From 0b47021504d463e5bd33d09a2982d504f67a9664 Mon Sep 17 00:00:00 2001
From: silver <silver.zachara@gmail.com>
Date: Wed, 24 Oct 2018 19:20:33 +0200
Subject: [PATCH 1/2] Prevent flickering preview dialog

Avoid instantiation of a preview dialog, when torrent is not
previewable
---
 src/gui/previewselectdialog.cpp |  4 ----
 src/gui/transferlistwidget.cpp  | 18 +++++++++++++++++-
 2 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/src/gui/previewselectdialog.cpp b/src/gui/previewselectdialog.cpp
index 4627d8be6..730591c2d 100644
--- a/src/gui/previewselectdialog.cpp
+++ b/src/gui/previewselectdialog.cpp
@@ -93,10 +93,6 @@ PreviewSelectDialog::PreviewSelectDialog(QWidget *parent, BitTorrent::TorrentHan
         }
     }
 
-    if (m_previewListModel->rowCount() == 0) {
-        QMessageBox::critical(this->parentWidget(), tr("Preview impossible"), tr("Sorry, we can't preview this file"));
-        close();
-    }
     connect(this, SIGNAL(readyToPreviewFile(QString)), parent, SLOT(previewFile(QString)));
     m_previewListModel->sort(NAME);
     previewList->header()->setSortIndicator(0, Qt::AscendingOrder);
diff --git a/src/gui/transferlistwidget.cpp b/src/gui/transferlistwidget.cpp
index 79606171f..c46bb64e2 100644
--- a/src/gui/transferlistwidget.cpp
+++ b/src/gui/transferlistwidget.cpp
@@ -48,6 +48,7 @@
 #include "base/preferences.h"
 #include "base/torrentfilter.h"
 #include "base/utils/fs.h"
+#include "base/utils/misc.h"
 #include "base/utils/string.h"
 #include "autoexpandabledialog.h"
 #include "deletionconfirmationdialog.h"
@@ -198,6 +199,19 @@ namespace
             setDefaultWidget(new MenuCheckBox(text, onToggle, initialState));
         }
     };
+
+    bool torrentContainsPreviewableFiles(const BitTorrent::TorrentHandle *const torrent)
+    {
+        if (!torrent->hasMetadata())
+            return false;
+
+        for (int i = 0; i < torrent->filesCount(); ++i) {
+            if (Utils::Misc::isPreviewable(Utils::Fs::fileExtension(torrent->fileName(i))))
+                return true;
+        }
+
+        return false;
+    }
 }
 
 TransferListWidget::TransferListWidget(QWidget *parent, MainWindow *mainWindow)
@@ -589,8 +603,10 @@ void TransferListWidget::openSelectedTorrentsFolder() const
 void TransferListWidget::previewSelectedTorrents()
 {
     for (BitTorrent::TorrentHandle *const torrent : asConst(getSelectedTorrents())) {
-        if (torrent->hasMetadata())
+        if (torrentContainsPreviewableFiles(torrent))
             new PreviewSelectDialog(this, torrent);
+        else
+            QMessageBox::critical(this, tr("Unable to preview"), tr("The selected torrent does not contain previewable files"));
     }
 }
 

From dd2763d7258ee0a8cc088496dfa5107b8290b396 Mon Sep 17 00:00:00 2001
From: Chocobo1 <Chocobo1@users.noreply.github.com>
Date: Sat, 29 Dec 2018 18:22:15 +0800
Subject: [PATCH 2/2] Forward declare TorrentHandle

---
 src/gui/previewselectdialog.cpp | 1 +
 src/gui/previewselectdialog.h   | 5 ++++-
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/gui/previewselectdialog.cpp b/src/gui/previewselectdialog.cpp
index 730591c2d..07da7aec2 100644
--- a/src/gui/previewselectdialog.cpp
+++ b/src/gui/previewselectdialog.cpp
@@ -35,6 +35,7 @@
 #include <QStandardItemModel>
 #include <QTableView>
 
+#include "base/bittorrent/torrenthandle.h"
 #include "base/preferences.h"
 #include "base/utils/fs.h"
 #include "base/utils/misc.h"
diff --git a/src/gui/previewselectdialog.h b/src/gui/previewselectdialog.h
index 715643b8a..1b9e6bb47 100644
--- a/src/gui/previewselectdialog.h
+++ b/src/gui/previewselectdialog.h
@@ -31,12 +31,15 @@
 
 #include <QDialog>
 
-#include "base/bittorrent/torrenthandle.h"
 #include "base/settingvalue.h"
 #include "ui_previewselectdialog.h"
 
 class QStandardItemModel;
 
+namespace BitTorrent
+{
+    class TorrentHandle;
+}
 class PreviewListDelegate;
 
 class PreviewSelectDialog : public QDialog, private Ui::preview