Shortcuts on this page
r m x toggle line displays
j k next/prev highlighted chunk
0 (zero) top of page
1 (one) first highlighted chunk
1"""
2Key bindings, for scrolling up and down through pages.
4This are separate bindings, because GNU readline doesn't have them, but
5they are very useful for navigating through long multiline buffers, like in
6Vi, Emacs, etc...
7"""
9from __future__ import annotations
11from prompt_toolkit.key_binding.key_processor import KeyPressEvent
13__all__ = [
14 "scroll_forward",
15 "scroll_backward",
16 "scroll_half_page_up",
17 "scroll_half_page_down",
18 "scroll_one_line_up",
19 "scroll_one_line_down",
20]
22E = KeyPressEvent
25def scroll_forward(event: E, half: bool = False) -> None:
26 """
27 Scroll window down.
28 """
29 w = event.app.layout.current_window
30 b = event.app.current_buffer
32 if w and w.render_info:
33 info = w.render_info
34 ui_content = info.ui_content
36 # Height to scroll.
37 scroll_height = info.window_height
38 if half:
39 scroll_height //= 2
41 # Calculate how many lines is equivalent to that vertical space.
42 y = b.document.cursor_position_row + 1
43 height = 0
44 while y < ui_content.line_count:
45 line_height = info.get_height_for_line(y)
47 if height + line_height < scroll_height:
48 height += line_height
49 y += 1
50 else:
51 break
53 b.cursor_position = b.document.translate_row_col_to_index(y, 0)
56def scroll_backward(event: E, half: bool = False) -> None:
57 """
58 Scroll window up.
59 """
60 w = event.app.layout.current_window
61 b = event.app.current_buffer
63 if w and w.render_info:
64 info = w.render_info
66 # Height to scroll.
67 scroll_height = info.window_height
68 if half:
69 scroll_height //= 2
71 # Calculate how many lines is equivalent to that vertical space.
72 y = max(0, b.document.cursor_position_row - 1)
73 height = 0
74 while y > 0:
75 line_height = info.get_height_for_line(y)
77 if height + line_height < scroll_height:
78 height += line_height
79 y -= 1
80 else:
81 break
83 b.cursor_position = b.document.translate_row_col_to_index(y, 0)
86def scroll_half_page_down(event: E) -> None:
87 """
88 Same as ControlF, but only scroll half a page.
89 """
90 scroll_forward(event, half=True)
93def scroll_half_page_up(event: E) -> None:
94 """
95 Same as ControlB, but only scroll half a page.
96 """
97 scroll_backward(event, half=True)
100def scroll_one_line_down(event: E) -> None:
101 """
102 scroll_offset += 1
103 """
104 w = event.app.layout.current_window
105 b = event.app.current_buffer
107 if w:
108 # When the cursor is at the top, move to the next line. (Otherwise, only scroll.)
109 if w.render_info:
110 info = w.render_info
112 if w.vertical_scroll < info.content_height - info.window_height:
113 if info.cursor_position.y <= info.configured_scroll_offsets.top:
114 b.cursor_position += b.document.get_cursor_down_position()
116 w.vertical_scroll += 1
119def scroll_one_line_up(event: E) -> None:
120 """
121 scroll_offset -= 1
122 """
123 w = event.app.layout.current_window
124 b = event.app.current_buffer
126 if w:
127 # When the cursor is at the bottom, move to the previous line. (Otherwise, only scroll.)
128 if w.render_info:
129 info = w.render_info
131 if w.vertical_scroll > 0:
132 first_line_height = info.get_height_for_line(info.first_visible_line())
134 cursor_up = info.cursor_position.y - (
135 info.window_height
136 - 1
137 - first_line_height
138 - info.configured_scroll_offsets.bottom
139 )
141 # Move cursor up, as many steps as the height of the first line.
142 # TODO: not entirely correct yet, in case of line wrapping and many long lines.
143 for _ in range(max(0, cursor_up)):
144 b.cursor_position += b.document.get_cursor_up_position()
146 # Scroll window
147 w.vertical_scroll -= 1
150def scroll_page_down(event: E) -> None:
151 """
152 Scroll page down. (Prefer the cursor at the top of the page, after scrolling.)
153 """
154 w = event.app.layout.current_window
155 b = event.app.current_buffer
157 if w and w.render_info:
158 # Scroll down one page.
159 line_index = max(w.render_info.last_visible_line(), w.vertical_scroll + 1)
160 w.vertical_scroll = line_index
162 b.cursor_position = b.document.translate_row_col_to_index(line_index, 0)
163 b.cursor_position += b.document.get_start_of_line_position(
164 after_whitespace=True
165 )
168def scroll_page_up(event: E) -> None:
169 """
170 Scroll page up. (Prefer the cursor at the bottom of the page, after scrolling.)
171 """
172 w = event.app.layout.current_window
173 b = event.app.current_buffer
175 if w and w.render_info:
176 # Put cursor at the first visible line. (But make sure that the cursor
177 # moves at least one line up.)
178 line_index = max(
179 0,
180 min(w.render_info.first_visible_line(), b.document.cursor_position_row - 1),
181 )
183 b.cursor_position = b.document.translate_row_col_to_index(line_index, 0)
184 b.cursor_position += b.document.get_start_of_line_position(
185 after_whitespace=True
186 )
188 # Set the scroll offset. We can safely set it to zero; the Window will
189 # make sure that it scrolls at least until the cursor becomes visible.
190 w.vertical_scroll = 0