From 082ef98c1c265ad927b728402d8803a86bbbaeef Mon Sep 17 00:00:00 2001
From: jao <jao@gnu.org>
Date: Mon, 18 Apr 2022 15:59:51 +0100
Subject: New dbus signal: SetAlpha (fixes #499)

---
 changelog.md                |  1 +
 doc/quick-start.org         | 20 +++++++++++---------
 doc/window-managers.org     | 10 +++++-----
 src/Xmobar/System/Signal.hs |  1 +
 src/Xmobar/X11/Loop.hs      |  3 +++
 5 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/changelog.md b/changelog.md
index 7c652b1..f9767bf 100644
--- a/changelog.md
+++ b/changelog.md
@@ -5,6 +5,7 @@ _New features_
   - New monitor `Load` providing load averages (stolen from Finn
     Lawler, with FreeBSD support thanks to Michał Zielonka).
   - New argument `scale` for `Memory` monitor to scale size units.
+  - New dbus signal: `SetAlpha` (see issue #499).
 
 _Bug fixes_
 
diff --git a/doc/quick-start.org b/doc/quick-start.org
index 831f97c..929deb6 100644
--- a/doc/quick-start.org
+++ b/doc/quick-start.org
@@ -428,12 +428,13 @@ available [[http://github.com/jaor/xmobar/raw/master/examples/xmobar.config][her
 
   When compiled with the optional =with_dbus= flag, xmobar can be
   controlled over dbus. All signals defined in [[https://github.com/jaor/xmobar/blob/master/src/Xmobar/System/Signal.hs][src/Signal.hs]] as =data
-  SignalType= can now be sent over dbus to xmobar. Due to current
-  limitations of the implementation only one process of xmobar can
-  acquire the dbus. This is handled on a first-come-first-served
-  basis, meaning that the first process will get the dbus
-  interface. Other processes will run without further problems, yet
-  have no dbus interface.
+  SignalType= can now be sent over dbus to xmobar.
+
+  Due to current limitations of the implementation only one process of
+  xmobar can acquire the dbus. This is handled on a
+  first-come-first-served basis, meaning that the first process will
+  get the dbus interface. Other processes will run without further
+  problems, yet have no dbus interface.
 
   - Bus Name: =org.Xmobar.Control=
   - Object Path: =/org/Xmobar/Control=
@@ -450,7 +451,7 @@ available [[http://github.com/jaor/xmobar/raw/master/examples/xmobar.config][her
       --print-reply \
       '/org/Xmobar/Control' \
       org.Xmobar.Control.SendSignal \
-      "string:Toggle 0"
+      "string:SetAlpha 192"
   #+end_src
 
   It is also possible to send multiple signals at once:
@@ -463,7 +464,8 @@ available [[http://github.com/jaor/xmobar/raw/master/examples/xmobar.config][her
 
   The =Toggle=, =Reveal=, and =Hide= signals take an additional integer
   argument that denotes an initial delay, in tenths of a second,
-  before the command takes effect.
+  before the command takes effect, while =SetAlpha= takes a new alpha
+  value (also an integer, between 0 and 255) as argument.
 
-  See [[window-managers.org::*Example of using][Interfacing with window managers]] for an example of how to use
+  See [[./window-managers.org::*Example of using][Interfacing with window managers]] for an example of how to use
   the DBus interface from xmonad.
diff --git a/doc/window-managers.org b/doc/window-managers.org
index e45784c..f60ee37 100644
--- a/doc/window-managers.org
+++ b/doc/window-managers.org
@@ -219,7 +219,7 @@ choice.
         xmonad configuration (=xmonad.hs=), e.g. by using a custom
         =~/.xmonad/build= script.
 
-*** Example for using the DBus IPC interface with XMonad
+*** Example of using the DBus IPC interface with XMonad
 
     Bind the key which should {,un}map xmobar to a dummy value. This is
     necessary for {,un}grabKey in xmonad.
@@ -245,10 +245,10 @@ choice.
 
       toggleDocksHook :: Int -> KeySym -> Event -> X All
       toggleDocksHook to ks ( KeyEvent { ev_event_display = d
-                                      , ev_event_type    = et
-                                      , ev_keycode       = ekc
-                                      , ev_time          = etime
-                                      } ) =
+                                       , ev_event_type    = et
+                                       , ev_keycode       = ekc
+                                       , ev_time          = etime
+                                       } ) =
               io (keysymToKeycode d ks) >>= toggleDocks >> return (All True)
           where
           toggleDocks kc
diff --git a/src/Xmobar/System/Signal.hs b/src/Xmobar/System/Signal.hs
index 3983654..81a4481 100644
--- a/src/Xmobar/System/Signal.hs
+++ b/src/Xmobar/System/Signal.hs
@@ -46,6 +46,7 @@ data SignalType = Wakeup
                 | Hide   Int
                 | Reveal Int
                 | Toggle Int
+                | SetAlpha Int
                 | TogglePersistent
                 | Action Button Position
     deriving (Read, Show)
diff --git a/src/Xmobar/X11/Loop.hs b/src/Xmobar/X11/Loop.hs
index 9c1a0f0..631855c 100644
--- a/src/Xmobar/X11/Loop.hs
+++ b/src/Xmobar/X11/Loop.hs
@@ -39,6 +39,7 @@ import qualified Data.List.NonEmpty as NE
 
 import Xmobar.System.Signal
 import Xmobar.Config.Types ( persistent
+                           , alpha
                            , font
                            , additionalFonts
                            , textOffset
@@ -146,6 +147,8 @@ signalLoop xc@(XConf d r w fs vos is cfg) as signal tv = do
          TogglePersistent -> signalLoop
             xc { config = cfg { persistent = not $ persistent cfg } } as signal tv
 
+         SetAlpha a -> signalLoop xc { config = cfg { alpha = a}} as signal tv
+
          Action but x -> action but x
 
     where
-- 
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