Maintain a stack of parent traverse. Minor tweaks.

README.md

@@ -310,7 +310,8 @@ Calling `machi.switcher.start()` will create a switcher supporting the following
  - `Shift` + arrow keys: move the focused window to other areas by the direction. In draft mode, move the window while preserving its size.
  - `Control`[ + `Shift`] + arrow keys: move the bottom-right (or top-left window if `Shift` is pressed) area of the focused window by direction. Only works in draft mode.
  - `Tab`: switch beteen windows covering the current areas.
- - `u` or `PageUp` (`Prior`): select the parent of the current area.
+ - `q` or `PageUp` (`Prior`): select the parent of the current area.
+ - `e` or `PageDown` (`Next`): select the previous child of the current area, if `q` or `PageUp` was used.
  - `f` or `.`: toggle the per-window setting of draft mode.
  - `/`: open the editor to edit the selected area using the same command interpretation.
    Note the final command may be transcoded to be embeddable, but the areas shall be the same.

switcher.lua

@@ -109,6 +109,14 @@ function module.start(c, exit_keys)
     end
 
     local selected_area_ = nil
+    local function set_selected_area(area)
+        selected_area_ = area
+        if area then
+            traverse_x = max(areas[area].x + traverse_radius, min(areas[area].x + areas[area].width - traverse_radius, traverse_x))
+            traverse_y = max(areas[area].y + traverse_radius, min(areas[area].y + areas[area].height - traverse_radius, traverse_y))
+        end
+    end
+
     local function selected_area()
         if selected_area_ == nil then
             local min_dis = nil
@@ -125,34 +133,12 @@ function module.start(c, exit_keys)
                 end
             end
 
-            if min_dis > 0 then
+            set_selected_area(selected_area_)
-                local a = areas[selected_area_]
-                local corners = {
-                    {a.x + traverse_radius, a.y + traverse_radius},
-                    {a.x + traverse_radius, a.y + a.height - traverse_radius},
-                    {a.x + a.width - traverse_radius, a.y + traverse_radius},
-                    {a.x + a.width - traverse_radius, a.y + a.height - traverse_radius}
-                }
-                min_dis = nil
-                local min_i
-                for i, c in ipairs(corners) do
-                    local dis = math.abs(c[1] - traverse_x) + math.abs(c[2] - traverse_y)
-                    if min_dis == nil or min_dis > dis then
-                        min_dis = dis
-                        min_i = i
-                    end
-                end
-
-                traverse_x = corners[min_i][1]
-                traverse_y = corners[min_i][2]
-            end
         end
         return selected_area_
     end
 
-    local function set_selected_area(a)
+    local parent_stack = {}
-        selected_area_ = a
-    end
 
     local function maintain_tablist()
         if tablist == nil then
@@ -422,10 +408,8 @@ function module.start(c, exit_keys)
             end
 
             if choice ~= nil then
-                traverse_x = max(areas[choice].x + traverse_radius, min(areas[choice].x + areas[choice].width - traverse_radius, traverse_x))
-                traverse_y = max(areas[choice].y + traverse_radius, min(areas[choice].y + areas[choice].height - traverse_radius, traverse_y))
                 tablist = nil
-                set_selected_area(nil)
+                set_selected_area(choice)
 
                 if c then
                     if ctrl and cd[c].draft ~= false then
@@ -510,11 +494,23 @@ function module.start(c, exit_keys)
 
                 infobox.bgimage = draw_info
             end
-        elseif (key == "u" or key == "Prior") then
+        elseif (key == "q" or key == "Prior") then
             local current_area = selected_area()
             if areas[current_area].parent_id then
                 tablist = nil
                 set_selected_area(areas[current_area].parent_id)
+                if #parent_stack == 0 or
+                    parent_stack[#parent_stack] ~= current_area then
+                    parent_stack = {current_area}
+                end
+                parent_stack[#parent_stack + 1] = areas[current_area].parent_id
+                infobox.bgimage = draw_info
+            end
+        elseif (key =="e" or key == "Next") then
+            local current_area = selected_area()
+            if #parent_stack > 1 and parent_stack[#parent_stack] == current_area then
+                set_selected_area(parent_stack[#parent_stack - 1])
+                table.remove(parent_stack, #parent_stack)
                 infobox.bgimage = draw_info
             end
         elseif key == "/" then