EasyHDR

A lightweight Windows utility that automatically enables HDR when you launch configured applications and disables it when you close them.

Preview

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How It Works

EasyHDR monitors running processes at regular intervals (500-1000ms). When a configured application starts, HDR is enabled globally across all capable displays within 1-2 seconds. When the last monitored application closes, HDR is automatically disabled. A 500ms debounce delay prevents rapid toggling if applications restart quickly.

The application uses Windows Display Configuration APIs to control HDR state, with version-specific implementations for Windows 10, Windows 11, and Windows 11 24H2+.

Installation

Requirements:

• Windows 10: 21H2 (Build 19044) or later
• Windows 11: 21H2 (Build 22000) or later
• HDR-capable display

Steps:

1. Download the latest release from the Releases page
2. Extract easyhdr.exe to a folder of your choice
3. Run easyhdr.exe
4. On first launch, Windows Defender SmartScreen will appear - click "More info" then "Run anyway"
5. Click "Add Application" and select the .exe files you want to monitor
6. Minimize to system tray

Configuration is stored at %APPDATA%\EasyHDR\config.json and saved automatically.

First Time Setup

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_{Launch: Bypassing SmartScreen warning (unsigned app)
Add Application: Adding applications to monitor}

Dependencies

Core:

• slint - GUI framework
• windows - Windows API bindings
• serde / serde_json - Configuration serialization
• tracing / tracing-subscriber - Logging
• parking_lot - Synchronization primitives

Windows Integration:

• winreg - Registry access for auto-start
• tray-icon - System tray integration
• rfd - Native file dialogs
• tauri-winrt-notification - Toast notifications
• reqwest - Update checking

Development

Performance Benchmarking

Baseline performance metrics (measured with Criterion on release builds):

• Config Serialization: ~20 µs
• Config Deserialization: ~35 µs
• Config Round Trip: ~55 µs
• HDR State Detection: Platform-dependent (Windows only)

Run benchmarks: cargo bench

To detect performance regressions, compare new benchmark results against these baselines. Criterion automatically tracks changes between runs and flags statistically significant regressions (>5% slower).

Fuzzing

Three fuzz targets are available to test robustness:

1. fuzz_config_json - Tests configuration JSON parsing for crashes/panics
2. fuzz_process_name - Tests process name extraction from arbitrary paths
3. fuzz_windows_api - Tests Windows API structures and bit field logic

Running fuzzing targets:

# Install cargo-fuzz (requires nightly)
cargo install cargo-fuzz

# Run a specific fuzz target for 60 seconds
cargo +nightly fuzz run fuzz_config_json -- -max_total_time=60

# Run all targets sequentially
cargo +nightly fuzz run fuzz_config_json -- -max_total_time=60
cargo +nightly fuzz run fuzz_process_name -- -max_total_time=60
cargo +nightly fuzz run fuzz_windows_api -- -max_total_time=60

License

This project is licensed under the GNU Affero General Public License v3.0 (AGPL-3.0). See LICENSE for details.