[FEATURE REQUEST] Add the ability to eject the current cartridge losing dldi capabilities.

[sergiotarxz]

I would want to be able to lose the dldi capabilities on hot to develop software that depends on the capability of extracting the flashcart, read a real cartridge and be able to recover the dldi capabilities later. Currently the feature of ejecting the cartridge exists, but toggling dldi requires restarting the emulator defeating this use case.

[sergiotarxz]

I got it working with this patch:

diff --git a/src/frontend/qt_sdl/EmuSettingsDialog.cpp b/src/frontend/qt_sdl/EmuSettingsDialog.cpp
index ca9c6716..2deaa562 100644
--- a/src/frontend/qt_sdl/EmuSettingsDialog.cpp
+++ b/src/frontend/qt_sdl/EmuSettingsDialog.cpp
@@ -37,6 +37,7 @@ EmuSettingsDialog* EmuSettingsDialog::currentDlg = nullptr;
 extern bool RunningSomething;

 bool EmuSettingsDialog::needsReset = false;
+bool EmuSettingsDialog::needsDLDIUpdate = false;

 inline void updateLastBIOSFolder(QString& filename)
 {
@@ -200,6 +201,7 @@ void EmuSettingsDialog::verifyFirmware()
 void EmuSettingsDialog::done(int r)
 {
     needsReset = false;
+    needsDLDIUpdate = false;

     if (r == QDialog::Accepted)
     {
@@ -283,12 +285,6 @@ void EmuSettingsDialog::done(int r)
             || dsiSDFolderSync != Config::DSiSDFolderSync
             || dsiSDFolderPath != Config::DSiSDFolderPath)
         {
-            if (RunningSomething
-                && QMessageBox::warning(this, "Reset necessary to apply changes",
-                    "The emulation will be reset for the changes to take place.",
-                    QMessageBox::Ok, QMessageBox::Cancel) != QMessageBox::Ok)
-                return;
-
             Config::ExternalBIOSEnable = externalBiosEnable;
             Config::BIOS9Path = bios9Path;
             Config::BIOS7Path = bios7Path;
@@ -334,7 +330,8 @@ void EmuSettingsDialog::done(int r)

             Config::Save();

-            needsReset = true;
+            needsReset = false;
+            needsDLDIUpdate = true;
         }
     }

diff --git a/src/frontend/qt_sdl/EmuSettingsDialog.h b/src/frontend/qt_sdl/EmuSettingsDialog.h
index b53d090b..c464d93e 100644
--- a/src/frontend/qt_sdl/EmuSettingsDialog.h
+++ b/src/frontend/qt_sdl/EmuSettingsDialog.h
@@ -51,6 +51,7 @@ public:
     }

     static bool needsReset;
+    static bool needsDLDIUpdate;

 private slots:
     void done(int r);
diff --git a/src/frontend/qt_sdl/EmuThread.cpp b/src/frontend/qt_sdl/EmuThread.cpp
index d16aead4..09488118 100644
--- a/src/frontend/qt_sdl/EmuThread.cpp
+++ b/src/frontend/qt_sdl/EmuThread.cpp
@@ -180,6 +180,19 @@ std::unique_ptr<NDS> EmuThread::CreateConsole(
     return std::make_unique<melonDS::NDS>(std::move(ndsargs));
 }

+void EmuThread::UpdateDLDI() {
+    std::unique_ptr<NDSCart::CartCommon> nextndscart;
+    nextndscart = NDS ? NDS->EjectCart() : nullptr;
+    if (auto* cartsd = dynamic_cast<NDSCart::CartSD*>(nextndscart.get()))
+    {
+        // LoadDLDISDCard will return nullopt if the SD card is disabled;
+        // SetSDCard will accept nullopt, which means no SD card
+        cartsd->SetSDCard(ROMManager::GetDLDISDCardArgs());
+    }
+    NDS->SetNDSCart(std::move(nextndscart));
+    NDS::Current = NDS.get();
+}
+
 bool EmuThread::UpdateConsole(UpdateConsoleNDSArgs&& ndsargs, UpdateConsoleGBAArgs&& gbaargs) noexcept
 {
     // Let's get the cart we want to use;
diff --git a/src/frontend/qt_sdl/EmuThread.h b/src/frontend/qt_sdl/EmuThread.h
index 4950ebbf..a07371ca 100644
--- a/src/frontend/qt_sdl/EmuThread.h
+++ b/src/frontend/qt_sdl/EmuThread.h
@@ -71,6 +71,7 @@ public:
     /// @return \c true if the console was updated.
     /// If this returns \c false, then the existing NDS console is not modified.
     bool UpdateConsole(UpdateConsoleNDSArgs&& ndsargs, UpdateConsoleGBAArgs&& gbaargs) noexcept;
+    void UpdateDLDI();
     std::unique_ptr<melonDS::NDS> NDS; // TODO: Proper encapsulation and synchronization
 signals:
     void windowUpdate();
diff --git a/src/frontend/qt_sdl/Window.cpp b/src/frontend/qt_sdl/Window.cpp
index 23ba784e..8c41bd75 100644
--- a/src/frontend/qt_sdl/Window.cpp
+++ b/src/frontend/qt_sdl/Window.cpp
@@ -1557,6 +1557,14 @@ void MainWindow::onPause(bool checked)
     }
 }

+void MainWindow::onDLDIUpdate()
+{
+    if (!RunningSomething) return;
+    emuThread->emuPause();
+    emuThread->UpdateDLDI();
+    emuThread->emuRun();
+}
+
 void MainWindow::onReset()
 {
     if (!RunningSomething) return;
@@ -1678,6 +1686,9 @@ void MainWindow::onEmuSettingsDialogFinished(int res)

     if (EmuSettingsDialog::needsReset)
         onReset();
+    if (EmuSettingsDialog::needsDLDIUpdate) {
+        onDLDIUpdate();
+    }

     actCurrentGBACart->setText("GBA slot: " + ROMManager::GBACartLabel());

diff --git a/src/frontend/qt_sdl/Window.h b/src/frontend/qt_sdl/Window.h
index bc207480..53419b83 100644
--- a/src/frontend/qt_sdl/Window.h
+++ b/src/frontend/qt_sdl/Window.h
@@ -150,6 +150,7 @@ private slots:

     void onPause(bool checked);
     void onReset();
+    void onDLDIUpdate();
     void onStop();
     void onFrameStep();
     void onOpenPowerManagement();

But it is not mergeable since it assumes every emu setting change is a dldi change.