ratatui/terminal/
frame.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
use crate::{
    buffer::Buffer,
    layout::{Position, Rect},
    widgets::{StatefulWidget, StatefulWidgetRef, Widget, WidgetRef},
};

/// A consistent view into the terminal state for rendering a single frame.
///
/// This is obtained via the closure argument of [`Terminal::draw`]. It is used to render widgets
/// to the terminal and control the cursor position.
///
/// The changes drawn to the frame are applied only to the current [`Buffer`]. After the closure
/// returns, the current buffer is compared to the previous buffer and only the changes are applied
/// to the terminal. This avoids drawing redundant cells.
///
/// [`Buffer`]: crate::buffer::Buffer
/// [`Terminal::draw`]: crate::Terminal::draw
#[derive(Debug, Hash)]
pub struct Frame<'a> {
    /// Where should the cursor be after drawing this frame?
    ///
    /// If `None`, the cursor is hidden and its position is controlled by the backend. If `Some((x,
    /// y))`, the cursor is shown and placed at `(x, y)` after the call to `Terminal::draw()`.
    pub(crate) cursor_position: Option<Position>,

    /// The area of the viewport
    pub(crate) viewport_area: Rect,

    /// The buffer that is used to draw the current frame
    pub(crate) buffer: &'a mut Buffer,

    /// The frame count indicating the sequence number of this frame.
    pub(crate) count: usize,
}

/// `CompletedFrame` represents the state of the terminal after all changes performed in the last
/// [`Terminal::draw`] call have been applied. Therefore, it is only valid until the next call to
/// [`Terminal::draw`].
///
/// [`Terminal::draw`]: crate::Terminal::draw
#[derive(Debug, Clone, Eq, PartialEq, Hash)]
pub struct CompletedFrame<'a> {
    /// The buffer that was used to draw the last frame.
    pub buffer: &'a Buffer,
    /// The size of the last frame.
    pub area: Rect,
    /// The frame count indicating the sequence number of this frame.
    pub count: usize,
}

impl Frame<'_> {
    /// The area of the current frame
    ///
    /// This is guaranteed not to change during rendering, so may be called multiple times.
    ///
    /// If your app listens for a resize event from the backend, it should ignore the values from
    /// the event for any calculations that are used to render the current frame and use this value
    /// instead as this is the area of the buffer that is used to render the current frame.
    pub const fn area(&self) -> Rect {
        self.viewport_area
    }

    /// The area of the current frame
    ///
    /// This is guaranteed not to change during rendering, so may be called multiple times.
    ///
    /// If your app listens for a resize event from the backend, it should ignore the values from
    /// the event for any calculations that are used to render the current frame and use this value
    /// instead as this is the area of the buffer that is used to render the current frame.
    #[deprecated = "use .area() as it's the more correct name"]
    pub const fn size(&self) -> Rect {
        self.viewport_area
    }

    /// Render a [`Widget`] to the current buffer using [`Widget::render`].
    ///
    /// Usually the area argument is the size of the current frame or a sub-area of the current
    /// frame (which can be obtained using [`Layout`] to split the total area).
    ///
    /// # Example
    ///
    /// ```rust
    /// # use ratatui::{backend::TestBackend, Terminal};
    /// # let backend = TestBackend::new(5, 5);
    /// # let mut terminal = Terminal::new(backend).unwrap();
    /// # let mut frame = terminal.get_frame();
    /// use ratatui::{layout::Rect, widgets::Block};
    ///
    /// let block = Block::new();
    /// let area = Rect::new(0, 0, 5, 5);
    /// frame.render_widget(block, area);
    /// ```
    ///
    /// [`Layout`]: crate::layout::Layout
    pub fn render_widget<W: Widget>(&mut self, widget: W, area: Rect) {
        widget.render(area, self.buffer);
    }

    /// Render a [`WidgetRef`] to the current buffer using [`WidgetRef::render_ref`].
    ///
    /// Usually the area argument is the size of the current frame or a sub-area of the current
    /// frame (which can be obtained using [`Layout`] to split the total area).
    ///
    /// # Example
    ///
    /// ```rust
    /// # #[cfg(feature = "unstable-widget-ref")] {
    /// # use ratatui::{backend::TestBackend, Terminal};
    /// # let backend = TestBackend::new(5, 5);
    /// # let mut terminal = Terminal::new(backend).unwrap();
    /// # let mut frame = terminal.get_frame();
    /// use ratatui::{layout::Rect, widgets::Block};
    ///
    /// let block = Block::new();
    /// let area = Rect::new(0, 0, 5, 5);
    /// frame.render_widget_ref(block, area);
    /// # }
    /// ```
    #[allow(clippy::needless_pass_by_value)]
    #[instability::unstable(feature = "widget-ref")]
    pub fn render_widget_ref<W: WidgetRef>(&mut self, widget: W, area: Rect) {
        widget.render_ref(area, self.buffer);
    }

    /// Render a [`StatefulWidget`] to the current buffer using [`StatefulWidget::render`].
    ///
    /// Usually the area argument is the size of the current frame or a sub-area of the current
    /// frame (which can be obtained using [`Layout`] to split the total area).
    ///
    /// The last argument should be an instance of the [`StatefulWidget::State`] associated to the
    /// given [`StatefulWidget`].
    ///
    /// # Example
    ///
    /// ```rust
    /// # use ratatui::{backend::TestBackend, Terminal};
    /// # let backend = TestBackend::new(5, 5);
    /// # let mut terminal = Terminal::new(backend).unwrap();
    /// # let mut frame = terminal.get_frame();
    /// use ratatui::{
    ///     layout::Rect,
    ///     widgets::{List, ListItem, ListState},
    /// };
    ///
    /// let mut state = ListState::default().with_selected(Some(1));
    /// let list = List::new(vec![ListItem::new("Item 1"), ListItem::new("Item 2")]);
    /// let area = Rect::new(0, 0, 5, 5);
    /// frame.render_stateful_widget(list, area, &mut state);
    /// ```
    ///
    /// [`Layout`]: crate::layout::Layout
    pub fn render_stateful_widget<W>(&mut self, widget: W, area: Rect, state: &mut W::State)
    where
        W: StatefulWidget,
    {
        widget.render(area, self.buffer, state);
    }

    /// Render a [`StatefulWidgetRef`] to the current buffer using
    /// [`StatefulWidgetRef::render_ref`].
    ///
    /// Usually the area argument is the size of the current frame or a sub-area of the current
    /// frame (which can be obtained using [`Layout`] to split the total area).
    ///
    /// The last argument should be an instance of the [`StatefulWidgetRef::State`] associated to
    /// the given [`StatefulWidgetRef`].
    ///
    /// # Example
    ///
    /// ```rust
    /// # #[cfg(feature = "unstable-widget-ref")] {
    /// # use ratatui::{backend::TestBackend, Terminal};
    /// # let backend = TestBackend::new(5, 5);
    /// # let mut terminal = Terminal::new(backend).unwrap();
    /// # let mut frame = terminal.get_frame();
    /// use ratatui::{
    ///     layout::Rect,
    ///     widgets::{List, ListItem, ListState},
    /// };
    ///
    /// let mut state = ListState::default().with_selected(Some(1));
    /// let list = List::new(vec![ListItem::new("Item 1"), ListItem::new("Item 2")]);
    /// let area = Rect::new(0, 0, 5, 5);
    /// frame.render_stateful_widget_ref(list, area, &mut state);
    /// # }
    /// ```
    #[allow(clippy::needless_pass_by_value)]
    #[instability::unstable(feature = "widget-ref")]
    pub fn render_stateful_widget_ref<W>(&mut self, widget: W, area: Rect, state: &mut W::State)
    where
        W: StatefulWidgetRef,
    {
        widget.render_ref(area, self.buffer, state);
    }

    /// After drawing this frame, make the cursor visible and put it at the specified (x, y)
    /// coordinates. If this method is not called, the cursor will be hidden.
    ///
    /// Note that this will interfere with calls to [`Terminal::hide_cursor`],
    /// [`Terminal::show_cursor`], and [`Terminal::set_cursor_position`]. Pick one of the APIs and
    /// stick with it.
    ///
    /// [`Terminal::hide_cursor`]: crate::Terminal::hide_cursor
    /// [`Terminal::show_cursor`]: crate::Terminal::show_cursor
    /// [`Terminal::set_cursor_position`]: crate::Terminal::set_cursor_position
    pub fn set_cursor_position<P: Into<Position>>(&mut self, position: P) {
        self.cursor_position = Some(position.into());
    }

    /// After drawing this frame, make the cursor visible and put it at the specified (x, y)
    /// coordinates. If this method is not called, the cursor will be hidden.
    ///
    /// Note that this will interfere with calls to [`Terminal::hide_cursor`],
    /// [`Terminal::show_cursor`], and [`Terminal::set_cursor_position`]. Pick one of the APIs and
    /// stick with it.
    ///
    /// [`Terminal::hide_cursor`]: crate::Terminal::hide_cursor
    /// [`Terminal::show_cursor`]: crate::Terminal::show_cursor
    /// [`Terminal::set_cursor_position`]: crate::Terminal::set_cursor_position
    #[deprecated = "the method set_cursor_position indicates more clearly what about the cursor to set"]
    pub fn set_cursor(&mut self, x: u16, y: u16) {
        self.set_cursor_position(Position { x, y });
    }

    /// Gets the buffer that this `Frame` draws into as a mutable reference.
    pub fn buffer_mut(&mut self) -> &mut Buffer {
        self.buffer
    }

    /// Returns the current frame count.
    ///
    /// This method provides access to the frame count, which is a sequence number indicating
    /// how many frames have been rendered up to (but not including) this one. It can be used
    /// for purposes such as animation, performance tracking, or debugging.
    ///
    /// Each time a frame has been rendered, this count is incremented,
    /// providing a consistent way to reference the order and number of frames processed by the
    /// terminal. When count reaches its maximum value (`usize::MAX`), it wraps around to zero.
    ///
    /// This count is particularly useful when dealing with dynamic content or animations where the
    /// state of the display changes over time. By tracking the frame count, developers can
    /// synchronize updates or changes to the content with the rendering process.
    ///
    /// # Examples
    ///
    /// ```rust
    /// # use ratatui::{backend::TestBackend, Terminal};
    /// # let backend = TestBackend::new(5, 5);
    /// # let mut terminal = Terminal::new(backend).unwrap();
    /// # let mut frame = terminal.get_frame();
    /// let current_count = frame.count();
    /// println!("Current frame count: {}", current_count);
    /// ```
    pub const fn count(&self) -> usize {
        self.count
    }
}