LVGL.Net.Assistant 0.1.2

LVGL.Net

Di port oleh Kang Fadhil dari Gravicode Studios. Ported by Kang Fadhil of Gravicode Studios.

A multi-platform .NET 10 wrapper for LVGL v9, the embedded graphics library — plus a WPF visual designer with an AI design assistant, a cross-platform component demo, and a live sensor dashboard for the Raspberry Pi 4.

Documentation: English · Bahasa Indonesia

What is here

Install

dotnet add package LVGL.Net          # core wrapper, ships the native lvglnet for every RID
dotnet add package LVGL.Net.Sdl      # windowed output on Windows, macOS and Linux
dotnet add package LVGL.Net.Linux    # framebuffer + evdev, no window system
dotnet add package LVGL.Net.Ui       # layout document model, loader and C# generator

LVGL.Net.Sdl needs SDL2 itself on the machine — the package does not redistribute it. Install libsdl2-2.0-0 on Debian/Ubuntu, sdl2 via Homebrew, or drop SDL2.dll into runtimes/win-x64/native/ on Windows.

Build from source

./native/build.sh                            # Linux/macOS - builds LVGL + the shim
./native/build.ps1                           # Windows

dotnet build LVGL.Net.slnx
dotnet test  LVGL.Net.slnx

dotnet run --project samples/LVGL.Desktop    # needs SDL2

using var backend = new SdlBackend(480, 320, "Hello LVGL");
using var app = LvglApplication.Create(backend);

var button = new LvButton(app.Screen, "Tap me");
button.SetSize(160, 48);
button.Center();
button.Clicked += (_, _) => Console.WriteLine("clicked");

app.Run();

Design notes

The native library contains no display drivers. LVGL renders into a buffer and calls a flush callback; everything after that — SDL window, Linux framebuffer, off-screen preview — is managed code behind a four-member ILvglBackend. One native artifact serves every target, adding an output device is a C# class, and the library links nothing but libc and libm.

A small C shim covers what P/Invoke cannot do safely. lv_color_t is a three-byte struct whose by-value ABI differs between Windows x64 and SysV; lv_style_t's size is a compile-time detail; LVGL's fonts are exported variables; and lv_event_code_t ordinals shifted during the 9.x series. Each of those goes through an ABI-stable lvn_* entry point. Everything else calls lv_* directly, and the render path does not touch the shim at all.

Built for constrained hardware. Partial render mode by default, unmanaged draw buffers, unmanaged function pointers instead of marshalled delegates on the hot path, workstation GC, and no allocation per chart sample. The Raspberry Pi sample runs on ~100 KiB of draw buffers at 800×480.

One layout model, three consumers. The designer edits a UiDocument, UiBuilder instantiates it at run time, and CSharpUiGenerator emits equivalent C#. A previewed layout and a running one cannot drift apart.

The assistant validates before it answers. Jack The Code Bender designs layouts through a kernel function that checks them against the real document model, so a malformed layout comes back as fixable problems rather than as plausible JSON that will not open. Anthropic goes through the official SDK rather than an OpenAI-compatible shim — Claude removed the sampling parameters on its current models, and the connector drops a configured temperature for those rather than letting the request fail.

Requirements

• .NET SDK 10.0
• CMake 3.20+ and a C compiler, to build the native library
• SDL2, only for the SDL backend

Status

The managed solution builds clean and its tests pass. The native library must be built once with CMake before anything renders; the wrapper reports a clear, actionable error until then, and the designer keeps working without it for everything except the preview.

License

LVGL is MIT-licensed. This wrapper follows suit.