Nilorea C Library

A portable C library providing common data structures, networking, GUI widgets, 2D/3D helpers, and more. Designed to be used as a monolith library or as a collection of individual source files dropped into your project.

Features

Core modules (no external dependencies beyond pthreads, zlib/LZ4 are vendored)

• Logging system with configurable levels and file output (n_log)
• No-duplicate logging to console, file, or syslog (n_nodup_log)
• Dynamic strings with formatting helpers (n_str)
• Generic linked lists (n_list)
• Hash tables (n_hash)
• Thread pools (n_thread_pool)
• Stack data structure (n_stack)
• Tree data structure (n_trees)
• Base64 encoding / decoding (n_base64)
• Vigenere cipher encoding / decoding (n_crypto)
• Enum-to-string macro helpers (n_enum)
• Signal handling helpers (n_signals)
• Exception-like macros (n_exceptions)
• Common macros and typedefs (n_common)
• File helpers (n_files)
• Time / timer utilities (n_time)
• Hexadecimal encode / decode helpers (n_hex)
• Cryptographically secure random bytes and hex tokens (n_random)
• Randomness / entropy metrics for byte samples, token-randomness analysis (n_entropy)
• Lightweight HTML/XML extraction: links, forms, and sitemap URLs (n_html)
• Lexical pretty-printers for JSON, XML/HTML, and JavaScript text (n_pretty, JSON needs cJSON)
• Domain-aware HTTP cookie jar: Set-Cookie parsing and Cookie header building (n_cookies)
• HTTP/2 (RFC 7540) wire framing plus HPACK header compression (n_http2)
• Minimal DNS message helpers: parse a query question, build an A-record response (n_dns)
• zlib compression helpers (n_zlib), vendored under external/zlib/, built into the library
• LZ4 block-compression helpers (n_lz4), vendored under external/lz4/, built unconditionally and used as an opt-in network compression backend

Networking (requires OpenSSL for SSL support)

• TCP / UDP network engine with optional SSL (n_network)
• HTTP CONNECT, HTTPS CONNECT, and SOCKS5 proxy tunneling (n_network)
• WebSocket client handshake and framing (n_network)
• Server-Sent Events (SSE) client (n_network)
• Network message framing (n_network_msg)
• Parallel accept pool, nginx-style multi-threaded accept (n_network_accept_pool)
• Single-threaded epoll reactor as an opt-in alternative to the per-connection thread engine (n_reactor, Linux/Android only)
• Clock synchronization estimator for networked games (n_clock_sync)
• URL parsing and canonicalization helpers (n_url_canonicalize, in n_network)
• Per-connection compression backend (netw_set_compression_mode): NETW_COMPRESS_NONE / _ZLIB / _LZ4. The wire layout is self-describing, so the two ends can run different codecs and still interop.
• Message digests, HMAC, PBKDF2, and AES-256-GCM AEAD over the OpenSSL EVP API (n_digest)
• X.509 helpers: self-signed CA generation and per-host leaf minting (n_x509)

PCRE (requires libpcre2)

• PCRE2 regex wrapper (n_pcre)
• Configuration file parser (n_config_file)
• Boolean query language over caller-named fields (n_query)

Allegro 5 GUI & game modules (require liballegro5)

• GUI widget system with pseudo-windows (n_gui) -- buttons, toggle buttons, horizontal & vertical sliders, text areas, checkboxes, scrollbars, listboxes, radio lists, combo boxes, labels/hyperlinks, images, dropdown menus, frameless windows, disabled/hidden widgets, auto-scrollbar windows, resizable windows, global display scrollbars, cross-platform DPI scale detection, and optional bitmap skinning for all widgets and windows
• Allegro 5 input and display helpers (n_allegro5)
• Isometric engine with height segments, depth-sorted object rendering, occlusion detection with clipped ghost overlay, 2D camera, multiple projection presets, and terrain transitions, with optional cross-chunk neighbor arrays so transition masks span chunk edges without water-clamp seams (n_iso_engine)
• A* pathfinding (n_astar)
• Dead reckoning / prediction (n_dead_reckoning)
• Trajectory helpers (n_trajectory)
• AABB collision (n_aabb)
• Particle system (n_particles)
• Fluid dynamics simulation (n_fluids)
• 3D helpers (n_3d)
• Animation helpers (n_anim)
• Game environment utilities (n_games)
• Network-oriented user handling (n_user)

SSL/TLS Hardening

• Security audit and hardened HTTPS example (SSL_SECURITY.md)
• TLS 1.2+ enforcement, strong cipher suites, HSTS, path traversal protection
• Persistent server scripts with auto-restart (serve_ssl.sh, serve_ssl_hardened.sh)

Data interchange (requires cJSON)

• Avro binary format encoding/decoding with JSON conversion (n_avro)
• Small JSON helper, a thin wrapper over the vendored cJSON (n_json)

Git operations (requires libgit2)

• Git repository operations via libgit2 (n_git), open/init/close repos, stage/unstage files, commit, log, diff, checkout, branch management, push/pull with auth (token, basic, SSH), fetch from remotes, ahead/behind counts, per-repo operation status reporting

Optional / extra

• Kafka consumer / producer wrappers (n_kafka, requires librdkafka): optional retry-after-timeout for errored events, transactional producing when a transactional.id is configured, and optional move-on-ack of produced files to a sended directory (n_kafka_set_sended_dir) instead of deleting them
• cJSON integration (included as git subtree)

Dependencies

Most core modules compile with only pthreads and a C17 compiler. The zlib and LZ4 codecs are vendored as git subtrees and built into the library, no system -lz dependency.

Dependency	Required for	How to get it
gcc / make	Building	Your system package manager
pthreads	Core (threads, network)	Usually bundled with your C toolchain
zlib	Compression helpers (n_zlib)	Included as git subtree under external/zlib/ (no system package needed)
LZ4	LZ4 block compression helpers (n_lz4)	Included as git subtree under external/lz4/ (no system package needed)
OpenSSL	SSL networking	apt install libssl-dev / pacman -S openssl / brew install openssl
libpcre2	Regex module	apt install libpcre2-dev / pacman -S pcre2
Allegro 5	GUI, isometric, particles, etc.	apt install liballegro5-dev liballegro-acodec5-dev liballegro-audio5-dev liballegro-image5-dev liballegro-primitives5-dev liballegro-ttf5-dev liballegro-font5-dev
cJSON	JSON parsing, Avro support	Included as git subtree (no compilation needed)
librdkafka	Kafka wrappers	Included as git subtree (make integrate-deps to compile) or apt install librdkafka-dev
libgit2	Git operations module	apt install libgit2-dev / pacman -S libgit2 / brew install libgit2
doxygen + graphviz	Documentation	apt install doxygen graphviz

Building

Supported platforms

Platform	Compiler	Notes
Linux (x86_64, aarch64)	gcc / clang	Primary development platform
Windows (MinGW-w64)	gcc (MinGW)	Cross-compile from Linux or native MinGW shell
Android	NDK clang	Via Allegro Android toolchain
Solaris	gcc	Legacy support

Quick start (Linux)

cd my_project_dir
git clone --recurse-submodules git@github.com:gullradriel/nilorea-library.git
cd nilorea-library
make            # builds the static + shared library
make examples   # builds all example programs
# or
make all        # library + examples in one step

Debug build

make DEBUG=1 clean all                   # ASan + UBSan + extra warnings
make DEBUG=1 DEBUG_THREADS=1 clean all   # ThreadSanitizer instead

Convenience targets wrap the above:

make asan        # alias for: make DEBUG=1 clean all
make tsan        # alias for: make DEBUG=1 DEBUG_THREADS=1 clean all
make asan-test   # build with ASan, then run examples/run_tests.sh
make tsan-test   # build with TSAN,  then run examples/run_tests.sh

Running tests

make asan-test   # or: make tsan-test
# equivalent to:
make DEBUG=1 clean all
cd examples && bash run_tests.sh

The test runner executes all non-GUI examples and checks for ASan/LSan/TSan reports. It verifies that binaries were compiled with DEBUG=1 before running (exits with an error otherwise). Network tests (TCP, SSL, accept pool) run both server and client through the sanitizer. Suppressions for system library leaks (Mesa, OpenSSL) are loaded automatically from examples/lsan-suppressions.cfg.

Disabling optional features

Use FORCE_NO_* flags to disable auto-detected optional dependencies:

make FORCE_NO_ALLEGRO=1   # disable Allegro 5 GUI/game modules
make FORCE_NO_OPENSSL=1   # disable SSL networking
make FORCE_NO_KAFKA=1     # disable Kafka integration
make FORCE_NO_PCRE=1      # disable PCRE2 regex support
make FORCE_NO_CJSON=1     # disable cJSON support
make FORCE_NO_LIBGIT2=1   # disable libgit2 Git operations

MinGW cross-compilation (Linux host targeting Windows)

# Install MinGW-w64 toolchain
apt install gcc-mingw-w64-x86-64
# Build with the MINGW flag
make CC=x86_64-w64-mingw32-gcc MINGW=1 clean all

Android (via Allegro Android toolchain)

1. Set up the Android NDK and Allegro 5 Android build as described in the Allegro Android docs.
2. Point your CC to the NDK clang and set appropriate CFLAGS / LDFLAGS.
3. Build with make.

Regenerating the documentation

make doc
# or directly:
doxygen Doxyfile

Running static analysis

make check                          # cppcheck (gating) + scan-build (informational)
make check SCAN_BUILD_STATUS_BUGS=1  # also fail on scan-build findings

Both cppcheck and scan-build (from the clang-tools package on Debian/Ubuntu) must be in PATH; the target reports a clear error and exits non-zero if either binary is missing. Override the resolved tools with CPPCHECK=... / SCAN_BUILD=... on the command line if needed.

Vendored third-party translation units under external/ (zlib, LZ4, cJSON) are pre-built without scan-build interception, then scan-build drives only the src/ rebuild. Their headers are also included via -isystem so warnings emitted from inside them when our src/*.c #includes them are suppressed at the source. Result: analyzer and compiler diagnostics come exclusively from code we own.

Compiling with extra dependencies

make update-deps       # update cJSON and librdkafka subtrees (needs git subtree)
make integrate-deps    # compile librdkafka, copy libs to the right directories
make clean ; make all  # full fresh build

Examples

All examples live in the examples/ directory and are built by make examples.

Example	Description	Requires
ex_gui	Full GUI demo: all widget types, dropdown menus, toggle buttons, vertical sliders, frameless windows, disabled/hidden widgets, auto-scrollbars, resizable windows, global display scrollbars, DPI detection, bitmap-skinned containers (listbox/radiolist/combobox/dropmenu/textarea), titlebar button bitmaps, focused-keycode bindings, layout save/load JSON	Allegro 5
ex_gui_particles	Particle system with real-time info overlay	Allegro 5
ex_gui_dictionary	Dictionary search app (text input, listbox, labels)	Allegro 5, PCRE2
ex_gui_isometric	Isometric map editor with dead reckoning	Allegro 5
ex_gui_network	TCP chat application with GUI	Allegro 5, OpenSSL
ex_gui_custom	Owner-draw custom widget (paint callback) demo	Allegro 5
ex_gui_datagrid	Datagrid rows, numeric sort, selection, right-click context menu	Allegro 5
ex_gui_dropmenu	Dropdown menu entry, label, and clear regression (headless)	Allegro 5
ex_gui_hexview	Hex view data round-trip regression (headless)	Allegro 5
ex_gui_kvtable	KV table adaptive-resize regression	Allegro 5
ex_gui_detach	Interactive native-window demo: per-panel detach/attach buttons, the three N_GUI_DETACH_* modes side by side, layout save/load	Allegro 5
ex_gui_multiwin	Native (detached) window regression: display routing, shared font/bitmap, clipboard, layout persistence (skips itself without a display)	Allegro 5
ex_gui_placeholder	Textarea placeholder/hint set, replace, and clear (headless)	Allegro 5
ex_gui_progressbar	Progress bar value set/get and clamping regression (headless)	Allegro 5
ex_gui_reentrant	n_gui_process_event re-entrancy regression (headless)	Allegro 5
ex_gui_splitpane	Split pane ratio and clamping regression (headless)	Allegro 5
ex_gui_syntaxview	Syntax view line-count, highlight modes, and selection/copy regression (headless)	Allegro 5
ex_gui_zorder	Topmost-overlapping-widget mouse dispatch regression (headless)	Allegro 5
ex_fluid	Fluid dynamics simulation	Allegro 5
ex_trajectory	Trajectory / ballistic helpers demo	Allegro 5
ex_common	Common macros and helpers demo	-
ex_exceptions	Exception handling demo	-
ex_hash	Hash table demo	-
ex_list	Linked list demo	-
ex_log	Logging system demo	-
ex_nstr	String helpers demo	-
ex_base64	Base64 encoding / decoding demo	-
ex_base64_encode	Base64 encoding demo (alternate binary built from the ex_base64 source)	-
ex_hex	Hexadecimal encode/decode round-trips and error paths	-
ex_random	Secure random bytes and hex token generation	-
ex_entropy	Randomness / entropy metrics regression	-
ex_html	HTML link, form, and sitemap extraction	-
ex_cookies	Cookie jar: Set-Cookie parsing, domain/path/secure/expiry matching	-
ex_http2	HTTP/2 frame codec, SETTINGS, and HPACK (RFC 7541 vectors)	-
ex_dns	DNS query parsing and A-record response building	-
ex_url	URL canonicalization (scheme/host case, default port, dot segments)	-
ex_crypto	Vigenere cipher encryption demo	-
ex_file	File operations demo	-
ex_zlib	Zlib compression / decompression demo	-
ex_stack	Stack data structure demo	-
ex_trees	Tree data structure demo	-
ex_threads	Thread pool demo	-
ex_network	Network client/server demo	OpenSSL
ex_network_mock	Mock HTTP server for testing (serves canned responses)	OpenSSL
ex_network_proxy	HTTP/HTTPS CONNECT and SOCKS5 proxy tunneling demo	OpenSSL
ex_network_ssl	SSL network demo	OpenSSL
ex_network_ssl_hardened	Hardened HTTPS server (TLS 1.2+, security headers, path traversal protection)	OpenSSL
ex_network_ws	WebSocket client demo	OpenSSL
ex_network_sse	Server-Sent Events (SSE) client demo	OpenSSL
ex_network_sni	SNI accept: per-host leaf minting, client-side trust evaluation	OpenSSL
ex_digest	MD5/SHA/HMAC/PBKDF2 and constant-time-compare vectors	OpenSSL
ex_x509	CA generation and per-host leaf minting	OpenSSL
ex_network_reactor	Single-threaded epoll reactor demo (n_reactor + netw_accept_into_reactor), Linux/Android only	-
ex_accept_pool_server	Accept pool server: single-inline, single-pool, and pooled accept modes	-
ex_accept_pool_client	Accept pool client: stress-tests the server with concurrent connections	-
ex_pcre	PCRE regex demo	PCRE2
ex_configfile	Config file parser demo	PCRE2
ex_query	Boolean query language: operators, AND/OR/NOT, error paths	PCRE2
ex_clock_sync	Clock synchronization over UDP (offset + RTT estimation)	OpenSSL
ex_signals	Signal handler demo	-
ex_iso_astar	A* pathfinding on isometric map	-
ex_avro	Avro binary encoding/decoding with JSON round-trip	cJSON
ex_json	JSON wrapper: parse, typed getters, arrays, and file parsing	cJSON
ex_pretty	JSON, XML/HTML, and JavaScript pretty-printing regression	cJSON
ex_kafka	Kafka event streaming demo	librdkafka, cJSON, PCRE2
ex_git	Git repository operations demo (init, stage, commit, log, diff, branch)	libgit2
ex_monolith	Monolith build test (all modules linked)	All

GUI System (n_gui)

The n_gui module provides a retained-mode widget system with pseudo-windows, built on top of Allegro 5 primitives and fonts.

Widget types

• Button (regular + toggle + bitmap)
• Slider (horizontal + vertical, value or percentage mode, configurable step with snap, mouse scroll + keyboard support, custom printf-style value readout format, toggleable value label)
• Text area (single-line + multiline with cursor)
• Checkbox
• Scrollbar (horizontal + vertical, rect or rounded)
• Listbox (none / single / multi select)
• Radio list
• Combo box (dropdown selector with scrollbar, auto-scroll to selected item on open, optional auto-width to fit longest item)
• Label (static text, left/center/right/justified, optional hyperlink)
• Image (fit / stretch / center)
• Dropdown menu (static + dynamic entries, rebuilt on open, scrollbar when entries overflow)
• Split pane (horizontal / vertical, draggable divider with ratio clamping)
• Hex view (read-only hexadecimal dump of a byte buffer)
• Syntax view (read-only source viewer with highlighting modes: plain, HTTP, JSON, XML, YAML, JavaScript; text selection/copy, scroll-to-offset)
• Datagrid (columns, sortable rows, selection, right-click context callback)
• Progress bar (value set/get with clamping)
• Custom (owner-draw widget with paint callback)
• KV table helper (n_gui_kvtable_*, key/value rows with per-row remove buttons, built on core widgets)

Window features

• Draggable title bar
• Minimise (title bar only)
• Frameless (no title bar, drag from body area)
• Fixed position (disable dragging)
• Resizable (drag handle at bottom-right)
• Auto-scrollbar (vertical + horizontal scrollbars appear when content overflows)
• Auto-size (fit window to widget extents)
• Z-ordering (click to raise, always-on-top, always-behind, fixed z-value)
• Show/hide via dropdown menu
• Adaptive resize (per-window policies: none / move / scale)
• Native window (detach a pop-up into a real OS window, see below)

Native (detached) windows

Any pseudo-window can be promoted to a real OS window, so a pop-up that the user wants to keep on a second monitor stops being confined to the host's display. Pop-ups keep working exactly as before, detaching is opt-in per window.

n_gui_set_event_queue(gui, queue);            /* once, before detaching */
n_gui_window_detach(gui, win_id, N_GUI_DETACH_RESIZABLE);
...
while (running) {
    while (al_get_next_event(queue, &ev))
        n_gui_process_event(gui, ev);         /* routes on the event's display */

    al_set_target_backbuffer(display);
    n_gui_draw(gui);                          /* main display, pop-ups only */
    al_flip_display();

    n_gui_draw_detached(gui);                 /* native windows: draws and flips */
}

A detached window is drawn frameless at the origin of its own display: the window manager supplies the title bar, so dragging, resizing, minimising and closing are handled by the OS. ALLEGRO_EVENT_DISPLAY_CLOSE runs the window's close callback (n_gui_window_set_close_callback) exactly like the pop-up close button does, and the display is released at the next n_gui_draw_detached, never from inside event processing.

• n_gui_window_attach() turns it back into a pop-up with its original geometry.
• Closing a detached window takes the OS window down but remembers the choice, so n_gui_open_window() brings the native window back rather than a pop-up.
• n_gui_save_layout_json() persists the detached state, the native size and the desktop position; loading re-creates the native window when the context already has an event queue.
• N_GUI_DETACH_RESIZABLE lets the user resize the OS window, N_GUI_DETACH_SCALE_CONTENT additionally scales the widgets with it.
• n_gui_window_set_native_icons() gives the OS window a taskbar icon.

Keeping N_GUI's own chrome

N_GUI_DETACH_OWN_CHROME creates the native window frameless and keeps the window drawing its own title bar, so a detached window looks and skins exactly like the pop-up it came from instead of picking up the desktop theme:

n_gui_window_set_flags(gui, win_id, N_GUI_WIN_RESIZABLE | N_GUI_WIN_BTN_ALL);
n_gui_window_detach(gui, win_id, N_GUI_DETACH_OWN_CHROME);

The chrome then drives the OS window: dragging the title bar moves it, the resize grip calls al_resize_display(), minimise shrinks it to the title bar (Allegro's ALLEGRO_MINIMIZED is read-only, so this is the portable mapping of "title bar only"), maximise toggles ALLEGRO_MAXIMIZED with a monitor-work-area fallback, and close takes the window down. The window's min_w/min_h are also pushed to the window manager via al_set_window_constraints().

Frameless windows are the less well trodden path on some window managers, which is why the OS chrome remains the default.

examples/ex_gui_detach.c is an interactive demo of all of this: three panels, one per detach mode, each with a button that promotes it to an OS window and back. -a detaches everything at startup and -q SECONDS quits on its own, so it also works as a sanitizer smoke test.

ALLEGRO_EVENT_DISPLAY_HALT_DRAWING / RESUME_DRAWING are acknowledged per native window and n_gui_draw_detached() skips a window whose surface the OS has taken away (Android) or that the window manager has iconified.

Caveats: the virtual canvas, global scroll and global scrollbars apply to the main display only, and n_gui_wants_mouse() keeps answering for the main display. Fonts and bitmaps are shared across displays by Allegro, so they must outlive every native window (ex_gui_multiwin checks this holds). Window constraints, ALLEGRO_FRAMELESS and ALLEGRO_MAXIMIZED are hints the window manager may ignore; N_GUI's own bookkeeping stays consistent either way.

Adaptive window resize

Two context-level resize modes control how windows respond to display size changes:

• N_GUI_RESIZE_VIRTUAL (default): fixed virtual canvas, a uniform transform scales all coordinates identically, the existing behaviour.
• N_GUI_RESIZE_ADAPTIVE: the virtual canvas is disabled and each window follows its own per-window resize policy:
  • N_GUI_WIN_RESIZE_NONE, window stays at its absolute position and size.
  • N_GUI_WIN_RESIZE_MOVE, window repositions proportionally but keeps its pixel size.
  • N_GUI_WIN_RESIZE_SCALE, window repositions and resizes proportionally; child widgets scale with it.

/* after creating all windows: */
n_gui_set_resize_mode(gui, N_GUI_RESIZE_ADAPTIVE);

/* assign policies per window */
n_gui_window_set_resize_policy(gui, win_menu,    N_GUI_WIN_RESIZE_SCALE);
n_gui_window_set_resize_policy(gui, win_buttons, N_GUI_WIN_RESIZE_MOVE);
n_gui_window_set_resize_policy(gui, win_fixed,   N_GUI_WIN_RESIZE_NONE);

When the user drags or resizes a window, the new position/size becomes the reference for future adaptive resizes.

Keyboard navigation

• Tab / Shift+Tab cycles focus between widgets in a window (wraps around)
• Sliders: Left/Right (horizontal) or Up/Down (vertical) adjust by one step; Home/End jump to min/max
• Listbox / Radiolist / Combobox: Up/Down selects previous/next item; Home/End jump to first/last
• Checkbox: Space/Enter toggles
• Scrollbar: Arrow keys scroll; Home/End jump to start/end
• Text areas: Ctrl+Tab inserts a literal tab; plain Tab moves focus

Button key bindings

• Global (n_gui_button_set_keycode): fires when the bound key is pressed and no interactive widget has focus. Single-line textareas let Enter pass through for backward compatibility.
• Focused (n_gui_button_set_keycode_focused): fires only when the button itself or one of the listed source widgets has focus. This allows e.g. Enter in a URL textarea to trigger a Send button without interfering with Enter in other textareas. Source widgets are specified as an array of widget IDs (up to N_GUI_KEY_SOURCES_MAX).
• Visual feedback: When a button is activated through its keybind, it briefly renders in its pressed (active) visual state, same colours/bitmaps as a mouse click, so keyboard activation is as perceivable as a pointer click.

Theme management

Widgets and windows inherit ctx->default_theme. Two helpers simplify bulk theme changes:

// Set a new default theme and auto-sync scrollbar colors
n_gui_set_default_theme(gui, my_theme);

// Push the default theme to every existing window and widget
n_gui_reset_all_widget_themes(gui);

// Re-apply individual overrides after the reset
n_gui_set_widget_theme(gui, accent_btn_id, accent_theme);

n_gui_set_default_theme() derives scrollbar track/thumb colors from the theme's bg_normal and border_normal fields so scrollbars stay in sync with the active palette.

Widget states

• Enabled/Disabled, disabled widgets are drawn dimmed and ignore all input
• Visible/Hidden, hidden widgets are removed from drawing and hit testing

Global display scrollbars

When the total GUI bounding box exceeds the display/viewport size, global scrollbars automatically appear at the edges. This works dynamically with resizable Allegro displays:

// On startup:
n_gui_set_display_size(gui, (float)display_w, (float)display_h);

// On ALLEGRO_EVENT_DISPLAY_RESIZE:
al_acknowledge_resize(display);
n_gui_set_display_size(gui, (float)al_get_display_width(display),
                            (float)al_get_display_height(display));

DPI scaling

Cross-platform DPI detection works on Linux, Windows, and Android:

// Auto-detect from display (compares framebuffer to logical window size)
float scale = n_gui_detect_dpi_scale(gui, display);

// Or set manually
n_gui_set_dpi_scale(gui, 1.5f);

// Query at any time
float current_scale = n_gui_get_dpi_scale(gui);

How it works:

• Compares the physical pixel size (backbuffer bitmap) to the logical window size. On HiDPI displays these differ (e.g. 2x on Retina, 1.25x at 125% Windows scaling).
• On Android, uses the display DPI relative to the 160 DPI baseline.
• The detected scale is stored in ctx->dpi_scale and can be used by the application to scale fonts, widget sizes, etc.

Windows multi-monitor DPI considerations

On Windows, when using per-monitor DPI awareness (e.g. laptop at 125%, external monitor at 100%), the OS changes the effective DPI when the window is moved between monitors. This can cause the window content to appear clipped by the scaling difference (e.g. 25% clipping when moving from 125% to 100%).

Recommended solution:

1. Enable per-monitor DPI awareness via your application manifest or by calling SetProcessDpiAwarenessContext(DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2) before creating the display.

2. Handle ALLEGRO_EVENT_DISPLAY_RESIZE (which Allegro fires when Windows sends WM_DPICHANGED) and update the display size:

   case ALLEGRO_EVENT_DISPLAY_RESIZE:
       al_acknowledge_resize(display);
       n_gui_set_display_size(gui, (float)al_get_display_width(display),
                                   (float)al_get_display_height(display));
       n_gui_detect_dpi_scale(gui, display);
       break;

3. Scale your fonts using the detected DPI factor:

   float scale = n_gui_get_dpi_scale(gui);
   int font_size = (int)(13.0f * scale);
   ALLEGRO_FONT* font = al_load_ttf_font("font.ttf", font_size, 0);

4. Use ALLEGRO_RESIZABLE display flag so the window can be resized by the OS during DPI changes.

The n_gui module already handles ALLEGRO_EVENT_DISPLAY_SWITCH_OUT to reset all drag/resize states, preventing GUI windows from being unintentionally moved or resized when the OS window changes focus during monitor transitions.

API Reference

Full API documentation is generated with Doxygen. Run make doc and open docs/html/index.html in your browser.

Support

• Issues: https://github.com/gullradriel/nilorea-library/issues
• Documentation: Run make doc to generate the full API reference
• Examples: See the examples/ directory for working code samples

License

This project is licensed under the Apache License, Version 2.0, see the LICENSE file for the full text and the NOTICE file for attribution.

SPDX-License-Identifier: Apache-2.0

Copyright (C) 2005-2026 Castagnier Mickael

Releases made before the relicensing remain available under the GNU General Public License v3.0 or later; that grant is not withdrawn.

Vendored third-party code under external/ keeps its own upstream license and is not covered by the Apache License. See NOTICE for the per-component breakdown.