Add public APIs for creating a Metal view attached to an SDL window. Add SDL_metal.h.

include/SDL.h

@@ -47,6 +47,7 @@
 #include "SDL_loadso.h"
 #include "SDL_log.h"
 #include "SDL_messagebox.h"
+#include "SDL_metal.h"
 #include "SDL_mutex.h"
 #include "SDL_power.h"
 #include "SDL_render.h"

include/SDL_config.h.cmake

@@ -388,6 +388,9 @@
 /* Enable Vulkan support */
 #cmakedefine SDL_VIDEO_VULKAN @SDL_VIDEO_VULKAN@
 
+/* Enable Metal support */
+#cmakedefine SDL_VIDEO_METAL @SDL_VIDEO_METAL@
+
 /* Enable system power support */
 #cmakedefine SDL_POWER_ANDROID @SDL_POWER_ANDROID@
 #cmakedefine SDL_POWER_LINUX @SDL_POWER_LINUX@

include/SDL_config.h.in

@@ -383,6 +383,9 @@
 /* Enable Vulkan support */
 #undef SDL_VIDEO_VULKAN
 
+/* Enable Metal support */
+#undef SDL_VIDEO_METAL
+
 /* Enable system power support */
 #undef SDL_POWER_LINUX
 #undef SDL_POWER_WINDOWS

include/SDL_config_iphoneos.h

@@ -181,6 +181,10 @@
 #define SDL_VIDEO_VULKAN 1
 #endif
 
+#if SDL_PLATFORM_SUPPORTS_METAL
+#define SDL_VIDEO_METAL 1
+#endif
+
 /* Enable system power support */
 #define SDL_POWER_UIKIT 1
 

include/SDL_config_macosx.h

@@ -193,9 +193,15 @@
 #define SDL_VIDEO_RENDER_OGL_ES2 1
 #endif
 
-#ifndef SDL_VIDEO_RENDER_METAL
 /* Metal only supported on 64-bit architectures with 10.11+ */
 #if TARGET_CPU_X86_64 && (MAC_OS_X_VERSION_MAX_ALLOWED >= 101100)
+#define SDL_PLATFORM_SUPPORTS_METAL    1
+#else
+#define SDL_PLATFORM_SUPPORTS_METAL    0
+#endif
+
+#ifndef SDL_VIDEO_RENDER_METAL
+#if SDL_PLATFORM_SUPPORTS_METAL
 #define SDL_VIDEO_RENDER_METAL    1
 #else
 #define SDL_VIDEO_RENDER_METAL    0
@@ -219,13 +225,22 @@
 #define SDL_VIDEO_OPENGL_GLX    1
 #endif
 
-/* Enable Vulkan support */
-/* Metal/Vulkan Portability only supported on 64-bit architectures with 10.11+ */
-#if TARGET_CPU_X86_64 && (MAC_OS_X_VERSION_MAX_ALLOWED >= 101100)
+/* Enable Vulkan and Metal support */
+#ifndef SDL_VIDEO_VULKAN
+#if SDL_PLATFORM_SUPPORTS_METAL
 #define SDL_VIDEO_VULKAN 1
 #else
 #define SDL_VIDEO_VULKAN 0
 #endif
+#endif
+
+#ifndef SDL_VIDEO_METAL
+#if SDL_PLATFORM_SUPPORTS_METAL
+#define SDL_VIDEO_METAL 1
+#else
+#define SDL_VIDEO_METAL 0
+#endif
+#endif
 
 /* Enable system power support */
 #define SDL_POWER_MACOSX 1

include/SDL_metal.h

@@ -0,0 +1,91 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2019 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+
+/**
+ *  \file SDL_metal.h
+ *
+ *  Header file for functions to creating Metal layers and views on SDL windows.
+ */
+
+#ifndef SDL_metal_h_
+#define SDL_metal_h_
+
+#include "SDL_video.h"
+
+#include "begin_code.h"
+/* Set up for C function definitions, even when using C++ */
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ *  \brief A handle to a CAMetalLayer-backed NSView (macOS) or UIView (iOS/tvOS).
+ *
+ *  \note This can be cast directly to an NSView or UIView.
+ */
+typedef void *SDL_MetalView;
+
+/**
+ *  \name Metal support functions
+ */
+/* @{ */
+
+/**
+ *  \brief Create a CAMetalLayer-backed NSView/UIView and attach it to the
+ *        specified window.
+ *
+ *  On macOS, this does *not* associate a MTLDevice with the CAMetalLayer on its
+ *  own. It is up to user code to do that.
+ *
+ *  The returned handle can be casted directly to a NSView or UIView, and the
+ *  CAMetalLayer can be accessed from the view's 'layer' property.
+ *
+ *  \code
+ *  SDL_MetalView metalview = SDL_Metal_CreateView(window);
+ *  UIView *uiview = (__bridge UIView *)metalview;
+ *  CAMetalLayer *metallayer = (CAMetalLayer *)uiview.layer;
+ *  // [...]
+ *  SDL_Metal_DestroyView(metalview);
+ *  \endcode
+ *
+ *  \sa SDL_Metal_DestroyView
+ */
+extern DECLSPEC SDL_MetalView SDLCALL SDL_Metal_CreateView(SDL_Window * window);
+
+/**
+ *  \brief Destroy an existing SDL_MetalView object.
+ *
+ *  This should be called before SDL_DestroyWindow, if SDL_Metal_CreateView was
+ *  called after SDL_CreateWindow.
+ *
+ *  \sa SDL_Metal_CreateView
+ */
+extern DECLSPEC void SDLCALL SDL_Metal_DestroyView(SDL_MetalView view);
+
+/* @} *//* Metal support functions */
+
+/* Ends C function definitions when using C++ */
+#ifdef __cplusplus
+}
+#endif
+#include "close_code.h"
+
+#endif /* SDL_metal_h_ */