MarkdownViewer

MarkdownViewer is a Windows project for viewing Markdown files with two primary targets:

• a standalone WPF desktop application: MdViewer
• a Total Commander Lister plugin: MdViewerWlx for *.md and related formats

Rendering is based on Markdig for Markdown parsing and WebView2 for HTML display. The WLX plugin uses a native C bootstrapper that loads the managed .NET components through hostfxr.

Overview

• Platform: Windows x64
• UI technology: WPF
• Runtime: .NET 10 Windows Desktop
• Markdown parser: Markdig
• HTML renderer: Microsoft.Web.WebView2
• Total Commander plugin type: WLX (Lister plugin)

Features

• Renders Markdown as HTML inside a WPF/WebView2 UI
• Uses advanced Markdig extensions via UseAdvancedExtensions()
• Supports emoji and smiley syntax
• Uses GitHub-inspired CSS with light/dark adaptation via prefers-color-scheme
• Sets a base path for relative content from Markdown files
• WLX plugin with Unicode entry points for Total Commander x64
• Fallback-first WLX behavior with immediate text preview
• Automatic switch to HTML/WebView2 once initialization completes

Repository Structure

MarkdownViewer/
|- MarkdownViewer/                     Desktop app (MdViewer)
|- MdViewer.Shared/                   Shared rendering and logging components
|- MdViewerWlx/                       Managed WLX layer for Total Commander
|- tools/
|  |- NativeBootstrapper/
|  |  |- wlx_bootstrapper.c           Native WLX bootstrapper in C
|  |  |- build-wlx.ps1                Build, deploy, and packaging script
|  |  |- pluginst.inf                 Total Commander installer descriptor
|- deploy/
|  |- wlx/                            Assembled WLX deploy directory
|  |- MdViewerWlx-<version>-tc.zip    Total Commander installation ZIP
|- README.md

The repository root contains MdViewer.slnx.

Projects

MarkdownViewer

Standalone WPF desktop application with the following profile:

• Project file: MarkdownViewer\MarkdownViewer.csproj
• Output type: WinExe
• Target framework: net10.0-windows
• WPF enabled
• App icon: MarkdownViewer\Resources\app.ico

The application uses MdViewer.Shared for rendering and logging.

MdViewer.Shared

Shared library used by both the desktop application and the WLX plugin.

Important files:

• MdViewer.Shared\MarkdownRenderService.cs
• MdViewer.Shared\FileLogger.cs

Responsibilities:

• render Markdown into a complete HTML document
• provide GitHub-inspired CSS
• write error and status logs to files

MdViewerWlx

Managed part of the Total Commander plugin.

• Project file: MdViewerWlx\MdViewerWlx.csproj
• Output type: Exe
• Target framework: net10.0-windows
• Platform: x64
• WPF enabled

Why Exe instead of Dll:

• the native bootstrapper initializes the CLR in app mode through hostfxr_initialize_for_dotnet_command_line
• this requires MdViewerWlx.exe as the app host
• this is necessary so WPF and WebView2 dependencies are resolved in the correct app context

Important files:

• MdViewerWlx\WlxExports.cs
• MdViewerWlx\WlxHost.cs
• MdViewerWlx\WlxContentView.cs
• MdViewerWlx\Program.cs

WLX Plugin Architecture

The Total Commander plugin is split into two layers.

1. Native Bootstrapper

File: tools\NativeBootstrapper\wlx_bootstrapper.c

Responsibilities:

• loaded directly by Total Commander as .wlx or .wlx64
• exports the WLX functions
• handles ListGetDetectString natively
• loads hostfxr.dll
• initializes the .NET runtime
• loads managed export methods from MdViewerWlx.dll

Important implementation details:

• uses hdt=5 for load_assembly_and_get_function_pointer
• uses hostfxr_initialize_for_dotnet_command_line
• passes MdViewerWlx.exe as argv[0]
• supports both ANSI and Unicode WLX API variants

Exported WLX functions:

• ListGetDetectString
• ListGetDetectStringW
• ListLoad
• ListLoadW
• ListLoadNext
• ListLoadNextW
• ListCloseWindow

Current detect string:

ext="MD" | ext="MARKDOWN" | ext="MDOWN" | ext="RST"

2. Managed WLX Layer

Files:

• MdViewerWlx\WlxExports.cs
• MdViewerWlx\WlxHost.cs
• MdViewerWlx\WlxContentView.cs

Responsibilities:

• receives WLX calls forwarded from the native layer
• creates a WPF child window inside the Total Commander parent window
• initializes WebView2 in a delayed and robust way
• shows a text preview until WebView2 is ready

Hosting details:

• HwndSource is created directly on the calling Total Commander UI thread
• this avoids child-window creation deadlocks
• actual WebView2 initialization is delayed slightly via DispatcherTimer
• focus and z-order are corrected explicitly so the first Lister instance does not remain behind Total Commander

Rendering

Rendering is implemented in MdViewer.Shared\MarkdownRenderService.cs.

Enabled Markdig pipeline features:

• UseAdvancedExtensions()
• UseEmojiAndSmiley()
• UseSoftlineBreakAsHardlineBreak()

Additional behavior:

• relative paths are resolved using a file:/// base tag
• empty files and file-read errors return a full HTML document instead of throwing exceptions
• light and dark CSS is embedded directly into the HTML output

Logging

File: MdViewer.Shared\FileLogger.cs

The logger writes log files into a Log subdirectory next to the executable:

[ProgramFolder]\Log\log-YYYY-MM-DD.log

Examples:

• desktop app: next to MdViewer.exe
• WLX plugin: inside the plugin folder next to MdViewerWlx.wlx and MdViewerWlx.exe

The remaining logging is intended for production use and focuses on errors and warnings.

Requirements

Runtime

• Windows x64
• installed .NET desktop runtime or SDK compatible with net10.0-windows
• installed WebView2 Runtime
• for Total Commander: x64 Total Commander is recommended

Build

• .NET 10 SDK
• One of the following native toolchains:

an initialized MSVC developer environment with cl.exe on PATH

or:

C:\Program Files\Microsoft Visual Studio\18\Insiders\SDK\ScopeCppSDK\vc15

The WLX build script first uses cl.exe from PATH. If none is available, it falls back to the ScopeCppSDK path above.

Building the Desktop App

Example:

dotnet build "D:\Projekte\MarkdownViewer\MarkdownViewer\MarkdownViewer.csproj" -c Release

Building and Packaging the Total Commander Plugin

The recommended path is the build script:

& "D:\Projekte\MarkdownViewer\tools\NativeBootstrapper\build-wlx.ps1"

The script performs the following steps:

1. runs dotnet publish for MdViewerWlx
2. compiles wlx_bootstrapper.c into MdViewerWlx.wlx
3. duplicates the binary to MdViewerWlx.wlx64
4. assembles all required files into deploy\wlx
5. creates an installable Total Commander ZIP package

Important build outputs:

• Deploy directory:

D:\Projekte\MarkdownViewer\deploy\wlx

• Installation ZIP:

D:\Projekte\MarkdownViewer\deploy\MdViewerWlx-<version>-tc.zip

The version number is read automatically from tools\NativeBootstrapper\pluginst.inf.

GitHub Releases

GitHub Releases are built automatically from version tags.

Workflow file:

• .github\workflows\release-wlx.yml

Release flow:

1. update tools\NativeBootstrapper\pluginst.inf
2. set version= to the release version, for example 1.0
3. create and push a matching Git tag, for example v1.0
4. GitHub Actions builds deploy\MdViewerWlx-<version>-tc.zip
5. the workflow publishes that ZIP as a GitHub Release asset

Important rule:

• the pushed Git tag must match the plugin version from pluginst.inf
• example: version=1.0 requires tag v1.0

WLX Deploy Contents

Typical contents of deploy\wlx:

• MdViewerWlx.wlx
• MdViewerWlx.wlx64
• MdViewerWlx.dll
• MdViewerWlx.exe
• MdViewerWlx.deps.json
• MdViewerWlx.runtimeconfig.json
• MdViewer.Shared.dll
• Markdig.dll
• Microsoft.Web.WebView2.Core.dll
• Microsoft.Web.WebView2.Wpf.dll
• WebView2Loader.dll
• pluginst.inf
• runtimes\...

Installing in Total Commander

Recommended: ZIP-based installation

1. Open Total Commander
2. Go to Configuration -> Plugins -> Install plugin
3. Select D:\Projekte\MarkdownViewer\deploy\MdViewerWlx-<version>-tc.zip
4. Total Commander reads pluginst.inf from the ZIP and installs the plugin automatically

Alternative: Manual installation

1. Copy the contents of deploy\wlx into a plugin folder
2. Register the plugin in Total Commander or install it through pluginst.inf

Active plugin folder in the current development environment:

C:\wincmd\plugins\wlx\wlx_mdviewer

Active Total Commander configuration file in the current development environment:

C:\Users\ThomasLeclaire\AppData\Roaming\GHISLER\WINCMD.INI

The relevant entry is stored in the [ListerPlugins] section.

Behavior in Total Commander

When opening a Markdown file with F3:

1. Total Commander loads MdViewerWlx.wlx or MdViewerWlx.wlx64
2. the native bootstrapper initializes the .NET runtime
3. the managed layer creates a WPF child window
4. an immediate text preview is shown first
5. the view then switches to the rendered HTML/WebView2 display

This behavior is intentional so the first load stays usable even when WebView2 startup is slow.

Notes

• the project is Windows-only by design
• the WLX plugin is x64-focused
• the first WebView2 startup can be slower than later launches
• the native WLX build needs either an MSVC developer environment on PATH or the configured ScopeCppSDK fallback path
• the installation ZIP is intended for Total Commander and contains pluginst.inf at the ZIP root

Important Files

• README.md
• MarkdownViewer\MarkdownViewer.csproj
• MdViewer.Shared\MarkdownRenderService.cs
• MdViewer.Shared\FileLogger.cs
• MdViewerWlx\MdViewerWlx.csproj
• MdViewerWlx\WlxExports.cs
• MdViewerWlx\WlxHost.cs
• MdViewerWlx\WlxContentView.cs
• tools\NativeBootstrapper\wlx_bootstrapper.c
• tools\NativeBootstrapper\build-wlx.ps1
• tools\NativeBootstrapper\pluginst.inf

Development Notes

• for rendering changes, MdViewer.Shared is usually the main entry point
• for WLX loading issues, start with the native bootstrapper and WlxExports
• for display issues inside Total Commander Lister, inspect WlxHost and WlxContentView
• for testing production artifacts, use deploy\wlx or the versioned Total Commander ZIP rather than arbitrary files from intermediate bin\ folders