ScopedMessageBox: Add new helper type to bound alert window lifetimes

The biggest new feature in this commit is the addition of
NativeMessageBox::scopedAsync and AlertWindow::scopedAsync, both of
which return an instance of ScopedMessageBox that will hide the message
box in its destructor.

The code for displaying modal dialogs on Windows has also been updated.
Now, the dialog itself is run from a new thread with its own message
loop. This means that when the dialog is dismissed, the background
thread can be joined safely. In plugins, this means that there's no
danger of the plugin view being destroyed from within the message box
runloop, for example.

Author: reuk

modules/juce_gui_basics/juce_gui_basics.cpp

@@ -254,7 +254,10 @@ namespace juce
 #include "widgets/juce_Toolbar.cpp"
 #include "widgets/juce_ToolbarItemPalette.cpp"
 #include "widgets/juce_TreeView.cpp"
+#include "windows/juce_MessageBoxOptions.cpp"
+#include "windows/juce_ScopedMessageBox.cpp"
 #include "windows/juce_AlertWindow.cpp"
+#include "windows/juce_NativeMessageBox.cpp"
 #include "windows/juce_CallOutBox.cpp"
 #include "windows/juce_ComponentPeer.cpp"
 #include "windows/juce_DialogWindow.cpp"
@@ -293,6 +296,7 @@ namespace juce
   #include "native/juce_ios_UIViewComponentPeer.mm"
   #include "native/accessibility/juce_ios_Accessibility.mm"
   #include "native/juce_ios_Windowing.mm"
+  #include "native/juce_ios_NativeMessageBox.mm"
   #include "native/juce_ios_FileChooser.mm"
 
   #if JUCE_CONTENT_SHARING
@@ -304,6 +308,7 @@ namespace juce
   #include "native/juce_mac_PerScreenDisplayLinks.h"
   #include "native/juce_mac_NSViewComponentPeer.mm"
   #include "native/juce_mac_Windowing.mm"
+  #include "native/juce_mac_NativeMessageBox.mm"
   #include "native/juce_mac_MainMenu.mm"
   #include "native/juce_mac_FileChooser.mm"
  #endif
@@ -319,6 +324,7 @@ namespace juce
  #include "native/accessibility/juce_win32_AccessibilityElement.cpp"
  #include "native/accessibility/juce_win32_Accessibility.cpp"
  #include "native/juce_win32_Windowing.cpp"
+ #include "native/juce_win32_NativeMessageBox.cpp"
  #include "native/juce_win32_DragAndDrop.cpp"
  #include "native/juce_win32_FileChooser.cpp"
 
@@ -330,6 +336,7 @@ namespace juce
 
  #include "native/x11/juce_linux_ScopedWindowAssociation.h"
  #include "native/juce_linux_Windowing.cpp"
+ #include "native/juce_linux_NativeMessageBox.cpp"
  #include "native/x11/juce_linux_XWindowSystem.cpp"
 
  JUCE_END_IGNORE_WARNINGS_GCC_LIKE
@@ -362,6 +369,7 @@ static jobject makeAndroidPoint (Point<int> p)
  #include "juce_core/files/juce_common_MimeTypes.h"
  #include "native/accessibility/juce_android_Accessibility.cpp"
  #include "native/juce_android_Windowing.cpp"
+ #include "native/juce_android_NativeMessageBox.cpp"
  #include "native/juce_android_FileChooser.cpp"
 
  #if JUCE_CONTENT_SHARING

modules/juce_gui_basics/juce_gui_basics.h

@@ -269,6 +269,7 @@ namespace juce
 #include "widgets/juce_TreeView.h"
 #include "windows/juce_TopLevelWindow.h"
 #include "windows/juce_MessageBoxOptions.h"
+#include "windows/juce_ScopedMessageBox.h"
 #include "windows/juce_AlertWindow.h"
 #include "windows/juce_CallOutBox.h"
 #include "windows/juce_ComponentPeer.h"

modules/juce_gui_basics/native/juce_android_NativeMessageBox.cpp

@@ -0,0 +1,115 @@
+/*
+  ==============================================================================
+
+   This file is part of the JUCE library.
+   Copyright (c) 2022 - Raw Material Software Limited
+
+   JUCE is an open source library subject to commercial or open-source
+   licensing.
+
+   By using JUCE, you agree to the terms of both the JUCE 7 End-User License
+   Agreement and JUCE Privacy Policy.
+
+   End User License Agreement: www.juce.com/juce-7-licence
+   Privacy Policy: www.juce.com/juce-privacy-policy
+
+   Or: You may also use this code under the terms of the GPL v3 (see
+   www.gnu.org/licenses).
+
+   JUCE IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL WARRANTIES, WHETHER
+   EXPRESSED OR IMPLIED, INCLUDING MERCHANTABILITY AND FITNESS FOR PURPOSE, ARE
+   DISCLAIMED.
+
+  ==============================================================================
+*/
+
+namespace juce
+{
+
+std::unique_ptr<ScopedMessageBoxInterface> ScopedMessageBoxInterface::create (const MessageBoxOptions& options)
+{
+    class AndroidMessageBox : public ScopedMessageBoxInterface
+    {
+    public:
+        explicit AndroidMessageBox (const MessageBoxOptions& o) : opts (o) {}
+
+        void runAsync (std::function<void (int)> recipient) override
+        {
+            const auto makeDialogListener = [&recipient] (int result)
+            {
+                return new DialogListener ([recipient, result] { recipient (result); });
+            };
+
+            auto* env = getEnv();
+
+            LocalRef<jobject> builder (env->NewObject (AndroidAlertDialogBuilder, AndroidAlertDialogBuilder.construct, getMainActivity().get()));
+
+            const auto setText = [&] (auto method, const String& text)
+            {
+                builder = LocalRef<jobject> (env->CallObjectMethod (builder, method, javaString (text).get()));
+            };
+
+            setText (AndroidAlertDialogBuilder.setTitle,   opts.getTitle());
+            setText (AndroidAlertDialogBuilder.setMessage, opts.getMessage());
+            builder = LocalRef<jobject> (env->CallObjectMethod (builder, AndroidAlertDialogBuilder.setCancelable, true));
+
+            builder = LocalRef<jobject> (env->CallObjectMethod (builder, AndroidAlertDialogBuilder.setOnCancelListener,
+                                                                CreateJavaInterface (makeDialogListener (0),
+                                                                                     "android/content/DialogInterface$OnCancelListener").get()));
+
+            const auto addButton = [&] (auto method, int index)
+            {
+                builder = LocalRef<jobject> (env->CallObjectMethod (builder,
+                                                                    method,
+                                                                    javaString (opts.getButtonText (index)).get(),
+                                                                    CreateJavaInterface (makeDialogListener (index),
+                                                                                         "android/content/DialogInterface$OnClickListener").get()));
+            };
+
+            addButton (AndroidAlertDialogBuilder.setPositiveButton, 0);
+
+            if (opts.getButtonText (1).isNotEmpty())
+                addButton (AndroidAlertDialogBuilder.setNegativeButton, 1);
+
+            if (opts.getButtonText (2).isNotEmpty())
+                addButton (AndroidAlertDialogBuilder.setNeutralButton, 2);
+
+            dialog = GlobalRef (LocalRef<jobject> (env->CallObjectMethod (builder, AndroidAlertDialogBuilder.create)));
+
+            LocalRef<jobject> window (env->CallObjectMethod (dialog, AndroidDialog.getWindow));
+
+            if (Desktop::getInstance().getKioskModeComponent() != nullptr)
+            {
+                env->CallVoidMethod (window, AndroidWindow.setFlags, FLAG_NOT_FOCUSABLE, FLAG_NOT_FOCUSABLE);
+                LocalRef<jobject> decorView (env->CallObjectMethod (window, AndroidWindow.getDecorView));
+                env->CallVoidMethod (decorView, AndroidView.setSystemUiVisibility, fullScreenFlags);
+            }
+
+            env->CallVoidMethod (dialog, AndroidDialog.show);
+
+            if (Desktop::getInstance().getKioskModeComponent() != nullptr)
+                env->CallVoidMethod (window, AndroidWindow.clearFlags, FLAG_NOT_FOCUSABLE);
+        }
+
+        int runSync() override
+        {
+            // Not implemented on this platform.
+            jassertfalse;
+            return 0;
+        }
+
+        void close() override
+        {
+            if (dialog != nullptr)
+                getEnv()->CallVoidMethod (dialog, AndroidDialogInterface.dismiss);
+        }
+
+    private:
+        const MessageBoxOptions opts;
+        GlobalRef dialog;
+    };
+
+    return std::make_unique<AndroidMessageBox> (options);
+}
+
+} // namespace juce

modules/juce_gui_basics/native/juce_android_Windowing.cpp

@@ -2349,164 +2349,31 @@ DECLARE_JNI_CLASS (AndroidDialogOnClickListener, "android/content/DialogInterfac
 class DialogListener  : public juce::AndroidInterfaceImplementer
 {
 public:
-    DialogListener (std::shared_ptr<ModalComponentManager::Callback> callbackToUse, int resultToUse)
-        : callback (std::move (callbackToUse)), result (resultToUse)
-    {}
+    explicit DialogListener (std::function<void()> cb) : callback (std::move (cb)) {}
 
-    void onResult (jobject dialog)
-    {
-        auto* env = getEnv();
-        env->CallVoidMethod (dialog, AndroidDialogInterface.dismiss);
-
-        if (callback != nullptr)
-            callback->modalStateFinished (result);
-
-        callback = nullptr;
-    }
-
-private:
     jobject invoke (jobject proxy, jobject method, jobjectArray args) override
     {
         auto* env = getEnv();
         auto methodName = juce::juceString ((jstring) env->CallObjectMethod (method, JavaMethod.getName));
 
         if (methodName == "onCancel" || methodName == "onClick")
         {
-            onResult (env->GetObjectArrayElement (args, 0));
+            auto* dialog = env->GetObjectArrayElement (args, 0);
+            env->CallVoidMethod (dialog, AndroidDialogInterface.dismiss);
+
+            NullCheckedInvocation::invoke (callback);
+
             return nullptr;
         }
 
         // invoke base class
         return AndroidInterfaceImplementer::invoke (proxy, method, args);
     }
 
-    std::shared_ptr<ModalComponentManager::Callback> callback;
-    int result;
+private:
+    std::function<void()> callback;
 };
 
-//==============================================================================
-static void createAndroidDialog (const MessageBoxOptions& opts,
-                                 ModalComponentManager::Callback* callbackIn,
-                                 AlertWindowMappings::MapFn mapFn)
-{
-    auto* env = getEnv();
-
-    LocalRef<jobject> builder (env->NewObject (AndroidAlertDialogBuilder, AndroidAlertDialogBuilder.construct, getMainActivity().get()));
-
-    builder = LocalRef<jobject> (env->CallObjectMethod (builder.get(), AndroidAlertDialogBuilder.setTitle,   javaString (opts.getTitle()).get()));
-    builder = LocalRef<jobject> (env->CallObjectMethod (builder.get(), AndroidAlertDialogBuilder.setMessage, javaString (opts.getMessage()).get()));
-    builder = LocalRef<jobject> (env->CallObjectMethod (builder.get(), AndroidAlertDialogBuilder.setCancelable, true));
-
-    std::shared_ptr<ModalComponentManager::Callback> sharedCallback (AlertWindowMappings::getWrappedCallback (callbackIn, mapFn));
-
-    builder = LocalRef<jobject> (env->CallObjectMethod (builder.get(), AndroidAlertDialogBuilder.setOnCancelListener,
-                                                        CreateJavaInterface (new DialogListener (sharedCallback, 0),
-                                                                             "android/content/DialogInterface$OnCancelListener").get()));
-
-    builder = LocalRef<jobject> (env->CallObjectMethod (builder.get(), AndroidAlertDialogBuilder.setPositiveButton,
-                                                        javaString (opts.getButtonText (0)).get(),
-                                                        CreateJavaInterface (new DialogListener (sharedCallback, 0),
-                                                                             "android/content/DialogInterface$OnClickListener").get()));
-
-    if (opts.getButtonText (1).isNotEmpty())
-        builder = LocalRef<jobject> (env->CallObjectMethod (builder.get(), AndroidAlertDialogBuilder.setNegativeButton,
-                                                            javaString (opts.getButtonText (1)).get(),
-                                                            CreateJavaInterface (new DialogListener (sharedCallback, 1),
-                                                                                 "android/content/DialogInterface$OnClickListener").get()));
-
-    if (opts.getButtonText (2).isNotEmpty())
-        builder = LocalRef<jobject> (env->CallObjectMethod (builder.get(), AndroidAlertDialogBuilder.setNeutralButton,
-                                                            javaString (opts.getButtonText (2)).get(),
-                                                            CreateJavaInterface (new DialogListener (sharedCallback, 2),
-                                                                                 "android/content/DialogInterface$OnClickListener").get()));
-
-    LocalRef<jobject> dialog (env->CallObjectMethod (builder.get(), AndroidAlertDialogBuilder.create));
-
-    LocalRef<jobject> window (env->CallObjectMethod (dialog.get(), AndroidDialog.getWindow));
-
-    if (Desktop::getInstance().getKioskModeComponent() != nullptr)
-    {
-        env->CallVoidMethod (window.get(), AndroidWindow.setFlags, FLAG_NOT_FOCUSABLE, FLAG_NOT_FOCUSABLE);
-        LocalRef<jobject> decorView (env->CallObjectMethod (window.get(), AndroidWindow.getDecorView));
-        env->CallVoidMethod (decorView.get(), AndroidView.setSystemUiVisibility, fullScreenFlags);
-    }
-
-    env->CallVoidMethod (dialog.get(), AndroidDialog.show);
-
-    if (Desktop::getInstance().getKioskModeComponent() != nullptr)
-        env->CallVoidMethod (window.get(), AndroidWindow.clearFlags, FLAG_NOT_FOCUSABLE);
-}
-
-void JUCE_CALLTYPE NativeMessageBox::showMessageBoxAsync (MessageBoxIconType /*iconType*/,
-                                                          const String& title, const String& message,
-                                                          Component* /*associatedComponent*/,
-                                                          ModalComponentManager::Callback* callback)
-{
-    createAndroidDialog (MessageBoxOptions()
-                           .withTitle (title)
-                           .withMessage (message)
-                           .withButton (TRANS("OK")),
-                         callback, AlertWindowMappings::messageBox);
-}
-
-bool JUCE_CALLTYPE NativeMessageBox::showOkCancelBox (MessageBoxIconType /*iconType*/,
-                                                      const String& title, const String& message,
-                                                      Component* /*associatedComponent*/,
-                                                      ModalComponentManager::Callback* callback)
-{
-    createAndroidDialog (MessageBoxOptions()
-                           .withTitle (title)
-                           .withMessage (message)
-                           .withButton (TRANS("OK"))
-                           .withButton (TRANS("Cancel")),
-                         callback, AlertWindowMappings::okCancel);
-
-    return false;
-}
-
-int JUCE_CALLTYPE NativeMessageBox::showYesNoCancelBox (MessageBoxIconType /*iconType*/,
-                                                        const String& title, const String& message,
-                                                        Component* /*associatedComponent*/,
-                                                        ModalComponentManager::Callback* callback)
-{
-    createAndroidDialog (MessageBoxOptions()
-                           .withTitle (title)
-                           .withMessage (message)
-                           .withButton (TRANS("Yes"))
-                           .withButton (TRANS("No"))
-                           .withButton (TRANS("Cancel")),
-                         callback, AlertWindowMappings::yesNoCancel);
-
-    return 0;
-}
-
-int JUCE_CALLTYPE NativeMessageBox::showYesNoBox (MessageBoxIconType /*iconType*/,
-                                                  const String& title, const String& message,
-                                                  Component* /*associatedComponent*/,
-                                                  ModalComponentManager::Callback* callback)
-{
-    createAndroidDialog (MessageBoxOptions()
-                           .withTitle (title)
-                           .withMessage (message)
-                           .withButton (TRANS("Yes"))
-                           .withButton (TRANS("No")),
-                         callback, AlertWindowMappings::okCancel);
-
-    return 0;
-}
-
-void JUCE_CALLTYPE NativeMessageBox::showAsync (const MessageBoxOptions& options,
-                                                ModalComponentManager::Callback* callback)
-{
-    createAndroidDialog (options, callback, AlertWindowMappings::noMapping);
-}
-
-void JUCE_CALLTYPE NativeMessageBox::showAsync (const MessageBoxOptions& options,
-                                                std::function<void (int)> callback)
-{
-    showAsync (options, ModalCallbackFunction::create (callback));
-}
-
 //==============================================================================
 static bool androidScreenSaverEnabled = true;