Add extension points to filter and process the cells written to a bra…

…ille display

source/braille.py

@@ -247,6 +247,11 @@
 )
 SELECTION_SHAPE = 0xC0 #: Dots 7 and 8
 
+#: The braille shape shown on a braille display when
+#: the number of cells used by the braille handler is lower than the actual number of cells.
+#: The 0 based position of the shape is equal to the number of cells used by the braille handler.
+END_OF_BRAILLE_OUTPUT_SHAPE = 0xFF #: All dots
+
 #: Unicode braille indicator at the start of untranslated braille input.
 INPUT_START_IND = u"⣏"
 #: Unicode braille indicator at the end of untranslated braille input.
@@ -1568,14 +1573,22 @@ def __init__(self):
 		self._detectionEnabled = False
 		self._detector = None
 
-		#: Notifies when cells are about to be written to a braille display,
-		#: and allows components or add-ons to filter or change the raw cell data.
+		#: Filter that allows components or add-ons to filter or change the raw cell data,
+		#: that is written to a braille display.
 		#: For example, the Handy Tech ATC functionality doesn't support empty lines,
 		#: and therefore, empty lines should at least contain some filled cells.
 		#: @param value: The list of braille cells.
 		#: @type value: [int]
 		self.filter_writeCells = extensionPoints.Filter()
 
+		#: Notifies when cells are about to be written to a braille display.
+		#: This allows components and add-ons to perform an action.
+		#: For example, when a system is controlled by a braille enabled remote system,
+		#: the remote system should know what cells to show on its display.
+		#: @param cells: The list of braille cells.
+		#: @type cells: [int]
+		self.pre_writeCells = extensionPoints.Action()
+
 		#: Filter that allows components or add-ons to change the display size used for braille output.
 		#: For example, when a system is controlled by a remote system while having a 80 cells display connected,
 		#: the display size should be lowered to 40 whenever the remote system has a 40 cells display connected.
@@ -1601,6 +1614,7 @@ def _get_displaySize(self):
 	def _set_displaySize(self, value):
 		raise AttributeError("Can't set displaySize to %r, consider registering a handler to filter_displaySize" % value)
 
+	_cache_enabled = True
 	def _get_enabled(self):
 		"""Returns whether braille is enabled.
 		Handlers can register themselves to L{decide_enabled} and return C{False} to forcefully disable the braille handler.
@@ -1717,7 +1731,7 @@ def setDisplayByName(self, name, isFallback=False, detected=None):
 				config.conf["braille"]["display"] = name
 			else: # detected:
 				self._disableDetection()
-			log.info("Loaded braille display driver %s, current display has %d cells." %(name, self.displaySize))
+			log.info("Loaded braille display driver %s, current display has %d cells." %(name, newDisplay.numCells))
 			self.initialDisplay()
 			return True
 		except:
@@ -1747,6 +1761,26 @@ def _updateDisplay(self):
 
 	def _writeCells(self, cells):
 		cells = self.filter_writeCells.apply(cells)
+		self.pre_writeCells.notify(cells=cells)
+		displayCellCount = self.display.numCells
+		handlerCellCount = self.displaySize
+		if not displayCellCount:
+			# No physical display to write to
+			return
+		# Braille displays expect cells to be padded up to displayCellCount.
+		# However, the braille handler uses handlerCellCount to calculate the number of cells.
+		cellCountDif = displayCellCount - len(cells)
+		if cellCountDif < 0:
+			# There are more cells than the connected display could take.
+			log.warning(
+				"Connected display %s has %d cells, while braille handler is using %d cells" %
+				(self.display.name, displayCellCount, handlerCellCount)
+			)
+			cells = cells[:displayCellCount]
+		elif cellCountDif > 0:
+			# The connected display could take more cells than the braille handler produces.
+			# Displays expect cells to be padded up to the number of cells.
+			cells += [END_OF_BRAILLE_OUTPUT_SHAPE] + [0]*cellCountDif
 		if not self.display.isThreadSafe:
 			try:
 				self.display.display(cells)

source/brailleDisplayDrivers/alva.py

@@ -118,7 +118,6 @@ def _get_model(self):
 		return self.model
 
 	def _updateSettings(self):
-		oldNumCells = self.numCells
 		if self.isHid:
 			displaySettings = self._dev.getFeature(ALVA_DISPLAY_SETTINGS_REPORT)
 			if ord(displaySettings[ALVA_DISPLAY_SETTINGS_STATUS_CELL_SIDE_POS]) > 1:
@@ -146,9 +145,6 @@ def _updateSettings(self):
 			self._ser6SendMessage(b"H", b"?")
 			# Get HID keyboard input state
 			self._ser6SendMessage(b"r", b"?")
-		if oldNumCells not in (0, self.numCells):
-			# In case of splitpoint changes, we need to update the braille handler as well
-			braille.handler.displaySize = self.numCells
 
 	def __init__(self, port="auto"):
 		super(BrailleDisplayDriver,self).__init__()

source/inputCore.py

@@ -411,7 +411,7 @@ def __init__(self):
 		#: Handlers are called with one argument:
 		#: @param gesture: The gesture that is about to be executed.
 		#: @type gesture: L{InputGesture}
-		self.decide_ExecuteGesture = extensionPoints.Decider()
+		self.decide_executeGesture = extensionPoints.Decider()
 
 	def executeGesture(self, gesture):
 		"""Perform the action associated with a gesture.