426 lines
No EOL
16 KiB
Python
426 lines
No EOL
16 KiB
Python
# scroll.py
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#
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# Copied from the stig project by rndusr@github
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# https://github.com/rndusr/stig
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation, either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details
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# http://www.gnu.org/licenses/gpl-3.0.txt
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import urwid
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from urwid.widget import BOX, FIXED, FLOW
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# Scroll actions
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SCROLL_LINE_UP = 'line up'
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SCROLL_LINE_DOWN = 'line down'
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SCROLL_PAGE_UP = 'page up'
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SCROLL_PAGE_DOWN = 'page down'
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SCROLL_TO_TOP = 'to top'
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SCROLL_TO_END = 'to end'
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# Scrollbar positions
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SCROLLBAR_LEFT = 'left'
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SCROLLBAR_RIGHT = 'right'
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class Scrollable(urwid.WidgetDecoration):
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def sizing(self):
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return frozenset([BOX,])
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def selectable(self):
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return True
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def __init__(self, widget):
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"""Box widget that makes a fixed or flow widget vertically scrollable
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TODO: Focusable widgets are handled, including switching focus, but
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possibly not intuitively, depending on the arrangement of widgets. When
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switching focus to a widget that is outside of the visible part of the
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original widget, the canvas scrolls up/down to the focused widget. It
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would be better to scroll until the next focusable widget is in sight
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first. But for that to work we must somehow obtain a list of focusable
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rows in the original canvas.
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"""
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if not any(s in widget.sizing() for s in (FIXED, FLOW)):
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raise ValueError('Not a fixed or flow widget: %r' % widget)
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self._trim_top = 0
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self._scroll_action = None
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self._forward_keypress = None
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self._old_cursor_coords = None
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self._rows_max_cached = 0
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self.__super.__init__(widget)
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def render(self, size, focus=False):
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maxcol, maxrow = size
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# Render complete original widget
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ow = self._original_widget
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ow_size = self._get_original_widget_size(size)
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canv_full = ow.render(ow_size, focus)
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# Make full canvas editable
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canv = urwid.CompositeCanvas(canv_full)
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canv_cols, canv_rows = canv.cols(), canv.rows()
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if canv_cols <= maxcol:
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pad_width = maxcol - canv_cols
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if pad_width > 0:
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# Canvas is narrower than available horizontal space
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canv.pad_trim_left_right(0, pad_width)
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if canv_rows <= maxrow:
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fill_height = maxrow - canv_rows
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if fill_height > 0:
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# Canvas is lower than available vertical space
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canv.pad_trim_top_bottom(0, fill_height)
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if canv_cols <= maxcol and canv_rows <= maxrow:
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# Canvas is small enough to fit without trimming
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return canv
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self._adjust_trim_top(canv, size)
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# Trim canvas if necessary
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trim_top = self._trim_top
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trim_end = canv_rows - maxrow - trim_top
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trim_right = canv_cols - maxcol
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if trim_top > 0:
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canv.trim(trim_top)
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if trim_end > 0:
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canv.trim_end(trim_end)
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if trim_right > 0:
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canv.pad_trim_left_right(0, -trim_right)
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# Disable cursor display if cursor is outside of visible canvas parts
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if canv.cursor is not None:
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curscol, cursrow = canv.cursor
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if cursrow >= maxrow or cursrow < 0:
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canv.cursor = None
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# Figure out whether we should forward keypresses to original widget
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if canv.cursor is not None:
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# Trimmed canvas contains the cursor, e.g. in an Edit widget
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self._forward_keypress = True
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else:
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if canv_full.cursor is not None:
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# Full canvas contains the cursor, but scrolled out of view
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self._forward_keypress = False
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else:
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# Original widget does not have a cursor, but may be selectable
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# FIXME: Using ow.selectable() is bad because the original
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# widget may be selectable because it's a container widget with
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# a key-grabbing widget that is scrolled out of view.
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# ow.selectable() returns True anyway because it doesn't know
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# how we trimmed our canvas.
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#
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# To fix this, we need to resolve ow.focus and somehow
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# ask canv whether it contains bits of the focused widget. I
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# can't see a way to do that.
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if ow.selectable():
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self._forward_keypress = True
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else:
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self._forward_keypress = False
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return canv
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def keypress(self, size, key):
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# Maybe offer key to original widget
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if self._forward_keypress:
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ow = self._original_widget
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ow_size = self._get_original_widget_size(size)
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# Remember previous cursor position if possible
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if hasattr(ow, 'get_cursor_coords'):
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self._old_cursor_coords = ow.get_cursor_coords(ow_size)
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key = ow.keypress(ow_size, key)
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if key is None:
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return None
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# Handle up/down, page up/down, etc
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command_map = self._command_map
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if command_map[key] == urwid.CURSOR_UP:
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self._scroll_action = SCROLL_LINE_UP
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elif command_map[key] == urwid.CURSOR_DOWN:
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self._scroll_action = SCROLL_LINE_DOWN
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elif command_map[key] == urwid.CURSOR_PAGE_UP:
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self._scroll_action = SCROLL_PAGE_UP
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elif command_map[key] == urwid.CURSOR_PAGE_DOWN:
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self._scroll_action = SCROLL_PAGE_DOWN
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elif command_map[key] == urwid.CURSOR_MAX_LEFT: # 'home'
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self._scroll_action = SCROLL_TO_TOP
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elif command_map[key] == urwid.CURSOR_MAX_RIGHT: # 'end'
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self._scroll_action = SCROLL_TO_END
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else:
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return key
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self._invalidate()
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def mouse_event(self, size, event, button, col, row, focus):
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ow = self._original_widget
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if hasattr(ow, 'mouse_event'):
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ow_size = self._get_original_widget_size(size)
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row += self._trim_top
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return ow.mouse_event(ow_size, event, button, col, row, focus)
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else:
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return False
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def _adjust_trim_top(self, canv, size):
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"""Adjust self._trim_top according to self._scroll_action"""
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action = self._scroll_action
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self._scroll_action = None
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maxcol, maxrow = size
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trim_top = self._trim_top
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canv_rows = canv.rows()
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if trim_top < 0:
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# Negative trim_top values use bottom of canvas as reference
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trim_top = canv_rows - maxrow + trim_top + 1
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if canv_rows <= maxrow:
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self._trim_top = 0 # Reset scroll position
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return
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def ensure_bounds(new_trim_top):
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return max(0, min(canv_rows - maxrow, new_trim_top))
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if action == SCROLL_LINE_UP:
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self._trim_top = ensure_bounds(trim_top - 1)
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elif action == SCROLL_LINE_DOWN:
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self._trim_top = ensure_bounds(trim_top + 1)
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elif action == SCROLL_PAGE_UP:
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self._trim_top = ensure_bounds(trim_top - maxrow + 1)
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elif action == SCROLL_PAGE_DOWN:
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self._trim_top = ensure_bounds(trim_top + maxrow - 1)
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elif action == SCROLL_TO_TOP:
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self._trim_top = 0
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elif action == SCROLL_TO_END:
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self._trim_top = canv_rows - maxrow
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else:
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self._trim_top = ensure_bounds(trim_top)
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# If the cursor was moved by the most recent keypress, adjust trim_top
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# so that the new cursor position is within the displayed canvas part.
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# But don't do this if the cursor is at the top/bottom edge so we can still scroll out
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if self._old_cursor_coords is not None and self._old_cursor_coords != canv.cursor:
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self._old_cursor_coords = None
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curscol, cursrow = canv.cursor
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if cursrow < self._trim_top:
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self._trim_top = cursrow
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elif cursrow >= self._trim_top + maxrow:
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self._trim_top = max(0, cursrow - maxrow + 1)
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def _get_original_widget_size(self, size):
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ow = self._original_widget
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sizing = ow.sizing()
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if FIXED in sizing:
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return ()
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elif FLOW in sizing:
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return (size[0],)
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def get_scrollpos(self, size=None, focus=False):
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"""Current scrolling position
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Lower limit is 0, upper limit is the maximum number of rows with the
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given maxcol minus maxrow.
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NOTE: The returned value may be too low or too high if the position has
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changed but the widget wasn't rendered yet.
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"""
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return self._trim_top
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def set_scrollpos(self, position):
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"""Set scrolling position
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If `position` is positive it is interpreted as lines from the top.
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If `position` is negative it is interpreted as lines from the bottom.
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Values that are too high or too low values are automatically adjusted
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during rendering.
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"""
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self._trim_top = int(position)
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self._invalidate()
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def rows_max(self, size=None, focus=False):
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"""Return the number of rows for `size`
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If `size` is not given, the currently rendered number of rows is returned.
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"""
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if size is not None:
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ow = self._original_widget
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ow_size = self._get_original_widget_size(size)
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sizing = ow.sizing()
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if FIXED in sizing:
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self._rows_max_cached = ow.pack(ow_size, focus)[1]
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elif FLOW in sizing:
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self._rows_max_cached = ow.rows(ow_size, focus)
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else:
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raise RuntimeError('Not a flow/box widget: %r' % self._original_widget)
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return self._rows_max_cached
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class ScrollBar(urwid.WidgetDecoration):
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def sizing(self):
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return frozenset((BOX,))
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def selectable(self):
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return True
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def __init__(self, widget, thumb_char=u'\u2588', trough_char=' ',
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side=SCROLLBAR_RIGHT, width=1):
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"""Box widget that adds a scrollbar to `widget`
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`widget` must be a box widget with the following methods:
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- `get_scrollpos` takes the arguments `size` and `focus` and returns
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the index of the first visible row.
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- `set_scrollpos` (optional; needed for mouse click support) takes the
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index of the first visible row.
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- `rows_max` takes `size` and `focus` and returns the total number of
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rows `widget` can render.
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`thumb_char` is the character used for the scrollbar handle.
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`trough_char` is used for the space above and below the handle.
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`side` must be 'left' or 'right'.
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`width` specifies the number of columns the scrollbar uses.
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"""
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if BOX not in widget.sizing():
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raise ValueError('Not a box widget: %r' % widget)
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self.__super.__init__(widget)
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self._thumb_char = thumb_char
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self._trough_char = trough_char
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self.scrollbar_side = side
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self.scrollbar_width = max(1, width)
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self._original_widget_size = (0, 0)
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def render(self, size, focus=False):
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maxcol, maxrow = size
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sb_width = self._scrollbar_width
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ow_size = (max(0, maxcol - sb_width), maxrow)
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sb_width = maxcol - ow_size[0]
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ow = self._original_widget
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ow_base = self.scrolling_base_widget
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ow_rows_max = ow_base.rows_max(size, focus)
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if ow_rows_max <= maxrow:
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# Canvas fits without scrolling - no scrollbar needed
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self._original_widget_size = size
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return ow.render(size, focus)
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ow_rows_max = ow_base.rows_max(ow_size, focus)
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ow_canv = ow.render(ow_size, focus)
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self._original_widget_size = ow_size
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pos = ow_base.get_scrollpos(ow_size, focus)
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posmax = ow_rows_max - maxrow
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# Thumb shrinks/grows according to the ratio of
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# <number of visible lines> / <number of total lines>
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thumb_weight = min(1, maxrow / max(1, ow_rows_max))
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thumb_height = max(1, round(thumb_weight * maxrow))
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# Thumb may only touch top/bottom if the first/last row is visible
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top_weight = float(pos) / max(1, posmax)
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top_height = int((maxrow - thumb_height) * top_weight)
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if top_height == 0 and top_weight > 0:
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top_height = 1
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# Bottom part is remaining space
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bottom_height = maxrow - thumb_height - top_height
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assert thumb_height + top_height + bottom_height == maxrow
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# Create scrollbar canvas
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# Creating SolidCanvases of correct height may result in "cviews do not
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# fill gaps in shard_tail!" or "cviews overflow gaps in shard_tail!"
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# exceptions. Stacking the same SolidCanvas is a workaround.
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# https://github.com/urwid/urwid/issues/226#issuecomment-437176837
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top = urwid.SolidCanvas(self._trough_char, sb_width, 1)
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thumb = urwid.SolidCanvas(self._thumb_char, sb_width, 1)
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bottom = urwid.SolidCanvas(self._trough_char, sb_width, 1)
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sb_canv = urwid.CanvasCombine(
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[(top, None, False)] * top_height +
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[(thumb, None, False)] * thumb_height +
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[(bottom, None, False)] * bottom_height,
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)
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combinelist = [(ow_canv, None, True, ow_size[0]),
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(sb_canv, None, False, sb_width)]
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if self._scrollbar_side != SCROLLBAR_LEFT:
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return urwid.CanvasJoin(combinelist)
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else:
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return urwid.CanvasJoin(reversed(combinelist))
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@property
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def scrollbar_width(self):
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"""Columns the scrollbar uses"""
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return max(1, self._scrollbar_width)
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@scrollbar_width.setter
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def scrollbar_width(self, width):
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self._scrollbar_width = max(1, int(width))
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self._invalidate()
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@property
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def scrollbar_side(self):
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"""Where to display the scrollbar; must be 'left' or 'right'"""
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return self._scrollbar_side
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@scrollbar_side.setter
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def scrollbar_side(self, side):
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if side not in (SCROLLBAR_LEFT, SCROLLBAR_RIGHT):
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raise ValueError('scrollbar_side must be "left" or "right", not %r' % side)
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self._scrollbar_side = side
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self._invalidate()
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@property
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def scrolling_base_widget(self):
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"""Nearest `original_widget` that is compatible with the scrolling API"""
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def orig_iter(w):
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while hasattr(w, 'original_widget'):
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w = w.original_widget
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yield w
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yield w
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def is_scrolling_widget(w):
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return hasattr(w, 'get_scrollpos') and hasattr(w, 'rows_max')
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for w in orig_iter(self):
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if is_scrolling_widget(w):
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return w
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raise ValueError('Not compatible to be wrapped by ScrollBar: %r' % w)
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def keypress(self, size, key):
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return self._original_widget.keypress(self._original_widget_size, key)
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def mouse_event(self, size, event, button, col, row, focus):
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ow = self._original_widget
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ow_size = self._original_widget_size
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handled = False
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if hasattr(ow, 'mouse_event'):
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handled = ow.mouse_event(ow_size, event, button, col, row, focus)
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if not handled and hasattr(ow, 'set_scrollpos'):
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if button == 4: # scroll wheel up
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pos = ow.get_scrollpos(ow_size)
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ow.set_scrollpos(pos - 1)
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return True
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elif button == 5: # scroll wheel down
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pos = ow.get_scrollpos(ow_size)
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ow.set_scrollpos(pos + 1)
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return True
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return False |