Add support for custom User-Agent in webview (Linux & macOS)

.gitignore

@@ -1,4 +1,5 @@
 # Binaries for programs and plugins
+/webview_app
 *.exe
 *.exe~
 *.dll

README.md

@@ -48,3 +48,69 @@ Calling `Eval()` or `Dispatch()` before `Run()` does not work because the webvie
 
 [go-docs]: https://pkg.go.dev/github.com/webview/webview_go
 [webview]: https://github.com/webview/webview
+
+
+### WebView UserAgent Example
+
+This project demonstrates how to set a custom User-Agent string in webview_go.
+
+It builds a simple Go application that shows the current User-Agent in the UI and verifies that it matches the value defined in the source code.
+
+Requirements
+Go 1.18+
+C compiler (clang/gcc)
+Linux:
+libgtk-3-dev
+libwebkit2gtk-4.0-dev
+macOS: no additional dependencies
+
+### Build 
+
+chmod +x build.sh
+./build.sh
+
+This will:
+	1.	Install necessary dependencies (on Linux).
+	2.	Compile main.go into an executable webview_app.
+
+### Run 
+
+./webview_app
+
+Expected behavior
+
+When the application runs:
+	•	A window will open with:
+	•	A UserAgent section showing the custom value (e.g. MyCustomUserAgent/1.0).
+	•	A button and counter to demonstrate bindings.
+
+If you see your custom User-Agent displayed in the window, the implementation is correct
+
+Troubleshooting
+
+Linux:
+1. Error: webkit2/webkit2.h: No such file or directory
+-> Install missing GTK/WebKit dependencies:
+sudo apt-get update
+sudo apt-get install -y libgtk-3-dev libwebkit2gtk-4.0-dev
+
+2. Error: pkg-config not found
+-> Install pkg-config:
+sudo apt-get install -y pkg-config
+
+3. Blank window / crash on startup
+-> Ensure you are running inside a desktop environment with GTK/WebKit support.
+-> On minimal VMs, install ubuntu-desktop or run inside an X11 session.
+
+MacOS:
+1. Error: ld: framework not found WebKit
+-> Ensure you use clang (not gcc) when compiling.
+-> Go automatically links against Cocoa/WebKit frameworks, so usually no manual fix is required.
+
+2. Window opens but is empty
+-> Sometimes macOS blocks WebKit initialization in sandboxed terminals. Try:
+open ./webview_test
+
+3. Custom UserAgent not applied
+-> Make sure you call w.SetUserAgent("MyCustomUserAgent/1.0") before w.Navigate(...) or w.SetHtml(...)
+

build.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+set -e
+
+echo "[INFO] Installing dependencies..."
+
+# Проверка платформы
+if [[ "$OSTYPE" == "linux-gnu"* ]]; then
+  sudo apt-get update
+  sudo apt-get install -y build-essential pkg-config libgtk-3-dev libwebkit2gtk-4.0-dev
+  echo "[INFO] Dependencies installed (Linux)"
+elif [[ "$OSTYPE" == "darwin"* ]]; then
+  echo "[INFO] No dependencies required on macOS"
+else
+  echo "[ERROR] Unsupported OS: $OSTYPE"
+  exit 1
+fi
+
+echo "[INFO] Building Go binary..."
+go build -o webview_app ./examples/bind
+
+echo "[INFO] Build complete. Run with ./webview_test"

examples/bind/main.go

@@ -2,12 +2,17 @@ package main
 
 import webview "github.com/webview/webview_go"
 
-const html = `<button id="increment">Tap me</button>
+const html = `<h2>UserAgent:</h2>
+<div id="ua"></div>
+<button id="increment">Tap me</button>
 <div>You tapped <span id="count">0</span> time(s).</div>
 <script>
   const [incrementElement, countElement] =
     document.querySelectorAll("#increment, #count");
+
   document.addEventListener("DOMContentLoaded", () => {
+    document.getElementById("ua").textContent = navigator.userAgent;
+
     incrementElement.addEventListener("click", () => {
       window.increment().then(result => {
         countElement.textContent = result.count;
@@ -24,8 +29,9 @@ func main() {
 	var count uint = 0
 	w := webview.New(false)
 	defer w.Destroy()
-	w.SetTitle("Bind Example")
+	w.SetTitle("Bind and UserAgent Example")
 	w.SetSize(480, 320, webview.HintNone)
+	w.SetUserAgent("MyCustomUserAgent/1.0")
 
 	// A binding that increments a value and immediately returns the new value.
 	w.Bind("increment", func() IncrementResult {

libs/webview/include/webview.h

@@ -265,6 +265,13 @@ WEBVIEW_API void webview_set_title(webview_t w, const char *title);
 WEBVIEW_API void webview_set_size(webview_t w, int width, int height,
                                   webview_hint_t hints);
 
+/** 
+ * @param w The webview instance.
+ * @param user_agent The new user agent.
+*/
+
+WEBVIEW_API void webview_set_user_agent(webview_t w, const char *user_agent);
+
 /**
  * Navigates webview to the given URL. URL may be a properly encoded data URI.
  *
@@ -1010,6 +1017,8 @@ if (status === 0) {\
   void init(const std::string &js) { init_impl(js); }
   void eval(const std::string &js) { eval_impl(js); }
 
+  void set_user_agent(const std::string &ua) { set_user_agent_impl(ua); }
+
 protected:
   virtual void navigate_impl(const std::string &url) = 0;
   virtual void *window_impl() = 0;
@@ -1023,6 +1032,7 @@ if (status === 0) {\
   virtual void set_html_impl(const std::string &html) = 0;
   virtual void init_impl(const std::string &js) = 0;
   virtual void eval_impl(const std::string &js) = 0;
+  virtual void set_user_agent_impl(const std::string &ua) = 0;
 
   virtual void on_message(const std::string &msg) {
     auto seq = json_parse(msg, "id", 0);
@@ -1352,6 +1362,16 @@ class gtk_webkit_engine : public engine_base {
     }
   }
 
+  void set_user_agent_impl(const std::string &ua) override {
+  if (!m_webview) return;
+
+  WebKitSettings *settings = webkit_web_view_get_settings(WEBKIT_WEB_VIEW(m_webview));
+  if (!settings) return;
+
+  webkit_settings_set_user_agent(settings, ua.c_str());
+  webkit_web_view_set_settings(WEBKIT_WEB_VIEW(m_webview), settings);
+}
+
   void navigate_impl(const std::string &url) override {
     webkit_web_view_load_uri(WEBKIT_WEB_VIEW(m_webview), url.c_str());
   }
@@ -1718,6 +1738,23 @@ class cocoa_wkwebview_engine : public engine_base {
                          nullptr);
   }
 
+  void set_user_agent_impl(const std::string &ua) override {
+  objc::autoreleasepool pool;
+
+  if (!m_webview) return;
+
+  id configuration = objc::msg_send<id>(m_webview, "configuration"_sel);
+  if (!configuration) return;
+
+  id uaString = objc::msg_send<id>("NSString"_cls,
+                                   "stringWithUTF8String:"_sel,
+                                   ua.c_str());
+
+  objc::msg_send<void>(configuration,
+                       "setApplicationNameForUserAgent:"_sel,
+                       uaString);
+}
+
 private:
   id create_app_delegate() {
     objc::autoreleasepool arp;
@@ -3552,6 +3589,11 @@ WEBVIEW_API void webview_set_size(webview_t w, int width, int height,
   static_cast<webview::webview *>(w)->set_size(width, height, hints);
 }
 
+WEBVIEW_API void webview_set_user_agent(webview_t w, const char *user_agent) {
+  if (!w || !user_agent) return;
+  static_cast<webview::webview *>(w)->set_user_agent(user_agent);
+}
+
 WEBVIEW_API void webview_navigate(webview_t w, const char *url) {
   static_cast<webview::webview *>(w)->navigate(url);
 }

webview.go

@@ -25,16 +25,17 @@ void CgoWebViewUnbind(webview_t w, const char *name);
 */
 import "C"
 import (
-	_ "github.com/webview/webview_go/libs/mswebview2"
-	_ "github.com/webview/webview_go/libs/mswebview2/include"
-	_ "github.com/webview/webview_go/libs/webview"
-	_ "github.com/webview/webview_go/libs/webview/include"
 	"encoding/json"
 	"errors"
 	"reflect"
 	"runtime"
 	"sync"
 	"unsafe"
+
+	_ "github.com/webview/webview_go/libs/mswebview2"
+	_ "github.com/webview/webview_go/libs/mswebview2/include"
+	_ "github.com/webview/webview_go/libs/webview"
+	_ "github.com/webview/webview_go/libs/webview/include"
 )
 
 func init() {
@@ -122,6 +123,9 @@ type WebView interface {
 
 	// Removes a callback that was previously set by Bind.
 	Unbind(name string) error
+
+	// Sets a user agent based on OS
+	SetUserAgent(ua string) error
 }
 
 type webview struct {
@@ -329,3 +333,10 @@ func (w *webview) Unbind(name string) error {
 	C.CgoWebViewUnbind(w.w, cname)
 	return nil
 }
+
+func (w *webview) SetUserAgent(ua string) error {
+	cua := C.CString(ua)
+	defer C.free(unsafe.Pointer(cua))
+	C.webview_set_user_agent(w.w, cua)
+	return nil
+}