From ae77a6e579252a894c82cccea98f390d1b17ea88 Mon Sep 17 00:00:00 2001
From: Ari Vuollet <ari.vuollet@kapsi.fi>
Date: Sun, 28 Jul 2024 17:49:12 +0300
Subject: [PATCH] Fallback to X11 message box implementation when SDL fails

---
 Source/Engine/Platform/Linux/LinuxPlatform.cpp |  9 +++++++--
 Source/Engine/Platform/MessageBox.h            |  5 +++++
 Source/Engine/Platform/SDL/SDLPlatform.cpp     | 10 +++++++++-
 3 files changed, 21 insertions(+), 3 deletions(-)

diff --git a/Source/Engine/Platform/Linux/LinuxPlatform.cpp b/Source/Engine/Platform/Linux/LinuxPlatform.cpp
index ccf5de3ff..0ba8c02f2 100644
--- a/Source/Engine/Platform/Linux/LinuxPlatform.cpp
+++ b/Source/Engine/Platform/Linux/LinuxPlatform.cpp
@@ -370,8 +370,6 @@ static int X11_MessageBoxInitPositions(MessageBoxData* data)
 	return 0;
 }
 
-#if !PLATFORM_SDL
-
 // Create and set up X11 dialog box window
 static int X11_MessageBoxCreateWindow(MessageBoxData* data)
 {
@@ -659,7 +657,11 @@ static int X11_MessageBoxLoop(MessageBoxData* data)
 	return 0;
 }
 
+#if !PLATFORM_SDL
 DialogResult MessageBox::Show(Window* parent, const StringView& text, const StringView& caption, MessageBoxButtons buttons, MessageBoxIcon icon)
+#else
+DialogResult MessageBox::ShowFallback(Window* parent, const StringView& text, const StringView& caption, MessageBoxButtons buttons, MessageBoxIcon icon)
+#endif
 {
     if (CommandLine::Options.Headless.IsTrue())
         return DialogResult::None;
@@ -846,6 +848,8 @@ DialogResult MessageBox::Show(Window* parent, const StringView& text, const Stri
 	return data.resultButtonIndex == -1 ? DialogResult::None : data.buttons[data.resultButtonIndex].result;
 }
 
+#if !PLATFORM_SDL
+
 int X11ErrorHandler(X11::Display* display, X11::XErrorEvent* event)
 {
     if (event->error_code == 5)
@@ -855,6 +859,7 @@ int X11ErrorHandler(X11::Display* display, X11::XErrorEvent* event)
 	LOG(Error, "X11 Error: {0}", String(buffer));
 	return 0;
 }
+
 #endif
 
 int32 CalculateDpi()
diff --git a/Source/Engine/Platform/MessageBox.h b/Source/Engine/Platform/MessageBox.h
index 16ae161cb..80c8e7938 100644
--- a/Source/Engine/Platform/MessageBox.h
+++ b/Source/Engine/Platform/MessageBox.h
@@ -237,4 +237,9 @@ DECLARE_SCRIPTING_TYPE_NO_SPAWN(MessageBox);
     /// <param name="icon">One of the MessageBoxIcon values that specifies which icon to display in the message box.</param>
     /// <returns>The message box dialog result.</returns>
     API_FUNCTION() static DialogResult Show(Window* parent, const StringView& text, const StringView& caption, MessageBoxButtons buttons, MessageBoxIcon icon);
+
+private:
+#if PLATFORM_SDL && PLATFORM_LINUX
+    static DialogResult ShowFallback(Window* parent, const StringView& text, const StringView& caption, MessageBoxButtons buttons, MessageBoxIcon icon);
+#endif
 };
diff --git a/Source/Engine/Platform/SDL/SDLPlatform.cpp b/Source/Engine/Platform/SDL/SDLPlatform.cpp
index 30d82962a..40dea2d07 100644
--- a/Source/Engine/Platform/SDL/SDLPlatform.cpp
+++ b/Source/Engine/Platform/SDL/SDLPlatform.cpp
@@ -475,7 +475,15 @@ DialogResult MessageBox::Show(Window* parent, const StringView& text, const Stri
     int result = -1;
     if (SDL_ShowMessageBox(&data, &result) != 0)
     {
-        LOG(Error, "Failed to show message box: {0}", String(SDL_GetError()));
+#if PLATFORM_LINUX
+        // Fallback to native messagebox implementation in case some system fonts are missing
+        if (SDLPlatform::UsesX11())
+        {
+            LOG(Warning, "Failed to show SDL message box: {0}", String(SDL_GetError()));
+            return ShowFallback(parent, text, caption, buttons, icon);
+        }
+#endif
+        LOG(Error, "Failed to show SDL message box: {0}", String(SDL_GetError()));
         return DialogResult::Abort;
     }
     if (result < 0)