495 lines
19 KiB
Python
495 lines
19 KiB
Python
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from __future__ import annotations
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from prompt_toolkit.data_structures import Point
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from prompt_toolkit.filters import FilterOrBool, to_filter
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from prompt_toolkit.key_binding import KeyBindingsBase
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from prompt_toolkit.mouse_events import MouseEvent
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from .containers import Container, ScrollOffsets
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from .dimension import AnyDimension, Dimension, sum_layout_dimensions, to_dimension
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from .mouse_handlers import MouseHandler, MouseHandlers
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from .screen import Char, Screen, WritePosition
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__all__ = ["ScrollablePane"]
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# Never go beyond this height, because performance will degrade.
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MAX_AVAILABLE_HEIGHT = 10_000
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class ScrollablePane(Container):
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"""
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Container widget that exposes a larger virtual screen to its content and
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displays it in a vertical scrollbale region.
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Typically this is wrapped in a large `HSplit` container. Make sure in that
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case to not specify a `height` dimension of the `HSplit`, so that it will
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scale according to the content.
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.. note::
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If you want to display a completion menu for widgets in this
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`ScrollablePane`, then it's still a good practice to use a
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`FloatContainer` with a `CompletionsMenu` in a `Float` at the top-level
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of the layout hierarchy, rather then nesting a `FloatContainer` in this
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`ScrollablePane`. (Otherwise, it's possible that the completion menu
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is clipped.)
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:param content: The content container.
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:param scrolloffset: Try to keep the cursor within this distance from the
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top/bottom (left/right offset is not used).
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:param keep_cursor_visible: When `True`, automatically scroll the pane so
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that the cursor (of the focused window) is always visible.
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:param keep_focused_window_visible: When `True`, automatically scroll the
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pane so that the focused window is visible, or as much visible as
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possible if it doesn't completely fit the screen.
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:param max_available_height: Always constraint the height to this amount
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for performance reasons.
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:param width: When given, use this width instead of looking at the children.
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:param height: When given, use this height instead of looking at the children.
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:param show_scrollbar: When `True` display a scrollbar on the right.
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"""
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def __init__(
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self,
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content: Container,
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scroll_offsets: ScrollOffsets | None = None,
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keep_cursor_visible: FilterOrBool = True,
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keep_focused_window_visible: FilterOrBool = True,
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max_available_height: int = MAX_AVAILABLE_HEIGHT,
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width: AnyDimension = None,
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height: AnyDimension = None,
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show_scrollbar: FilterOrBool = True,
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display_arrows: FilterOrBool = True,
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up_arrow_symbol: str = "^",
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down_arrow_symbol: str = "v",
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) -> None:
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self.content = content
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self.scroll_offsets = scroll_offsets or ScrollOffsets(top=1, bottom=1)
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self.keep_cursor_visible = to_filter(keep_cursor_visible)
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self.keep_focused_window_visible = to_filter(keep_focused_window_visible)
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self.max_available_height = max_available_height
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self.width = width
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self.height = height
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self.show_scrollbar = to_filter(show_scrollbar)
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self.display_arrows = to_filter(display_arrows)
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self.up_arrow_symbol = up_arrow_symbol
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self.down_arrow_symbol = down_arrow_symbol
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self.vertical_scroll = 0
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def __repr__(self) -> str:
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return f"ScrollablePane({self.content!r})"
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def reset(self) -> None:
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self.content.reset()
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def preferred_width(self, max_available_width: int) -> Dimension:
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if self.width is not None:
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return to_dimension(self.width)
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# We're only scrolling vertical. So the preferred width is equal to
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# that of the content.
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content_width = self.content.preferred_width(max_available_width)
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# If a scrollbar needs to be displayed, add +1 to the content width.
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if self.show_scrollbar():
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return sum_layout_dimensions([Dimension.exact(1), content_width])
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return content_width
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def preferred_height(self, width: int, max_available_height: int) -> Dimension:
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if self.height is not None:
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return to_dimension(self.height)
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# Prefer a height large enough so that it fits all the content. If not,
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# we'll make the pane scrollable.
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if self.show_scrollbar():
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# If `show_scrollbar` is set. Always reserve space for the scrollbar.
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width -= 1
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dimension = self.content.preferred_height(width, self.max_available_height)
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# Only take 'preferred' into account. Min/max can be anything.
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return Dimension(min=0, preferred=dimension.preferred)
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def write_to_screen(
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self,
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screen: Screen,
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mouse_handlers: MouseHandlers,
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write_position: WritePosition,
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parent_style: str,
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erase_bg: bool,
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z_index: int | None,
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) -> None:
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"""
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Render scrollable pane content.
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This works by rendering on an off-screen canvas, and copying over the
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visible region.
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"""
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show_scrollbar = self.show_scrollbar()
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if show_scrollbar:
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virtual_width = write_position.width - 1
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else:
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virtual_width = write_position.width
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# Compute preferred height again.
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virtual_height = self.content.preferred_height(
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virtual_width, self.max_available_height
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).preferred
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# Ensure virtual height is at least the available height.
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virtual_height = max(virtual_height, write_position.height)
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virtual_height = min(virtual_height, self.max_available_height)
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# First, write the content to a virtual screen, then copy over the
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# visible part to the real screen.
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temp_screen = Screen(default_char=Char(char=" ", style=parent_style))
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temp_screen.show_cursor = screen.show_cursor
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temp_write_position = WritePosition(
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xpos=0, ypos=0, width=virtual_width, height=virtual_height
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)
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temp_mouse_handlers = MouseHandlers()
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self.content.write_to_screen(
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temp_screen,
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temp_mouse_handlers,
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temp_write_position,
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parent_style,
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erase_bg,
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z_index,
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)
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temp_screen.draw_all_floats()
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# If anything in the virtual screen is focused, move vertical scroll to
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from prompt_toolkit.application import get_app
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focused_window = get_app().layout.current_window
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try:
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visible_win_write_pos = temp_screen.visible_windows_to_write_positions[
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focused_window
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]
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except KeyError:
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pass # No window focused here. Don't scroll.
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else:
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# Make sure this window is visible.
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self._make_window_visible(
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write_position.height,
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virtual_height,
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visible_win_write_pos,
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temp_screen.cursor_positions.get(focused_window),
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)
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# Copy over virtual screen and zero width escapes to real screen.
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self._copy_over_screen(screen, temp_screen, write_position, virtual_width)
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# Copy over mouse handlers.
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self._copy_over_mouse_handlers(
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mouse_handlers, temp_mouse_handlers, write_position, virtual_width
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)
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# Set screen.width/height.
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ypos = write_position.ypos
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xpos = write_position.xpos
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screen.width = max(screen.width, xpos + virtual_width)
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screen.height = max(screen.height, ypos + write_position.height)
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# Copy over window write positions.
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self._copy_over_write_positions(screen, temp_screen, write_position)
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if temp_screen.show_cursor:
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screen.show_cursor = True
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# Copy over cursor positions, if they are visible.
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for window, point in temp_screen.cursor_positions.items():
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if (
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0 <= point.x < write_position.width
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and self.vertical_scroll
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<= point.y
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< write_position.height + self.vertical_scroll
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):
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screen.cursor_positions[window] = Point(
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x=point.x + xpos, y=point.y + ypos - self.vertical_scroll
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)
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# Copy over menu positions, but clip them to the visible area.
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for window, point in temp_screen.menu_positions.items():
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screen.menu_positions[window] = self._clip_point_to_visible_area(
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Point(x=point.x + xpos, y=point.y + ypos - self.vertical_scroll),
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write_position,
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)
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# Draw scrollbar.
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if show_scrollbar:
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self._draw_scrollbar(
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write_position,
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virtual_height,
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screen,
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)
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def _clip_point_to_visible_area(
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self, point: Point, write_position: WritePosition
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) -> Point:
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"""
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Ensure that the cursor and menu positions always are always reported
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"""
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if point.x < write_position.xpos:
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point = point._replace(x=write_position.xpos)
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if point.y < write_position.ypos:
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point = point._replace(y=write_position.ypos)
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if point.x >= write_position.xpos + write_position.width:
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point = point._replace(x=write_position.xpos + write_position.width - 1)
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if point.y >= write_position.ypos + write_position.height:
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point = point._replace(y=write_position.ypos + write_position.height - 1)
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return point
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def _copy_over_screen(
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self,
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screen: Screen,
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temp_screen: Screen,
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write_position: WritePosition,
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virtual_width: int,
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) -> None:
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"""
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Copy over visible screen content and "zero width escape sequences".
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"""
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ypos = write_position.ypos
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xpos = write_position.xpos
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for y in range(write_position.height):
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temp_row = temp_screen.data_buffer[y + self.vertical_scroll]
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row = screen.data_buffer[y + ypos]
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temp_zero_width_escapes = temp_screen.zero_width_escapes[
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y + self.vertical_scroll
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]
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zero_width_escapes = screen.zero_width_escapes[y + ypos]
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for x in range(virtual_width):
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row[x + xpos] = temp_row[x]
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if x in temp_zero_width_escapes:
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zero_width_escapes[x + xpos] = temp_zero_width_escapes[x]
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def _copy_over_mouse_handlers(
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self,
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mouse_handlers: MouseHandlers,
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temp_mouse_handlers: MouseHandlers,
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write_position: WritePosition,
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virtual_width: int,
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) -> None:
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"""
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Copy over mouse handlers from virtual screen to real screen.
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Note: we take `virtual_width` because we don't want to copy over mouse
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handlers that we possibly have behind the scrollbar.
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"""
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ypos = write_position.ypos
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xpos = write_position.xpos
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# Cache mouse handlers when wrapping them. Very often the same mouse
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# handler is registered for many positions.
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mouse_handler_wrappers: dict[MouseHandler, MouseHandler] = {}
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def wrap_mouse_handler(handler: MouseHandler) -> MouseHandler:
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"Wrap mouse handler. Translate coordinates in `MouseEvent`."
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if handler not in mouse_handler_wrappers:
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def new_handler(event: MouseEvent) -> None:
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new_event = MouseEvent(
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position=Point(
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x=event.position.x - xpos,
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y=event.position.y + self.vertical_scroll - ypos,
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),
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event_type=event.event_type,
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button=event.button,
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modifiers=event.modifiers,
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)
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handler(new_event)
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mouse_handler_wrappers[handler] = new_handler
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return mouse_handler_wrappers[handler]
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# Copy handlers.
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mouse_handlers_dict = mouse_handlers.mouse_handlers
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temp_mouse_handlers_dict = temp_mouse_handlers.mouse_handlers
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for y in range(write_position.height):
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if y in temp_mouse_handlers_dict:
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temp_mouse_row = temp_mouse_handlers_dict[y + self.vertical_scroll]
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mouse_row = mouse_handlers_dict[y + ypos]
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for x in range(virtual_width):
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if x in temp_mouse_row:
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mouse_row[x + xpos] = wrap_mouse_handler(temp_mouse_row[x])
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def _copy_over_write_positions(
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self, screen: Screen, temp_screen: Screen, write_position: WritePosition
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) -> None:
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"""
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Copy over window write positions.
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"""
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ypos = write_position.ypos
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xpos = write_position.xpos
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for win, write_pos in temp_screen.visible_windows_to_write_positions.items():
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screen.visible_windows_to_write_positions[win] = WritePosition(
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xpos=write_pos.xpos + xpos,
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ypos=write_pos.ypos + ypos - self.vertical_scroll,
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# TODO: if the window is only partly visible, then truncate width/height.
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# This could be important if we have nested ScrollablePanes.
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height=write_pos.height,
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width=write_pos.width,
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)
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def is_modal(self) -> bool:
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return self.content.is_modal()
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def get_key_bindings(self) -> KeyBindingsBase | None:
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return self.content.get_key_bindings()
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def get_children(self) -> list[Container]:
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return [self.content]
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def _make_window_visible(
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self,
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visible_height: int,
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virtual_height: int,
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visible_win_write_pos: WritePosition,
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cursor_position: Point | None,
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) -> None:
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"""
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Scroll the scrollable pane, so that this window becomes visible.
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:param visible_height: Height of this `ScrollablePane` that is rendered.
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:param virtual_height: Height of the virtual, temp screen.
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:param visible_win_write_pos: `WritePosition` of the nested window on the
|
||
|
|
temp screen.
|
||
|
|
:param cursor_position: The location of the cursor position of this
|
||
|
|
window on the temp screen.
|
||
|
|
"""
|
||
|
|
# Start with maximum allowed scroll range, and then reduce according to
|
||
|
|
# the focused window and cursor position.
|
||
|
|
min_scroll = 0
|
||
|
|
max_scroll = virtual_height - visible_height
|
||
|
|
|
||
|
|
if self.keep_cursor_visible():
|
||
|
|
# Reduce min/max scroll according to the cursor in the focused window.
|
||
|
|
if cursor_position is not None:
|
||
|
|
offsets = self.scroll_offsets
|
||
|
|
cpos_min_scroll = (
|
||
|
|
cursor_position.y - visible_height + 1 + offsets.bottom
|
||
|
|
)
|
||
|
|
cpos_max_scroll = cursor_position.y - offsets.top
|
||
|
|
min_scroll = max(min_scroll, cpos_min_scroll)
|
||
|
|
max_scroll = max(0, min(max_scroll, cpos_max_scroll))
|
||
|
|
|
||
|
|
if self.keep_focused_window_visible():
|
||
|
|
# Reduce min/max scroll according to focused window position.
|
||
|
|
# If the window is small enough, bot the top and bottom of the window
|
||
|
|
# should be visible.
|
||
|
|
if visible_win_write_pos.height <= visible_height:
|
||
|
|
window_min_scroll = (
|
||
|
|
visible_win_write_pos.ypos
|
||
|
|
+ visible_win_write_pos.height
|
||
|
|
- visible_height
|
||
|
|
)
|
||
|
|
window_max_scroll = visible_win_write_pos.ypos
|
||
|
|
else:
|
||
|
|
# Window does not fit on the screen. Make sure at least the whole
|
||
|
|
# screen is occupied with this window, and nothing else is shown.
|
||
|
|
window_min_scroll = visible_win_write_pos.ypos
|
||
|
|
window_max_scroll = (
|
||
|
|
visible_win_write_pos.ypos
|
||
|
|
+ visible_win_write_pos.height
|
||
|
|
- visible_height
|
||
|
|
)
|
||
|
|
|
||
|
|
min_scroll = max(min_scroll, window_min_scroll)
|
||
|
|
max_scroll = min(max_scroll, window_max_scroll)
|
||
|
|
|
||
|
|
if min_scroll > max_scroll:
|
||
|
|
min_scroll = max_scroll # Should not happen.
|
||
|
|
|
||
|
|
# Finally, properly clip the vertical scroll.
|
||
|
|
if self.vertical_scroll > max_scroll:
|
||
|
|
self.vertical_scroll = max_scroll
|
||
|
|
if self.vertical_scroll < min_scroll:
|
||
|
|
self.vertical_scroll = min_scroll
|
||
|
|
|
||
|
|
def _draw_scrollbar(
|
||
|
|
self, write_position: WritePosition, content_height: int, screen: Screen
|
||
|
|
) -> None:
|
||
|
|
"""
|
||
|
|
Draw the scrollbar on the screen.
|
||
|
|
|
||
|
|
Note: There is some code duplication with the `ScrollbarMargin`
|
||
|
|
implementation.
|
||
|
|
"""
|
||
|
|
|
||
|
|
window_height = write_position.height
|
||
|
|
display_arrows = self.display_arrows()
|
||
|
|
|
||
|
|
if display_arrows:
|
||
|
|
window_height -= 2
|
||
|
|
|
||
|
|
try:
|
||
|
|
fraction_visible = write_position.height / float(content_height)
|
||
|
|
fraction_above = self.vertical_scroll / float(content_height)
|
||
|
|
|
||
|
|
scrollbar_height = int(
|
||
|
|
min(window_height, max(1, window_height * fraction_visible))
|
||
|
|
)
|
||
|
|
scrollbar_top = int(window_height * fraction_above)
|
||
|
|
except ZeroDivisionError:
|
||
|
|
return
|
||
|
|
else:
|
||
|
|
|
||
|
|
def is_scroll_button(row: int) -> bool:
|
||
|
|
"True if we should display a button on this row."
|
||
|
|
return scrollbar_top <= row <= scrollbar_top + scrollbar_height
|
||
|
|
|
||
|
|
xpos = write_position.xpos + write_position.width - 1
|
||
|
|
ypos = write_position.ypos
|
||
|
|
data_buffer = screen.data_buffer
|
||
|
|
|
||
|
|
# Up arrow.
|
||
|
|
if display_arrows:
|
||
|
|
data_buffer[ypos][xpos] = Char(
|
||
|
|
self.up_arrow_symbol, "class:scrollbar.arrow"
|
||
|
|
)
|
||
|
|
ypos += 1
|
||
|
|
|
||
|
|
# Scrollbar body.
|
||
|
|
scrollbar_background = "class:scrollbar.background"
|
||
|
|
scrollbar_background_start = "class:scrollbar.background,scrollbar.start"
|
||
|
|
scrollbar_button = "class:scrollbar.button"
|
||
|
|
scrollbar_button_end = "class:scrollbar.button,scrollbar.end"
|
||
|
|
|
||
|
|
for i in range(window_height):
|
||
|
|
style = ""
|
||
|
|
if is_scroll_button(i):
|
||
|
|
if not is_scroll_button(i + 1):
|
||
|
|
# Give the last cell a different style, because we want
|
||
|
|
# to underline this.
|
||
|
|
style = scrollbar_button_end
|
||
|
|
else:
|
||
|
|
style = scrollbar_button
|
||
|
|
else:
|
||
|
|
if is_scroll_button(i + 1):
|
||
|
|
style = scrollbar_background_start
|
||
|
|
else:
|
||
|
|
style = scrollbar_background
|
||
|
|
|
||
|
|
data_buffer[ypos][xpos] = Char(" ", style)
|
||
|
|
ypos += 1
|
||
|
|
|
||
|
|
# Down arrow
|
||
|
|
if display_arrows:
|
||
|
|
data_buffer[ypos][xpos] = Char(
|
||
|
|
self.down_arrow_symbol, "class:scrollbar.arrow"
|
||
|
|
)
|