View Mode Persistence

Overview

Per-tab view mode persistence allows each tab to maintain its own view mode (Raw or Rendered) independently, with modes persisting across application restarts.

Key Files

• src/config/settings.rs - TabInfo struct with view_mode field, ViewMode enum
• src/state.rs - Tab struct with view mode methods, session restoration
• src/app.rs - Per-tab view mode usage in UI

Implementation Details

ViewMode Enum

Defined in settings.rs:

pub enum ViewMode {
    Raw,       // Plain markdown text editing
    Rendered,  // WYSIWYG rendered editing
}

Per-Tab Storage

View mode is stored at two levels:

1. Runtime (Tab struct): view_mode: ViewMode field on each tab
2. Persistence (TabInfo struct): Serialized to config JSON via last_open_tabs

Default Behavior

Scenario	Default Mode
New tab created (Tab::new())	Raw
File opened (Tab::with_file())	Raw
Session restored (Tab::from_tab_info())	Saved mode
Old config (no view_mode field)	Raw (backward compatible)

Tab Methods

impl Tab {
    pub fn get_view_mode(&self) -> ViewMode;
    pub fn set_view_mode(&mut self, mode: ViewMode);
    pub fn toggle_view_mode(&mut self) -> ViewMode;
}

Session Persistence

On shutdown:

1. Tab::to_tab_info() includes view_mode
2. AppState::save_settings_if_dirty() serializes to config

On startup:

1. Tab::from_tab_info() restores saved view mode
2. Missing view_mode field defaults to Raw (serde default)

Config Format

{
  "last_open_tabs": [
    {
      "path": "/path/to/file.md",
      "modified": false,
      "cursor_position": [0, 0],
      "scroll_offset": 0.0,
      "view_mode": "rendered"
    }
  ]
}

Usage

Toggle View Mode (Active Tab)

// In app.rs
if let Some(tab) = self.state.active_tab_mut() {
    let new_mode = tab.toggle_view_mode();
}

Get Current Tab's Mode

let view_mode = self.state.active_tab()
    .map(|t| t.view_mode)
    .unwrap_or(ViewMode::Raw);

Keyboard Shortcut

Ctrl+Shift+V toggles view mode for the active tab.

Tests

Run tests with:

cargo test view_mode
cargo test tab_from_tab_info
cargo test restore_session

Key tests:

• test_tab_view_mode_toggle - Toggle functionality
• test_tab_view_mode_get_set - Getter/setter
• test_tab_info_backward_compatibility - Old config support
• test_restore_session_tabs_with_temp_file - Session restoration
• test_restore_multiple_tabs_with_temp_files - Multi-tab persistence

Backward Compatibility

Old config files without view_mode in TabInfo will deserialize correctly due to #[serde(default)] attribute, defaulting to ViewMode::Raw.