Magnifier

A low-latency screen magnifier for Windows. Built for streamers, accessibility users, photographers, retro-gaming, pixel art, and anyone who has ever shouted at the built-in Windows Magnifier for stuttering, blurring, or collapsing the desktop on launch.

Status: pre-1.0 (current release v0.1.4). API surface, config keys, and default hotkeys may shift between minor versions. Patch bumps are bug fixes only.

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Why not just use Windows Magnifier?

The shipped Magnifier (magnify.exe) is fine for occasional reading, but it has three structural problems that this project sidesteps:

1. Lens mode jitters because the system magnifier ticks on the regular Windows timer, which is coalesced at low load. This project uses a high-resolution waitable timer pinned to the display's refresh rate, then calls DwmFlush() once per tick so the magnified frame composites in the same vsync interval that produced it. Result: no smear trails, even at 240 Hz.
2. Full-screen mode hijacks the desktop and on multi-monitor setups it routinely picks the wrong display. This project keeps the lens confined to the monitor your cursor is on and lets you move it between displays without re-entering the mode.
3. You cannot rebind a single hotkey without registry surgery. Here every action is rebindable from a UI tab, with conflict detection for the GPU rotation defaults that Intel / AMD ship.

If you want pure accessibility (high-contrast colour inversion, keyboard navigation reading, screen-reader integration) the built-in Magnifier is still the better choice. If you want a fast, low-latency zoom tool with a controller-friendly UX, keep reading.

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Features

• Lens mode — a movable rectangle that magnifies whatever is under it. Follows the mouse by default; recenter / nudge from the keyboard or a game controller.
• Full-screen mode — magnifies the entire desktop with the cursor as the anchor.
• Configurable smoothing — independent time-constants for position and zoom (position_tau, zoom_tau) so you can dial in everything from "instant" to "buttery cinematic".
• Refresh-rate aware — auto-detects the monitor's dmDisplayFrequency (re-queried on WM_DISPLAYCHANGE) and ticks the magnifier loop once per panel refresh. Pinning to vsync via DwmFlush() eliminates the low-zoom ghost trails common on 240 Hz panels.
• Controller support across three back-ends:
  • XInput for Xbox 360 / Xbox One / Xbox Series pads and most third-party Xbox-style controllers.
  • Windows.Gaming.Input (WGI) for the modern UWP path — picks up Bluetooth Xbox controllers, Sony DualSense (over USB), and most Steam Input virtual gamepads.
  • Raw HID for everything else, including DualShock 4 / DualSense not running through DS4Windows.
• Rebindable hotkeys for every action, with conflict warnings surfaced inline (e.g. if you bind Ctrl+Alt+Left and your Intel / AMD GPU has display rotation enabled, you'll see a yellow banner).
• Local IPC over a named pipe so magnifier --toggle from any shell controls the already-running instance instead of spawning a duplicate.
• Tray-first UX with a hover tooltip that surfaces the current mode + key shortcuts, a right-click menu for every action, and a one-shot welcome balloon on first run.
• Self-updater that polls GitHub Releases anonymously, downloads the new MSI, and re-launches msiexec /i /passive. One network request, no telemetry, no PAT used. Disable from Settings → Updates.
• Crash dumps automatically written to %LOCALAPPDATA%\Magnifier\crashes\ on any unhandled exception, so you can attach a .dmp to a bug report instead of describing the problem from memory.

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Install

MSI (recommended)

1. Download the latest Magnifier-x64.msi from the Releases page.
2. Double-click it. The installer is silent-capable (msiexec /i Magnifier-x64.msi /passive) and creates a Start Menu entry.
3. Launch from the Start Menu, or run Magnifier.exe from %ProgramFiles%\AMSA\Magnifier\.

Portable ZIP

1. Download Magnifier-x64-portable.zip from the Releases page.
2. Unzip anywhere (USB stick, network share, etc.).
3. Run Magnifier.exe. Config + logs land in %LOCALAPPDATA%\Magnifier\ (the portable variant does not write to Program Files).

SmartScreen warning

The release binaries are not currently EV-code-signed, so Windows may show "Windows protected your PC" the first time you run them. Click More info → Run anyway. The binary is being submitted to Microsoft for SmartScreen analysis so it can be white-labeled across users; the warning typically disappears after a few hundred organic downloads or after Microsoft completes the analysis.

If you would rather verify before running, use either of:

Get-FileHash .\Magnifier-x64.msi -Algorithm SHA256

# Confirm digital signature (when signed)
Get-AuthenticodeSignature .\Magnifier-x64.msi

The SHA-256 hash of each release artifact is included in the release notes on the GitHub Releases page.

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Quick start

After install, Magnifier sits silently in the tray. The defaults are:

Action	Default hotkey	What it does
Toggle lens	Ctrl+Alt+Z	Show / hide the lens rectangle.
Toggle full-screen	Ctrl+Alt+F	Switch the whole desktop into magnified mode.
Turn off	Ctrl+Alt+X	Exit any active magnification mode.
Show settings	Ctrl+Alt+S	Open the Settings window.
Zoom in	Ctrl+Alt++	Increase zoom by one step.
Zoom out	Ctrl+Alt+-	Decrease zoom by one step.
Lens size up	Ctrl+Alt+]	Grow the lens rectangle.
Lens size down	Ctrl+Alt+[	Shrink the lens rectangle.
Recenter	Ctrl+Alt+C	Snap the lens / zoom back to the cursor.
Pan left / right / up / down	unbound	Move the lens without using the mouse.
Reload config	unbound	Re-read config.toml from disk.
Quit	unbound	Exit the application.

Every binding above is rebindable from Settings → Hotkeys. The "unbound" actions are intentional defaults to avoid colliding with common keyboard shortcuts; assign them to whatever you like.

GPU rotation conflict: Intel and AMD display drivers default to reserving Ctrl+Alt+Arrow for screen rotation. If you bind any pan_* action to those combos the Hotkeys tab will show a yellow warning banner — fix it from your GPU control panel or pick a different combo.

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Settings reference

The Settings window opens with Ctrl+Alt+S (or right-click the tray icon → Settings…). It's organised by tab. Every change persists immediately to config.toml.

General

• Start with Windows — registers a per-user Run key entry. Stored under HKCU\Software\Microsoft\Windows\CurrentVersion\Run. Safe to toggle off; does not require admin.
• High process priority — sets ABOVE_NORMAL_PRIORITY_CLASS while a mode is active and reverts to NORMAL_PRIORITY_CLASS when off. Concern: on heavily loaded machines this can briefly starve background audio / capture threads. Leave off if you record OBS with software encoders.

Lens

• Width / Height — the lens rectangle in screen pixels.
• Follow mouse — lens center tracks the cursor. Off = use pan_* hotkeys or the controller to move it.
• Magnify cursor — when on, the cursor itself is magnified (Win32 MAG_SHOWMAGNIFIEDCURSOR). When off, the magnified surface shows the desktop but the cursor stays at OS-native size — useful for precision pixel work where you want to see exactly which pixel the hotspot is on.
• Position smoothing (τ) — exponential time-constant in seconds for lens position easing. 0.0 = instant; 0.15 = cinematic.
• Zoom smoothing (τ) — same idea for zoom changes triggered by zoom_in / zoom_out.

Zoom

• Minimum zoom / Maximum zoom — clamps the user-configurable zoom range. Clamping is enforced both for the slider and for programmatic --zoom IPC calls.
• Default zoom — applied when entering a magnification mode.
• Step — used by zoom_in / zoom_out and --zoom-in / --zoom-out CLI flags.

Controller

• Enable controller — master switch for all three back-ends.
• Back-end priority — XInput is polled first because it is the lowest-latency path; WGI fills in for modern Bluetooth controllers; raw HID catches devices the first two ignore.
• Deadzones — separate values for stick X / Y and trigger axes.
• Cursor speed — multiplier for the virtual cursor when the controller owns it (suppresses follow-mouse while a stick is held).

The Controller tab will list "0 of N devices" if controller.enabled is false; flip the switch and the count updates within a poll cycle (~16 ms).

Capture / OBS

• Window class hint — surfaces the underlying class name (MagnifierWindow) so OBS / streaming tools can target Magnifier with Window Capture (BitBlt) or Window Capture (Windows 10).
• Concern: WGC (Windows.Graphics.Capture) on some GPU drivers shows a yellow border around captured windows. If that's a problem, switch OBS to Display Capture of the monitor Magnifier is on and crop.

Advanced

• Use low-level keyboard hook — replaces RegisterHotKey with a WH_KEYBOARD_LL hook. Required in some corporate environments where RegisterHotKey is blocked. Concern: low-level hooks are flagged by some AV vendors; expect a one-time SmartScreen / AV prompt the first time you toggle this on.
• Reset all settings — wipes config.toml back to factory defaults and re-bakes the embedded defaults next launch.

Updates

• Check now — runs the updater on-demand. The only network call the app makes: an anonymous GET https://api.github.com/repos/almakarem/Magnifier/releases/latest.
• Auto-check on startup — same call, run once a day, cached.
• Source repository is read-only and pinned to https://github.com/almakarem/Magnifier. Forks should fork the repo and rebuild; we deliberately removed the editable Owner / Repo / PAT fields in 0.1.4 to avoid users pointing the updater at arbitrary repos.

Hotkeys

• One row per action. Click the binding cell to capture a new combo (Esc cancels). Conflicting bindings — both between Magnifier actions and against known GPU shortcuts — surface inline.
• "Show settings" is in the table; rebind it freely. The default is Ctrl+Alt+S.

Diagnostics

• Hotkey state — currently-armed combos, last fire time, conflict count.
• Controller state — number of XInput slots in use, number of WGI gamepads, raw HID devices.
• Reading guide — short text explaining what each number means and what "expected" looks like.

About

• Author bio, source link, donations (Ko-fi, PayPal), contact channels (Discord, X, email), acknowledgements, and the MIT license attribution.

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Controller support in detail

Magnifier polls three back-ends concurrently and merges their state. This is intentional: a single physical controller often shows up on more than one path (e.g. an Xbox pad over Bluetooth appears in WGI but not XInput), and there is no robust de-duplication API. We rely on the user to plug in one controller at a time and trust the back-end priority.

Back-end	Best for	Latency	Setup
XInput 1.4	Xbox / Xbox-style wired	lowest	none
Windows.Gaming.Input	Bluetooth Xbox, DualSense (USB)	low	none
Raw HID	DS4 / DualSense without DS4Windows	medium	none

DS4Windows users: keep DS4Windows running. It re-exposes your DS4 / DualSense as a virtual XInput device, which Magnifier picks up via the XInput back-end (lowest latency path). No extra config.

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Command line

Magnifier.exe is also a CLI. When invoked with any IPC flag below, it forwards to the running instance over a named pipe and exits; when invoked without flags it launches normally.

General:
  -h, --help                 Print help and exit.
  -v, --version              Print version and exit.
  --start-minimized          Start in the tray with no balloon.

Mode control (IPC):
  --lens                     Enter lens mode.
  --fullscreen               Enter full-screen mode.
  --off                      Exit current mode.
  --toggle                   Toggle lens on / off.
  --status                   Print JSON status to stdout.

Zoom and lens (IPC):
  --zoom <factor>            Set zoom to <factor> (clamped).
  --zoom-in [step]           Increase zoom (default step from config).
  --zoom-out [step]          Decrease zoom (default step from config).
  --lens-size <w>x<h>        Set lens dimensions.

Process control (IPC):
  --quit                     Graceful shutdown.
  --force-quit               Skip cleanup; for stuck instances only.
  --reload-config            Re-read config.toml from disk.

Controller:
  --enable-controller        Turn controller polling on.
  --disable-controller       Turn controller polling off.

Example: bind a stream-deck button to Magnifier.exe --zoom 4 to flick to 4× magnification on demand without giving the deck focus of your input app.

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Files Magnifier writes

Path	Contents	When
%LOCALAPPDATA%\Magnifier\config.toml	All settings	On any setting change.
%LOCALAPPDATA%\Magnifier\logs\magnifier.log	Rotating log file	Continuously; rotated at 5 MB, 3 files kept.
%LOCALAPPDATA%\Magnifier\crashes\*.dmp	Mini-dumps	Only on unhandled exception.
%LOCALAPPDATA%\Magnifier\magnifier.pid	PID of the running instance	At startup; removed on graceful exit.
\\.\pipe\Magnifier-IPC-<user-sid>	Named pipe	While the app is running.

Uninstalling via the MSI does not wipe %LOCALAPPDATA%\Magnifier\ (your settings survive across upgrades). Delete the folder manually to factory-reset.

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Privacy & telemetry

Magnifier makes exactly one kind of outbound network request, and only if you keep the updater enabled:

• GET https://api.github.com/repos/almakarem/Magnifier/releases/latest — public endpoint, no authentication, no PAT, no cookies. Response is parsed locally; the only thing transmitted is the standard GitHub User-Agent.

That's it. There is:

• No analytics of any kind. No usage pings, no error reporting service, no Sentry, no GA, no Mixpanel.
• No background telemetry. The updater check runs at most once per day and only when enabled.
• No third-party SDKs that phone home.
• No PAT is requested or stored anywhere. The Updates tab is read-only on the repository identity for exactly this reason.

If you want to verify, the relevant code is src/update/Updater.cpp and src/ipc/IpcServer.cpp (local-only named pipe, ACL'd to the current user).

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Known limitations

• Exclusive full-screen games bypass the Win32 Magnification API. Use borderless full-screen / windowed mode.
• HDR. The Magnification API runs in SDR. On HDR-enabled displays the magnified surface looks dimmer than the source. There is no workaround at the API level today.
• Anti-cheat. Some kernel-mode anti-cheats (Vanguard, EAC in some titles, BattlEye in some titles) flag any process injecting a capture surface. Magnifier doesn't inject — it asks DWM via the Magnification API — but you may still hit a false positive. If this affects you, quit Magnifier before launching the game.
• Per-monitor DPI scaling. Settings inherits the launching monitor's scale factor and does not re-scale if you drag it across displays at different DPI. The magnification view itself is DPI- aware.

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Build from source

Requirements: Visual Studio 2019+ (or Build Tools), CMake 3.20+, PowerShell 5+, Windows 10 SDK 10.0.19041+. WiX is optional, only needed for the MSI step.

git clone https://github.com/almakarem/Magnifier.git
cd Magnifier
scripts\build.cmd
build\tests\magnifier_tests.exe --gtest_brief=1

The build script bootstraps all dependencies via CMake's FetchContent (spdlog, tomlplusplus, nlohmann/json, imgui, googletest). No vcpkg or conan needed.

To package an MSI:

scripts\release.cmd

This produces artifacts\Magnifier-x64.msi and a matching portable zip. WiX 3.14+ must be on PATH.

Custom app icon

The build is icon-optional. To bake the app icon into the executable:

1. Place a square PNG (≥256×256, transparent background recommended) at app/icon.png.
2. Run pwsh scripts/make-icon.ps1. This produces app/Magnifier.ico (multi-resolution 16/24/32/48/64/128/256 PNG-encoded entries).
3. Re-run cmake -S . -B build (CMake re-checks EXISTS app/Magnifier.ico and defines HAVE_ICON for both targets).
4. Re-run scripts\build.cmd.

Without app/Magnifier.ico, the build still succeeds and the tray falls back to IDI_APPLICATION.

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License

MIT — see LICENSE.

Copyright (c) 2026 AMSA (https://github.com/almakarem)

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software…

Acknowledgements: this project links against spdlog, tomlplusplus, nlohmann/json, Dear ImGui, and GoogleTest, all under their respective permissive licenses.

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Author and contact

AMSA

• GitHub: @almakarem
• X / Twitter: @AlmakaremA
• Email: AMSAbualmakarem@gmail.com
• Discord: AMSA

Donations

If Magnifier saves you time or makes streaming / accessibility work easier, a tip is hugely appreciated and goes directly toward the EV code-signing certificate that will retire the SmartScreen warning:

• Ko-fi
• PayPal