awful.widget.button: Port to new widget layout

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

lib/awful/widget/button.lua.in

@@ -7,16 +7,15 @@
 local setmetatable = setmetatable
 local type = type
 local button = require("awful.button")
-local capi = { widget = widget,
-               mouse = mouse,
+local imagebox = require("wibox.widget.imagebox")
+local capi = { mouse = mouse,
                oocairo = oocairo }
 
 module("awful.widget.button")
 
 --- Create a button widget. When clicked, the image is deplaced to make it like
 -- a real button.
--- @param args Standard widget table arguments, plus image for the image path or
--- the image object.
+-- @param args Widget arguments. "image" is the image to display.
 -- @return A textbox widget configured as a button.
 function new(args)
     if not args or not args.image then return end
@@ -25,22 +24,15 @@ function new(args)
         img_release = capi.oocairo.image_surface_create_from_png(args.image)
     elseif type(args.image) == "userdata" and args.image.type and args.image:type() == "cairo_surface_t" then
         img_release = args.image
-    else
-        return
     end
     local img_press = capi.oocairo.image_surface_create("argb32", img_release:get_width(), img_release:get_height())
     local cr = capi.oocairo.context_create(img_press)
     cr:set_source(img_release, 2, 2)
     cr:paint()
 
-    args.type = "imagebox"
-    local w = capi.widget(args)
-    w.image = img_release
-    w:buttons(button({}, 1, function () w.image = img_press end, function () w.image = img_release end))
-    w:connect_signal("mouse::leave", function () w.image = img_release end)
-    w:connect_signal("mouse::enter", function ()
-                                     if capi.mouse.coords().buttons[1] then w.image = img_press end
-                                 end)
+    local w = imagebox()
+    w:set_image(img_release)
+    w:buttons(button({}, 1, function () w:set_image(img_press) end, function () w:set_image(img_release) end))
     return w
 end