thumbnailer: use a struct of callbacks

In order to behave like the vlc_preparser.h API.

include/vlc_thumbnailer.h

@@ -32,20 +32,29 @@ typedef size_t vlc_thumbnailer_req_id;
 #define VLC_THUMBNAILER_REQ_ID_INVALID 0
 
 /**
- * \brief vlc_thumbnailer_cb defines a callback invoked on thumbnailing completion or error
- *
- * This callback will always be called, provided vlc_thumbnailer_Request returned
- * a non NULL request, and provided the request is not cancelled before its
- * completion.
- * In case of failure, p_thumbnail will be NULL.
- * The picture, if any, is owned by the thumbnailer, and must be acquired by using
- * \link picture_Hold \endlink to use it pass the callback's scope.
- *
- * \param data Is the opaque pointer passed as vlc_thumbnailer_Request last parameter
- * \param thumbnail The generated thumbnail, or NULL in case of failure or timeout
+ * thumbnailer callbacks
  */
-typedef void(*vlc_thumbnailer_cb)( void* data, picture_t* thumbnail );
-
+struct vlc_thumbnailer_cbs
+{
+    /**
+     * Event received on thumbnailing completion or error
+     *
+     * This callback will always be called, provided vlc_thumbnailer_Request
+     * returned a valid request, and provided the request is not cancelled
+     * before its completion.
+     *
+     * @note This callback is mandatory.
+     *
+     * In case of failure, p_thumbnail will be NULL.  The picture, if any, is
+     * owned by the thumbnailer, and must be acquired by using \link
+     * picture_Hold \endlink to use it pass the callback's scope.
+     * \param thumbnail The generated thumbnail, or NULL in case of failure or
+     * timeout
+     * \param data Is the opaque pointer passed as vlc_thumbnailer_Request last
+     * parameter
+     */
+    void (*on_ended)(picture_t* thumbnail, void *data);
+};
 
 /**
  * \brief vlc_thumbnailer_Create Creates a thumbnailer object
@@ -93,8 +102,8 @@ struct vlc_thumbnailer_seek_arg
  * \param seek_arg pointer to a seek struct, that tell at which time the
  * thumbnail should be taken, NULL to disable seek
  * \param timeout A timeout value, or VLC_TICK_INVALID to disable timeout
- * \param cb A user callback to be called on completion (success & error)
- * \param user_data An opaque value, provided as pf_cb's first parameter
+ * \param cbs callback to listen to events (can't be NULL)
+ * \param cbs_userdata opaque pointer used by the callbacks
  * \returns > 0 if the item was scheduled for thumbnailing, 0 in case of error.
  *
  * If this function returns a valid id, the callback is guaranteed
@@ -107,7 +116,8 @@ VLC_API vlc_thumbnailer_req_id
 vlc_thumbnailer_Request( vlc_thumbnailer_t *thumbnailer,
                          input_item_t *input_item,
                          const struct vlc_thumbnailer_seek_arg *seek_arg,
-                         vlc_thumbnailer_cb cb, void* user_data );
+                         const struct vlc_thumbnailer_cbs *cbs,
+                         void *cbs_userdata );
 
 /**
  * \brief vlc_thumbnailer_Camcel Cancel a thumbnail request

lib/media.c

@@ -927,7 +927,7 @@ struct libvlc_media_thumbnail_request_t
     vlc_thumbnailer_req_id id;
 };
 
-static void media_on_thumbnail_ready( void* data, picture_t* thumbnail )
+static void media_on_thumbnail_ready( picture_t* thumbnail, void* data )
 {
     libvlc_media_thumbnail_request_t *req = data;
     libvlc_media_t *p_media = req->md;
@@ -972,8 +972,11 @@ libvlc_media_thumbnail_request( libvlc_instance_t *inst,
     req->type = picture_type;
     req->crop = crop;
     libvlc_media_retain( md );
+    static const struct vlc_thumbnailer_cbs cbs = {
+        .on_ended = media_on_thumbnail_ready,
+    };
     req->id = vlc_thumbnailer_Request( thumb, md->p_input_item, seek_arg,
-                                       media_on_thumbnail_ready, req );
+                                       &cbs, req );
     if ( req->id == VLC_PREPARSER_REQ_ID_INVALID )
     {
         free( req );

modules/misc/medialibrary/Thumbnailer.cpp

@@ -43,7 +43,7 @@ Thumbnailer::Thumbnailer( vlc_medialibrary_module_t* ml )
         throw std::runtime_error( "Failed to instantiate a vlc_thumbnailer_t" );
 }
 
-void Thumbnailer::onThumbnailComplete( void* data, picture_t* thumbnail )
+void Thumbnailer::onThumbnailComplete( picture_t* thumbnail, void *data )
 {
     ThumbnailerCtx* ctx = static_cast<ThumbnailerCtx*>( data );
 
@@ -76,9 +76,13 @@ bool Thumbnailer::generate( const medialibrary::IMedia&, const std::string& mrl,
             .pos = position,
             .speed = vlc_thumbnailer_seek_arg::VLC_THUMBNAILER_SEEK_FAST,
         };
+
+        static const struct vlc_thumbnailer_cbs cbs = {
+            .on_ended = onThumbnailComplete,
+        };
         vlc_thumbnailer_req_id requestId =
             vlc_thumbnailer_Request( m_thumbnailer.get(), item.get(), &seek_arg,
-                                     &onThumbnailComplete, &ctx );
+                                     &cbs, &ctx );
 
         if (requestId == VLC_THUMBNAILER_REQ_ID_INVALID)
         {

modules/misc/medialibrary/medialibrary.h

@@ -137,7 +137,7 @@ public:
     void stop() override;
 
 private:
-    static void onThumbnailComplete( void* data, picture_t* thumbnail );
+    static void onThumbnailComplete( picture_t* thumbnail, void* data );
 
 private:
     vlc_medialibrary_module_t* m_ml;

src/input/thumbnailer.c

@@ -47,7 +47,7 @@ typedef struct task
 
     struct vlc_thumbnailer_seek_arg seek_arg;
     input_item_t *item;
-    vlc_thumbnailer_cb cb;
+    const struct vlc_thumbnailer_cbs *cbs;
     void* userdata;
 
     enum
@@ -69,7 +69,7 @@ static void RunnableRun(void *);
 static task_t *
 TaskNew(vlc_thumbnailer_t *thumbnailer, input_item_t *item,
         const struct vlc_thumbnailer_seek_arg *seek_arg,
-        vlc_thumbnailer_cb cb, void *userdata)
+        const struct vlc_thumbnailer_cbs *cbs, void *userdata )
 {
     task_t *task = malloc(sizeof(*task));
     if (!task)
@@ -84,7 +84,7 @@ TaskNew(vlc_thumbnailer_t *thumbnailer, input_item_t *item,
     else
         task->seek_arg = *seek_arg;
 
-    task->cb = cb;
+    task->cbs = cbs;
     task->userdata = userdata;
 
     task->status = RUNNING;
@@ -107,8 +107,7 @@ TaskDestroy(task_t *task)
 
 static void NotifyThumbnail(task_t *task, picture_t *pic)
 {
-    assert(task->cb);
-    task->cb(task->userdata, pic);
+    task->cbs->on_ended(pic, task->userdata);
 }
 
 static void
@@ -232,9 +231,11 @@ vlc_thumbnailer_req_id
 vlc_thumbnailer_Request( vlc_thumbnailer_t *thumbnailer,
                          input_item_t *item,
                          const struct vlc_thumbnailer_seek_arg *seek_arg,
-                         vlc_thumbnailer_cb cb, void* userdata )
+                         const struct vlc_thumbnailer_cbs *cbs, void *userdata )
 {
-    task_t *task = TaskNew(thumbnailer, item, seek_arg, cb, userdata);
+    assert( cbs != NULL && cbs->on_ended != NULL );
+
+    task_t *task = TaskNew(thumbnailer, item, seek_arg, cbs, userdata);
     if (!task)
         return 0;
 

test/src/input/thumbnail.c

@@ -68,7 +68,7 @@ struct test_ctx
     bool b_done;
 };
 
-static void thumbnailer_callback( void* data, picture_t* thumbnail )
+static void thumbnailer_callback( picture_t* thumbnail, void *data )
 {
     struct test_ctx* p_ctx = data;
     vlc_mutex_lock( &p_ctx->lock );
@@ -152,8 +152,11 @@ static void test_thumbnails( libvlc_instance_t* p_vlc )
             seek_arg.speed = test_params[i].b_fast_seek ?
                 VLC_THUMBNAILER_SEEK_FAST : VLC_THUMBNAILER_SEEK_PRECISE;
         }
+        static const struct vlc_thumbnailer_cbs cbs = {
+            .on_ended = thumbnailer_callback,
+        };
         id = vlc_thumbnailer_Request( p_thumbnailer, p_item, &seek_arg,
-                                      thumbnailer_callback, &ctx );
+                                      &cbs, &ctx );
         assert( id != VLC_THUMBNAILER_REQ_ID_INVALID );
 
         while ( ctx.b_done == false )
@@ -168,7 +171,7 @@ static void test_thumbnails( libvlc_instance_t* p_vlc )
     }
 }
 
-static void thumbnailer_callback_cancel( void* data, picture_t* p_thumbnail )
+static void thumbnailer_callback_cancel( picture_t* p_thumbnail, void *data )
 {
     (void) data; (void) p_thumbnail;
     /* This callback should not be called since the request is cancelled */
@@ -188,9 +191,12 @@ static void test_cancel_thumbnail( libvlc_instance_t* p_vlc )
     input_item_t* p_item = input_item_New( psz_mrl, "mock item" );
     assert( p_item != NULL );
 
+    static const struct vlc_thumbnailer_cbs cbs = {
+        .on_ended = thumbnailer_callback_cancel,
+    };
+
     vlc_thumbnailer_req_id id =
-        vlc_thumbnailer_Request( p_thumbnailer, p_item, NULL,
-                                 thumbnailer_callback_cancel, NULL );
+        vlc_thumbnailer_Request( p_thumbnailer, p_item, NULL, &cbs, NULL );
 
     vlc_thumbnailer_Cancel( p_thumbnailer, id );