ar, pc_dyn->idname);
+					ED_region_tag_redraw(ar);
+				}
+			}
+		}
+		return WM_UI_HANDLER_BREAK;
+	}
+
+	return WM_UI_HANDLER_CONTINUE;
+}
+
 /* XXX should become modal keymap */
 /* AKey is opening/closing panels, independent of button state now */
 
@@ -1853,6 +1899,7 @@ int ui_handler_panel_region(bContext *C, const wmEvent *event, ARegion *ar, cons
 
 	retval = WM_UI_HANDLER_CONTINUE;
 
+	/* handle category tabs */
 	if (has_category_tabs) {
 		if (event->val == KM_PRESS) {
 			if (event->type == LEFTMOUSE) {
@@ -1867,32 +1914,9 @@ int ui_handler_panel_region(bContext *C, const wmEvent *event, ARegion *ar, cons
 					retval = WM_UI_HANDLER_BREAK;
 				}
 			}
-			else if (ELEM(event->type, WHEELUPMOUSE, WHEELDOWNMOUSE)) {
-				/* mouse wheel cycle tabs */
-
-				/* first check if the mouse is in the tab region */
-				if (event->ctrl || (event->mval[0] < ((PanelCategoryDyn *)ar->panels_category.first)->rect.xmax)) {
-					if (active_but && ui_but_supports_cycling(active_but)) {
-						/* skip - exception to make cycling buttons
-						 * using ctrl+mousewheel work in tabbed regions */
-					}
-					else {
-						const char *category = UI_panel_category_active_get(ar, false);
-						if (LIKELY(category)) {
-							PanelCategoryDyn *pc_dyn = UI_panel_category_find(ar, category);
-							if (LIKELY(pc_dyn)) {
-								pc_dyn = (event->type == WHEELDOWNMOUSE) ? pc_dyn->next : pc_dyn->prev;
-								if (pc_dyn) {
-									/* intentionally don't reset scroll in this case,
-									 * this allows for quick browsing between tabs */
-									UI_panel_category_active_set(ar, pc_dyn->idname);
-									ED_region_tag_redraw(ar);
-								}
-							}
-						}
-						retval = WM_UI_HANDLER_BREAK;
-					}
-				}
+			else if ((event->type == TABKEY && event->ctrl) || ELEM(event->type, WHEELUPMOUSE, WHEELDOWNMOUSE)) {
+				/* cycle tabs */
+				retval = ui_handle_panel_category_cycling(event, ar, active_but);
 			}
 		}
 	}