webview

A tiny C++ webview library focused on Windows. It provides backends for Microsoft Edge WebView2 (Chromium), EdgeHTML (legacy Edge), and MSHTML (Trident).

This repository is forked from MichaelKim/webview and builds on ideas from zerge's webview. Recent development and testing have focused on Windows. macOS and Linux backends remain in the source, but have not been tested since the versions noted below and are not part of the current support matrix.

Support

Platform	Backend	Engine	Notes
Windows	WebView2 (WEBVIEW_EDGE)	Microsoft Edge (Chromium)	Recommended; requires the WebView2 Runtime.
Windows	EdgeHTML (WEBVIEW_WIN)	Microsoft Edge Legacy	Requires Windows 10 version 1809 or later; deprecated.
Windows	MSHTML (WEBVIEW_MSHTML)	Trident	Industrial and legacy application compatibility; requires ATL.

The macOS WebKit backend was last listed as tested on macOS Mojave and Catalina. The Linux WebKitGTK backend was last listed as tested on Ubuntu 18.04.02 LTS. Neither has been tested against newer releases as part of recent Windows-focused work.

Shared local-file-only mode

setLocalFileOnly(true) is a common feature available in all three Windows backends: MSHTML, EdgeHTML, and WebView2. It is intended for applications that should display local pages rather than external websites, while still allowing those pages to reference external resources such as scripts and stylesheets. Attempts to navigate the main document or a frame to an external site are blocked and show a built-in Forbidden page. This controls page navigation; it is not a network sandbox and does not filter subresource requests.

WelsonJS and MSHTML

MSHTML support was added to help WelsonJS, a lightweight Windows JavaScript framework for application development and industrial-system automation, maintain compatibility with existing industrial systems and their web-based interfaces. WelsonJS applications combine JavaScript (including transpiled languages) with HTML and CSS. The MSHTML backend provides access to the system's Trident engine for environments where compatibility with existing applications and workflows is important.

The MSHTML implementation includes balanced COM/OLE initialization and cleanup, navigation and new-window event handling, defensive initialization and teardown, and JavaScript/native callback support.

See MSHTML build instructions and the mshtml example.

Build and examples

See Build Steps for backend requirements and configuration. For a Visual Studio x64 WebView2 build, configure with -A x64; use -A Win32 for 32-bit. The CMake configuration selects the WebView2 loader for the chosen architecture.

Examples are in examples/:

• basic opens https://google.com.
• local-only loads index.html from the current directory and displays Not Found if it is missing. External page navigation is blocked with a Forbidden page.
• mshtml demonstrates the legacy MSHTML backend, local content, and a JavaScript-to-native callback.

The local-only setting applies to document navigation, not to resources referenced by the page. Do not treat it as a network sandbox for untrusted HTML.

TODO

• Add compatibility for the HTA (.hta) file format. HTA (HTML Application) files are HTML-based Windows applications, traditionally hosted by mshta.exe, and can include an <HTA:APPLICATION> element to configure application-window behavior such as its border. Compatibility should account for these application-specific semantics, rather than only opening the file as an ordinary HTML page. HTA content has different security assumptions from normal browser content, so this work must also define and document its security behavior. See Microsoft's documentation for the HTA:APPLICATION element and HTA security model.
• Add support for the inter-process communication (IPC) planned for the WelsonJS project.

Usage

Include webview.hpp and link/configure the dependencies for the selected backend (see Build Steps). By default, the Windows CMake configuration uses WebView2.

#include "webview.hpp"

WEBVIEW_MAIN {
  wv::WebView webview{800, 600, true, true, Str("Hello world!")};
  webview.navigate(Str("https://google.com"));

  if (webview.init() == -1) {
    return 1;
  }

  while (webview.run() == 0)
    ;

  return 0;
}

To enable local-file-only document navigation, set the option before initialization:

webview.setLocalFileOnly(true);

The local-only example demonstrates this option. On Windows, string values use std::wstring; wrap string literals with Str("..."). WEBVIEW_MAIN selects the appropriate Win32 or standard C++ entry point.

The library supports HTTP(S), local file:/// URLs, and inline data: URLs. EdgeHTML does not support local file URLs; see Limitations.

Documentation

• Build Steps
• API Reference
• Limitations
• Examples