code / btui

   1 #!/usr/bin/env python3
   2 #
   3 # bed - the BTUI editor
   4 #
   5 # This is a simple example program demonstrating a minimal text editor
   6 # implemented with the Python BTUI bindings.
   7 #
   8 # Usage: ./bed.py [-d|--debug] <file>
   9 # You can move around with arrow keys, PgUp/PgDn and make basic file edits.
  10 # Save with Ctrl-S, Quit with Ctrl-Q or Ctrl-C
  11 #
  12 import sys
  13 import btui
  14 from collections import namedtuple
  15 
  16 Vec2 = namedtuple('Vec2', 'x y')
  17 
  18 def clamp(x, low, high):
  19     if x < low: return low
  20     elif x > high: return high
  21     return x
  22 
  23 class BedFile:
  24     def __init__(self, bt, lines, pos=Vec2(0,0), size=None):
  25         self.bt = bt
  26         self.lines = lines
  27         self.drawn = set()
  28         self.numlen = len(str(len(self.lines)))
  29         self.pos = pos
  30         self.size = size if size else Vec2(self.bt.width-pos.x, self.bt.height-pos.y)
  31         self.scroll = 0
  32         self._cursor = Vec2(0, 0)
  33         self.unsaved = False
  34 
  35     @property
  36     def cursor(self):
  37         return self._cursor
  38 
  39     @cursor.setter
  40     def cursor(self, p):
  41         x, y = p.x, p.y
  42         y = clamp(y, 0, len(self.lines)-1)
  43         x = clamp(x, 0, len(self.lines[y]))
  44         self._cursor = Vec2(x, y)
  45 
  46     def update_term_cursor(self):
  47         self.bt.move(self.pos.x + self.numlen + 1 + self.cursor.x,
  48                      self.pos.y + self.cursor.y - self.scroll)
  49 
  50     def set_scroll(self, newscroll):
  51         newscroll = clamp(newscroll, 0, len(self.lines)-1 - (self.size.y-1))
  52         if newscroll == self.scroll: return
  53         delta = newscroll - self.scroll
  54         self.bt.scroll(self.pos.y, self.pos.y + self.size.y - 1, delta)
  55         self.scroll = newscroll
  56         self.drawn &= set(range(self.scroll, self.scroll + (self.size.y-1)+1))
  57         if self.cursor.y < newscroll:
  58             self.cursor = Vec2(self.cursor.x, newscroll)
  59         elif self.cursor.y > newscroll + (self.size.y-1):
  60             self.cursor = Vec2(self.cursor.x, newscroll + (self.size.y-1))
  61 
  62     def handle_input(self, key, mx=None, my=None):
  63         if key == 'Space': key = ' '
  64         if key == 'Tab': key = '    '
  65 
  66         if key == 'Left':
  67             self.cursor = Vec2(self.cursor.x - 1, self.cursor.y)
  68         elif key == 'Right':
  69             self.cursor = Vec2(self.cursor.x + 1, self.cursor.y)
  70         elif key == 'Up':
  71             self.cursor = Vec2(self.cursor.x, self.cursor.y - 1)
  72             if self.cursor.y < self.scroll:
  73                 self.set_scroll(self.cursor.y)
  74         elif key == 'Down':
  75             self.cursor = Vec2(self.cursor.x, self.cursor.y + 1)
  76             newscroll = clamp(self.scroll, self.cursor.y - (self.size.y-1), self.cursor.y)
  77             if self.cursor.y > self.scroll + (self.size.y-1):
  78                 self.set_scroll(self.cursor.y - (self.size.y-1))
  79         elif key == 'Home' or key == 'Ctrl-a':
  80             self.cursor = Vec2(0, self.cursor.y)
  81         elif key == 'End' or key == 'Ctrl-e':
  82             self.cursor = Vec2(len(self.lines[self.cursor.y]), self.cursor.y)
  83         elif key == 'Page Down' or key == 'Ctrl-d':
  84             self.set_scroll(self.scroll + self.bt.height // 2)
  85         elif key == 'Page Up' or key == 'Ctrl-u':
  86             self.set_scroll(self.scroll - self.bt.height // 2)
  87         elif key == 'Delete':
  88             line = self.lines[self.cursor.y]
  89             i = self.cursor.x
  90             if i == len(line) and self.cursor.y < len(self.lines)-1:
  91                 line.extend(self.lines.pop(self.cursor.y+1))
  92                 self.drawn &= {d for d in self.drawn if d < self.cursor.y or d >= len(self.lines)+1}
  93                 self.unsaved = True
  94             elif i < len(line):
  95                 del line[i:i+1]
  96                 self.drawn.discard(self.cursor.y)
  97                 self.unsaved = True
  98         elif key == 'Backspace':
  99             line = self.lines[self.cursor.y]
 100             i = self.cursor.x
 101             if i == 0 and self.cursor.y > 0:
 102                 self.lines.pop(self.cursor.y)
 103                 prevline = self.lines[self.cursor.y - 1]
 104                 self.cursor = Vec2(len(prevline), self.cursor.y-1)
 105                 prevline.extend(line)
 106                 self.drawn &= {d for d in self.drawn if d < self.cursor.y or d >= len(self.lines)+1}
 107                 self.unsaved = True
 108             elif i > 0:
 109                 del line[i-1:i]
 110                 self.drawn.discard(self.cursor.y)
 111                 self.cursor = Vec2(self.cursor.x - 1, self.cursor.y)
 112                 self.unsaved = True
 113         elif key == 'Enter':
 114             line = self.lines[self.cursor.y]
 115             before, after = line[:self.cursor.x], line[self.cursor.x:]
 116             self.lines[self.cursor.y] = before
 117             self.lines.insert(self.cursor.y+1, after)
 118             self.drawn &= {d for d in self.drawn if d < self.cursor.y or d >= len(self.lines)}
 119             self.cursor = Vec2(0, self.cursor.y + 1)
 120             self.unsaved = True
 121         elif key == 'Left release':
 122             self.cursor = Vec2(mx-(self.numlen + 1), my - 1 + self.scroll)
 123         elif key == 'Mouse wheel down':
 124             self.set_scroll(self.scroll + 3)
 125         elif key == 'Mouse wheel up':
 126             self.set_scroll(self.scroll - 3)
 127         elif key and (len(key) == 1 or key == '    '):
 128             line = self.lines[self.cursor.y]
 129             i = self.cursor.x
 130             line[i:i] = bytearray(key, 'utf8')
 131             self.cursor = Vec2(self.cursor.x + len(key), self.cursor.y)
 132             self.drawn.discard(self.cursor.y)
 133             self.unsaved = True
 134 
 135     def render(self):
 136         self.bt.hide_cursor()
 137         for i in range(self.size.y):
 138             lineno = self.scroll + i
 139             if lineno in self.drawn: continue
 140             y = self.pos.y + i
 141             x = self.pos.x
 142             self.bt.move(x, y)
 143             if lineno >= len(self.lines):
 144                 self.bt.clear(btui.ClearType.LINE)
 145                 self.drawn.add(lineno)
 146                 continue
 147             with self.bt.attributes("faint"):
 148                 self.bt.write(("{:>"+str(self.numlen)+"}").format(lineno + 1))
 149                 x += self.numlen + 1
 150             self.bt.move(x, y)
 151             self.bt.write_bytes(bytes(self.lines[lineno]))
 152             self.bt.clear(btui.ClearType.RIGHT)
 153             self.drawn.add(lineno)
 154 
 155 class BED:
 156     def __init__(self, bt, filename):
 157         self.bt = bt
 158         self.filename = filename
 159         try:
 160             lines = [bytearray(line.rstrip(b'\n')) for line in open(filename, 'rb').readlines()]
 161         except FileNotFoundError:
 162             lines = [bytearray(b'')]
 163         self.file = BedFile(bt, lines, Vec2(0, 1), Vec2(bt.width, bt.height-2))
 164         self.drawn = set()
 165         self.renders = 0
 166 
 167     def edit(self):
 168         self.bt.set_cursor(btui.CursorType.BLINKING_BAR)
 169         self.render()
 170         key, mx, my = self.bt.getkey()
 171         while True:
 172             if key == 'Ctrl-c':
 173                 sys.exit(1)
 174             elif key == 'Ctrl-q':
 175                 if self.file.unsaved:
 176                     self.confirm_save()
 177                 break
 178             elif key == 'Ctrl-s':
 179                 self.save()
 180             else:
 181                 self.file.handle_input(key, mx, my)
 182             self.render()
 183             key, mx, my = self.bt.getkey()
 184 
 185     def confirm_save(self):
 186         self.bt.move(0, self.bt.height)
 187         with self.bt.attributes('bold'):
 188             self.bt.write(f"Do you want to save {self.filename}? [y/n]")
 189         key, mx, my = self.bt.getkey()
 190         if key in ('y', 'Y'):
 191             self.save()
 192             return True
 193         elif key in ('n', 'N', 'Ctrl-c', 'Escape', 'Ctrl-q'):
 194             return False
 195 
 196     def save(self):
 197         with open(self.filename, 'wb') as f:
 198             for line in self.file.lines:
 199                 f.write(line)
 200                 f.write(b'\n')
 201         self.file.unsaved = False
 202 
 203     def render(self):
 204         self.renders += 1
 205 
 206         k = 'title-modified' if self.file.unsaved else 'title'
 207         if k not in self.drawn:
 208             self.drawn -= {'title', 'title-modified'}
 209             self.bt.move(0,0)
 210             with self.bt.attributes("bold"):
 211                 self.bt.write(self.filename)
 212             if self.file.unsaved:
 213                 with self.bt.attributes("dim"):
 214                     self.bt.write(" (modified)")
 215             self.bt.clear(btui.ClearType.RIGHT)
 216             self.drawn.add(k)
 217 
 218         self.file.render()
 219 
 220         # Just redraw this every time:
 221         with self.bt.attributes("bold"):
 222             self.bt.move(0, self.bt.height-1)
 223             self.bt.write("Ctrl-Q to quit, Ctrl-S to save")
 224             self.bt.clear(btui.ClearType.RIGHT)
 225         with self.bt.attributes("faint"):
 226             s = f"Line {self.file.cursor.y}, Col {self.file.cursor.x}, {self.renders} redraws"
 227             self.bt.move(self.bt.width-len(s), self.bt.height-1)
 228             self.bt.write(s)
 229 
 230         self.file.update_term_cursor()
 231         self.bt.show_cursor()
 232 
 233 
 234 if __name__ == '__main__':
 235     args = sys.argv[1:]
 236     debug = False
 237     if args and args[0] in ('-d', '--debug'):
 238         args.pop(0)
 239         debug = True
 240 
 241     if not args:
 242         print("Usage: bed.py [-d|--debug] file")
 243         sys.exit(1)
 244 
 245     filename = args[0]
 246     with btui.open(debug=debug) as bt:
 247         bed = BED(bt, filename)
 248         bed.edit()