writer.py: Disallow glyph clipping.

Author: peterhinch

writer/writer.py

@@ -1,6 +1,7 @@
 # writer.py Implements the Writer class.
 # Handles colour, word wrap and tab stops
 
+# V0.5.2 May 2025 Fix bug whereby glyph clipping might be attempted.
 # V0.5.1 Dec 2022 Support 4-bit color display drivers.
 # V0.5.0 Sep 2021 Color now requires firmware >= 1.17.
 # V0.4.3 Aug 2021 Support for fast blit to color displays (PR7682).
@@ -23,24 +24,24 @@
 
 import framebuf
 from uctypes import bytearray_at, addressof
-from sys import implementation
 
-__version__ = (0, 5, 1)
+__version__ = (0, 5, 2)
 
-fast_mode = True # Does nothing. Kept to avoid breaking code.
 
-class DisplayState():
+class DisplayState:
  def __init__(self):
  self.text_row = 0
  self.text_col = 0
 
+
 def _get_id(device):
  if not isinstance(device, framebuf.FrameBuffer):
- raise ValueError('Device must be derived from FrameBuffer.')
+ raise ValueError("Device must be derived from FrameBuffer.")
  return id(device)
 
+
 # Basic Writer class for monochrome displays
-class Writer():
+class Writer:
 
  state = {} # Holds a display state for each device
 
@@ -52,13 +53,13 @@ def set_textpos(device, row=None, col=None):
  s = Writer.state[devid] # Current state
  if row is not None:
  if row < 0 or row >= device.height:
- raise ValueError('row is out of range')
+ raise ValueError("row is out of range")
  s.text_row = row
  if col is not None:
  if col < 0 or col >= device.width:
- raise ValueError('col is out of range')
+ raise ValueError("col is out of range")
  s.text_col = col
- return s.text_row,  s.text_col
+ return s.text_row, s.text_col
 
  def __init__(self, device, font, verbose=True):
  self.devid = _get_id(device)
@@ -67,16 +68,20 @@ def __init__(self, device, font, verbose=True):
  Writer.state[self.devid] = DisplayState()
  self.font = font
  if font.height() >= device.height or font.max_width() >= device.width:
- raise ValueError('Font too large for screen')
+ raise ValueError("Font too large for screen")
  # Allow to work with reverse or normal font mapping
  if font.hmap():
  self.map = framebuf.MONO_HMSB if font.reverse() else framebuf.MONO_HLSB
  else:
- raise ValueError('Font must be horizontally mapped.')
+ raise ValueError("Font must be horizontally mapped.")
  if verbose:
- fstr = 'Orientation: Horizontal. Reversal: {}. Width: {}. Height: {}.'
+ fstr = "Orientation: Horizontal. Reversal: {}. Width: {}. Height: {}."
  print(fstr.format(font.reverse(), device.width, device.height))
- print('Start row = {} col = {}'.format(self._getstate().text_row, self._getstate().text_col))
+ print(
+ "Start row = {} col = {}".format(
+ self._getstate().text_row, self._getstate().text_col
+ )
+ )
  self.screenwidth = device.width # In pixels
  self.screenheight = device.height
  self.bgcolor = 0 # Monochrome background and foreground colors
@@ -90,7 +95,6 @@ def __init__(self, device, font, verbose=True):
  self.glyph = None # Current char
  self.char_height = 0
  self.char_width = 0
- self.clip_width = 0
 
  def _getstate(self):
  return Writer.state[self.devid]
@@ -123,30 +127,30 @@ def height(self): # Property for consistency with device
 
  def printstring(self, string, invert=False):
  # word wrapping. Assumes words separated by single space.
- q = string.split('\n')
+ q = string.split("\n")
  last = len(q) - 1
  for n, s in enumerate(q):
  if s:
  self._printline(s, invert)
  if n != last:
- self._printchar('\n')
+ self._printchar("\n")
 
  def _printline(self, string, invert):
  rstr = None
  if self.wrap and self.stringlen(string, True): # Length > self.screenwidth
  pos = 0
  lstr = string[:]
  while self.stringlen(lstr, True): # Length > self.screenwidth
- pos = lstr.rfind(' ')
+ pos = lstr.rfind(" ")
  lstr = lstr[:pos].rstrip()
  if pos > 0:
- rstr = string[pos + 1:]
+ rstr = string[pos + 1 :]
  string = lstr
- 
+
  for char in string:
  self._printchar(char, invert)
  if rstr is not None:
- self._printchar('\n')
+ self._printchar("\n")
  self._printline(rstr, invert) # Recurse
 
  def stringlen(self, string, oh=False):
@@ -176,7 +180,7 @@ def _truelen(self, char):
  mc = 0 # Max non-blank column
  data = glyph[(wd - 1) // 8] # Last byte of row 0
  for row in range(ht): # Glyph row
- for col in range(wd -1, -1, -1): # Glyph column
+ for col in range(wd - 1, -1, -1): # Glyph column
  gbyte, gbit = divmod(col, 8)
  if gbit == 0: # Next glyph byte
  data = glyph[row * gbytes + gbyte]
@@ -187,47 +191,42 @@ def _truelen(self, char):
  break
  if mc + 1 == wd:
  break # All done: no trailing space
- # print('Truelen', char, wd, mc + 1) # TEST 
+ # print('Truelen', char, wd, mc + 1) # TEST
  return mc + 1
 
  def _get_char(self, char, recurse):
  if not recurse: # Handle tabs
- if char == '\n':
+ if char == "\n":
  self.cpos = 0
- elif char == '\t':
+ elif char == "\t":
  nspaces = self.tab - (self.cpos % self.tab)
  if nspaces == 0:
  nspaces = self.tab
  while nspaces:
  nspaces -= 1
- self._printchar(' ', recurse=True)
+ self._printchar(" ", recurse=True)
  self.glyph = None # All done
  return
 
  self.glyph = None # Assume all done
- if char == '\n':
+ if char == "\n":
  self._newline()
  return
  glyph, char_height, char_width = self.font.get_ch(char)
  s = self._getstate()
- np = None # Allow restriction on printable columns
  if s.text_row + char_height > self.screenheight:
  if self.row_clip:
  return
  self._newline()
- oh = s.text_col + char_width - self.screenwidth # Overhang (+ve)
- if oh > 0:
+ if s.text_col + char_width - self.screenwidth > 0: # Glyph would overhang
  if self.col_clip or self.wrap:
- np = char_width - oh # No. of printable columns
- if np <= 0:
- return
+ return # Can't clip a glyph: discard
  else:
  self._newline()
  self.glyph = glyph
  self.char_height = char_height
  self.char_width = char_width
- self.clip_width = char_width if np is None else np
- 
+
  # Method using blitting. Efficient rendering for monochrome displays.
  # Tested on SSD1306. Invert is for black-on-white rendering.
  def _printchar(self, char, invert=False, recurse=False):
@@ -238,8 +237,8 @@ def _printchar(self, char, invert=False, recurse=False):
  buf = bytearray(self.glyph)
  if invert:
  for i, v in enumerate(buf):
- buf[i] = 0xFF & ~ v
- fbc = framebuf.FrameBuffer(buf, self.clip_width, self.char_height, self.map)
+ buf[i] = 0xFF & ~v
+ fbc = framebuf.FrameBuffer(buf, self.char_width, self.char_height, self.map)
  self.device.blit(fbc, s.text_col, s.text_row)
  s.text_col += self.char_width
  self.cpos += 1
@@ -252,26 +251,24 @@ def tabsize(self, value=None):
  def setcolor(self, *_):
  return self.fgcolor, self.bgcolor
 
+
 # Writer for colour displays.
 class CWriter(Writer):
-
  @staticmethod
  def create_color(ssd, idx, r, g, b):
  c = ssd.rgb(r, g, b)
- if not hasattr(ssd, 'lut'):
+ if not hasattr(ssd, "lut"):
  return c
  if not 0 <= idx <= 15:
- raise ValueError('Color nos must be 0..15')
+ raise ValueError("Color nos must be 0..15")
  x = idx << 1
- ssd.lut[x] = c & 0xff
+ ssd.lut[x] = c & 0xFF
  ssd.lut[x + 1] = c >> 8
  return idx
 
  def __init__(self, device, font, fgcolor=None, bgcolor=None, verbose=True):
- if not hasattr(device, 'palette'):
- raise OSError('Incompatible device driver.')
- if implementation[1] < (1, 17, 0):
- raise OSError('Firmware must be >= 1.17.')
+ if not hasattr(device, "palette"):
+ raise OSError("Incompatible device driver.")
 
  super().__init__(device, font, verbose)
  if bgcolor is not None: # Assume monochrome.
@@ -287,7 +284,7 @@ def _printchar(self, char, invert=False, recurse=False):
  if self.glyph is None:
  return # All done
  buf = bytearray_at(addressof(self.glyph), len(self.glyph))
- fbc = framebuf.FrameBuffer(buf, self.clip_width, self.char_height, self.map)
+ fbc = framebuf.FrameBuffer(buf, self.char_width, self.char_height, self.map)
  palette = self.device.palette
  palette.bg(self.fgcolor if invert else self.bgcolor)
  palette.fg(self.bgcolor if invert else self.fgcolor)