#!/usr/bin/python # # Urwid Text Layout classes # Copyright (C) 2004-2011 Ian Ward # # This library is free software; you can redistribute it and/or # modify it under the terms of the GNU Lesser General Public # License as published by the Free Software Foundation; either # version 2.1 of the License, or (at your option) any later version. # # This library is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU # Lesser General Public License for more details. # # You should have received a copy of the GNU Lesser General Public # License along with this library; if not, write to the Free Software # Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA # # Urwid web site: https://urwid.org/ from __future__ import annotations import typing from urwid.util import calc_text_pos, calc_trim_text, calc_width, is_wide_char, move_next_char, move_prev_char if typing.TYPE_CHECKING: from typing_extensions import Literal class TextLayout: def supports_align_mode(self, align): """Return True if align is a supported align mode.""" return True def supports_wrap_mode(self, wrap): """Return True if wrap is a supported wrap mode.""" return True def layout(self, text, width, align, wrap ): """ Return a layout structure for text. :param text: string in current encoding or unicode string :param width: number of screen columns available :param align: align mode for text :param wrap: wrap mode for text Layout structure is a list of line layouts, one per output line. Line layouts are lists than may contain the following tuples: * (column width of text segment, start offset, end offset) * (number of space characters to insert, offset or None) * (column width of insert text, offset, "insert text") The offset in the last two tuples is used to determine the attribute used for the inserted spaces or text respectively. The attribute used will be the same as the attribute at that text offset. If the offset is None when inserting spaces then no attribute will be used. """ raise NotImplementedError( "This function must be overridden by a real text layout class. (see StandardTextLayout)" ) class CanNotDisplayText(Exception): pass class StandardTextLayout(TextLayout): def __init__(self):#, tab_stops=(), tab_stop_every=8): pass #""" #tab_stops -- list of screen column indexes for tab stops #tab_stop_every -- repeated interval for following tab stops #""" #assert tab_stop_every is None or type(tab_stop_every)==int #if not tab_stops and tab_stop_every: # self.tab_stops = (tab_stop_every,) #self.tab_stops = tab_stops #self.tab_stop_every = tab_stop_every def supports_align_mode(self, align: str) -> bool: """Return True if align is 'left', 'center' or 'right'.""" return align in ('left', 'center', 'right') def supports_wrap_mode(self, wrap: str) -> bool: """Return True if wrap is 'any', 'space', 'clip' or 'ellipsis'.""" return wrap in ('any', 'space', 'clip', 'ellipsis') def layout( self, text, width: int, align: Literal['left', 'center', 'right'], wrap: Literal['any', 'space', 'clip', 'ellipsis'], ): """Return a layout structure for text.""" try: segs = self.calculate_text_segments( text, width, wrap ) return self.align_layout( text, width, segs, wrap, align ) except CanNotDisplayText: return [[]] def pack(self, maxcol: int, layout) -> int: """ Return a minimal maxcol value that would result in the same number of lines for layout. layout must be a layout structure returned by self.layout(). """ maxwidth = 0 assert layout, f"huh? empty layout?: {layout!r}" for l in layout: lw = line_width(l) if lw >= maxcol: return maxcol maxwidth = max(maxwidth, lw) return maxwidth def align_layout( self, text, width: int, segs, wrap: Literal['any', 'space', 'clip', 'ellipsis'], align: Literal['left', 'center', 'right'], ): """Convert the layout segs to an aligned layout.""" out = [] for l in segs: sc = line_width(l) if sc == width or align=='left': out.append(l) continue if align == 'right': out.append([(width-sc, None)] + l) continue assert align == 'center' pad_trim_left = (width-sc+1) // 2 out.append([(pad_trim_left, None)] + l if pad_trim_left else l) return out def calculate_text_segments( self, text, width: int, wrap: Literal['any', 'space', 'clip', 'ellipsis'], ): """ Calculate the segments of text to display given width screen columns to display them. text - unicode text or byte string to display width - number of available screen columns wrap - wrapping mode used Returns a layout structure without alignment applied. """ nl, nl_o, sp_o = "\n", "\n", " " if isinstance(text, bytes): nl = nl.encode('iso8859-1') # can only find bytes in python3 bytestrings nl_o = ord(nl_o) # + an item of a bytestring is the ordinal value sp_o = ord(sp_o) b = [] p = 0 if wrap in ('clip', 'ellipsis'): # no wrapping to calculate, so it's easy. while p <= len(text): n_cr = text.find(nl, p) if n_cr == -1: n_cr = len(text) sc = calc_width(text, p, n_cr) # trim line to max width if needed, add ellipsis if trimmed if wrap == 'ellipsis' and sc > width: trimmed = True spos, n_end, pad_left, pad_right = calc_trim_text(text, p, n_cr, 0, width-1) # pad_left should be 0, because the start_col parameter was 0 (no trimming on the left) # similarly spos should not be changed from p assert pad_left == 0 assert spos == p sc = width - 1 - pad_right else: trimmed = False n_end = n_cr pad_right = 0 l = [] if p!=n_end: l += [(sc, p, n_end)] if trimmed: l += [(1, n_end, '…'.encode())] l += [(pad_right,n_end)] b.append(l) p = n_cr+1 return b while p <= len(text): # look for next eligible line break n_cr = text.find(nl, p) if n_cr == -1: n_cr = len(text) sc = calc_width(text, p, n_cr) if sc == 0: # removed character hint b.append([(0, n_cr)]) p = n_cr + 1 continue if sc <= width: # this segment fits b.append([(sc, p, n_cr), (0, n_cr)]) # removed character hint p = n_cr + 1 continue pos, sc = calc_text_pos( text, p, n_cr, width ) if pos == p: # pathological width=1 double-byte case raise CanNotDisplayText("Wide character will not fit in 1-column width") if wrap == 'any': b.append([(sc, p, pos)]) p = pos continue assert wrap == 'space' if text[pos] == sp_o: # perfect space wrap b.append([(sc, p, pos), (0,pos)]) # removed character hint p = pos + 1 continue if is_wide_char(text, pos): # perfect next wide b.append([(sc, p, pos)]) p = pos continue prev = pos while prev > p: prev = move_prev_char(text, p, prev) if text[prev] == sp_o: sc = calc_width(text, p, prev) l = [(0, prev)] if p != prev: l = [(sc, p, prev)] + l b.append(l) p = prev+1 break if is_wide_char(text, prev): # wrap after wide char next = move_next_char(text, prev, pos) sc = calc_width(text, p, next) b.append([(sc, p, next)]) p = next break else: # unwrap previous line space if possible to # fit more text (we're breaking a word anyway) if b and (len(b[-1]) == 2 or (len(b[-1]) == 1 and len(b[-1][0]) == 2)): # look for removed space above if len(b[-1]) == 1: [(h_sc, h_off)] = b[-1] p_sc = 0 p_off = p_end = h_off else: [(p_sc, p_off, p_end), (h_sc, h_off)] = b[-1] if p_sc < width and h_sc == 0 and text[h_off] == sp_o: # combine with previous line del b[-1] p = p_off pos, sc = calc_text_pos( text, p, n_cr, width ) b.append([(sc, p, pos)]) # check for trailing " " or "\n" p = pos if p < len(text) and (text[p] in (sp_o, nl_o)): # removed character hint b[-1].append((0, p)) p += 1 continue # force any char wrap b.append([(sc, p, pos)]) p = pos return b ###################################### # default layout object to use default_layout = StandardTextLayout() ###################################### class LayoutSegment: def __init__(self, seg: tuple[int, int, bytes | int] | tuple[int, int | None]) -> None: """Create object from line layout segment structure""" assert isinstance(seg, tuple), repr(seg) assert len(seg) in (2, 3), repr(seg) self.sc, self.offs = seg[:2] assert isinstance(self.sc, int), repr(self.sc) if len(seg) == 3: assert isinstance(self.offs, int), repr(self.offs) assert self.sc > 0, repr(seg) t = seg[2] if isinstance(t, bytes): self.text: bytes | None = t self.end = None else: assert isinstance(t, int), repr(t) self.text = None self.end = t else: assert len(seg) == 2, repr(seg) if self.offs is not None: assert self.sc >= 0, repr(seg) assert isinstance(self.offs, int) self.text = self.end = None def subseg(self, text, start: int, end: int): """ Return a "sub-segment" list containing segment structures that make up a portion of this segment. A list is returned to handle cases where wide characters need to be replaced with a space character at either edge so two or three segments will be returned. """ if start < 0: start = 0 if end > self.sc: end = self.sc if start >= end: return [] # completely gone if self.text: # use text stored in segment (self.text) spos, epos, pad_left, pad_right = calc_trim_text(self.text, 0, len(self.text), start, end) return [(end-start, self.offs, b''.ljust(pad_left) + self.text[spos:epos] + b''.ljust(pad_right))] elif self.end: # use text passed as parameter (text) spos, epos, pad_left, pad_right = calc_trim_text(text, self.offs, self.end, start, end) l = [] if pad_left: l.append((1, spos-1)) l.append((end-start-pad_left-pad_right, spos, epos)) if pad_right: l.append((1, epos)) return l else: # simple padding adjustment return [(end-start ,self.offs)] def line_width(segs): """ Return the screen column width of one line of a text layout structure. This function ignores any existing shift applied to the line, represented by an (amount, None) tuple at the start of the line. """ sc = 0 seglist = segs if segs and len(segs[0]) == 2 and segs[0][1] is None: seglist = segs[1:] for s in seglist: sc += s[0] return sc def shift_line(segs, amount: int): """ Return a shifted line from a layout structure to the left or right. segs -- line of a layout structure amount -- screen columns to shift right (+ve) or left (-ve) """ assert isinstance(amount, int), repr(amount) if segs and len(segs[0]) == 2 and segs[0][1] is None: # existing shift amount += segs[0][0] if amount: return [(amount,None)]+segs[1:] return segs[1:] if amount: return [(amount,None)]+segs return segs def trim_line(segs, text, start: int, end: int): """ Return a trimmed line of a text layout structure. text -- text to which this layout structure applies start -- starting screen column end -- ending screen column """ l = [] x = 0 for seg in segs: sc = seg[0] if start or sc < 0: if start >= sc: start -= sc x += sc continue s = LayoutSegment(seg) if x+sc >= end: # can all be done at once return s.subseg( text, start, end-x ) l += s.subseg( text, start, sc ) start = 0 x += sc continue if x >= end: break if x+sc > end: s = LayoutSegment(seg) l += s.subseg( text, 0, end-x ) break l.append( seg ) return l def calc_line_pos(text, line_layout, pref_col: Literal['left', 'right'] | int): """ Calculate the closest linear position to pref_col given a line layout structure. Returns None if no position found. """ closest_sc = None closest_pos = None current_sc = 0 if pref_col == 'left': for seg in line_layout: s = LayoutSegment(seg) if s.offs is not None: return s.offs return elif pref_col == 'right': for seg in line_layout: s = LayoutSegment(seg) if s.offs is not None: closest_pos = s s = closest_pos if s is None: return if s.end is None: return s.offs return calc_text_pos(text, s.offs, s.end, s.sc-1)[0] for seg in line_layout: s = LayoutSegment(seg) if s.offs is not None: if s.end is not None: if current_sc <= pref_col < current_sc + s.sc: # exact match within this segment return calc_text_pos(text, s.offs, s.end, pref_col - current_sc)[0] elif current_sc <= pref_col: closest_sc = current_sc + s.sc - 1 closest_pos = s if closest_sc is None or (abs(pref_col-current_sc) < abs(pref_col-closest_sc)): # this screen column is closer closest_sc = current_sc closest_pos = s.offs if current_sc > closest_sc: # we're moving past break current_sc += s.sc if closest_pos is None or isinstance(closest_pos, int): return closest_pos # return the last positions in the segment "closest_pos" s = closest_pos return calc_text_pos( text, s.offs, s.end, s.sc-1)[0] def calc_pos(text, layout, pref_col: Literal['left', 'right'] | int, row: int) -> int: """ Calculate the closest linear position to pref_col and row given a layout structure. """ if row < 0 or row >= len(layout): raise ValueError("calculate_pos: out of layout row range") pos = calc_line_pos(text, layout[row], pref_col) if pos is not None: return pos rows_above = list(range(row-1, -1, -1)) rows_below = list(range(row+1, len(layout))) while rows_above and rows_below: if rows_above: r = rows_above.pop(0) pos = calc_line_pos(text, layout[r], pref_col) if pos is not None: return pos if rows_below: r = rows_below.pop(0) pos = calc_line_pos(text, layout[r], pref_col) if pos is not None: return pos return 0 def calc_coords(text, layout, pos, clamp: int = 1): """ Calculate the coordinates closest to position pos in text with layout. text -- raw string or unicode string layout -- layout structure applied to text pos -- integer position into text clamp -- ignored right now """ closest = None y = 0 for line_layout in layout: x = 0 for seg in line_layout: s = LayoutSegment(seg) if s.offs is None: x += s.sc continue if s.offs == pos: return x, y if s.end is not None and s.offs <= pos < s.end: x += calc_width(text, s.offs, pos) return x, y distance = abs(s.offs - pos) if s.end is not None and s.end