Fix problems with navigation events that aren't generated by GtkWebKit.

(used lib: libwebkit2gtk-4.1-0 on linux Mint).

The WebKit engine to apparently doesn't catch the navigations and does not produce navigation events, when something like "webui_bind(_webui_win, "", webui_event_handler);" is called. Although this should be expected behaviour.

By implementing a handler for the GtkWebKit decision signal, this navigation event can still be generated.

Signed-off-by: Hans Dijkema <hans@dijkewijk.nl>

Author: hdijkema

include/webui.h

@@ -523,6 +523,31 @@ WEBUI_EXPORT void webui_set_browser_folder(const char* path);
  */
 WEBUI_EXPORT bool webui_set_default_root_folder(const char* path);
 
+/**
+ * @brief Set a callback function on the given window to allow navigations.
+ * Must return false if navigation is not allowed, true, otherwise.
+ *
+ * A 'NULL' navigation handler will remove the current navigation_handler.
+ *
+ * NB. This currently works only for GtkWebKit WebView implementations.
+ * Because GtkWebKit allways navigates, i.e. doesnt react to
+ * webui_bind(_webui_win, "", webui_event_handler) which is supposed to
+ * catch navigation requests.
+ *
+ * Also, although bind(win, "", evt_handler) does not work for GtkWebKit,
+ * this implementation will always fire an event on navigation, unless
+ * mayNavigate() returns true (which is the default, when the callback is not set).
+ *
+ * @example
+ * bool mayNavigate(size_t window)
+ * {
+ *  if (_just_called_show_with_url) { return true; }
+ *  else { return false; } // expect a navigation event to be handled
+ * }
+ */
+WEBUI_EXPORT void webui_set_navigation_handler(size_t window, bool (*may_navigate_handler)(size_t window));
+
+
 /**
  * @brief Set a callback to catch the close event of the WebView window.
  * Must return `false` to prevent the close event, `true` otherwise.

src/webui.c

@@ -8,6 +8,8 @@
   Canada.
 */
 
+#define webui_log_debug printf
+
 // 64Mb max dynamic memory allocation
 #define WEBUI_MAX_BUF (64000000)
 
@@ -247,10 +249,18 @@ typedef struct webui_event_inf_t {
     typedef void *(*webkit_web_view_new_func)(void);
     typedef void (*webkit_web_view_load_uri_func)(void *, const char *);
     typedef const char *(*webkit_web_view_get_title_func)(void *);
+    typedef void (*webkit_1ptr_arg_func)(void *);
+    typedef int (*webkit_1ptr_arg_2int_func)(void *);
+    typedef void *(*webkit_1ptr_arg_2ptr_func)(void *);
+    typedef const char *(*webkit_1ptr_arg_2str_func)(void *);
     static webkit_web_view_new_func webkit_web_view_new = NULL;
     static webkit_web_view_load_uri_func webkit_web_view_load_uri = NULL;
     static webkit_web_view_get_title_func webkit_web_view_get_title = NULL;
-    
+    static webkit_1ptr_arg_func webkit_policy_decision_ignore = NULL;
+    static webkit_1ptr_arg_2int_func webkit_navigation_policy_decision_get_navigation_type = NULL;
+    static webkit_1ptr_arg_2ptr_func webkit_navigation_policy_decision_get_request = NULL;
+    static webkit_1ptr_arg_2str_func webkit_uri_request_get_uri = NULL;
+
     typedef struct _webui_wv_linux_t {
         // Linux WebView
         void* gtk_win;
@@ -355,6 +365,7 @@ typedef struct _webui_window_t {
     int x;
     int y;
     bool position_set;
+    bool (*may_navigate_handler)(size_t window);
     bool (*close_handler_wv)(size_t window);
     const void*(*files_handler)(const char* filename, int* length);
     const void*(*files_handler_window)(size_t window, const char* filename, int* length);
@@ -759,6 +770,21 @@ void webui_run(size_t window, const char* script) {
     _webui_send_all(win, 0, WEBUI_CMD_JS_QUICK, script, js_len);
 }
 
+void webui_set_navigation_handler(size_t window, bool (*may_navigate_handler)(size_t window)) {
+    #ifdef WEBUI_LOG
+        webui_log_debug("[User]webui_set_navigation_handler(%zu, %p)", window, may_navigate_handler);
+    #endif
+
+    // Dereference
+    if (_webui_mutex_app_is_exit_now(WEBUI_MUTEX_GET_STATUS) || _webui.wins[window] == NULL)
+        return;
+
+    _webui_window_t* win = _webui.wins[window];
+
+    // Set the navigation handler
+    win->may_navigate_handler = may_navigate_handler;
+}
+
 void webui_set_close_handler_wv(size_t window, bool(*close_handler)(size_t window)) {
 
     // Initialization
@@ -11763,6 +11789,84 @@ BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpReserved) {
         }
     }
 
+    // Decision Event
+    #define WEBKIT_POLICY_DECISION_TYPE_NAVIGATION_ACTION 0
+    #define WEBKIT_NAVIGATION_TYPE_LINK_CLICKED     0
+    #define WEBKIT_NAVIGATION_TYPE_FORM_SUBMITTED   1
+    #define WEBKIT_NAVIGATION_TYPE_BACK_FORWARD     2
+    #define WEBKIT_NAVIGATION_TYPE_RELOAD           3
+    #define WEBKIT_NAVIGATION_TYPE_FORM_RESUBMITTED 4
+    #define WEBKIT_NAVIGATION_TYPE_OTHER            5
+
+    static bool _webui_wv_event_decision(void *widget, void *decision, int decision_type, void *user_data) {
+        switch(decision_type) {
+            case WEBKIT_POLICY_DECISION_TYPE_NAVIGATION_ACTION: {
+
+                int navigation_type = webkit_navigation_policy_decision_get_navigation_type(decision);
+                bool intercept_navigation = false;
+
+                _webui_window_t* win = _webui_dereference_win_ptr(user_data);
+                if (win->may_navigate_handler) {
+                    intercept_navigation = !(win->may_navigate_handler(win->num));
+                }
+
+                if (intercept_navigation) {
+                    webkit_policy_decision_ignore(decision);
+
+                    void *uri_request = webkit_navigation_policy_decision_get_request(decision);
+                    const char *webkit_uri = webkit_uri_request_get_uri(uri_request);
+
+                    size_t s = strlen(webkit_uri) + 1;
+                    char *uri = (char *) _webui_malloc(s);
+                    strncpy(uri, webkit_uri, s - 1);
+                    uri[s] = '\0';
+
+                    char buf[20];
+                    snprintf(buf, 20, "%d", navigation_type);
+                    size_t nt_s = strlen(buf) + 1;
+                    char *type = (char *) _webui_malloc(nt_s);
+                    strncpy(uri, buf, nt_s - 1);
+                    uri[nt_s] = '\0';
+
+                    webui_event_inf_t* event_inf = NULL;
+                    size_t event_num = _webui_new_event_inf(win, &event_inf);
+
+                    // TODO: Not sure how this works and if the right connection_id is taken.
+                    int connection_id = 0;
+                    // TODO: Not sure if this is the way to get the client.
+                    struct mg_connection* client = win->single_client;
+
+                    event_inf->client = client;
+                    event_inf->connection_id = connection_id;
+
+                    // Event Info Extras
+                    event_inf->event_data[0] = uri;
+                    event_inf->event_size[0] = strlen(uri);
+                    event_inf->event_data[1] = type;
+                    event_inf->event_size[1] = strlen(type);
+
+                    _webui_window_event(
+                        win, // Event -> Window
+                        connection_id, // Event -> Client Unique ID
+                        WEBUI_EVENT_NAVIGATION, // Event -> Type of this event
+                        "", // Event -> HTML Element
+                        event_num, // Event -> Event Number
+                        _webui_client_get_id(win, client), // Event -> Client ID
+                        _webui_get_cookies_full(client) // Event -> Full cookies
+                    );
+
+                    // Free event
+                    _webui_free_event_inf(win, event_num);
+
+                    // Return that this event is handled.
+                    return true;
+                }
+            }
+            break;
+        }
+        return false;
+    }
+
     // Close Event
     static void _webui_wv_event_closed(void *widget, void *arg) {
         #ifdef WEBUI_LOG
@@ -12095,6 +12199,14 @@ BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpReserved) {
                 libwebkit, "webkit_web_view_load_uri");
             webkit_web_view_get_title = (webkit_web_view_get_title_func)dlsym(
                 libwebkit, "webkit_web_view_get_title");
+            webkit_policy_decision_ignore = (webkit_1ptr_arg_func)dlsym(
+                libwebkit, "webkit_policy_decision_ignore");
+            webkit_navigation_policy_decision_get_navigation_type = (webkit_1ptr_arg_2int_func)dlsym(
+                libwebkit, "webkit_navigation_policy_decision_get_navigation_type");
+            webkit_navigation_policy_decision_get_request = (webkit_1ptr_arg_2ptr_func)dlsym(
+                libwebkit, "webkit_navigation_policy_decision_get_request");
+            webkit_uri_request_get_uri = (webkit_1ptr_arg_2str_func)dlsym(
+                libwebkit, "webkit_uri_request_get_uri");
 
             // Check GTK
             if (
@@ -12119,7 +12231,10 @@ BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpReserved) {
             }
 
             // Check WebView
-            if (!webkit_web_view_new || !webkit_web_view_load_uri || !webkit_web_view_get_title) {
+            if (!webkit_web_view_new || !webkit_web_view_load_uri || !webkit_web_view_get_title ||
+                    !webkit_policy_decision_ignore || !webkit_navigation_policy_decision_get_navigation_type ||
+                    !webkit_navigation_policy_decision_get_request || !webkit_uri_request_get_uri
+                    ) {
                 #ifdef WEBUI_LOG
                 printf("[Core]\t\t_webui_load_gtk_and_webkit() -> WebKit symbol addresses failed\n");
                 #endif