docs/README-winrt.md
author David Ludwig <dludwig@pobox.com>
Tue, 19 Sep 2017 10:33:08 -0400
changeset 11503 084b3caa1bc8
parent 11502 f778543ed8dd
child 11720 9cbb45a5874f
permissions -rw-r--r--
WinRT: minor formatting tweak in README-winrt
     1 WinRT
     2 =====
     3 
     4 This port allows SDL applications to run on Microsoft's platforms that require
     5 use of "Windows Runtime", aka. "WinRT", APIs.  Microsoft may, in some cases,
     6 refer to them as either "Windows Store", or for Windows 10, "UWP" apps.
     7 
     8 Some of the operating systems that include WinRT, are:
     9 
    10 * Windows 10, via its Universal Windows Platform (UWP) APIs
    11 * Windows 8.x
    12 * Windows RT 8.x (aka. Windows 8.x for ARM processors)
    13 * Windows Phone 8.x
    14 
    15 
    16 Requirements
    17 ------------
    18 
    19 * Microsoft Visual C++ (aka Visual Studio), either 2017, 2015, 2013, or 2012
    20   - Free, "Community" or "Express" editions may be used, so long as they
    21     include  support for either "Windows Store" or "Windows Phone" apps.
    22     "Express" versions marked as supporting "Windows Desktop" development
    23     typically do not include support for creating WinRT apps, to note.
    24     (The "Community" editions of Visual C++ do, however, support both
    25     desktop/Win32 and WinRT development).
    26   - Visual Studio 2017 can be used, however it is recommented that you install
    27     the Visual C++ 2015 build tools.  These build tools can be installed
    28     using VS 2017's installer.  Be sure to also install the workload for
    29     "Universal Windows Platform development", its optional component, the
    30     "C++ Universal Windows Platform tools", and for UWP / Windows 10
    31     development, the "Windows 10 SDK (10.0.10240.0)".  Please note that
    32     targeting UWP / Windows 10 apps from development machine(s) running
    33     earlier versions of Windows, such as Windows 7, is not always supported
    34     by Visual Studio, and you may get error(s) when attempting to do so.
    35   - Visual C++ 2012 can only build apps that target versions 8.0 of Windows,
    36     or  Windows Phone.  8.0-targetted apps will run on devices running 8.1
    37     editions of Windows, however they will not be able to take advantage of
    38     8.1-specific features.
    39   - Visual C++ 2013 cannot create app projects that target Windows 8.0.
    40     Visual C++ 2013 Update 4, can create app projects for Windows Phone 8.0,
    41     Windows Phone 8.1, and Windows 8.1, but not Windows 8.0.  An optional
    42     Visual Studio add-in, "Tools for Maintaining Store apps for Windows 8",
    43     allows Visual C++ 2013 to load and build Windows 8.0 projects that were
    44     created with Visual C++ 2012, so long as Visual C++ 2012 is installed
    45     on the same machine.  More details on targeting different versions of
    46     Windows can found at the following web pages:
    47       - [Develop apps by using Visual Studio 2013](http://msdn.microsoft.com/en-us/library/windows/apps/br211384.aspx)
    48       - [To add the Tools for Maintaining Store apps for Windows 8](http://msdn.microsoft.com/en-us/library/windows/apps/dn263114.aspx#AddMaintenanceTools)
    49 * A valid Microsoft account - This requirement is not imposed by SDL, but
    50   rather by Microsoft's Visual C++ toolchain.  This is required to launch or 
    51   debug apps.
    52 
    53 
    54 Status
    55 ------
    56 
    57 Here is a rough list of what works, and what doens't:
    58 
    59 * What works:
    60   * compilation via Visual C++ 2012 through 2015
    61   * compile-time platform detection for SDL programs.  The C/C++ #define,
    62     `__WINRT__`, will be set to 1 (by SDL) when compiling for WinRT.
    63   * GPU-accelerated 2D rendering, via SDL_Renderer.
    64   * OpenGL ES 2, via the ANGLE library (included separately from SDL)
    65   * software rendering, via either SDL_Surface (optionally in conjunction with
    66     SDL_GetWindowSurface() and SDL_UpdateWindowSurface()) or via the
    67     SDL_Renderer APIs
    68   * threads
    69   * timers (via SDL_GetTicks(), SDL_AddTimer(), SDL_GetPerformanceCounter(),
    70     SDL_GetPerformanceFrequency(), etc.)
    71   * file I/O via SDL_RWops
    72   * mouse input  (unsupported on Windows Phone)
    73   * audio, via a modified version of SDL's XAudio2 backend
    74   * .DLL file loading.  Libraries *MUST* be packaged inside applications.  Loading
    75     anything outside of the app is not supported.
    76   * system path retrieval via SDL's filesystem APIs
    77   * game controllers.  Support is provided via the SDL_Joystick and
    78     SDL_GameController APIs, and is backed by Microsoft's XInput API.  Please
    79     note, however, that Windows limits game-controller support in UWP apps to,
    80     "Xbox compatible controllers" (many controllers that work in Win32 apps,
    81     do not work in UWP, due to restrictions in UWP itself.) 
    82   * multi-touch input
    83   * app events.  SDL_APP_WILLENTER* and SDL_APP_DIDENTER* events get sent out as
    84     appropriate.
    85   * window events
    86   * using Direct3D 11.x APIs outside of SDL.  Non-XAML / Direct3D-only apps can
    87     choose to render content directly via Direct3D, using SDL to manage the
    88     internal WinRT window, as well as input and audio.  (Use
    89     SDL_GetWindowWMInfo() to get the WinRT 'CoreWindow', and pass it into
    90     IDXGIFactory2::CreateSwapChainForCoreWindow() as appropriate.)
    91 
    92 * What partially works:
    93   * keyboard input.  Most of WinRT's documented virtual keys are supported, as
    94     well as many keys with documented hardware scancodes.  Converting
    95     SDL_Scancodes to or from SDL_Keycodes may not work, due to missing APIs
    96     (MapVirtualKey()) in Microsoft's Windows Store / UWP APIs.
    97   * SDLmain.  WinRT uses a different signature for each app's main() function.
    98     SDL-based apps that use this port must compile in SDL_winrt_main_NonXAML.cpp
    99     (in `SDL\src\main\winrt\`) directly in order for their C-style main()
   100     functions to be called.
   101 
   102 * What doesn't work:
   103   * compilation with anything other than Visual C++
   104   * programmatically-created custom cursors.  These don't appear to be supported
   105     by WinRT.  Different OS-provided cursors can, however, be created via
   106     SDL_CreateSystemCursor() (unsupported on Windows Phone)
   107   * SDL_WarpMouseInWindow() or SDL_WarpMouseGlobal().  This are not currently
   108     supported by WinRT itself.
   109   * joysticks and game controllers that either are not supported by
   110     Microsoft's XInput API, or are not supported within UWP apps (many
   111     controllers that work in Win32, do not work in UWP, due to restrictions in
   112     UWP itself).
   113   * turning off VSync when rendering on Windows Phone.  Attempts to turn VSync
   114     off on Windows Phone result either in Direct3D not drawing anything, or it
   115     forcing VSync back on.  As such, SDL_RENDERER_PRESENTVSYNC will always get
   116     turned-on on Windows Phone.  This limitation is not present in non-Phone
   117     WinRT (such as Windows 8.x), where turning off VSync appears to work.
   118   * probably anything else that's not listed as supported
   119 
   120 
   121 
   122 Upgrade Notes
   123 -------------
   124 
   125 #### SDL_GetPrefPath() usage when upgrading WinRT apps from SDL 2.0.3
   126 
   127 SDL 2.0.4 fixes two bugs found in the WinRT version of SDL_GetPrefPath().
   128 The fixes may affect older, SDL 2.0.3-based apps' save data.  Please note
   129 that these changes only apply to SDL-based WinRT apps, and not to apps for
   130 any other platform.
   131 
   132 1. SDL_GetPrefPath() would return an invalid path, one in which the path's
   133    directory had not been created.  Attempts to create files there
   134    (via fopen(), for example), would fail, unless that directory was
   135    explicitly created beforehand.
   136 
   137 2. SDL_GetPrefPath(), for non-WinPhone-based apps, would return a path inside
   138    a WinRT 'Roaming' folder, the contents of which get automatically
   139    synchronized across multiple devices.  This process can occur while an
   140    application runs, and can cause existing save-data to be overwritten
   141    at unexpected times, with data from other devices.  (Windows Phone apps
   142    written with SDL 2.0.3 did not utilize a Roaming folder, due to API
   143    restrictions in Windows Phone 8.0).
   144 
   145 
   146 SDL_GetPrefPath(), starting with SDL 2.0.4, addresses these by:
   147 
   148 1. making sure that SDL_GetPrefPath() returns a directory in which data
   149    can be written to immediately, without first needing to create directories.
   150 
   151 2. basing SDL_GetPrefPath() off of a different, non-Roaming folder, the
   152    contents of which do not automatically get synchronized across devices
   153    (and which require less work to use safely, in terms of data integrity).
   154 
   155 Apps that wish to get their Roaming folder's path can do so either by using
   156 SDL_WinRTGetFSPathUTF8(), SDL_WinRTGetFSPathUNICODE() (which returns a
   157 UCS-2/wide-char string), or directly through the WinRT class,
   158 Windows.Storage.ApplicationData.
   159 
   160 
   161 
   162 Setup, High-Level Steps
   163 -----------------------
   164 
   165 The steps for setting up a project for an SDL/WinRT app looks like the
   166 following, at a high-level:
   167 
   168 1. create a new Visual C++ project using Microsoft's template for a,
   169    "Direct3D App".
   170 2. remove most of the files from the project.
   171 3. make your app's project directly reference SDL/WinRT's own Visual C++
   172    project file, via use of Visual C++'s "References" dialog.  This will setup
   173    the linker, and will copy SDL's .dll files to your app's final output.
   174 4. adjust your app's build settings, at minimum, telling it where to find SDL's
   175    header files.
   176 5. add files that contains a WinRT-appropriate main function, along with some
   177    data to make sure mouse-cursor-hiding (via SDL_ShowCursor(SDL_DISABLE) calls)
   178    work properly.
   179 6. add SDL-specific app code.
   180 7. build and run your app.
   181 
   182 
   183 Setup, Detailed Steps
   184 ---------------------
   185 
   186 ### 1. Create a new project ###
   187 
   188 Create a new project using one of Visual C++'s templates for a plain, non-XAML,
   189 "Direct3D App" (XAML support for SDL/WinRT is not yet ready for use).  If you
   190 don't see one of these templates, in Visual C++'s 'New Project' dialog, try
   191 using the textbox titled, 'Search Installed Templates' to look for one.
   192 
   193 
   194 ### 2. Remove unneeded files from the project ###
   195 
   196 In the new project, delete any file that has one of the following extensions:
   197 
   198 - .cpp
   199 - .h
   200 - .hlsl
   201 
   202 When you are done, you should be left with a few files, each of which will be a
   203 necessary part of your app's project.  These files will consist of:
   204 
   205 - an .appxmanifest file, which contains metadata on your WinRT app.  This is
   206   similar to an Info.plist file on iOS, or an AndroidManifest.xml on Android.
   207 - a few .png files, one of which is a splash screen (displayed when your app
   208   launches), others are app icons.
   209 - a .pfx file, used for code signing purposes.
   210 
   211 
   212 ### 3. Add references to SDL's project files ###
   213 
   214 SDL/WinRT can be built in multiple variations, spanning across three different
   215 CPU architectures (x86, x64, and ARM) and two different configurations
   216 (Debug and Release).  WinRT and Visual C++ do not currently provide a means
   217 for combining multiple variations of one library into a single file.
   218 Furthermore, it does not provide an easy means for copying pre-built .dll files
   219 into your app's final output (via Post-Build steps, for example).  It does,
   220 however, provide a system whereby an app can reference the MSVC projects of
   221 libraries such that, when the app is built:
   222 
   223 1. each library gets built for the appropriate CPU architecture(s) and WinRT
   224    platform(s).
   225 2. each library's output, such as .dll files, get copied to the app's build 
   226    output.
   227 
   228 To set this up for SDL/WinRT, you'll need to run through the following steps:
   229 
   230 1. open up the Solution Explorer inside Visual C++ (under the "View" menu, then
   231    "Solution Explorer")
   232 2. right click on your app's solution.
   233 3. navigate to "Add", then to "Existing Project..."
   234 4. find SDL/WinRT's Visual C++ project file and open it.  Different project
   235    files exist for different WinRT platforms.  All of them are in SDL's
   236    source distribution, in the following directories:
   237     * `VisualC-WinRT/UWP_VS2015/`        - for Windows 10 / UWP apps
   238     * `VisualC-WinRT/WinPhone81_VS2013/` - for Windows Phone 8.1 apps
   239     * `VisualC-WinRT/WinRT80_VS2012/`    - for Windows 8.0 apps
   240     * `VisualC-WinRT/WinRT81_VS2013/`    - for Windows 8.1 apps
   241 5. once the project has been added, right-click on your app's project and
   242    select, "References..."
   243 6. click on the button titled, "Add New Reference..."
   244 7. check the box next to SDL
   245 8. click OK to close the dialog
   246 9. SDL will now show up in the list of references.  Click OK to close that
   247    dialog.
   248 
   249 Your project is now linked to SDL's project, insofar that when the app is
   250 built, SDL will be built as well, with its build output getting included with
   251 your app.
   252 
   253 
   254 ### 4. Adjust Your App's Build Settings ###
   255 
   256 Some build settings need to be changed in your app's project.  This guide will
   257 outline the following:
   258 
   259 - making sure that the compiler knows where to find SDL's header files
   260 - **Optional for C++, but NECESSARY for compiling C code:** telling the
   261   compiler not to use Microsoft's C++ extensions for WinRT development.
   262 - **Optional:** telling the compiler not generate errors due to missing
   263   precompiled header files.
   264 
   265 To change these settings:
   266 
   267 1. right-click on the project
   268 2. choose "Properties"
   269 3. in the drop-down box next to "Configuration", choose, "All Configurations"
   270 4. in the drop-down box next to "Platform", choose, "All Platforms"
   271 5. in the left-hand list, expand the "C/C++" section
   272 6. select "General"
   273 7. edit the "Additional Include Directories" setting, and add a path to SDL's
   274    "include" directory
   275 8. **Optional: to enable compilation of C code:** change the setting for
   276    "Consume Windows Runtime Extension" from "Yes (/ZW)" to "No".  If you're 
   277    working with a completely C++ based project, this step can usually be 
   278    omitted.
   279 9. **Optional: to disable precompiled headers (which can produce 
   280    'stdafx.h'-related build errors, if setup incorrectly:** in the left-hand 
   281    list, select "Precompiled Headers", then change the setting for "Precompiled 
   282    Header" from "Use (/Yu)" to "Not Using Precompiled Headers".
   283 10. close the dialog, saving settings, by clicking the "OK" button
   284 
   285 
   286 ### 5. Add a WinRT-appropriate main function, and a blank-cursor image, to the app. ###
   287 
   288 A few files should be included directly in your app's MSVC project, specifically:
   289 1. a WinRT-appropriate main function (which is different than main() functions on
   290    other platforms)
   291 2. a Win32-style cursor resource, used by SDL_ShowCursor() to hide the mouse cursor
   292    (if and when the app needs to do so).  *If this cursor resource is not
   293    included, mouse-position reporting may fail if and when the cursor is
   294    hidden, due to possible bugs/design-oddities in Windows itself.*
   295 
   296 To include these files:
   297 
   298 1. right-click on your project (again, in Visual C++'s Solution Explorer), 
   299    navigate to "Add", then choose "Existing Item...".
   300 2. navigate to the directory containing SDL's source code, then into its
   301    subdirectory, 'src/main/winrt/'.  Select, then add, the following files:
   302    - `SDL_winrt_main_NonXAML.cpp`
   303    - `SDL2-WinRTResources.rc`
   304    - `SDL2-WinRTResource_BlankCursor.cur`
   305 3. right-click on the file `SDL_winrt_main_NonXAML.cpp` (as listed in your
   306    project), then click on "Properties...".
   307 4. in the drop-down box next to "Configuration", choose, "All Configurations"
   308 5. in the drop-down box next to "Platform", choose, "All Platforms"
   309 6. in the left-hand list, click on "C/C++"
   310 7. change the setting for "Consume Windows Runtime Extension" to "Yes (/ZW)".
   311 8. click the OK button.  This will close the dialog.
   312 
   313 
   314 **NOTE: C++/CX compilation is currently required in at least one file of your 
   315 app's project.  This is to make sure that Visual C++'s linker builds a 'Windows 
   316 Metadata' file (.winmd) for your app.  Not doing so can lead to build errors.**
   317 
   318 
   319 ### 6. Add app code and assets ###
   320 
   321 At this point, you can add in SDL-specific source code.  Be sure to include a 
   322 C-style main function (ie: `int main(int argc, char *argv[])`).  From there you 
   323 should be able to create a single `SDL_Window` (WinRT apps can only have one 
   324 window, at present), as well as an `SDL_Renderer`.  Direct3D will be used to 
   325 draw content.  Events are received via SDL's usual event functions 
   326 (`SDL_PollEvent`, etc.)  If you have a set of existing source files and assets, 
   327 you can start adding them to the project now.  If not, or if you would like to 
   328 make sure that you're setup correctly, some short and simple sample code is 
   329 provided below.
   330 
   331 
   332 #### 6.A. ... when creating a new app ####
   333 
   334 If you are creating a new app (rather than porting an existing SDL-based app), 
   335 or if you would just like a simple app to test SDL/WinRT with before trying to 
   336 get existing code working, some working SDL/WinRT code is provided below.  To 
   337 set this up:
   338 
   339 1. right click on your app's project
   340 2. select Add, then New Item.  An "Add New Item" dialog will show up.
   341 3. from the left-hand list, choose "Visual C++"
   342 4. from the middle/main list, choose "C++ File (.cpp)"
   343 5. near the bottom of the dialog, next to "Name:", type in a name for your 
   344 source file, such as, "main.cpp".
   345 6. click on the Add button.  This will close the dialog, add the new file to 
   346 your project, and open the file in Visual C++'s text editor.
   347 7. Copy and paste the following code into the new file, then save it.
   348 
   349 
   350     #include <SDL.h>
   351     
   352     int main(int argc, char **argv)
   353     {
   354         SDL_DisplayMode mode;
   355         SDL_Window * window = NULL;
   356         SDL_Renderer * renderer = NULL;
   357         SDL_Event evt;
   358     
   359         if (SDL_Init(SDL_INIT_VIDEO) != 0) {
   360             return 1;
   361         }
   362     
   363         if (SDL_GetCurrentDisplayMode(0, &mode) != 0) {
   364             return 1;
   365         }
   366     
   367         if (SDL_CreateWindowAndRenderer(mode.w, mode.h, SDL_WINDOW_FULLSCREEN, &window, &renderer) != 0) {
   368             return 1;
   369         }
   370     
   371         while (1) {
   372             while (SDL_PollEvent(&evt)) {
   373             }
   374     
   375             SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255);
   376             SDL_RenderClear(renderer);
   377             SDL_RenderPresent(renderer);
   378         }
   379     }
   380 
   381 
   382 #### 6.B. Adding code and assets ####
   383 
   384 If you have existing code and assets that you'd like to add, you should be able 
   385 to add them now.  The process for adding a set of files is as such.
   386 
   387 1. right click on the app's project
   388 2. select Add, then click on "New Item..."
   389 3. open any source, header, or asset files as appropriate.  Support for C and 
   390 C++ is available.
   391 
   392 Do note that WinRT only supports a subset of the APIs that are available to 
   393 Win32-based apps.  Many portions of the Win32 API and the C runtime are not 
   394 available.
   395 
   396 A list of unsupported C APIs can be found at 
   397 <http://msdn.microsoft.com/en-us/library/windows/apps/jj606124.aspx>
   398 
   399 General information on using the C runtime in WinRT can be found at 
   400 <https://msdn.microsoft.com/en-us/library/hh972425.aspx>
   401 
   402 A list of supported Win32 APIs for WinRT apps can be found at 
   403 <http://msdn.microsoft.com/en-us/library/windows/apps/br205757.aspx>.  To note, 
   404 the list of supported Win32 APIs for Windows Phone 8.0 is different.  
   405 That list can be found at 
   406 <http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj662956(v=vs.105).aspx>
   407 
   408 
   409 ### 7. Build and run your app ###
   410 
   411 Your app project should now be setup, and you should be ready to build your app.  
   412 To run it on the local machine, open the Debug menu and choose "Start 
   413 Debugging".  This will build your app, then run your app full-screen.  To switch 
   414 out of your app, press the Windows key.  Alternatively, you can choose to run 
   415 your app in a window.  To do this, before building and running your app, find 
   416 the drop-down menu in Visual C++'s toolbar that says, "Local Machine".  Expand 
   417 this by clicking on the arrow on the right side of the list, then click on 
   418 Simulator.  Once you do that, any time you build and run the app, the app will 
   419 launch in window, rather than full-screen.
   420 
   421 
   422 #### 7.A. Running apps on older, ARM-based, "Windows RT" devices ####
   423 
   424 **These instructions do not include Windows Phone, despite Windows Phone
   425 typically running on ARM processors.**  They are specifically for devices
   426 that use the "Windows RT" operating system, which was a modified version of
   427 Windows 8.x that ran primarily on ARM-based tablet computers.
   428 
   429 To build and run the app on ARM-based, "Windows RT" devices, you'll need to:
   430 
   431 - install Microsoft's "Remote Debugger" on the device.  Visual C++ installs and 
   432   debugs ARM-based apps via IP networks.
   433 - change a few options on the development machine, both to make sure it builds 
   434   for ARM (rather than x86 or x64), and to make sure it knows how to find the 
   435   Windows RT device (on the network).
   436 
   437 Microsoft's Remote Debugger can be found at 
   438 <https://msdn.microsoft.com/en-us/library/hh441469.aspx>.  Please note 
   439 that separate versions of this debugger exist for different versions of Visual 
   440 C++, one each for MSVC 2015, 2013, and 2012.
   441 
   442 To setup Visual C++ to launch your app on an ARM device:
   443 
   444 1. make sure the Remote Debugger is running on your ARM device, and that it's on 
   445    the same IP network as your development machine.
   446 2. from Visual C++'s toolbar, find a drop-down menu that says, "Win32".  Click 
   447    it, then change the value to "ARM".
   448 3. make sure Visual C++ knows the hostname or IP address of the ARM device.  To 
   449    do this:
   450     1. open the app project's properties
   451     2. select "Debugging"
   452     3. next to "Machine Name", enter the hostname or IP address of the ARM 
   453        device
   454     4. if, and only if, you've turned off authentication in the Remote Debugger,
   455        then change the setting for "Require Authentication" to No
   456     5. click "OK"
   457 4. build and run the app (from Visual C++).  The first time you do this, a 
   458    prompt will show up on the ARM device, asking for a Microsoft Account.  You 
   459    do, unfortunately, need to log in here, and will need to follow the 
   460    subsequent registration steps in order to launch the app.  After you do so, 
   461    if the app didn't already launch, try relaunching it again from within Visual 
   462    C++.
   463 
   464 
   465 Troubleshooting
   466 ---------------
   467 
   468 #### Build fails with message, "error LNK2038: mismatch detected for 'vccorlib_lib_should_be_specified_before_msvcrt_lib_to_linker'"
   469 
   470 Try adding the following to your linker flags.  In MSVC, this can be done by
   471 right-clicking on the app project, navigating to Configuration Properties ->
   472 Linker -> Command Line, then adding them to the Additional Options
   473 section.
   474 
   475 * For Release builds / MSVC-Configurations, add:
   476 
   477     /nodefaultlib:vccorlib /nodefaultlib:msvcrt vccorlib.lib msvcrt.lib
   478 
   479 * For Debug builds / MSVC-Configurations, add:
   480 
   481     /nodefaultlib:vccorlibd /nodefaultlib:msvcrtd vccorlibd.lib msvcrtd.lib
   482 
   483 
   484 #### Mouse-motion events fail to get sent, or SDL_GetMouseState() fails to return updated values
   485 
   486 This may be caused by a bug in Windows itself, whereby hiding the mouse
   487 cursor can cause mouse-position reporting to fail.
   488 
   489 SDL provides a workaround for this, but it requires that an app links to a
   490 set of Win32-style cursor image-resource files.  A copy of suitable resource
   491 files can be found in `src/main/winrt/`.  Adding them to an app's Visual C++
   492 project file should be sufficient to get the app to use them.
   493 
   494 
   495 #### SDL's Visual Studio project file fails to open, with message, "The system can't find the file specified."
   496 
   497 This can be caused for any one of a few reasons, which Visual Studio can
   498 report, but won't always do so in an up-front manner.
   499 
   500 To help determine why this error comes up:
   501 
   502 1. open a copy of Visual Studio without opening a project file.  This can be
   503    accomplished via Windows' Start Menu, among other means.
   504 2. show Visual Studio's Output window.  This can be done by going to VS'
   505    menu bar, then to View, and then to Output.
   506 3. try opening the SDL project file directly by going to VS' menu bar, then
   507    to File, then to Open, then to Project/Solution.  When a File-Open dialog
   508    appears, open the SDL project (such as the one in SDL's source code, in its
   509    directory, VisualC-WinRT/UWP_VS2015/).
   510 4. after attempting to open SDL's Visual Studio project file, additional error
   511    information will be output to the Output window.
   512 
   513 If Visual Studio reports (via its Output window) that the project:
   514 
   515 "could not be loaded because it's missing install components. To fix this launch Visual Studio setup with the following selections:
   516 Microsoft.VisualStudio.ComponentGroup.UWP.VC"
   517 
   518 ... then you will need to re-launch Visual Studio's installer, and make sure that
   519 the workflow for "Universal Windows Platform development" is checked, and that its
   520 optional component, "C++ Universal Windows Platform tools" is also checked.  While
   521 you are there, if you are planning on targeting UWP / Windows 10, also make sure
   522 that you check the optional component, "Windows 10 SDK (10.0.10240.0)".  After
   523 making sure these items are checked as-appropriate, install them.
   524 
   525 Once you install these components, try re-launching Visual Studio, and re-opening
   526 the SDL project file.  If you still get the error dialog, try using the Output
   527 window, again, seeing what Visual Studio says about it.
   528 
   529 
   530 #### Game controllers / joysticks aren't working!
   531 
   532 Windows only permits certain game controllers and joysticks to work within
   533 WinRT / UWP apps.  Even if a game controller or joystick works in a Win32
   534 app, that device is not guaranteed to work inside a WinRT / UWP app.
   535 
   536 According to Microsoft, "Xbox compatible controllers" should work inside
   537 UWP apps, potentially with more working in the future.  This includes, but
   538 may not be limited to, Microsoft-made Xbox controllers and USB adapters.
   539 (Source: https://social.msdn.microsoft.com/Forums/en-US/9064838b-e8c3-4c18-8a83-19bf0dfe150d/xinput-fails-to-detect-game-controllers?forum=wpdevelop)
   540 
   541