[processing] make location of GRASS 7 help files configurable

This prevents errors when algorithm help requested and there is no
access to the Internet (e.g. closed networks)

Author: alexbruy

python/plugins/processing/algs/grass7/Grass7Algorithm.py

@@ -104,34 +104,14 @@ def getIcon(self):
         return self._icon
 
     def help(self):
-        localDoc = None
-        html = self.grass7Name + '.html'
-        if system.isWindows():
-            # For MS-Windows, use the configured GRASS7 path
-            localPath = os.path.join(Grass7Utils.grassPath(), 'docs/html', html)
-            if os.path.exists(localPath):
-                localDoc = os.path.abspath(localPath)
-        elif system.isMac():
-            # For MacOSX official package
-            localPath = os.path.join('/Applications/GRASS-7.0.app/Contents/MacOS/docs/html', html)
-            if os.path.exists(localPath):
-                localDoc = os.path.abspath(localPath)
+        helpPath = Grass7Utils.grassHelpPath()
+        if helpPath == '':
+            return False, None
+
+        if os.path.exists(helpPath):
+            return False, QUrl.fromLocalFile(os.path.join(helpPath, '{}.html'.format(self.grass7Name))).toString()
         else:
-            # For GNU/Linux distributions
-            searchPaths = ['/usr/share/doc/grass-doc/html', '/opt/grass/docs/html',
-                           '/usr/share/doc/grass/docs/html']
-            for path in searchPaths:
-                localPath = os.path.join(path, html)
-                if os.path.exists(localPath):
-                    localDoc = os.path.abspath(localPath)
-
-        # Found the local documentation
-        if localDoc:
-            localDoc = QUrl.fromLocalFile(localDoc).toString()
-            return False, localDoc
-
-        # Return the URL if local doc is not found
-        return False, 'http://grass.osgeo.org/grass70/manuals/' + self.grass7Name + '.html'
+            return False, helpPath + '{}.html'.format(self.grass7Name)
 
     def getParameterDescriptions(self):
         descs = {}
@@ -195,7 +175,7 @@ def defineCharacteristicsFromFile(self):
                     elif isinstance(output, OutputVector):
                         vectorOutputs += 1
                     if isinstance(output, OutputHTML):
-                        self.addOutput(OutputFile("rawoutput", output.description + 
+                        self.addOutput(OutputFile("rawoutput", output.description +
                                                   " (raw output)", "txt"))
                 line = lines.readline().strip('\n').strip()
             except Exception as e:

python/plugins/processing/algs/grass7/Grass7AlgorithmProvider.py

@@ -60,13 +60,19 @@ def initializeSettings(self):
             self.getDescription(),
             Grass7Utils.GRASS_LOG_CONSOLE,
             self.tr('Log console output'), False))
+        ProcessingConfig.addSetting(Setting(
+            self.getDescription(),
+            Grass7Utils.GRASS_HELP_PATH,
+            self.tr('Location of GRASS 7 docs'),
+            Grass7Utils.grassHelpPath()))
 
     def unload(self):
         AlgorithmProvider.unload(self)
         if isWindows() or isMac():
             ProcessingConfig.removeSetting(Grass7Utils.GRASS_FOLDER)
         ProcessingConfig.removeSetting(Grass7Utils.GRASS_LOG_COMMANDS)
         ProcessingConfig.removeSetting(Grass7Utils.GRASS_LOG_CONSOLE)
+        ProcessingConfig.removeSetting(Grass7Utils.GRASS_HELP_PATH)
 
     def createAlgsList(self):
         self.preloadedAlgs = []

python/plugins/processing/algs/grass7/Grass7Utils.py

@@ -47,6 +47,7 @@ class Grass7Utils:
     GRASS_FOLDER = 'GRASS7_FOLDER'
     GRASS_LOG_COMMANDS = 'GRASS7_LOG_COMMANDS'
     GRASS_LOG_CONSOLE = 'GRASS7_LOG_CONSOLE'
+    GRASS_HELP_PATH = 'GRASS7_HELP_PATH'
 
     sessionRunning = False
     sessionLayers = {}
@@ -399,3 +400,27 @@ def writeCommand(output, command):
         except TypeError:
             # Python 3
             output.write(command + '\n')
+
+    @staticmethod
+    def grassHelpPath():
+        helpPath = ProcessingConfig.getSetting(Grass7Utils.GRASS_HELP_PATH)
+
+        if helpPath is None:
+            if isWindows():
+                localPath = os.path.join(Grass7Utils.grassPath(), 'docs/html')
+                if os.path.exists(localPath):
+                    helpPath = os.path.abspath(localPath)
+            elif isMac():
+                localPath = '/Applications/GRASS-7.0.app/Contents/MacOS/docs/html'
+                if os.path.exists(localPath):
+                    helpPath = os.path.abspath(localPath)
+            else:
+                searchPaths = ['/usr/share/doc/grass-doc/html',
+                               '/opt/grass/docs/html',
+                               '/usr/share/doc/grass/docs/html']
+                for path in searchPaths:
+                    if os.path.exists(path):
+                        helpPath = os.path.abspath(path)
+                        break
+
+        return helpPath if helpPath is not None else 'http://grass.osgeo.org/grass70/manuals/'