186 lines
5.6 KiB
Python
186 lines
5.6 KiB
Python
"""
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Key bindings, for scrolling up and down through pages.
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This are separate bindings, because GNU readline doesn't have them, but
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they are very useful for navigating through long multiline buffers, like in
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Vi, Emacs, etc...
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"""
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from __future__ import unicode_literals
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from libs.prompt_toolkit.layout.utils import find_window_for_buffer_name
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from six.moves import range
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__all__ = (
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'scroll_forward',
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'scroll_backward',
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'scroll_half_page_up',
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'scroll_half_page_down',
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'scroll_one_line_up',
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'scroll_one_line_down',
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)
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def _current_window_for_event(event):
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"""
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Return the `Window` for the currently focussed Buffer.
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"""
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return find_window_for_buffer_name(event.cli, event.cli.current_buffer_name)
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def scroll_forward(event, half=False):
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"""
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Scroll window down.
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"""
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w = _current_window_for_event(event)
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b = event.cli.current_buffer
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if w and w.render_info:
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info = w.render_info
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ui_content = info.ui_content
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# Height to scroll.
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scroll_height = info.window_height
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if half:
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scroll_height //= 2
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# Calculate how many lines is equivalent to that vertical space.
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y = b.document.cursor_position_row + 1
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height = 0
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while y < ui_content.line_count:
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line_height = info.get_height_for_line(y)
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if height + line_height < scroll_height:
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height += line_height
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y += 1
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else:
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break
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b.cursor_position = b.document.translate_row_col_to_index(y, 0)
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def scroll_backward(event, half=False):
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"""
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Scroll window up.
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"""
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w = _current_window_for_event(event)
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b = event.cli.current_buffer
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if w and w.render_info:
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info = w.render_info
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# Height to scroll.
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scroll_height = info.window_height
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if half:
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scroll_height //= 2
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# Calculate how many lines is equivalent to that vertical space.
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y = max(0, b.document.cursor_position_row - 1)
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height = 0
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while y > 0:
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line_height = info.get_height_for_line(y)
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if height + line_height < scroll_height:
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height += line_height
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y -= 1
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else:
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break
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b.cursor_position = b.document.translate_row_col_to_index(y, 0)
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def scroll_half_page_down(event):
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"""
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Same as ControlF, but only scroll half a page.
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"""
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scroll_forward(event, half=True)
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def scroll_half_page_up(event):
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"""
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Same as ControlB, but only scroll half a page.
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"""
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scroll_backward(event, half=True)
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def scroll_one_line_down(event):
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"""
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scroll_offset += 1
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"""
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w = find_window_for_buffer_name(event.cli, event.cli.current_buffer_name)
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b = event.cli.current_buffer
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if w:
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# When the cursor is at the top, move to the next line. (Otherwise, only scroll.)
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if w.render_info:
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info = w.render_info
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if w.vertical_scroll < info.content_height - info.window_height:
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if info.cursor_position.y <= info.configured_scroll_offsets.top:
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b.cursor_position += b.document.get_cursor_down_position()
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w.vertical_scroll += 1
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def scroll_one_line_up(event):
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"""
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scroll_offset -= 1
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"""
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w = find_window_for_buffer_name(event.cli, event.cli.current_buffer_name)
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b = event.cli.current_buffer
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if w:
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# When the cursor is at the bottom, move to the previous line. (Otherwise, only scroll.)
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if w.render_info:
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info = w.render_info
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if w.vertical_scroll > 0:
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first_line_height = info.get_height_for_line(info.first_visible_line())
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cursor_up = info.cursor_position.y - (info.window_height - 1 - first_line_height -
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info.configured_scroll_offsets.bottom)
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# Move cursor up, as many steps as the height of the first line.
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# TODO: not entirely correct yet, in case of line wrapping and many long lines.
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for _ in range(max(0, cursor_up)):
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b.cursor_position += b.document.get_cursor_up_position()
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# Scroll window
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w.vertical_scroll -= 1
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def scroll_page_down(event):
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"""
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Scroll page down. (Prefer the cursor at the top of the page, after scrolling.)
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"""
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w = _current_window_for_event(event)
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b = event.cli.current_buffer
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if w and w.render_info:
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# Scroll down one page.
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line_index = max(w.render_info.last_visible_line(), w.vertical_scroll + 1)
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w.vertical_scroll = line_index
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b.cursor_position = b.document.translate_row_col_to_index(line_index, 0)
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b.cursor_position += b.document.get_start_of_line_position(after_whitespace=True)
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def scroll_page_up(event):
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"""
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Scroll page up. (Prefer the cursor at the bottom of the page, after scrolling.)
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"""
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w = _current_window_for_event(event)
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b = event.cli.current_buffer
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if w and w.render_info:
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# Put cursor at the first visible line. (But make sure that the cursor
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# moves at least one line up.)
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line_index = max(0, min(w.render_info.first_visible_line(),
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b.document.cursor_position_row - 1))
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b.cursor_position = b.document.translate_row_col_to_index(line_index, 0)
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b.cursor_position += b.document.get_start_of_line_position(after_whitespace=True)
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# Set the scroll offset. We can safely set it to zero; the Window will
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# make sure that it scrolls at least until the cursor becomes visible.
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w.vertical_scroll = 0
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