Image Viewer Tab

Dedicated image viewer tabs for opening image files (PNG, JPEG, GIF, WebP, BMP) directly in Ferrite, intercepting them before the binary file error path.

Architecture

FileType Detection

FileType::Image variant in src/state.rs detects extensions: png, jpg, jpeg, gif, webp, bmp (case-insensitive via from_extension()).

Tab Kind

TabKind::ImageViewer(ImageViewerState) holds per-tab viewer state:

Field	Type	Purpose
zoom	f32	Current zoom level (default 1.0, auto-fitted on first render)
dimensions	Option<(u32, u32)>	Image width/height, populated after first load
file_size	u64	File size in bytes
format_label	String	Uppercase extension (e.g., "PNG", "JPEG")
fitted	bool	Whether initial fit-to-window has been applied

File Opening Flow

In AppState::open_file_with_focus(), image files are intercepted before the binary content check:

open_file_with_focus()
  → check already open (dedup by path)
  → FileType::from_path().is_image()? → open_image_tab()  ← early return
  → is_binary_content()? → error
  → normal text tab

open_image_tab() creates a lightweight tab without reading file content as text — only metadata (file size, extension) is captured. The image bytes are loaded lazily on first render.

Texture Loading & Caching

Image textures are loaded via load_viewer_image() in central_panel.rs, reusing the same image crate infrastructure as markdown image rendering. Textures are cached in egui's temp data store keyed by file path (egui::Id::new("image_viewer_texture").with(&path)).

Rendering

render_image_viewer_tab() in central_panel.rs:

1. Fit-to-window: On first render, computes scale to fit available area without upscaling beyond 1:1
2. Ctrl+Scroll zoom: Multiplicative zoom (0.1x to 10.0x range), applied via smooth_scroll_delta.y
3. Centered display: Image centered in a ScrollArea::both() with computed padding
4. Metadata bar: Bottom separator with dimensions, format, file size, and zoom percentage

Tab Behavior

• Tab title shows framed picture emoji + filename
• should_prompt_to_save() returns false (read-only, no modifications)
• Image viewer tabs skip editor focus (needs_focus = false)
• Invalid images show an error message in the tab instead of crashing

Supported Formats

PNG, JPEG, GIF, WebP, BMP — handled by the image crate with corresponding feature flags in Cargo.toml.

Key Files

File	Changes
src/state.rs	FileType::Image, ImageViewerState, TabKind::ImageViewer, open_image_tab()
src/app/central_panel.rs	render_image_viewer_tab(), load_viewer_image(), ImageViewerTexture
src/editor/folding.rs	FileType::Image added to no-fold branch
Cargo.toml	Added bmp feature to image crate