Create XCB Connection mechanism for WSISurface implementation for Linux (#2400)

- Add new Linux Trait to determine which display driver client API to use (only xcb supported for now)
- Add support for xcb connections (initial) for Linux/Vulkan
- Fix minor assertion caused by wrong use of sizeof
- Fix casing issue in a couple of material files (Linux is case sensitive)

Code/Framework/AzFramework/Platform/Linux/AzFramework/API/ApplicationAPI_Linux.h

@@ -9,8 +9,13 @@
 
 #pragma once
 
+#include <AzCore/Interface/Interface.h>
 #include <AzCore/EBus/EBus.h>
 
+#if PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB
+#include <xcb/xcb.h>
+#endif // LY_COMPILE_DEFINITIONS
+
 namespace AzFramework
 {
     class LinuxLifecycleEvents
@@ -25,4 +30,31 @@ namespace AzFramework
 
         using Bus = AZ::EBus<LinuxLifecycleEvents>;
     };
+
+#if PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB
+    class LinuxXcbConnectionManager
+    {
+    public:
+        AZ_RTTI(LinuxXcbConnectionManager, "{649951316-3626-4C9D-9DCA-2E7ABF84C0A9}");
+
+        virtual ~LinuxXcbConnectionManager() = default;
+
+        virtual xcb_connection_t* GetXcbConnection() const = 0;
+    };
+
+    class LinuxXcbConnectionManagerBusTraits
+        : public AZ::EBusTraits
+    {
+        public:
+            //////////////////////////////////////////////////////////////////////////
+            // EBusTraits overrides
+            static constexpr AZ::EBusHandlerPolicy HandlerPolicy = AZ::EBusHandlerPolicy::Single;
+            static constexpr AZ::EBusAddressPolicy AddressPolicy = AZ::EBusAddressPolicy::Single;
+            //////////////////////////////////////////////////////////////////////////
+    };
+
+    using LinuxXcbConnectionManagerBus = AZ::EBus<LinuxXcbConnectionManager, LinuxXcbConnectionManagerBusTraits>;
+    using LinuxXcbConnectionManagerInterface = AZ::Interface<LinuxXcbConnectionManager>;
+
+#endif // PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB
 } // namespace AzFramework

Code/Framework/AzFramework/Platform/Linux/AzFramework/Application/Application_Linux.cpp

@@ -12,6 +12,32 @@
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 namespace AzFramework
 {
+#if PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB
+    class LinuxXcbConnectionManagerImpl
+        : public LinuxXcbConnectionManagerBus::Handler
+    {
+    public:
+        LinuxXcbConnectionManagerImpl()
+        {
+            m_xcbConnection = xcb_connect(nullptr, nullptr);
+            AZ_Error("ApplicationLinux", m_xcbConnection != nullptr, "Unable to connect to X11 Server.");
+            LinuxXcbConnectionManagerBus::Handler::BusConnect();
+        }
+
+        ~LinuxXcbConnectionManagerImpl()
+        {
+            LinuxXcbConnectionManagerBus::Handler::BusDisconnect();
+            xcb_disconnect(m_xcbConnection);   
+        }
+        xcb_connection_t* GetXcbConnection() const override
+        {
+            return m_xcbConnection;
+        }
+    private:
+        xcb_connection_t*   m_xcbConnection = nullptr;
+    };
+#endif // PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB
+
     ////////////////////////////////////////////////////////////////////////////////////////////////
     class ApplicationLinux
         : public Application::Implementation
@@ -27,6 +53,12 @@ namespace AzFramework
         // Application::Implementation
         void PumpSystemEventLoopOnce() override;
         void PumpSystemEventLoopUntilEmpty() override;
+    private:
+
+#if PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB
+        AZStd::unique_ptr<LinuxXcbConnectionManager>    m_xcbConnectionManager;
+#endif // PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB
+
     };
 
     ////////////////////////////////////////////////////////////////////////////////////////////////
@@ -39,11 +71,26 @@ namespace AzFramework
     ApplicationLinux::ApplicationLinux()
     {
         LinuxLifecycleEvents::Bus::Handler::BusConnect();
+
+#if PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB
+        m_xcbConnectionManager = AZStd::make_unique<LinuxXcbConnectionManagerImpl>();
+        if (LinuxXcbConnectionManagerInterface::Get() == nullptr)
+        {
+            LinuxXcbConnectionManagerInterface::Register(m_xcbConnectionManager.get());
+        }
+#endif // PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB
     }
 
     ////////////////////////////////////////////////////////////////////////////////////////////////
     ApplicationLinux::~ApplicationLinux()
     {
+#if PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB
+        if (LinuxXcbConnectionManagerInterface::Get() == m_xcbConnectionManager.get())
+        {
+            LinuxXcbConnectionManagerInterface::Unregister(m_xcbConnectionManager.get());
+        }
+        m_xcbConnectionManager.reset();
+#endif // PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB        
         LinuxLifecycleEvents::Bus::Handler::BusDisconnect();
     }
 

Code/Framework/AzFramework/Platform/Linux/platform_linux.cmake

@@ -5,3 +5,30 @@
 # SPDX-License-Identifier: Apache-2.0 OR MIT
 #
 #
+
+# Based on the linux window manager trait, perform the appropriate additional build configurations
+# Only 'xcb', 'wayland', and 'xlib' are recognized
+if (${PAL_TRAIT_LINUX_WINDOW_MANAGER} STREQUAL "xcb")
+
+    find_library(XCB_LIBRARY xcb)
+
+    set(LY_BUILD_DEPENDENCIES
+        PRIVATE
+            ${XCB_LIBRARY}
+    )
+
+    set(LY_COMPILE_DEFINITIONS PUBLIC PAL_TRAIT_LINUX_WINDOW_MANAGER_XCB)
+
+elseif(PAL_TRAIT_LINUX_WINDOW_MANAGER STREQUAL "wayland")
+
+    set(LY_COMPILE_DEFINITIONS PUBLIC PAL_TRAIT_LINUX_WINDOW_MANAGER_WAYLAND)
+
+elseif(PAL_TRAIT_LINUX_WINDOW_MANAGER STREQUAL "xlib")
+
+    set(LY_COMPILE_DEFINITIONS PUBLIC PAL_TRAIT_LINUX_WINDOW_MANAGER_XLIB)
+
+else()
+
+    message(FATAL_ERROR, "Linux Window Manager ${PAL_TRAIT_LINUX_WINDOW_MANAGER} is not recognized")
+
+endif()