Module image_diff 

Image diff support for displaying image files in the TUI.

This module handles:

• Detection of image files by extension (dynamic via image crate)
• SVG rasterization via resvg
• Image loading, downscaling, and caching
• LRU cache eviction

Structs

CachedImage

A loaded and cached image ready for display

ImageCache

LRU cache for loaded images

ImageDiffState

Image diff state for a single file (before and after versions)

Constants

FONT_HEIGHT_PX

Terminal font height in pixels (used for image sizing calculations). Most monospace terminal fonts are 16 pixels tall per character cell.

FONT_WIDTH_PX

Terminal font width in pixels (used for image sizing calculations). Most monospace terminal fonts are 8 pixels wide per character cell.

IMAGE_BOTTOM_MARGIN

Margin between image and metadata (rows)

IMAGE_PANEL_OVERHEAD

Total overhead for an image panel: borders (2) + margins (2) + metadata (1) This is subtracted from the panel height to get the available image height.

IMAGE_TOP_MARGIN

Margin above the image within the panel (rows)

MAX_CACHED_IMAGES

Maximum number of images to keep in cache

MAX_CACHE_DIMENSION

Maximum dimension for cached images (larger images are downscaled)

MAX_IMAGE_HEIGHT_ROWS

Maximum height in terminal rows for an image diff panel. Prevents very tall images from consuming excessive vertical space.

METADATA_HEIGHT

Height of the metadata line below each image panel (rows)

Functions

center_in_area

Center a smaller rectangle within a larger area

fit_dimensions

Calculate display dimensions maintaining aspect ratio. Converts image pixel dimensions to terminal cell dimensions using font metrics, then scales to fit the available space without upscaling.

format_file_size

Format file size for human-readable display

format_name_from_path

Get format name from file path extension

is_image_file

Check if a file is a supported image format. Uses the image crate’s format detection - no hardcoded extension list.

is_lfs_pointer

Check if content is a Git LFS pointer (not actual file content)

is_svg

Check if a file is an SVG (handled via resvg, not image crate)

load_and_cache

Load image bytes and create a cached image with optional downscaling

load_image_diff

Load image diff state for a file (before and after versions).

rasterize_svg

Rasterize SVG bytes to a DynamicImage