add backlight support through sysfs

Signed-off-by: Mattias Andrée <maandree@operamail.com>

2 files changed, 98 insertions, 0 deletions

diff --git a/src/__main__.py b/src/__main__.py
index 1ea51b0..f66f974 100755
--- a/src/__main__.py
+++ b/src/__main__.py
@@ -40,6 +40,7 @@ from solar import *
 from curve import *
 from colour import *
 from monitor import *
+from backlight import *
 
 
 config_file = None
diff --git a/src/backlight.py b/src/backlight.py
new file mode 100644
index 0000000..54090ae
--- /dev/null
+++ b/src/backlight.py
@@ -0,0 +1,97 @@
+#!/usr/bin/env python3
+
+# Copyright © 2014  Mattias Andrée (maandree@member.fsf.org)
+# 
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+import os
+import sys
+from subprocess import Popen
+
+
+def list_backlights():
+    '''
+    List backlight controllers
+    
+    @return  list<str>  List of all backlight controllers on the system
+    '''
+    return os.listdir('/sys/class/backlight')
+
+
+class Backlight:
+    '''
+    Backlight controller
+    
+    @variable  maxmimum:int  The maximum value, after minimum value modification
+    '''
+    
+    def __init__(self, controller, adjbacklight = True, minimum = 0):
+        '''
+        Constructor
+        
+        @param  controller:str     The name or path of the backlight controller
+        @param  adjbacklight:bool  Whether to the `adjbacklight` commmand when adjusting
+        @param  minimum:int        Artificially raise the minimum from zero to avoid the
+                                   backlight from getting stuck at zero when reached,
+                                   as happens on some controllers
+        '''
+        self.__controller = controller
+        if '/' not in controller:
+            self.__controller = '/sys/class/backlight/%s' % controller
+        
+        with open('%s/max_brightness' % self.__controller, 'rb') as file:
+            self.maximum = int(file.read().decode('utf-8', 'replace')[:-1]) - minimum
+        
+        self.__minimum = minimum
+        self.__adjbacklight = adjbacklight
+    
+    
+    @property
+    def actual(self):
+        '''
+        Get the actual brightness
+        
+        @return  :int  The brightness, can be below zero if the minimum value was modified at contruction
+        '''
+        with open('%s/actual_brightness' % self.__controller, 'rb') as file:
+            return int(file.read().decode('utf-8', 'replace')[:-1]) - self.__minimum
+    
+    
+    @property
+    def brightness(self):
+        '''
+        Get the brightness
+        
+        @return  :int  The brightness, can be below zero if the minimum value was modified at contruction
+        '''
+        with open('%s/brightness' % self.__controller, 'rb') as file:
+            return int(file.read().decode('utf-8', 'replace')[:-1]) - self.__minimum
+    
+    
+    @brightness.setter
+    def brightness(self, value):
+        '''
+        Set the brightness
+        
+        @param  value:int  The brightness, inside the range [0, `self.maxmimum`], can be below zero,
+                           but should not be below zero, if the minimum value was modified at contruction
+        '''
+        if not self.__adjbacklight:
+            with open('%s/brightness' % self.__controller, 'wb') as file:
+                file.write((str(value + self.__minimum) + '\n').encode('utf-8'))
+                file.flush()
+        else:
+            cmd = ['adjbacklight', self.__controller, '--set', str(value + self.__minimum)]
+            Popen(cmd, stdout = sys.stdout, stderr = sys.stderr).wait()
+