Use QML WorkerScript for loading and updating models

common/GPodderEpisodeListModel.qml

@@ -62,6 +62,10 @@ ListModel {
         });
     }
 
+    property var worker: ModelWorkerScript {
+        id: modelWorker
+    }
+
     function forEachEpisode(callback) {
         // Go from bottom up (= chronological order)
         for (var i=count-1; i>=0; i--) {
@@ -122,11 +126,12 @@ ListModel {
 
         ready = false;
         py.call('main.load_episodes', [podcast_id, query], function (episodes) {
-            Util.updateModelFrom(episodeListModel, episodes);
-            episodeListModel.ready = true;
-            if (callback !== undefined) {
-                callback();
-            }
+            modelWorker.updateModelFrom(episodeListModel, episodes, function () {
+                episodeListModel.ready = true;
+                if (callback !== undefined) {
+                    callback();
+                }
+            });
         });
     }
 }

common/GPodderEpisodeListModelConnections.qml

@@ -26,11 +26,11 @@ Connections {
     target: py
 
     onDownloadProgress: {
-        Util.updateModelWith(episodeListModel, 'id', episode_id,
+        episodeListModel.worker.updateModelWith(episodeListModel, 'id', episode_id,
             {'progress': progress});
     }
     onPlaybackProgress: {
-        Util.updateModelWith(episodeListModel, 'id', episode_id,
+        episodeListModel.worker.updateModelWith(episodeListModel, 'id', episode_id,
             {'playbackProgress': progress});
     }
     onUpdatedEpisode: {

common/GPodderPodcastListModel.qml

@@ -25,9 +25,13 @@ import 'util.js' as Util
 ListModel {
     id: podcastListModel
 
+    property var worker: ModelWorkerScript {
+        id: modelWorker
+    }
+
     function reload() {
         py.call('main.load_podcasts', [], function (podcasts) {
-            Util.updateModelFrom(podcastListModel, podcasts);
+            modelWorker.updateModelFrom(podcastListModel, podcasts);
         });
     }
 }

common/ModelWorkerScript.qml

@@ -0,0 +1,67 @@
+
+/**
+ *
+ * gPodder QML UI Reference Implementation
+ * Copyright (c) 2015, Thomas Perl <m@thp.io>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ *
+ */
+
+import QtQuick 2.0
+
+
+WorkerScript {
+    source: 'modelworker.js'
+
+    property int callbacks_seq: 1
+    property var callbacks: ({})
+
+    function refCallback(callback) {
+        var id = callbacks_seq++;
+        callbacks[id] = callback;
+        return id;
+    }
+
+    function unrefCallback(callback) {
+        var result = callbacks[callback];
+        delete callbacks[callback];
+        return result;
+    }
+
+    function updateModelFrom(model, data, callback) {
+        sendMessage({
+            action: 'updateModelFrom',
+            model: model,
+            data: data,
+            callback: refCallback(callback),
+        });
+    }
+
+    function updateModelWith(model, key, value, update, callback) {
+        sendMessage({
+            action: 'updateModelWith',
+            model: model,
+            key: key,
+            value: value,
+            update: update,
+            callback: refCallback(callback),
+        });
+    }
+
+    onMessage: {
+        if (messageObject.callback !== undefined) {
+            unrefCallback(messageObject.callback)();
+        }
+    }
+}

common/modelworker.js

@@ -0,0 +1,42 @@
+function updateModelFrom(model, data) {
+    // TODO: This is very naive at the moment, we should do proper remove(),
+    // move(), set() and insert() calls, so that the UI can animate changes.
+    for (var i=0; i<data.length; i++) {
+        if (model.count < i) {
+            model.append(data[i]);
+        } else {
+            model.set(i, data[i]);
+        }
+    }
+
+    while (model.count > data.length) {
+        model.remove(model.count-1);
+    }
+
+    model.sync();
+}
+
+function updateModelWith(model, key, value, update) {
+    for (var row=0; row<model.count; row++) {
+        var current = model.get(row);
+        if (current[key] == value) {
+            for (var key in update) {
+                model.setProperty(row, key, update[key]);
+            }
+        }
+    }
+
+    model.sync();
+}
+
+WorkerScript.onMessage = function (msg) {
+    if (msg.action === 'updateModelFrom') {
+        updateModelFrom(msg.model, msg.data);
+        WorkerScript.sendMessage({callback: msg.callback});
+    } else if (msg.action === 'updateModelWith') {
+        updateModelWith(msg.model, msg.key, msg.value, msg.update);
+        WorkerScript.sendMessage({callback: msg.callback});
+    } else {
+        console.log('Unknown action: ' + msg.action);
+    }
+}

common/util.js

@@ -18,31 +18,6 @@
  *
  */
 
-function updateModelFrom(model, data) {
-    for (var i=0; i<data.length; i++) {
-        if (model.count < i) {
-            model.append(data[i]);
-        } else {
-            model.set(i, data[i]);
-        }
-    }
-
-    while (model.count > data.length) {
-        model.remove(model.count-1);
-    }
-}
-
-function updateModelWith(model, key, value, update) {
-    for (var row=0; row<model.count; row++) {
-        var current = model.get(row);
-        if (current[key] == value) {
-            for (var key in update) {
-                model.setProperty(row, key, update[key]);
-            }
-        }
-    }
-}
-
 function formatDuration(duration) {
     if (duration !== 0 && !duration) {
         return ''