pager: cache desktop widgets

Creating them anew all the time leads to large memory usage.

1 files changed, 46 insertions, 37 deletions

diff --git a/pager.lua b/pager.lua
index 9bfd611..d3b672a 100644
--- a/pager.lua
+++ b/pager.lua
@@ -36,14 +36,14 @@ function Page:update()
         client:connect_signal("property::name", function() tb:set_text(client.name or "") end)
         client:connect_signal("focus",
             function(c)
-                if c.screen == self.pager.screen then
+                if c.screen == self.screen then
                     bg:set_bg(bg_focus)
                     bg:set_fg(fg_focus)
                 end
             end)
         client:connect_signal("unfocus",
             function(c)
-                if c.screen == self.pager.screen then
+                if c.screen == self.screen then
                     bg:set_bg(bg_normal)
                     bg:set_fg(fg_normal)
                 end
@@ -53,7 +53,7 @@ function Page:update()
     end
 end
 
-function Page:new(tag, index, width, height, pager)
+function Page:new(tag, index, width, height, screen)
     local ret = setmetatable({}, self)
     self.__index = self
 
@@ -69,7 +69,7 @@ function Page:new(tag, index, width, height, pager)
     ret.client_container = client_container
     ret.border           = margin
     ret.tag              = tag
-    ret.pager            = pager
+    ret.screen           = screen
 
     tag:connect_signal('tagged',   function (c) ret:update() end)
     tag:connect_signal('untagged', function (c) ret:update() end)
@@ -80,35 +80,16 @@ function Page:new(tag, index, width, height, pager)
     return ret
 end
 
-local Pager = {}
-
-function Pager:_set_active(screen, page_idx)
-    if self.screen == screen then
-        if self.active_page then
-            self.active_page:set_active(false)
-        end
-        self.pages[page_idx]:set_active(true)
-        self.active_page = self.pages[page_idx]
-    end
-end
-
-function Pager:set_desktop(desktop)
-    if self._desktop == desktop then
-        print('same desktop')
-        return
-    end
-
-    print("pager " .. self.screen.index .. " set desktop")
+local PagerDesk = {}
 
-    self.widget:reset()
-
-    self.active_page = nil
-    self.pages       = {}
+function PagerDesk:new(desktop, screen, width, height)
+    local ret = setmetatable({}, self)
+    self.__index = self
 
-    local nb_pages = #desktop.pages
-    local page_height = self.height / nb_pages
+    local nb_pages    = #desktop.pages
+    local page_height = height / nb_pages
 
-    local title = wibox.widget.textbox(desktop.name, false)
+    local title = wibox.widget.textbox()
     title:set_align("center")
     local title_bg = beautiful.bg_focus or "#ffffff"
     local title_fg = beautiful.fg_focus or "#000000"
@@ -119,27 +100,55 @@ function Pager:set_desktop(desktop)
         function(desktop, name)
             title:set_text(name)
         end)
+    title:set_text(desktop.name)
 
-    self.widget:add(title_container)
+    ret.widget = wibox.layout.fixed.vertical(title_container)
 
+    ret.pages = {}
     for i = 1, nb_pages do
         local page = desktop.pages[i]
-        self.pages[i] = Page:new(page, i, self.width, page_height, self)
-        self.widget:add(self.pages[i].widget)
+        ret.pages[i] = Page:new(page, i, width, page_height, screen)
+        ret.widget:add(ret.pages[i].widget)
     end
 
     desktop:connect_signal("page:view",
-        function(desktop, s, page_idx)
-            self:_set_active(s, page_idx) end)
+        function(desktop, s, page_idx) ret:_set_active(s, page_idx) end)
+
+    ret.desktop     = desktop
+    ret.screen      = screen
+    ret.active_page = nil
 
-    self._desktop = desktop
+    return ret
+end
+
+function PagerDesk:_set_active(screen, page_idx)
+    if self.screen == screen then
+        if self.active_page then
+            self.active_page:set_active(false)
+        end
+        self.pages[page_idx]:set_active(true)
+        self.active_page = self.pages[page_idx]
+    end
+end
+
+local Pager = {}
+
+function Pager:set_desktop(desktop)
+    if self._desktops[desktop] == nil then
+        self._desktops[desktop] = PagerDesk:new(desktop, self.screen,
+                                                self.width, self.height)
+    end
+
+    self.widget:set_widget(self._desktops[desktop].widget)
 end
 
 function Pager:new(screen, width, height)
     local ret = setmetatable({}, self)
     self.__index = self
 
-    ret.widget = wibox.layout.fixed.vertical()
+    ret.widget = wibox.container.constraint()
+
+    ret._desktops = {}
 
     ret.screen = screen
     ret.width  = width