Adding upstream version 3.0.36.upstream/3.0.36upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 494 insertions, 0 deletions

diff --git a/src/prompt_toolkit/layout/scrollable_pane.py b/src/prompt_toolkit/layout/scrollable_pane.py
new file mode 100644
index 0000000..810e405
--- /dev/null
+++ b/src/prompt_toolkit/layout/scrollable_pane.py
@@ -0,0 +1,494 @@
+from typing import Dict, List, Optional
+
+from prompt_toolkit.data_structures import Point
+from prompt_toolkit.filters import FilterOrBool, to_filter
+from prompt_toolkit.key_binding import KeyBindingsBase
+from prompt_toolkit.mouse_events import MouseEvent
+
+from .containers import Container, ScrollOffsets
+from .dimension import AnyDimension, Dimension, sum_layout_dimensions, to_dimension
+from .mouse_handlers import MouseHandler, MouseHandlers
+from .screen import Char, Screen, WritePosition
+
+__all__ = ["ScrollablePane"]
+
+# Never go beyond this height, because performance will degrade.
+MAX_AVAILABLE_HEIGHT = 10_000
+
+
+class ScrollablePane(Container):
+    """
+    Container widget that exposes a larger virtual screen to its content and
+    displays it in a vertical scrollbale region.
+
+    Typically this is wrapped in a large `HSplit` container. Make sure in that
+    case to not specify a `height` dimension of the `HSplit`, so that it will
+    scale according to the content.
+
+    .. note::
+
+        If you want to display a completion menu for widgets in this
+        `ScrollablePane`, then it's still a good practice to use a
+        `FloatContainer` with a `CompletionsMenu` in a `Float` at the top-level
+        of the layout hierarchy, rather then nesting a `FloatContainer` in this
+        `ScrollablePane`. (Otherwise, it's possible that the completion menu
+        is clipped.)
+
+    :param content: The content container.
+    :param scrolloffset: Try to keep the cursor within this distance from the
+        top/bottom (left/right offset is not used).
+    :param keep_cursor_visible: When `True`, automatically scroll the pane so
+        that the cursor (of the focused window) is always visible.
+    :param keep_focused_window_visible: When `True`, automatically scroll th e
+        pane so that the focused window is visible, or as much visible as
+        possible if it doen't completely fit the screen.
+    :param max_available_height: Always constraint the height to this amount
+        for performance reasons.
+    :param width: When given, use this width instead of looking at the children.
+    :param height: When given, use this height instead of looking at the children.
+    :param show_scrollbar: When `True` display a scrollbar on the right.
+    """
+
+    def __init__(
+        self,
+        content: Container,
+        scroll_offsets: Optional[ScrollOffsets] = None,
+        keep_cursor_visible: FilterOrBool = True,
+        keep_focused_window_visible: FilterOrBool = True,
+        max_available_height: int = MAX_AVAILABLE_HEIGHT,
+        width: AnyDimension = None,
+        height: AnyDimension = None,
+        show_scrollbar: FilterOrBool = True,
+        display_arrows: FilterOrBool = True,
+        up_arrow_symbol: str = "^",
+        down_arrow_symbol: str = "v",
+    ) -> None:
+        self.content = content
+        self.scroll_offsets = scroll_offsets or ScrollOffsets(top=1, bottom=1)
+        self.keep_cursor_visible = to_filter(keep_cursor_visible)
+        self.keep_focused_window_visible = to_filter(keep_focused_window_visible)
+        self.max_available_height = max_available_height
+        self.width = width
+        self.height = height
+        self.show_scrollbar = to_filter(show_scrollbar)
+        self.display_arrows = to_filter(display_arrows)
+        self.up_arrow_symbol = up_arrow_symbol
+        self.down_arrow_symbol = down_arrow_symbol
+
+        self.vertical_scroll = 0
+
+    def __repr__(self) -> str:
+        return f"ScrollablePane({self.content!r})"
+
+    def reset(self) -> None:
+        self.content.reset()
+
+    def preferred_width(self, max_available_width: int) -> Dimension:
+        if self.width is not None:
+            return to_dimension(self.width)
+
+        # We're only scrolling vertical. So the preferred width is equal to
+        # that of the content.
+        content_width = self.content.preferred_width(max_available_width)
+
+        # If a scrollbar needs to be displayed, add +1 to the content width.
+        if self.show_scrollbar():
+            return sum_layout_dimensions([Dimension.exact(1), content_width])
+
+        return content_width
+
+    def preferred_height(self, width: int, max_available_height: int) -> Dimension:
+        if self.height is not None:
+            return to_dimension(self.height)
+
+        # Prefer a height large enough so that it fits all the content. If not,
+        # we'll make the pane scrollable.
+        if self.show_scrollbar():
+            # If `show_scrollbar` is set. Always reserve space for the scrollbar.
+            width -= 1
+
+        dimension = self.content.preferred_height(width, self.max_available_height)
+
+        # Only take 'preferred' into account. Min/max can be anything.
+        return Dimension(min=0, preferred=dimension.preferred)
+
+    def write_to_screen(
+        self,
+        screen: Screen,
+        mouse_handlers: MouseHandlers,
+        write_position: WritePosition,
+        parent_style: str,
+        erase_bg: bool,
+        z_index: Optional[int],
+    ) -> None:
+        """
+        Render scrollable pane content.
+
+        This works by rendering on an off-screen canvas, and copying over the
+        visible region.
+        """
+        show_scrollbar = self.show_scrollbar()
+
+        if show_scrollbar:
+            virtual_width = write_position.width - 1
+        else:
+            virtual_width = write_position.width
+
+        # Compute preferred height again.
+        virtual_height = self.content.preferred_height(
+            virtual_width, self.max_available_height
+        ).preferred
+
+        # Ensure virtual height is at least the available height.
+        virtual_height = max(virtual_height, write_position.height)
+        virtual_height = min(virtual_height, self.max_available_height)
+
+        # First, write the content to a virtual screen, then copy over the
+        # visible part to the real screen.
+        temp_screen = Screen(default_char=Char(char=" ", style=parent_style))
+        temp_screen.show_cursor = screen.show_cursor
+        temp_write_position = WritePosition(
+            xpos=0, ypos=0, width=virtual_width, height=virtual_height
+        )
+
+        temp_mouse_handlers = MouseHandlers()
+
+        self.content.write_to_screen(
+            temp_screen,
+            temp_mouse_handlers,
+            temp_write_position,
+            parent_style,
+            erase_bg,
+            z_index,
+        )
+        temp_screen.draw_all_floats()
+
+        # If anything in the virtual screen is focused, move vertical scroll to
+        from prompt_toolkit.application import get_app
+
+        focused_window = get_app().layout.current_window
+
+        try:
+            visible_win_write_pos = temp_screen.visible_windows_to_write_positions[
+                focused_window
+            ]
+        except KeyError:
+            pass  # No window focused here. Don't scroll.
+        else:
+            # Make sure this window is visible.
+            self._make_window_visible(
+                write_position.height,
+                virtual_height,
+                visible_win_write_pos,
+                temp_screen.cursor_positions.get(focused_window),
+            )
+
+        # Copy over virtual screen and zero width escapes to real screen.
+        self._copy_over_screen(screen, temp_screen, write_position, virtual_width)
+
+        # Copy over mouse handlers.
+        self._copy_over_mouse_handlers(
+            mouse_handlers, temp_mouse_handlers, write_position, virtual_width
+        )
+
+        # Set screen.width/height.
+        ypos = write_position.ypos
+        xpos = write_position.xpos
+
+        screen.width = max(screen.width, xpos + virtual_width)
+        screen.height = max(screen.height, ypos + write_position.height)
+
+        # Copy over window write positions.
+        self._copy_over_write_positions(screen, temp_screen, write_position)
+
+        if temp_screen.show_cursor:
+            screen.show_cursor = True
+
+        # Copy over cursor positions, if they are visible.
+        for window, point in temp_screen.cursor_positions.items():
+            if (
+                0 <= point.x < write_position.width
+                and self.vertical_scroll
+                <= point.y
+                < write_position.height + self.vertical_scroll
+            ):
+                screen.cursor_positions[window] = Point(
+                    x=point.x + xpos, y=point.y + ypos - self.vertical_scroll
+                )
+
+        # Copy over menu positions, but clip them to the visible area.
+        for window, point in temp_screen.menu_positions.items():
+            screen.menu_positions[window] = self._clip_point_to_visible_area(
+                Point(x=point.x + xpos, y=point.y + ypos - self.vertical_scroll),
+                write_position,
+            )
+
+        # Draw scrollbar.
+        if show_scrollbar:
+            self._draw_scrollbar(
+                write_position,
+                virtual_height,
+                screen,
+            )
+
+    def _clip_point_to_visible_area(
+        self, point: Point, write_position: WritePosition
+    ) -> Point:
+        """
+        Ensure that the cursor and menu positions always are always reported
+        """
+        if point.x < write_position.xpos:
+            point = point._replace(x=write_position.xpos)
+        if point.y < write_position.ypos:
+            point = point._replace(y=write_position.ypos)
+        if point.x >= write_position.xpos + write_position.width:
+            point = point._replace(x=write_position.xpos + write_position.width - 1)
+        if point.y >= write_position.ypos + write_position.height:
+            point = point._replace(y=write_position.ypos + write_position.height - 1)
+
+        return point
+
+    def _copy_over_screen(
+        self,
+        screen: Screen,
+        temp_screen: Screen,
+        write_position: WritePosition,
+        virtual_width: int,
+    ) -> None:
+        """
+        Copy over visible screen content and "zero width escape sequences".
+        """
+        ypos = write_position.ypos
+        xpos = write_position.xpos
+
+        for y in range(write_position.height):
+            temp_row = temp_screen.data_buffer[y + self.vertical_scroll]
+            row = screen.data_buffer[y + ypos]
+            temp_zero_width_escapes = temp_screen.zero_width_escapes[
+                y + self.vertical_scroll
+            ]
+            zero_width_escapes = screen.zero_width_escapes[y + ypos]
+
+            for x in range(virtual_width):
+                row[x + xpos] = temp_row[x]
+
+                if x in temp_zero_width_escapes:
+                    zero_width_escapes[x + xpos] = temp_zero_width_escapes[x]
+
+    def _copy_over_mouse_handlers(
+        self,
+        mouse_handlers: MouseHandlers,
+        temp_mouse_handlers: MouseHandlers,
+        write_position: WritePosition,
+        virtual_width: int,
+    ) -> None:
+        """
+        Copy over mouse handlers from virtual screen to real screen.
+
+        Note: we take `virtual_width` because we don't want to copy over mouse
+              handlers that we possibly have behind the scrollbar.
+        """
+        ypos = write_position.ypos
+        xpos = write_position.xpos
+
+        # Cache mouse handlers when wrapping them. Very often the same mouse
+        # handler is registered for many positions.
+        mouse_handler_wrappers: Dict[MouseHandler, MouseHandler] = {}
+
+        def wrap_mouse_handler(handler: MouseHandler) -> MouseHandler:
+            "Wrap mouse handler. Translate coordinates in `MouseEvent`."
+            if handler not in mouse_handler_wrappers:
+
+                def new_handler(event: MouseEvent) -> None:
+                    new_event = MouseEvent(
+                        position=Point(
+                            x=event.position.x - xpos,
+                            y=event.position.y + self.vertical_scroll - ypos,
+                        ),
+                        event_type=event.event_type,
+                        button=event.button,
+                        modifiers=event.modifiers,
+                    )
+                    handler(new_event)
+
+                mouse_handler_wrappers[handler] = new_handler
+            return mouse_handler_wrappers[handler]
+
+        # Copy handlers.
+        mouse_handlers_dict = mouse_handlers.mouse_handlers
+        temp_mouse_handlers_dict = temp_mouse_handlers.mouse_handlers
+
+        for y in range(write_position.height):
+            if y in temp_mouse_handlers_dict:
+                temp_mouse_row = temp_mouse_handlers_dict[y + self.vertical_scroll]
+                mouse_row = mouse_handlers_dict[y + ypos]
+                for x in range(virtual_width):
+                    if x in temp_mouse_row:
+                        mouse_row[x + xpos] = wrap_mouse_handler(temp_mouse_row[x])
+
+    def _copy_over_write_positions(
+        self, screen: Screen, temp_screen: Screen, write_position: WritePosition
+    ) -> None:
+        """
+        Copy over window write positions.
+        """
+        ypos = write_position.ypos
+        xpos = write_position.xpos
+
+        for win, write_pos in temp_screen.visible_windows_to_write_positions.items():
+            screen.visible_windows_to_write_positions[win] = WritePosition(
+                xpos=write_pos.xpos + xpos,
+                ypos=write_pos.ypos + ypos - self.vertical_scroll,
+                # TODO: if the window is only partly visible, then truncate width/height.
+                #       This could be important if we have nested ScrollablePanes.
+                height=write_pos.height,
+                width=write_pos.width,
+            )
+
+    def is_modal(self) -> bool:
+        return self.content.is_modal()
+
+    def get_key_bindings(self) -> Optional[KeyBindingsBase]:
+        return self.content.get_key_bindings()
+
+    def get_children(self) -> List["Container"]:
+        return [self.content]
+
+    def _make_window_visible(
+        self,
+        visible_height: int,
+        virtual_height: int,
+        visible_win_write_pos: WritePosition,
+        cursor_position: Optional[Point],
+    ) -> None:
+        """
+        Scroll the scrollable pane, so that this window becomes visible.
+
+        :param visible_height: Height of this `ScrollablePane` that is rendered.
+        :param virtual_height: Height of the virtual, temp screen.
+        :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"
+                )