Fix EcoBraille and Lilly braille display drivers (nvaccess#17635)

Fixes nvaccess#17502

Summary of the issue:
In nvaccess#15386, support was added for numRows and numCols on braille displays. Setting numCells explicitly would also set numCols.
In nvaccess#17011, we're much more relying on numCols and numRows.

For the eco braille and Lilli drivers, numCells was implemented by overriding _get_numCells. However this way, the setter of numCells would never be called and therefore numCols would always be 0.

Description of user facing changes
Fix braille for Eco Braille and Lilli displays.

Description of development approach
When calculating display dimensions on the braille handler, when display.numRows is 1, use display.numCells instead of display.numCols. This accounts for cases where numCells is implemented and numRows/numCols are not.
Worked around the ZeroDevisionError when getting windowStartPost on a buffer
Initialize _windowRowBufferOffsets to [(0, 0)] instead of [(0, 1)]. The latter suggests that the window contains one cell, which is not the case. @michaelDCurran you might want to check this.

source/braille.py

@@ -1769,7 +1769,7 @@ def __init__(self, handler):
 		#: The translated braille representation of the entire buffer.
 		#: @type: [int, ...]
 		self.brailleCells = []
-		self._windowRowBufferOffsets: list[tuple[int, int]] = [(0, 1)]
+		self._windowRowBufferOffsets: list[tuple[int, int]] = [(0, 0)]
 		"""
 		A list representing the rows in the braille window,
 		each item being a tuple of start and end braille buffer offsets.
@@ -1879,11 +1879,13 @@ def windowPosToBufferPos(self, windowPos: int) -> int:
 		"""
 		Converts a position relative to the braille window to a position relative to the braille buffer.
 		"""
+		if self.handler.displaySize == 0:
+			return 0
 		windowPos = max(min(windowPos, self.handler.displaySize), 0)
 		row, col = divmod(windowPos, self.handler.displayDimensions.numCols)
 		if row < len(self._windowRowBufferOffsets):
 			start, end = self._windowRowBufferOffsets[row]
-			return min(start + col, end - 1)
+			return max(min(start + col, end - 1), 0)
 		raise ValueError("Position outside window")
 
 	windowStartPos: int
@@ -1905,7 +1907,7 @@ def _calculateWindowRowBufferOffsets(self, pos: int) -> None:
 		self._windowRowBufferOffsets.clear()
 		if len(self.brailleCells) == 0:
 			# Initialising with no actual braille content.
-			self._windowRowBufferOffsets = [(0, 1)]
+			self._windowRowBufferOffsets = [(0, 0)]
 			return
 		doWordWrap = config.conf["braille"]["wordWrap"]
 		bufferEnd = len(self.brailleCells)
@@ -2539,9 +2541,14 @@ def _set_displaySize(self, value):
 	_cache_displayDimensions = True
 
 	def _get_displayDimensions(self) -> DisplayDimensions:
+		if not self.display:
+			numRows = numCols = 0
+		else:
+			numRows = self.display.numRows
+			numCols = self.display.numCols if numRows > 1 else self.display.numCells
 		rawDisplayDimensions = DisplayDimensions(
-			numRows=self.display.numRows if self.display else 0,
-			numCols=self.display.numCols if self.display else 0,
+			numRows=numRows,
+			numCols=numCols,
 		)
 		filteredDisplayDimensions = filter_displayDimensions.apply(rawDisplayDimensions)
 		# Would be nice if there were a more official way to find out if the displaySize filter is currently registered by at least 1 handler.
@@ -3279,29 +3286,36 @@ def terminate():
 
 
 class BrailleDisplayDriver(driverHandler.Driver):
-	"""Abstract base braille display driver.
-	Each braille display driver should be a separate Python module in the root brailleDisplayDrivers directory
-	containing a BrailleDisplayDriver class which inherits from this base class.
+	"""
+	Abstract base braille display driver.
+
+	Each braille display driver should be a separate Python module in the root ``brailleDisplayDrivers`` directory,
+	containing a ``BrailleDisplayDriver`` class that inherits from this base class.
+
+	At a minimum, drivers must:
+		- Set :attr:`name` and :attr:`description`.
+		- Override :meth:`check`.
 
-	At a minimum, drivers must set L{name} and L{description} and override the L{check} method.
-	To display braille, L{numCells} and L{display} must be implemented.
+	To display braille:
+		- :meth:`display` must be implemented.
+		- For a single-line display, :attr:`numCells` must be implemented.
+		- For a multi-line display, :attr:`numRows` and :attr:`numCols` must be implemented.
 
 	To support automatic detection of braille displays belonging to this driver:
-		* The driver must be thread safe and L{isThreadSafe} should be set to C{True}
-		* L{supportsAutomaticDetection} must be set to C{True}.
-		* L{registerAutomaticDetection} must be implemented.
+		* The driver must be thread-safe, and :attr:`isThreadSafe` should be set to ``True``.
+		* :attr:`supportsAutomaticDetection` must be set to ``True``.
+		* :meth:`registerAutomaticDetection` must be implemented.
 
-	Drivers should dispatch input such as presses of buttons, wheels or other controls
-	using the L{inputCore} framework.
-	They should subclass L{BrailleDisplayGesture}
-	and execute instances of those gestures using L{inputCore.manager.executeGesture}.
-	These gestures can be mapped in L{gestureMap}.
-	A driver can also inherit L{baseObject.ScriptableObject} to provide display specific scripts.
+	Drivers should dispatch input (e.g., button presses or controls) using the :mod:`inputCore` framework.
+	They should subclass :class:`BrailleDisplayGesture` and execute instances of those gestures
+	using :meth:`inputCore.manager.executeGesture`. These gestures can be mapped in :attr:`gestureMap`.
+	A driver can also inherit from :class:`baseObject.ScriptableObject` to provide display-specific scripts.
 
-	@see: L{hwIo} for raw serial and HID I/O.
+	.. seealso::
+		:mod:`hwIo` for raw serial and HID I/O.
 
-	There are factory functions to create L{autoSettingsUtils.driverSetting.DriverSetting} instances
-	for common display specific settings; e.g. L{DotFirmnessSetting}.
+	There are factory functions to create :class:`autoSettingsUtils.driverSetting.DriverSetting` instances
+	for common display-specific settings, such as :meth:`DotFirmnessSetting`.
 	"""
 
 	_configSection = "braille"