fix issues with multi-window and OpenGL on Windows

src/frontend/qt_sdl/EmuInstance.cpp

@@ -408,6 +408,15 @@ void EmuInstance::makeCurrentGL()
     mainWindow->makeCurrentGL();
 }
 
+void EmuInstance::releaseGL()
+{
+    for (int i = 0; i < kMaxWindows; i++)
+    {
+        if (windowList[i])
+            windowList[i]->releaseGL();
+    }
+}
+
 void EmuInstance::drawScreenGL()
 {
     for (int i = 0; i < kMaxWindows; i++)

src/frontend/qt_sdl/EmuInstance.h

@@ -120,6 +120,7 @@ public:
     void deinitOpenGL(int win);
     void setVSyncGL(bool vsync);
     void makeCurrentGL();
+    void releaseGL();
     void drawScreenGL();
 
     // return: empty string = setup OK, non-empty = error message

src/frontend/qt_sdl/EmuThread.cpp

@@ -485,6 +485,8 @@ void EmuThread::waitAllMessages()
 
 void EmuThread::handleMessages()
 {
+    bool glborrow = false;
+
     msgMutex.lock();
     while (!msgQueue.empty())
     {
@@ -576,6 +578,11 @@ void EmuThread::handleMessages()
                 useOpenGL = false;
             break;
 
+        case msg_BorrowGL:
+            emuInstance->releaseGL();
+            glborrow = true;
+            break;
+
         case msg_BootROM:
             msgResult = 0;
             if (!emuInstance->loadROM(msg.param.value<QStringList>(), true, msgError))
@@ -667,6 +674,13 @@ void EmuThread::handleMessages()
         msgSemaphore.release();
     }
     msgMutex.unlock();
+
+    if (glborrow)
+    {
+        glBorrowMutex.lock();
+        glBorrowCond.wait(&glBorrowMutex);
+        glBorrowMutex.unlock();
+    }
 }
 
 void EmuThread::changeWindowTitle(char* title)
@@ -686,6 +700,19 @@ void EmuThread::deinitContext(int win)
     waitMessage();
 }
 
+void EmuThread::borrowGL()
+{
+    sendMessage(msg_BorrowGL);
+    waitMessage();
+}
+
+void EmuThread::returnGL()
+{
+    glBorrowMutex.lock();
+    glBorrowCond.wakeAll();
+    glBorrowMutex.unlock();
+}
+
 void EmuThread::emuRun()
 {
     sendMessage(msg_EmuRun);

src/frontend/qt_sdl/EmuThread.h

@@ -22,6 +22,7 @@
 #include <QThread>
 #include <QMutex>
 #include <QSemaphore>
+#include <QWaitCondition>
 #include <QQueue>
 #include <QVariant>
 
@@ -66,6 +67,7 @@ public:
 
         msg_InitGL,
         msg_DeInitGL,
+        msg_BorrowGL,
 
         msg_BootROM,
         msg_BootFirmware,
@@ -130,12 +132,17 @@ public:
 
     void initContext(int win);
     void deinitContext(int win);
+    void borrowGL();
+    void returnGL();
     void updateVideoSettings() { videoSettingsDirty = true; }
     void updateVideoRenderer() { videoSettingsDirty = true; lastVideoRenderer = -1; }
 
     int frontBuffer = 0;
     QMutex frontBufferLock;
 
+    QWaitCondition glBorrowCond;
+    QMutex glBorrowMutex;
+
 signals:
     void windowUpdate();
     void windowTitleChange(QString title);

src/frontend/qt_sdl/Screen.cpp

@@ -1055,6 +1055,13 @@ void ScreenPanelGL::makeCurrentGL()
     glContext->MakeCurrent();
 }
 
+void ScreenPanelGL::releaseGL()
+{
+    if (!glContext) return;
+
+    glContext->DoneCurrent();
+}
+
 void ScreenPanelGL::osdRenderItem(OSDItem* item)
 {
     ScreenPanel::osdRenderItem(item);

src/frontend/qt_sdl/Screen.h

@@ -189,6 +189,7 @@ public:
     void initOpenGL();
     void deinitOpenGL();
     void makeCurrentGL();
+    void releaseGL();
     void drawScreenGL();
 
     GL::Context* getContext() { return glContext.get(); }

src/frontend/qt_sdl/Window.cpp

@@ -864,7 +864,10 @@ void MainWindow::createScreenPanel()
         ScreenPanelGL* panelGL = new ScreenPanelGL(this);
         panelGL->show();
 
-        panel = panelGL;
+        // make sure no GL context is in use by the emu thread
+        // otherwise we may fail to create a shared context
+        if (windowID != 0)
+            emuThread->borrowGL();
 
         // Check that creating the context hasn't failed
         if (panelGL->createContext() == false)
@@ -874,7 +877,15 @@ void MainWindow::createScreenPanel()
 
             globalCfg.SetBool("Screen.UseGL", false);
             globalCfg.SetInt("3D.Renderer", renderer3D_Software);
+
+            delete panelGL;
+            panelGL = nullptr;
         }
+
+        if (windowID != 0)
+            emuThread->returnGL();
+
+        panel = panelGL;
     }
 
     if (!hasOGL)
@@ -924,6 +935,7 @@ void MainWindow::setGLSwapInterval(int intv)
     if (!hasOGL) return;
 
     ScreenPanelGL* glpanel = static_cast<ScreenPanelGL*>(panel);
+    if (!glpanel) return;
     return glpanel->setSwapInterval(intv);
 }
 
@@ -932,14 +944,25 @@ void MainWindow::makeCurrentGL()
     if (!hasOGL) return;
 
     ScreenPanelGL* glpanel = static_cast<ScreenPanelGL*>(panel);
+    if (!glpanel) return;
     return glpanel->makeCurrentGL();
 }
 
+void MainWindow::releaseGL()
+{
+    if (!hasOGL) return;
+
+    ScreenPanelGL* glpanel = static_cast<ScreenPanelGL*>(panel);
+    if (!glpanel) return;
+    return glpanel->releaseGL();
+}
+
 void MainWindow::drawScreenGL()
 {
     if (!hasOGL) return;
 
     ScreenPanelGL* glpanel = static_cast<ScreenPanelGL*>(panel);
+    if (!glpanel) return;
     return glpanel->drawScreenGL();
 }
 
@@ -2263,42 +2286,49 @@ void MainWindow::onUpdateVideoSettings(bool glchange)
     if (parentwin)
         return parentwin->onUpdateVideoSettings(glchange);
 
+    auto childwins = findChildren<MainWindow *>(nullptr, Qt::FindDirectChildrenOnly);
+
     bool hadOGL = hasOGL;
     if (glchange)
     {
         emuThread->emuPause();
-        if (hadOGL) emuThread->deinitContext(windowID);
+        if (hadOGL)
+        {
+            emuThread->deinitContext(windowID);
+            for (auto child: childwins)
+            {
+                auto thread = child->getEmuInstance()->getEmuThread();
+                thread->deinitContext(child->windowID);
+            }
+        }
 
         createScreenPanel();
+        for (auto child: childwins)
+        {
+            child->createScreenPanel();
+        }
     }
 
     emuThread->updateVideoSettings();
-
-    if (glchange)
-    {
-        if (hasOGL) emuThread->initContext(windowID);
-    }
-
-    // update any child windows we have
-    auto childwins = findChildren<MainWindow *>(nullptr, Qt::FindDirectChildrenOnly);
     for (auto child: childwins)
     {
         // child windows may belong to a different instance
         // in that case we need to signal their thread appropriately
         auto thread = child->getEmuInstance()->getEmuThread();
-
-        if (glchange)
-        {
-            if (hadOGL) thread->deinitContext(child->windowID);
-            child->createScreenPanel();
-        }
-
         if (child->getWindowID() == 0)
             thread->updateVideoSettings();
+    }
 
     if (glchange)
     {
-            if (hasOGL) thread->initContext(child->windowID);
+        if (hasOGL) 
+        {
+            emuThread->initContext(windowID);
+            for (auto child: childwins)
+            {
+                auto thread = child->getEmuInstance()->getEmuThread();
+                thread->initContext(child->windowID);
+            }
         }
     }
 

src/frontend/qt_sdl/Window.h

@@ -124,6 +124,7 @@ public:
     void deinitOpenGL();
     void setGLSwapInterval(int intv);
     void makeCurrentGL();
+    void releaseGL();
     void drawScreenGL();
 
     bool preloadROMs(QStringList file, QStringList gbafile, bool boot);