oops, GUI elements may only be updated from main thread

otherwise may lead to memory corruption; hopefully this also fixes a random segfault when calling QLabel::setText() in MainWindow::OnSeek()
derselbst · Jun 13, 2016 · 2dcccaa · 2dcccaa
1 parent b509139
commit 2dcccaa
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Showing 2 changed files with 31 additions and 21 deletions.
diff --git a/src/GUI/mainwindow.cpp b/src/GUI/mainwindow.cpp
@@ -18,16 +18,26 @@
 #include <utility>      // std::pair
 #include <cmath>
 
-void MainWindow::onSeek(void* ctx, frame_t pos)
+void MainWindow::callbackSeek(void* context, frame_t pos)
 {
-    MainWindow* context = static_cast<MainWindow*>(ctx);
+    MainWindow* ctx = static_cast<MainWindow*>(context);
+    QMetaObject::invokeMethod( ctx, "slotSeek", Qt::QueuedConnection, Q_ARG(long long, pos ) );
+}
+
+void MainWindow::callbackCurrentSongChanged(void * context)
+{
+    MainWindow* ctx = static_cast<MainWindow*>(context);
+    QMetaObject::invokeMethod( ctx, "slotCurrentSongChanged", Qt::QueuedConnection);
+}
 
-    QSlider* playheadSlider = context->ui->seekBar;
+void MainWindow::slotSeek(long long pos)
+{
+    QSlider* playheadSlider = this->ui->seekBar;
     bool oldState = playheadSlider->blockSignals(true);
     playheadSlider->setSliderPosition(pos);
     playheadSlider->blockSignals(oldState);
 
-    const Song* s = context->player->getCurrentSong();
+    const Song* s = this->player->getCurrentSong();
     if(s==nullptr)
     {
         return;
@@ -40,25 +50,24 @@ void MainWindow::onSeek(void* ctx, frame_t pos)
 	if((void*)temp.c_str() == (void*)strTimePast.constData())
 	puts("asdf");
 
-	context->ui->labelTimePast->setText(strTimePast);
+    this->ui->labelTimePast->setText(strTimePast);
     }
 
     {
 	temp = framesToTimeStr(s->getFrames()-pos, s->Format.SampleRate);
 	QString strTimeLeft = QString("-") + QString::fromStdString(temp);
-	context->ui->labelTimeLeft->setText(strTimeLeft);
+    this->ui->labelTimeLeft->setText(strTimeLeft);
     }
 }
 
-void MainWindow::onCurrentSongChanged(void* context)
+void MainWindow::slotCurrentSongChanged()
 {
-    MainWindow* ctx = static_cast<MainWindow*>(context);
-    QSlider* playheadSlider = ctx->ui->seekBar;
+    QSlider* playheadSlider = this->ui->seekBar;
 
-    const Song* s = ctx->player->getCurrentSong();
+    const Song* s = this->player->getCurrentSong();
     if(s==nullptr)
     {
-        ctx->setWindowTitle("ANMP");
+        this->setWindowTitle("ANMP");
 
         bool oldState = playheadSlider->blockSignals(true);
         playheadSlider->setSliderPosition(0);
@@ -71,11 +80,11 @@ void MainWindow::onCurrentSongChanged(void* context)
         QString interpret = QString::fromStdString(s->Metadata.Artist);
         if(title == "" || interpret == "")
         {
-            ctx->setWindowTitle(QString::fromStdString(s->Filename) + " :: ANMP");
+            this->setWindowTitle(QString::fromStdString(s->Filename) + " :: ANMP");
         }
         else
         {
-            ctx->setWindowTitle(interpret + " - " + title  + " :: ANMP");
+            this->setWindowTitle(interpret + " - " + title  + " :: ANMP");
         }
         playheadSlider->setMaximum(s->getFrames());
     }
@@ -91,8 +100,8 @@ MainWindow::MainWindow(QWidget *parent) :
     this->setWindowState(Qt::WindowMaximized);
 
     // set callbacks
-    this->player->onPlayheadChanged += make_pair(this, &MainWindow::onSeek);
-    this->player->onCurrentSongChanged += make_pair(this, &MainWindow::onCurrentSongChanged);
+    this->player->onPlayheadChanged += make_pair(this, &MainWindow::callbackSeek);
+    this->player->onCurrentSongChanged += make_pair(this, &MainWindow::callbackCurrentSongChanged);
 
     this->buildFileBrowser();
     this->buildPlaylistView();

diff --git a/src/GUI/mainwindow.h b/src/GUI/mainwindow.h
@@ -28,6 +28,9 @@ class MainWindow : public QMainWindow
     explicit MainWindow(QWidget *parent = 0);
     ~MainWindow();
 
+    static void callbackSeek(void*, frame_t pos);
+    static void callbackCurrentSongChanged(void*);
+
 protected:
     void resizeEvent(QResizeEvent* event) override;
     void closeEvent(QCloseEvent* e) override;
@@ -47,11 +50,6 @@ class MainWindow : public QMainWindow
     QFileSystemModel *drivesModel = new QFileSystemModel(this);
     QFileSystemModel *filesModel = new QFileSystemModel(this);
 
-
-    static void onSeek(void*, frame_t);
-    static void onCurrentSongChanged(void *);
-
-
     void buildPlaylistView();
     void buildFileBrowser();
     void createShortcuts();
@@ -61,7 +59,10 @@ class MainWindow : public QMainWindow
 
 private slots:
   friend class PlaylistModel;
-
+
+  void slotSeek(long long);
+  void slotCurrentSongChanged();
+
     void on_actionAdd_Songs_triggered();
     void on_actionPlay_triggered();
     void on_actionStop_triggered();