11 KiB
Ebox user guide
Ebox is the low-level box, layout, and buffer-rendering package. Use it directly when an application needs precise geometry or use it as the rendering substrate below ETAF. This guide intentionally does not introduce Components, reactive state, behaviors, or application data. For the complete function/property/configuration inventory, see the public API reference.
1. Load the package
(add-to-list 'load-path "/path/to/github/ebox")
(require 'ebox)
Loading defines the public package and its pure layout modules. It does not create a buffer, install a mode, build Rust code, or change the current editing buffer.
2. Build a node tree
ebox-create makes a node. Container helpers accept child nodes and return another node:
(ebox-column
(ebox-create :content "Title"
:font 'bold
:color "#263244"
:bgcolor "#F4F6FB"
:padding '(1 2))
(ebox-row
(ebox-create :content "Left" :width 12)
(ebox-create :content "Right" :width 12)))
The public shape is data, not rendered text. A node may contain string
:content or child nodes supplied to a container helper; wrapper bookkeeping
stays internal. Use :key when siblings have stable application identity and
:host-ref when an application needs a public handle position after rendering.
3. Dimensions and surface properties
Ordinary horizontal numbers are character columns. A one-element list denotes a pixel width; vertical numbers are line counts. Padding and margins accept scalar or CSS-like 1–4-value forms. Borders are width, style, and color:
(ebox-create
:content "A readable panel"
:width '(420)
:padding '(1 2)
:margin '(0 1)
:border '((1) solid "#8A93A6")
:color "#263244"
:bgcolor "#FFFFFF")
Keep foreground and background explicit on tinted surfaces. :font may be a face symbol or a face plist; use :color and :bgcolor when the surface itself carries semantic colors. :font-family, :font-height/:font-size, :font-weight, and :font-slant are the supported typography longhands.
Stylesheet rules
Inline properties are compiled by Ebox's ECSS-backed style domain. Selector-driven rules use the isolated stylesheet:
(ebox-style-reset-rules)
(ebox-style-add-rule ".card"
'(:color "#1F2937" :padding '(1 (12)))
:layer 'base)
Rules use ECSS cascade semantics, including :origin, :layer, and :scope. A rule change does not publish an already-mounted buffer automatically; rerender or commit the affected buffer after changing rules. See the API reference for the complete property schema.
4. Row, column, flex, and Grid
Use row and column for simple one-dimensional composition. Use flex when free space is distributed among items. Use Grid when two-dimensional tracks or stable placement matter:
(ebox-grid
:width '(640)
:grid-template-columns '((200) 1fr 1fr)
:grid-template-rows '(1 1)
:gap '(1 (12))
:padding '(1 2)
:border '((1) solid "#8A93A6")
(ebox-create :content "Header" :grid-column 1 :grid-column-span 3)
(ebox-create :content "Navigation" :grid-column 1 :grid-row 2)
(ebox-create :content "Main" :grid-column 2 :grid-row 2)
(ebox-create :content "Aside" :grid-column 3 :grid-row 2))
Grid tracks can be fixed, fractional, auto, minmax, or repeated. Explicit placement is one-based. Use positive integer spans and let implicit tracks fill omitted positions. Multiline items are aligned line by line to their grid rectangle before a wrapper border is painted, keeping a bordered Grid's right edge continuous even when child lines have different natural widths.
5. Render text or a buffer
ebox-render is pure with respect to buffers and returns propertized text through an ephemeral TP surface. ebox-render-to-buffer copies the declarative source and mounts a retained TP surface for initial publication:
(let ((node (ebox-column
(ebox-create :id "status" :content "Ready" :width '(240))
(ebox-create :content "Rendered by Ebox"))))
(ebox-render node)
(ebox-render-to-buffer "*Ebox Demo*" node))
The returned text carries display, face, region, and identity properties needed by Ebox. Do not edit those properties by hand. The source node remains caller-owned and can be mounted in more than one buffer; each buffer receives independent runtime identity and state.
6. Update an existing buffer
Build a fresh root tree and commit it to the existing buffer:
(ebox-commit
"*Ebox Demo*"
(ebox-column
(ebox-create :content "Updated" :key 'title :width '(240))))
Ebox compares stable keys and region identity, prepares the semantic dirty/owner plan, and asks TP to atomically publish the new retained surface and Ebox runtime state. It records both the Ebox plan and TP execution summary:
(ebox-buffer-update-report "*Ebox Demo*")
If a candidate cannot be proven safe, Ebox escalates to an owner or root rerender. A failed render, publication, runtime-state swap, or publication callback leaves the previous buffer, TP surface, Ebox runtime state, and last successful report intact.
7. Selectors and handles
Selectors query the rendered tree and return public match records. They do not own application state. Give an editable box a logical :id, resolve it in one live buffer, and pass the opaque surface-scoped handle to ebox-region-update:
(let ((handle (ebox-region-resolve "*Ebox Demo*" "status")))
(ebox-region-update handle :content "Ready" :color "#166534"))
The same logical id in two buffers resolves to two different handles, so updating one surface cannot accidentally mutate the other. A handle becomes stale when its retained object is removed or its buffer is killed. ebox-region-update accepts only a live handle; numeric region ids are internal render metadata and are not an update API.
ebox-selector-parse compiles CSS-like strings directly to ECSS's structured selector AST. Queries support selector lists, type, #id, .class, attribute presence and =, ~=, |=, ^=, $=, *= operators, state pseudos, :is(), :where(), :not(), :has(), descendant whitespace, child >, adjacent sibling +, and general sibling ~. Ebox maps logical children and indexed candidates to ECSS subjects; ecss-selector-match-p is the only final matcher, so query and cascade semantics cannot diverge. Attribute selectors see built-in :id/:key plus metadata explicitly supplied through :selector-attributes, for example :selector-attributes '((role . button)); visible content, layout properties, Ebox runtime containers, and internal :ebox-* slots never become selector attributes implicitly.
(ebox-selector-query-buffer "*Ebox Demo*" ".toolbar > box.action")
(ebox-selector-query-buffer "*Ebox Demo*" "#first + .later")
(ebox-selector-query-buffer "*Ebox Demo*" "#first ~ [role=button]")
(ebox-selector-update-buffer "*Ebox Demo*" ".action" :color "#2563EB")
ebox-selector-update-buffer returns :matched, :updated, structured :skipped, and :reports fields. The compatibility aliases ebox-select-all and ebox-update-selector refer to the query and update functions.
8. Scroll and viewport context
Give a box :overflow 'scroll (the default) and a finite :height to create a scroll window:
(ebox-create :id "log" :width '(420) :height 8
:overflow 'scroll
:content (mapconcat #'identity lines "\n"))
ebox-scroll-down, ebox-scroll-up, ebox-scroll-page-down, and ebox-scroll-page-up start at the innermost scroll owner under point. Keyboard line intent is allocated one line at a time through semantic scroll ancestors; any residual continues to the parent and then ordinary Emacs buffer scrolling. ebox-wheel-scroll-down and ebox-wheel-scroll-up anchor at the mouse event position (not point) and use the same inner-to-outer residual rule. When no Ebox region can consume the request they delegate to normal Emacs scrolling. ebox-buffer-mode installs ebox-scroll-map locally; ebox-render-to-buffer enables it on its returned buffer. ebox-scroll-state exposes read-only scroll facts for a numeric region id; use scroll commands or ebox-region-update with :scroll-offset to change position.
Viewport-dependent values use (viewport) and (viewport-height). Rerender a mounted buffer with an explicit context:
(ebox-rerender-buffer-with-context (get-buffer "*Ebox Demo*") 800 30)
The call preserves node and region identity. In an interactive preview, a complete chrome-free root document owner is idle-materialized once and then follows Emacs's native line-oriented window scrolling; nested or still-lazy owners keep the transactional retained-window path. The API reference lists lazy prefix, idle prefetch, cache, and scroll customization variables.
9. Standalone .ebox files
ebox-build reads one data-oriented Ebox form:
(ebox-build
'(grid :width (640)
:grid-template-columns ((200) 1fr 1fr)
:gap (1 (12))
(box :content "A")
(box :content "B")
(box :content "C")))
Inside a .ebox fixture, keep the structural form unquoted. Quote list and symbol constants in property positions (for example, :gap '(1 (12)) and :justify-content 'center), while leaving executable Elisp property expressions unquoted. ebox-playground evaluates those property expressions before passing the form to ebox-build, matching the etaf-view value convention.
Executable .ebox references are maintained by the sibling ebox-playground package. Its examples/ directory contains the migrated Basic, Comprehensive, Flex, Responsive, and complete Grid reference files; they remain low-level layout examples and do not require the ETAF framework.
10. Optional native reflow
The Rust module accelerates eligible reflow work; it is not required for correctness. Load Ebox normally, run make native-build when you want a local module, and configure ebox-native-reflow-module-path if the module is outside its default location. Ebox keeps the Elisp path as the exact fallback and never builds native code while loading. ebox-native-status shows toolchain, module, ABI, and load diagnosis; ebox-native-build starts an asynchronous build and accepts a prefix argument for a clean private Cargo cache rebuild.
11. Public boundary
Use the functions and properties listed in the public API reference and the ebox-public-api facade inventory. Names beginning with ebox-- are private implementation details and may change. ETAF is the sibling package for Components, View trees, state, behavior, Context, data, and application lifecycle; Ebox should stay focused on geometry and publication.
12. Verification
From the repository root:
make load EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs
make compile EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs
make check EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs
make docs-contract-tests EMACS=/Applications/Emacs.app/Contents/MacOS/Emacs
Use make grid-tests, make dsl-tests, make selector-tests, make surface-tests, or make visual-check-tests for focused changes. Use make native-rust-tests after changing the native module.