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, 39 insertions, 0 deletions

diff --git a/source/blender/makesrna/intern/rna_access.c b/source/blender/makesrna/intern/rna_access.c
index 047e5ea17ab..6879a0534e9 100644
--- a/source/blender/makesrna/intern/rna_access.c
+++ b/source/blender/makesrna/intern/rna_access.c
@@ -2873,6 +2873,45 @@ void *RNA_property_enum_py_data_get(PropertyRNA *prop)
 	return eprop->py_data;
 }
 
+/**
+ * Get the value of the item that is \a step items away from \a from_value.
+ *
+ * \param from_value: Item value to start stepping from.
+ * \param step: Absolute value defines step size, sign defines direction.
+ *              E.g to get the next item, pass 1, for the previous -1.
+ */
+int RNA_property_enum_step(const bContext *C, PointerRNA *ptr, PropertyRNA *prop, int from_value, int step)
+{
+	EnumPropertyItem *item_array;
+	int totitem;
+	bool free;
+	int result_value = from_value;
+	int i, i_init;
+	int single_step = (step < 0) ? -1 : 1;
+	int step_tot = 0;
+
+	RNA_property_enum_items((bContext *)C, ptr, prop, &item_array, &totitem, &free);
+	i = RNA_enum_from_value(item_array, from_value);
+	i_init = i;
+
+	do {
+		i = mod_i(i + single_step, totitem);
+		if (item_array[i].identifier[0]) {
+			step_tot += single_step;
+		}
+	} while ((i != i_init) && (step_tot != step));
+
+	if (i != i_init) {
+		result_value = item_array[i].value;
+	}
+
+	if (free) {
+		MEM_freeN(item_array);
+	}
+
+	return result_value;
+}
+
 PointerRNA RNA_property_pointer_get(PointerRNA *ptr, PropertyRNA *prop)
 {
 	PointerPropertyRNA *pprop = (PointerPropertyRNA *)prop;