wibox.widget.systray: Properly work when rotated (FS#1115)

The systray widget's fit() function worked in the (rotated) user coordinate
space while the draw() function used device coordinates (unrotated). This meant
that width and height were swapped up in the calculations and the systray ended
up being way too small.

Fix this by making the draw() function use user coordinates, too. This means
that it needs some new magic to detect a rotated coordinate space. This, in
turn, means that the systray is now automatically rotated when you put it into a
rotate layout.

This might cause some minor breakage because people no longer need to call
:set_horizontal() on the widgets.

Thanks a lot to Alexander Gehrke for his help!

Signed-off-by: Uli Schlachter <psychon@znc.in>

lib/wibox/widget/systray.lua.in

@@ -10,6 +10,7 @@ local beautiful = require("beautiful")
 local capi = { awesome = awesome }
 local setmetatable = setmetatable
 local error = error
+local abs = math.abs
 
 --- wibox.widget.systray
 local systray = { mt = {} }
@@ -19,13 +20,18 @@ local horizontal = true
 local base_size = nil
 
 function systray:draw(wibox, cr, width, height)
-    local x, y, width, height = lbase.rect_to_device_geometry(cr, 0, 0, width, height)
+    local x, y, _, _ = lbase.rect_to_device_geometry(cr, 0, 0, width, height)
     local num_entries = capi.awesome.systray()
     local bg = beautiful.bg_systray or beautiful.bg_normal or "#000000"
 
+    -- Figure out if the cairo context is rotated
+    local dir_x, dir_y = cr:user_to_device_distance(1, 0)
+    local is_rotated = abs(dir_x) < abs(dir_y)
+
     local in_dir, ortho, base
     if horizontal then
         in_dir, ortho = width, height
+        is_rotated = not is_rotated
     else
         ortho, in_dir = width, height
     end
@@ -34,7 +40,7 @@ function systray:draw(wibox, cr, width, height)
     else
         base = in_dir / num_entries
     end
-    capi.awesome.systray(wibox.drawin, x, y, base, horizontal, bg)
+    capi.awesome.systray(wibox.drawin, x, y, base, is_rotated, bg)
 end
 
 function systray:fit(width, height)