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Diffstat (limited to 'src/prompt_toolkit/renderer.py')
| -rw-r--r-- | src/prompt_toolkit/renderer.py | 813 |
1 files changed, 813 insertions, 0 deletions
diff --git a/src/prompt_toolkit/renderer.py b/src/prompt_toolkit/renderer.py new file mode 100644 index 0000000..d9bb171 --- /dev/null +++ b/src/prompt_toolkit/renderer.py @@ -0,0 +1,813 @@ +""" +Renders the command line on the console. +(Redraws parts of the input line that were changed.) +""" +from asyncio import FIRST_COMPLETED, Future, ensure_future, sleep, wait +from collections import deque +from enum import Enum +from typing import TYPE_CHECKING, Any, Callable, Deque, Dict, Hashable, Optional, Tuple + +from prompt_toolkit.application.current import get_app +from prompt_toolkit.cursor_shapes import CursorShape +from prompt_toolkit.data_structures import Point, Size +from prompt_toolkit.filters import FilterOrBool, to_filter +from prompt_toolkit.formatted_text import AnyFormattedText, to_formatted_text +from prompt_toolkit.layout.mouse_handlers import MouseHandlers +from prompt_toolkit.layout.screen import Char, Screen, WritePosition +from prompt_toolkit.output import ColorDepth, Output +from prompt_toolkit.styles import ( + Attrs, + BaseStyle, + DummyStyleTransformation, + StyleTransformation, +) + +if TYPE_CHECKING: + from prompt_toolkit.application import Application + from prompt_toolkit.layout.layout import Layout + + +__all__ = [ + "Renderer", + "print_formatted_text", +] + + +def _output_screen_diff( + app: "Application[Any]", + output: Output, + screen: Screen, + current_pos: Point, + color_depth: ColorDepth, + previous_screen: Optional[Screen], + last_style: Optional[str], + is_done: bool, # XXX: drop is_done + full_screen: bool, + attrs_for_style_string: "_StyleStringToAttrsCache", + style_string_has_style: "_StyleStringHasStyleCache", + size: Size, + previous_width: int, +) -> Tuple[Point, Optional[str]]: + """ + Render the diff between this screen and the previous screen. + + This takes two `Screen` instances. The one that represents the output like + it was during the last rendering and one that represents the current + output raster. Looking at these two `Screen` instances, this function will + render the difference by calling the appropriate methods of the `Output` + object that only paint the changes to the terminal. + + This is some performance-critical code which is heavily optimized. + Don't change things without profiling first. + + :param current_pos: Current cursor position. + :param last_style: The style string, used for drawing the last drawn + character. (Color/attributes.) + :param attrs_for_style_string: :class:`._StyleStringToAttrsCache` instance. + :param width: The width of the terminal. + :param previous_width: The width of the terminal during the last rendering. + """ + width, height = size.columns, size.rows + + #: Variable for capturing the output. + write = output.write + write_raw = output.write_raw + + # Create locals for the most used output methods. + # (Save expensive attribute lookups.) + _output_set_attributes = output.set_attributes + _output_reset_attributes = output.reset_attributes + _output_cursor_forward = output.cursor_forward + _output_cursor_up = output.cursor_up + _output_cursor_backward = output.cursor_backward + + # Hide cursor before rendering. (Avoid flickering.) + output.hide_cursor() + + def reset_attributes() -> None: + "Wrapper around Output.reset_attributes." + nonlocal last_style + _output_reset_attributes() + last_style = None # Forget last char after resetting attributes. + + def move_cursor(new: Point) -> Point: + "Move cursor to this `new` point. Returns the given Point." + current_x, current_y = current_pos.x, current_pos.y + + if new.y > current_y: + # Use newlines instead of CURSOR_DOWN, because this might add new lines. + # CURSOR_DOWN will never create new lines at the bottom. + # Also reset attributes, otherwise the newline could draw a + # background color. + reset_attributes() + write("\r\n" * (new.y - current_y)) + current_x = 0 + _output_cursor_forward(new.x) + return new + elif new.y < current_y: + _output_cursor_up(current_y - new.y) + + if current_x >= width - 1: + write("\r") + _output_cursor_forward(new.x) + elif new.x < current_x or current_x >= width - 1: + _output_cursor_backward(current_x - new.x) + elif new.x > current_x: + _output_cursor_forward(new.x - current_x) + + return new + + def output_char(char: Char) -> None: + """ + Write the output of this character. + """ + nonlocal last_style + + # If the last printed character has the same style, don't output the + # style again. + if last_style == char.style: + write(char.char) + else: + # Look up `Attr` for this style string. Only set attributes if different. + # (Two style strings can still have the same formatting.) + # Note that an empty style string can have formatting that needs to + # be applied, because of style transformations. + new_attrs = attrs_for_style_string[char.style] + if not last_style or new_attrs != attrs_for_style_string[last_style]: + _output_set_attributes(new_attrs, color_depth) + + write(char.char) + last_style = char.style + + def get_max_column_index(row: Dict[int, Char]) -> int: + """ + Return max used column index, ignoring whitespace (without style) at + the end of the line. This is important for people that copy/paste + terminal output. + + There are two reasons we are sometimes seeing whitespace at the end: + - `BufferControl` adds a trailing space to each line, because it's a + possible cursor position, so that the line wrapping won't change if + the cursor position moves around. + - The `Window` adds a style class to the current line for highlighting + (cursor-line). + """ + numbers = ( + index + for index, cell in row.items() + if cell.char != " " or style_string_has_style[cell.style] + ) + return max(numbers, default=0) + + # Render for the first time: reset styling. + if not previous_screen: + reset_attributes() + + # Disable autowrap. (When entering a the alternate screen, or anytime when + # we have a prompt. - In the case of a REPL, like IPython, people can have + # background threads, and it's hard for debugging if their output is not + # wrapped.) + if not previous_screen or not full_screen: + output.disable_autowrap() + + # When the previous screen has a different size, redraw everything anyway. + # Also when we are done. (We might take up less rows, so clearing is important.) + if ( + is_done or not previous_screen or previous_width != width + ): # XXX: also consider height?? + current_pos = move_cursor(Point(x=0, y=0)) + reset_attributes() + output.erase_down() + + previous_screen = Screen() + + # Get height of the screen. + # (height changes as we loop over data_buffer, so remember the current value.) + # (Also make sure to clip the height to the size of the output.) + current_height = min(screen.height, height) + + # Loop over the rows. + row_count = min(max(screen.height, previous_screen.height), height) + + for y in range(row_count): + new_row = screen.data_buffer[y] + previous_row = previous_screen.data_buffer[y] + zero_width_escapes_row = screen.zero_width_escapes[y] + + new_max_line_len = min(width - 1, get_max_column_index(new_row)) + previous_max_line_len = min(width - 1, get_max_column_index(previous_row)) + + # Loop over the columns. + c = 0 # Column counter. + while c <= new_max_line_len: + new_char = new_row[c] + old_char = previous_row[c] + char_width = new_char.width or 1 + + # When the old and new character at this position are different, + # draw the output. (Because of the performance, we don't call + # `Char.__ne__`, but inline the same expression.) + if new_char.char != old_char.char or new_char.style != old_char.style: + current_pos = move_cursor(Point(x=c, y=y)) + + # Send injected escape sequences to output. + if c in zero_width_escapes_row: + write_raw(zero_width_escapes_row[c]) + + output_char(new_char) + current_pos = Point(x=current_pos.x + char_width, y=current_pos.y) + + c += char_width + + # If the new line is shorter, trim it. + if previous_screen and new_max_line_len < previous_max_line_len: + current_pos = move_cursor(Point(x=new_max_line_len + 1, y=y)) + reset_attributes() + output.erase_end_of_line() + + # Correctly reserve vertical space as required by the layout. + # When this is a new screen (drawn for the first time), or for some reason + # higher than the previous one. Move the cursor once to the bottom of the + # output. That way, we're sure that the terminal scrolls up, even when the + # lower lines of the canvas just contain whitespace. + + # The most obvious reason that we actually want this behaviour is the avoid + # the artifact of the input scrolling when the completion menu is shown. + # (If the scrolling is actually wanted, the layout can still be build in a + # way to behave that way by setting a dynamic height.) + if current_height > previous_screen.height: + current_pos = move_cursor(Point(x=0, y=current_height - 1)) + + # Move cursor: + if is_done: + current_pos = move_cursor(Point(x=0, y=current_height)) + output.erase_down() + else: + current_pos = move_cursor(screen.get_cursor_position(app.layout.current_window)) + + if is_done or not full_screen: + output.enable_autowrap() + + # Always reset the color attributes. This is important because a background + # thread could print data to stdout and we want that to be displayed in the + # default colors. (Also, if a background color has been set, many terminals + # give weird artifacts on resize events.) + reset_attributes() + + if screen.show_cursor or is_done: + output.show_cursor() + + return current_pos, last_style + + +class HeightIsUnknownError(Exception): + "Information unavailable. Did not yet receive the CPR response." + + +class _StyleStringToAttrsCache(Dict[str, Attrs]): + """ + A cache structure that maps style strings to :class:`.Attr`. + (This is an important speed up.) + """ + + def __init__( + self, + get_attrs_for_style_str: Callable[["str"], Attrs], + style_transformation: StyleTransformation, + ) -> None: + + self.get_attrs_for_style_str = get_attrs_for_style_str + self.style_transformation = style_transformation + + def __missing__(self, style_str: str) -> Attrs: + attrs = self.get_attrs_for_style_str(style_str) + attrs = self.style_transformation.transform_attrs(attrs) + + self[style_str] = attrs + return attrs + + +class _StyleStringHasStyleCache(Dict[str, bool]): + """ + Cache for remember which style strings don't render the default output + style (default fg/bg, no underline and no reverse and no blink). That way + we know that we should render these cells, even when they're empty (when + they contain a space). + + Note: we don't consider bold/italic/hidden because they don't change the + output if there's no text in the cell. + """ + + def __init__(self, style_string_to_attrs: Dict[str, Attrs]) -> None: + self.style_string_to_attrs = style_string_to_attrs + + def __missing__(self, style_str: str) -> bool: + attrs = self.style_string_to_attrs[style_str] + is_default = bool( + attrs.color + or attrs.bgcolor + or attrs.underline + or attrs.strike + or attrs.blink + or attrs.reverse + ) + + self[style_str] = is_default + return is_default + + +class CPR_Support(Enum): + "Enum: whether or not CPR is supported." + SUPPORTED = "SUPPORTED" + NOT_SUPPORTED = "NOT_SUPPORTED" + UNKNOWN = "UNKNOWN" + + +class Renderer: + """ + Typical usage: + + :: + + output = Vt100_Output.from_pty(sys.stdout) + r = Renderer(style, output) + r.render(app, layout=...) + """ + + CPR_TIMEOUT = 2 # Time to wait until we consider CPR to be not supported. + + def __init__( + self, + style: BaseStyle, + output: Output, + full_screen: bool = False, + mouse_support: FilterOrBool = False, + cpr_not_supported_callback: Optional[Callable[[], None]] = None, + ) -> None: + + self.style = style + self.output = output + self.full_screen = full_screen + self.mouse_support = to_filter(mouse_support) + self.cpr_not_supported_callback = cpr_not_supported_callback + + self._in_alternate_screen = False + self._mouse_support_enabled = False + self._bracketed_paste_enabled = False + self._cursor_key_mode_reset = False + + # Future set when we are waiting for a CPR flag. + self._waiting_for_cpr_futures: Deque[Future[None]] = deque() + self.cpr_support = CPR_Support.UNKNOWN + + if not output.responds_to_cpr: + self.cpr_support = CPR_Support.NOT_SUPPORTED + + # Cache for the style. + self._attrs_for_style: Optional[_StyleStringToAttrsCache] = None + self._style_string_has_style: Optional[_StyleStringHasStyleCache] = None + self._last_style_hash: Optional[Hashable] = None + self._last_transformation_hash: Optional[Hashable] = None + self._last_color_depth: Optional[ColorDepth] = None + + self.reset(_scroll=True) + + def reset(self, _scroll: bool = False, leave_alternate_screen: bool = True) -> None: + + # Reset position + self._cursor_pos = Point(x=0, y=0) + + # Remember the last screen instance between renderers. This way, + # we can create a `diff` between two screens and only output the + # difference. It's also to remember the last height. (To show for + # instance a toolbar at the bottom position.) + self._last_screen: Optional[Screen] = None + self._last_size: Optional[Size] = None + self._last_style: Optional[str] = None + self._last_cursor_shape: Optional[CursorShape] = None + + # Default MouseHandlers. (Just empty.) + self.mouse_handlers = MouseHandlers() + + #: Space from the top of the layout, until the bottom of the terminal. + #: We don't know this until a `report_absolute_cursor_row` call. + self._min_available_height = 0 + + # In case of Windows, also make sure to scroll to the current cursor + # position. (Only when rendering the first time.) + # It does nothing for vt100 terminals. + if _scroll: + self.output.scroll_buffer_to_prompt() + + # Quit alternate screen. + if self._in_alternate_screen and leave_alternate_screen: + self.output.quit_alternate_screen() + self._in_alternate_screen = False + + # Disable mouse support. + if self._mouse_support_enabled: + self.output.disable_mouse_support() + self._mouse_support_enabled = False + + # Disable bracketed paste. + if self._bracketed_paste_enabled: + self.output.disable_bracketed_paste() + self._bracketed_paste_enabled = False + + self.output.reset_cursor_shape() + + # NOTE: No need to set/reset cursor key mode here. + + # Flush output. `disable_mouse_support` needs to write to stdout. + self.output.flush() + + @property + def last_rendered_screen(self) -> Optional[Screen]: + """ + The `Screen` class that was generated during the last rendering. + This can be `None`. + """ + return self._last_screen + + @property + def height_is_known(self) -> bool: + """ + True when the height from the cursor until the bottom of the terminal + is known. (It's often nicer to draw bottom toolbars only if the height + is known, in order to avoid flickering when the CPR response arrives.) + """ + if self.full_screen or self._min_available_height > 0: + return True + try: + self._min_available_height = self.output.get_rows_below_cursor_position() + return True + except NotImplementedError: + return False + + @property + def rows_above_layout(self) -> int: + """ + Return the number of rows visible in the terminal above the layout. + """ + if self._in_alternate_screen: + return 0 + elif self._min_available_height > 0: + total_rows = self.output.get_size().rows + last_screen_height = self._last_screen.height if self._last_screen else 0 + return total_rows - max(self._min_available_height, last_screen_height) + else: + raise HeightIsUnknownError("Rows above layout is unknown.") + + def request_absolute_cursor_position(self) -> None: + """ + Get current cursor position. + + We do this to calculate the minimum available height that we can + consume for rendering the prompt. This is the available space below te + cursor. + + For vt100: Do CPR request. (answer will arrive later.) + For win32: Do API call. (Answer comes immediately.) + """ + # Only do this request when the cursor is at the top row. (after a + # clear or reset). We will rely on that in `report_absolute_cursor_row`. + assert self._cursor_pos.y == 0 + + # In full-screen mode, always use the total height as min-available-height. + if self.full_screen: + self._min_available_height = self.output.get_size().rows + return + + # For Win32, we have an API call to get the number of rows below the + # cursor. + try: + self._min_available_height = self.output.get_rows_below_cursor_position() + return + except NotImplementedError: + pass + + # Use CPR. + if self.cpr_support == CPR_Support.NOT_SUPPORTED: + return + + def do_cpr() -> None: + # Asks for a cursor position report (CPR). + self._waiting_for_cpr_futures.append(Future()) + self.output.ask_for_cpr() + + if self.cpr_support == CPR_Support.SUPPORTED: + do_cpr() + return + + # If we don't know whether CPR is supported, only do a request if + # none is pending, and test it, using a timer. + if self.waiting_for_cpr: + return + + do_cpr() + + async def timer() -> None: + await sleep(self.CPR_TIMEOUT) + + # Not set in the meantime -> not supported. + if self.cpr_support == CPR_Support.UNKNOWN: + self.cpr_support = CPR_Support.NOT_SUPPORTED + + if self.cpr_not_supported_callback: + # Make sure to call this callback in the main thread. + self.cpr_not_supported_callback() + + get_app().create_background_task(timer()) + + def report_absolute_cursor_row(self, row: int) -> None: + """ + To be called when we know the absolute cursor position. + (As an answer of a "Cursor Position Request" response.) + """ + self.cpr_support = CPR_Support.SUPPORTED + + # Calculate the amount of rows from the cursor position until the + # bottom of the terminal. + total_rows = self.output.get_size().rows + rows_below_cursor = total_rows - row + 1 + + # Set the minimum available height. + self._min_available_height = rows_below_cursor + + # Pop and set waiting for CPR future. + try: + f = self._waiting_for_cpr_futures.popleft() + except IndexError: + pass # Received CPR response without having a CPR. + else: + f.set_result(None) + + @property + def waiting_for_cpr(self) -> bool: + """ + Waiting for CPR flag. True when we send the request, but didn't got a + response. + """ + return bool(self._waiting_for_cpr_futures) + + async def wait_for_cpr_responses(self, timeout: int = 1) -> None: + """ + Wait for a CPR response. + """ + cpr_futures = list(self._waiting_for_cpr_futures) # Make copy. + + # When there are no CPRs in the queue. Don't do anything. + if not cpr_futures or self.cpr_support == CPR_Support.NOT_SUPPORTED: + return None + + async def wait_for_responses() -> None: + for response_f in cpr_futures: + await response_f + + async def wait_for_timeout() -> None: + await sleep(timeout) + + # Got timeout, erase queue. + for response_f in cpr_futures: + response_f.cancel() + self._waiting_for_cpr_futures = deque() + + tasks = { + ensure_future(wait_for_responses()), + ensure_future(wait_for_timeout()), + } + _, pending = await wait(tasks, return_when=FIRST_COMPLETED) + for task in pending: + task.cancel() + + def render( + self, app: "Application[Any]", layout: "Layout", is_done: bool = False + ) -> None: + """ + Render the current interface to the output. + + :param is_done: When True, put the cursor at the end of the interface. We + won't print any changes to this part. + """ + output = self.output + + # Enter alternate screen. + if self.full_screen and not self._in_alternate_screen: + self._in_alternate_screen = True + output.enter_alternate_screen() + + # Enable bracketed paste. + if not self._bracketed_paste_enabled: + self.output.enable_bracketed_paste() + self._bracketed_paste_enabled = True + + # Reset cursor key mode. + if not self._cursor_key_mode_reset: + self.output.reset_cursor_key_mode() + self._cursor_key_mode_reset = True + + # Enable/disable mouse support. + needs_mouse_support = self.mouse_support() + + if needs_mouse_support and not self._mouse_support_enabled: + output.enable_mouse_support() + self._mouse_support_enabled = True + + elif not needs_mouse_support and self._mouse_support_enabled: + output.disable_mouse_support() + self._mouse_support_enabled = False + + # Create screen and write layout to it. + size = output.get_size() + screen = Screen() + screen.show_cursor = False # Hide cursor by default, unless one of the + # containers decides to display it. + mouse_handlers = MouseHandlers() + + # Calculate height. + if self.full_screen: + height = size.rows + elif is_done: + # When we are done, we don't necessary want to fill up until the bottom. + height = layout.container.preferred_height( + size.columns, size.rows + ).preferred + else: + last_height = self._last_screen.height if self._last_screen else 0 + height = max( + self._min_available_height, + last_height, + layout.container.preferred_height(size.columns, size.rows).preferred, + ) + + height = min(height, size.rows) + + # When the size changes, don't consider the previous screen. + if self._last_size != size: + self._last_screen = None + + # When we render using another style or another color depth, do a full + # repaint. (Forget about the previous rendered screen.) + # (But note that we still use _last_screen to calculate the height.) + if ( + self.style.invalidation_hash() != self._last_style_hash + or app.style_transformation.invalidation_hash() + != self._last_transformation_hash + or app.color_depth != self._last_color_depth + ): + self._last_screen = None + self._attrs_for_style = None + self._style_string_has_style = None + + if self._attrs_for_style is None: + self._attrs_for_style = _StyleStringToAttrsCache( + self.style.get_attrs_for_style_str, app.style_transformation + ) + if self._style_string_has_style is None: + self._style_string_has_style = _StyleStringHasStyleCache( + self._attrs_for_style + ) + + self._last_style_hash = self.style.invalidation_hash() + self._last_transformation_hash = app.style_transformation.invalidation_hash() + self._last_color_depth = app.color_depth + + layout.container.write_to_screen( + screen, + mouse_handlers, + WritePosition(xpos=0, ypos=0, width=size.columns, height=height), + parent_style="", + erase_bg=False, + z_index=None, + ) + screen.draw_all_floats() + + # When grayed. Replace all styles in the new screen. + if app.exit_style: + screen.append_style_to_content(app.exit_style) + + # Process diff and write to output. + self._cursor_pos, self._last_style = _output_screen_diff( + app, + output, + screen, + self._cursor_pos, + app.color_depth, + self._last_screen, + self._last_style, + is_done, + full_screen=self.full_screen, + attrs_for_style_string=self._attrs_for_style, + style_string_has_style=self._style_string_has_style, + size=size, + previous_width=(self._last_size.columns if self._last_size else 0), + ) + self._last_screen = screen + self._last_size = size + self.mouse_handlers = mouse_handlers + + # Handle cursor shapes. + new_cursor_shape = app.cursor.get_cursor_shape(app) + if ( + self._last_cursor_shape is None + or self._last_cursor_shape != new_cursor_shape + ): + output.set_cursor_shape(new_cursor_shape) + self._last_cursor_shape = new_cursor_shape + + # Flush buffered output. + output.flush() + + # Set visible windows in layout. + app.layout.visible_windows = screen.visible_windows + + if is_done: + self.reset() + + def erase(self, leave_alternate_screen: bool = True) -> None: + """ + Hide all output and put the cursor back at the first line. This is for + instance used for running a system command (while hiding the CLI) and + later resuming the same CLI.) + + :param leave_alternate_screen: When True, and when inside an alternate + screen buffer, quit the alternate screen. + """ + output = self.output + + output.cursor_backward(self._cursor_pos.x) + output.cursor_up(self._cursor_pos.y) + output.erase_down() + output.reset_attributes() + output.enable_autowrap() + + output.flush() + + self.reset(leave_alternate_screen=leave_alternate_screen) + + def clear(self) -> None: + """ + Clear screen and go to 0,0 + """ + # Erase current output first. + self.erase() + + # Send "Erase Screen" command and go to (0, 0). + output = self.output + + output.erase_screen() + output.cursor_goto(0, 0) + output.flush() + + self.request_absolute_cursor_position() + + +def print_formatted_text( + output: Output, + formatted_text: AnyFormattedText, + style: BaseStyle, + style_transformation: Optional[StyleTransformation] = None, + color_depth: Optional[ColorDepth] = None, +) -> None: + """ + Print a list of (style_str, text) tuples in the given style to the output. + """ + fragments = to_formatted_text(formatted_text) + style_transformation = style_transformation or DummyStyleTransformation() + color_depth = color_depth or output.get_default_color_depth() + + # Reset first. + output.reset_attributes() + output.enable_autowrap() + last_attrs: Optional[Attrs] = None + + # Print all (style_str, text) tuples. + attrs_for_style_string = _StyleStringToAttrsCache( + style.get_attrs_for_style_str, style_transformation + ) + + for style_str, text, *_ in fragments: + attrs = attrs_for_style_string[style_str] + + # Set style attributes if something changed. + if attrs != last_attrs: + if attrs: + output.set_attributes(attrs, color_depth) + else: + output.reset_attributes() + last_attrs = attrs + + # Print escape sequences as raw output + if "[ZeroWidthEscape]" in style_str: + output.write_raw(text) + else: + # Eliminate carriage returns + text = text.replace("\r", "") + # Insert a carriage return before every newline (important when the + # front-end is a telnet client). + text = text.replace("\n", "\r\n") + output.write(text) + + # Reset again. + output.reset_attributes() + output.flush() |