Struct SplitViewState 

pub struct SplitViewState {

    pub cursors: Cursors,
    pub viewport: Viewport,
    pub open_buffers: Vec<BufferId>,
    pub tab_scroll_offset: usize,
    pub view_mode: ViewMode,
    pub compose_width: Option<u16>,
    pub compose_column_guides: Option<Vec<u16>>,
    pub compose_prev_line_numbers: Option<bool>,
    pub view_transform: Option<ViewTransformPayload>,
    pub layout: Option<Layout>,
    pub layout_dirty: bool,
    pub previous_buffer: Option<BufferId>,
    pub sync_group: Option<u32>,
    pub composite_view: Option<BufferId>,
}

Per-split view state (independent of buffer content)

Following the Emacs model where each window (split) has its own:

• Point (cursor position) - independent per split
• Window-start (scroll position) - independent per split
• Tabs (open buffers) - independent per split

This allows multiple splits to display the same buffer at different positions with independent cursor and scroll positions, and each split has its own set of tabs.

Fields

cursors: Cursors

Independent cursor set for this split (supports multi-cursor)

viewport: Viewport

Independent scroll position for this split

open_buffers: Vec<BufferId>

List of buffer IDs open in this split’s tab bar (in order) The currently displayed buffer is tracked in the SplitNode::Leaf

tab_scroll_offset: usize

Horizontal scroll offset for the tabs in this split

view_mode: ViewMode

View mode (Source/Compose) per split

compose_width: Option<u16>

Optional compose width for centering/wrapping in this split

compose_column_guides: Option<Vec<u16>>

Column guides for this split (e.g., tables)

compose_prev_line_numbers: Option<bool>

Previously configured line number visibility (restored when leaving Compose)

view_transform: Option<ViewTransformPayload>

Optional view transform payload for this split/viewport

layout: Option<Layout>

Computed layout for this view (from view_transform or base tokens) This is View state - each split has its own Layout

layout_dirty: bool

Whether the layout needs to be rebuilt (buffer changed, transform changed, etc.)

previous_buffer: Option<BufferId>

Previously active buffer in this split (for “Switch to Previous Tab” command)

sync_group: Option<u32>

Sync group ID for synchronized scrolling Splits with the same sync_group will scroll together

composite_view: Option<BufferId>

When set, this split renders a composite view (e.g., side-by-side diff). The split’s buffer_id is the focused source buffer, but rendering uses the composite layout. This makes the source buffer the “active buffer” so normal keybindings work directly.

Implementations

impl SplitViewState

pub fn new(width: u16, height: u16) -> Self

Create a new split view state with default cursor at position 0

pub fn with_buffer(width: u16, height: u16, buffer_id: BufferId) -> Self

Create a new split view state with an initial buffer open

pub fn invalidate_layout(&mut self)

Mark layout as needing rebuild (call after buffer changes)

pub fn ensure_layout( &mut self, tokens: &[ViewTokenWire], source_range: Range<usize>, tab_size: usize, ) -> &Layout

Ensure layout is valid, rebuilding if needed. Returns the Layout - never returns None. Following VSCode’s ViewModel pattern.

Arguments

• tokens - ViewTokenWire array (from view_transform or built from buffer)
• source_range - The byte range this layout covers
• tab_size - Tab width for rendering

pub fn get_layout(&self) -> Option<&Layout>

Get the current layout if it exists and is valid

pub fn add_buffer(&mut self, buffer_id: BufferId)

Add a buffer to this split’s tabs (if not already present)

pub fn remove_buffer(&mut self, buffer_id: BufferId)

Remove a buffer from this split’s tabs

pub fn has_buffer(&self, buffer_id: BufferId) -> bool

Check if a buffer is open in this split

Trait Implementations

impl Clone for SplitViewState

fn clone(&self) -> SplitViewState

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SplitViewState

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.