Status detail scrollbar feature

Uses scroll.py from https://github.com/rndusr/stig

.flake8

@@ -1,4 +1,4 @@
 [flake8]
-exclude=build,tests,tmp
+exclude=build,tests,tmp,toot/tui/scroll.py
 ignore=E128
 max-line-length=120

toot/tui/scroll.py

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

toot/tui/timeline.py

@@ -7,6 +7,7 @@ from toot.utils.language import language_name
 
 from .utils import highlight_hashtags, parse_datetime, highlight_keys
 from .widgets import SelectableText, SelectableColumns
+from toot.tui.scroll import Scrollable, ScrollBar
 
 logger = logging.getLogger("toot")
 
@@ -43,10 +44,32 @@ class Timeline(urwid.Columns):
         self.can_translate = can_translate
         self.status_list = self.build_status_list(statuses, focus=focus)
         self.followed_tags = followed_tags
+        opts_footer = urwid.Text(self.get_option_text(statuses[focus]))
         try:
-            self.status_details = StatusDetails(statuses[focus], is_thread, can_translate, followed_tags)
+            self.status_details = urwid.Frame(
+                body=ScrollBar(
+                    Scrollable(
+                        urwid.Padding(
+                            StatusDetails(
+                                statuses[focus],
+                                is_thread,
+                                can_translate,
+                                followed_tags,
+                            ),
+                            right=1,
+                        )
+                    ),
+                    thumb_char="\u2588",
+                    trough_char="\u2591",
+                ),
+                footer=opts_footer,
+            )
+
         except IndexError:
-            self.status_details = StatusDetails(None, is_thread, can_translate, followed_tags)
+            # we have no statuses to display
+            self.status_details = StatusDetails(
+                None, is_thread, can_translate, followed_tags
+            )
 
         super().__init__([
             ("weight", 40, self.status_list),
@@ -74,6 +97,25 @@ class Timeline(urwid.Columns):
             None: "green_selected",
         })
 
+    def get_option_text(self, status):
+        options = [
+            "[B]oost",
+            "[D]elete" if status.is_mine else "",
+            "B[o]okmark",
+            "[F]avourite",
+            "[V]iew",
+            "[T]hread" if not self.is_thread else "",
+            "[L]inks",
+            "[R]eply",
+            "So[u]rce",
+            "[Z]oom",
+            "Tra[n]slate" if self.can_translate else "",
+            "[H]elp",
+        ]
+        options = "\n" + " ".join(o for o in options if o)
+        options = highlight_keys(options, "white_bold", "cyan")
+        return options
+
     def get_focused_status(self):
         try:
             return self.statuses[self.status_list.body.focus]
@@ -104,8 +146,23 @@ class Timeline(urwid.Columns):
         self.draw_status_details(status)
 
     def draw_status_details(self, status):
-        self.status_details = StatusDetails(status, self.is_thread, self.can_translate, self.followed_tags)
-        self.contents[2] = urwid.Padding(self.status_details, left=1), ("weight", 60, False)
+        opts_footer = urwid.Text(self.get_option_text(status))
+        self.status_details = StatusDetails(
+            status, self.is_thread, self.can_translate, self.followed_tags
+        )
+        self.contents[2] = (
+            urwid.Padding(
+                urwid.Frame(
+                    body=ScrollBar(
+                        Scrollable(urwid.Padding(self.status_details, right=1)),
+                        thumb_char="\u2588",
+                        trough_char="\u2591",
+                    ),
+                    footer=opts_footer,
+                ),
+                left=1,
+            )
+        ), ("weight", 60, False)
 
     def keypress(self, size, key):
         status = self.get_focused_status()
@@ -339,26 +396,7 @@ class StatusDetails(urwid.Pile):
         ]))
 
         # Push things to bottom
-        yield ("weight", 1, urwid.SolidFill(" "))
-
-        options = [
-            "[B]oost",
-            "[D]elete" if status.is_mine else "",
-            "[F]avourite",
-            "B[o]okmark",
-            "[V]iew",
-            "[T]hread" if not self.in_thread else "",
-            "[L]inks",
-            "[R]eply",
-            "So[u]rce",
-            "[Z]oom",
-            "Tra[n]slate" if self.can_translate else "",
-            "[H]elp",
-        ]
-        options = " ".join(o for o in options if o)
-
-        options = highlight_keys(options, "white_bold", "cyan")
-        yield ("pack", urwid.Text(options))
+        yield ("weight", 1, urwid.BoxAdapter(urwid.SolidFill(" "), 1))
 
     def build_linebox(self, contents):
         contents = urwid.Pile(list(contents))