Struct ListCursor

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pub struct ListCursor { /* private fields */ }

Expand description

A focus over len rows and the window of rows shown around it.

The window’s place lives in the cursor, so it doesn’t jump from frame to frame: ask for it with window (rows of one height) or window_by_heights each time the list is shown.

Implementations§

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impl ListCursor

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pub fn new(len: usize) -> Self

A cursor on the first of len rows, keeping the focus in view.

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pub fn scrolling(self, scroll: Scroll) -> Self

The same cursor, its window following the focus by scroll.

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pub fn at(self, index: usize) -> Self

The same cursor on row index (the last row, if there is no such row).

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pub fn focus(&self) -> usize

The focused row. With no rows it is 0, which isn’t a row.

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pub fn len(&self) -> usize

How many rows there are.

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pub fn is_empty(&self) -> bool

Whether there are no rows.

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pub fn scroll(&self) -> Scroll

How the window follows the focus.

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pub fn first_shown(&self) -> usize

The first row of the window, as the last window or window_by_heights left it.

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pub fn step( &mut self, forward: bool, wrap: bool, enabled: impl Fn(usize) -> bool, ) -> bool

Moves the focus to the next (forward) or previous row that enabled accepts, going round the ends if wrap, else stopping at them. Returns whether the focus moved, so the caller knows to play its move sound. With no such row it stays put.

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pub fn settle(&mut self, enabled: impl Fn(usize) -> bool) -> bool

Moves the focus off a row enabled rejects: to the next row it accepts, else the nearest one before. Returns whether it moved. For after the rows changed (a row was used up, or removed).

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pub fn set_len(&mut self, len: usize)

Sets the number of rows, after some were added or removed. A focus past the new end moves to the last row; the window is clamped the next time it is asked for.

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pub fn window(&mut self, rows_shown: usize) -> Range<usize> ⓘ

The rows a box of rows_shown rows shows: always the focus, placed by the cursor’s Scroll rule, and never past the end of the list while there are rows before it to show instead. A box of no rows still shows the focused one. With no rows it is empty.

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pub fn window_by_heights( &mut self, heights: &[usize], room: usize, ) -> Range<usize> ⓘ

The rows a box room tall shows when the rows have different heights (heights[i] is row i’s, in the box’s units: a backlog of wrapped lines). As window: always the focus, even a focused row taller than the box, placed by the Scroll rule, and as many rows as fit. heights has one entry per row.