Speed up initial loading of Watch Recordings screen.

Fixes #10161.  Defer initialization of string properties and states in
the PlaybackBox button list items until the item receives the
itemVisible signal.  This can greatly improve responsiveness when the
recording group being displayed has 1000+ recordings and the frontend
CPU is relatively weak, e.g. an ION-based system.  The improvement is
particularly noticeable when using the Change Group Filter menu item
within the Watch Recordings screen.

Author: stichnot

mythtv/programs/mythfrontend/playbackbox.cpp

@@ -824,6 +824,47 @@ void PlaybackBox::UpdateUIListItem(MythUIButtonListItem *item,
 
     SetItemIcons(item, pginfo);
 
+    QMap<AudioProps, QString> audioFlags;
+    audioFlags[AUD_DOLBY] = "dolby";
+    audioFlags[AUD_SURROUND] = "surround";
+    audioFlags[AUD_STEREO] = "stereo";
+    audioFlags[AUD_MONO] = "mono";
+
+    QMap<VideoProps, QString> videoFlags;
+    videoFlags[VID_1080] = "hd1080";
+    videoFlags[VID_720] = "hd720";
+    videoFlags[VID_HDTV] = "hdtv";
+    videoFlags[VID_WIDESCREEN] = "widescreen";
+
+    QMap<SubtitleTypes, QString> subtitleFlags;
+    subtitleFlags[SUB_SIGNED] = "deafsigned";
+    subtitleFlags[SUB_ONSCREEN] = "onscreensub";
+    subtitleFlags[SUB_NORMAL] = "subtitles";
+    subtitleFlags[SUB_HARDHEAR] = "cc";
+
+    QMap<AudioProps, QString>::iterator ait;
+    for (ait = audioFlags.begin(); ait != audioFlags.end(); ++ait)
+    {
+        if (pginfo->GetAudioProperties() & ait.key())
+            item->DisplayState(ait.value(), "audioprops");
+    }
+
+    QMap<VideoProps, QString>::iterator vit;
+    for (vit = videoFlags.begin(); vit != videoFlags.end(); ++vit)
+    {
+        if (pginfo->GetVideoProperties() & vit.key())
+            item->DisplayState(vit.value(), "videoprops");
+    }
+
+    QMap<SubtitleTypes, QString>::iterator sit;
+    for (sit = subtitleFlags.begin(); sit != subtitleFlags.end(); ++sit)
+    {
+        if (pginfo->GetSubtitleType() & sit.key())
+            item->DisplayState(sit.value(), "subtitletypes");
+    }
+
+    item->DisplayState(pginfo->GetCategoryType(), "categorytype");
+
     QString rating = QString::number(pginfo->GetStars(10));
 
     item->DisplayState(rating, "ratingstate");
@@ -920,6 +961,7 @@ void PlaybackBox::ItemVisible(MythUIButtonListItem *item)
                 m_helper.GetPreviewImage(*sel_pginfo, false));
         }
     }
+    UpdateUIListItem(item, item == sel_item, false);
 }
 
 
@@ -1316,24 +1358,6 @@ void PlaybackBox::updateRecList(MythUIButtonListItem *sel_item)
 
     ProgramList &progList = *pmit;
 
-    QMap<AudioProps, QString> audioFlags;
-    audioFlags[AUD_DOLBY] = "dolby";
-    audioFlags[AUD_SURROUND] = "surround";
-    audioFlags[AUD_STEREO] = "stereo";
-    audioFlags[AUD_MONO] = "mono";
-
-    QMap<VideoProps, QString> videoFlags;
-    videoFlags[VID_1080] = "hd1080";
-    videoFlags[VID_720] = "hd720";
-    videoFlags[VID_HDTV] = "hdtv";
-    videoFlags[VID_WIDESCREEN] = "widescreen";
-
-    QMap<SubtitleTypes, QString> subtitleFlags;
-    subtitleFlags[SUB_SIGNED] = "deafsigned";
-    subtitleFlags[SUB_ONSCREEN] = "onscreensub";
-    subtitleFlags[SUB_NORMAL] = "subtitles";
-    subtitleFlags[SUB_HARDHEAR] = "cc";
-
     ProgramList::iterator it = progList.begin();
     for (; it != progList.end(); ++it)
     {
@@ -1343,48 +1367,8 @@ void PlaybackBox::updateRecList(MythUIButtonListItem *sel_item)
 
         MythUIButtonListItem *item =
             new PlaybackBoxListItem(this, m_recordingList, *it);
-
-        QString state = extract_main_state(**it, m_player);
-
-        item->SetFontState(state);
-
-        InfoMap infoMap;
-        (*it)->ToMap(infoMap);
-        item->SetTextFromMap(infoMap);
-
-        QString tempSubTitle  = extract_subtitle(**it, groupname);
-
-        if (groupname == (*it)->GetTitle().toLower())
-            item->SetText(tempSubTitle,       "titlesubtitle");
-
-        item->DisplayState(state, "status");
-
-        item->DisplayState(QString::number((*it)->GetStars(10)), "ratingstate");
-
-        SetItemIcons(item, (*it));
-
-        QMap<AudioProps, QString>::iterator ait;
-        for (ait = audioFlags.begin(); ait != audioFlags.end(); ++ait)
-        {
-            if ((*it)->GetAudioProperties() & ait.key())
-                item->DisplayState(ait.value(), "audioprops");
-        }
-
-        QMap<VideoProps, QString>::iterator vit;
-        for (vit = videoFlags.begin(); vit != videoFlags.end(); ++vit)
-        {
-            if ((*it)->GetVideoProperties() & vit.key())
-                item->DisplayState(vit.value(), "videoprops");
-        }
-
-        QMap<SubtitleTypes, QString>::iterator sit;
-        for (sit = subtitleFlags.begin(); sit != subtitleFlags.end(); ++sit)
-        {
-            if ((*it)->GetSubtitleType() & sit.key())
-                item->DisplayState(sit.value(), "subtitletypes");
-        }
-
-        item->DisplayState((*it)->GetCategoryType(), "categorytype");
+        // Defer initialization of the item's properties until it
+        // first becomes visible.
     }
 
     if (m_noRecordingsText)