docs/README-winrt.md
author David Ludwig <dludwig@pobox.com>
Sun, 03 Sep 2017 16:36:22 -0400
changeset 11446 d1c34d85b47c
parent 10828 2160677a2f0f
child 11502 f778543ed8dd
permissions -rw-r--r--
WinRT: listed VS 2017 optional-component requirements
     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.
    79   * multi-touch input
    80   * app events.  SDL_APP_WILLENTER* and SDL_APP_DIDENTER* events get sent out as
    81     appropriate.
    82   * window events
    83   * using Direct3D 11.x APIs outside of SDL.  Non-XAML / Direct3D-only apps can
    84     choose to render content directly via Direct3D, using SDL to manage the
    85     internal WinRT window, as well as input and audio.  (Use
    86     SDL_GetWindowWMInfo() to get the WinRT 'CoreWindow', and pass it into
    87     IDXGIFactory2::CreateSwapChainForCoreWindow() as appropriate.)
    88 
    89 * What partially works:
    90   * keyboard input.  Most of WinRT's documented virtual keys are supported, as
    91     well as many keys with documented hardware scancodes.  Converting
    92     SDL_Scancodes to or from SDL_Keycodes may not work, due to missing APIs
    93     (MapVirtualKey()) in Microsoft's Windows Store / UWP APIs.
    94   * SDLmain.  WinRT uses a different signature for each app's main() function.
    95     SDL-based apps that use this port must compile in SDL_winrt_main_NonXAML.cpp
    96     (in `SDL\src\main\winrt\`) directly in order for their C-style main()
    97     functions to be called.
    98 
    99 * What doesn't work:
   100   * compilation with anything other than Visual C++
   101   * programmatically-created custom cursors.  These don't appear to be supported
   102     by WinRT.  Different OS-provided cursors can, however, be created via
   103     SDL_CreateSystemCursor() (unsupported on Windows Phone)
   104   * SDL_WarpMouseInWindow() or SDL_WarpMouseGlobal().  This are not currently
   105     supported by WinRT itself.
   106   * joysticks and game controllers that aren't supported by Microsoft's XInput
   107     API.
   108   * turning off VSync when rendering on Windows Phone.  Attempts to turn VSync
   109     off on Windows Phone result either in Direct3D not drawing anything, or it
   110     forcing VSync back on.  As such, SDL_RENDERER_PRESENTVSYNC will always get
   111     turned-on on Windows Phone.  This limitation is not present in non-Phone
   112     WinRT (such as Windows 8.x), where turning off VSync appears to work.
   113   * probably anything else that's not listed as supported
   114 
   115 
   116 
   117 Upgrade Notes
   118 -------------
   119 
   120 #### SDL_GetPrefPath() usage when upgrading WinRT apps from SDL 2.0.3
   121 
   122 SDL 2.0.4 fixes two bugs found in the WinRT version of SDL_GetPrefPath().
   123 The fixes may affect older, SDL 2.0.3-based apps' save data.  Please note
   124 that these changes only apply to SDL-based WinRT apps, and not to apps for
   125 any other platform.
   126 
   127 1. SDL_GetPrefPath() would return an invalid path, one in which the path's
   128    directory had not been created.  Attempts to create files there
   129    (via fopen(), for example), would fail, unless that directory was
   130    explicitly created beforehand.
   131 
   132 2. SDL_GetPrefPath(), for non-WinPhone-based apps, would return a path inside
   133    a WinRT 'Roaming' folder, the contents of which get automatically
   134    synchronized across multiple devices.  This process can occur while an
   135    application runs, and can cause existing save-data to be overwritten
   136    at unexpected times, with data from other devices.  (Windows Phone apps
   137    written with SDL 2.0.3 did not utilize a Roaming folder, due to API
   138    restrictions in Windows Phone 8.0).
   139 
   140 
   141 SDL_GetPrefPath(), starting with SDL 2.0.4, addresses these by:
   142 
   143 1. making sure that SDL_GetPrefPath() returns a directory in which data
   144    can be written to immediately, without first needing to create directories.
   145 
   146 2. basing SDL_GetPrefPath() off of a different, non-Roaming folder, the
   147    contents of which do not automatically get synchronized across devices
   148    (and which require less work to use safely, in terms of data integrity).
   149 
   150 Apps that wish to get their Roaming folder's path can do so either by using
   151 SDL_WinRTGetFSPathUTF8(), SDL_WinRTGetFSPathUNICODE() (which returns a
   152 UCS-2/wide-char string), or directly through the WinRT class,
   153 Windows.Storage.ApplicationData.
   154 
   155 
   156 
   157 Setup, High-Level Steps
   158 -----------------------
   159 
   160 The steps for setting up a project for an SDL/WinRT app looks like the
   161 following, at a high-level:
   162 
   163 1. create a new Visual C++ project using Microsoft's template for a,
   164    "Direct3D App".
   165 2. remove most of the files from the project.
   166 3. make your app's project directly reference SDL/WinRT's own Visual C++
   167    project file, via use of Visual C++'s "References" dialog.  This will setup
   168    the linker, and will copy SDL's .dll files to your app's final output.
   169 4. adjust your app's build settings, at minimum, telling it where to find SDL's
   170    header files.
   171 5. add files that contains a WinRT-appropriate main function, along with some
   172    data to make sure mouse-cursor-hiding (via SDL_ShowCursor(SDL_DISABLE) calls)
   173    work properly.
   174 6. add SDL-specific app code.
   175 7. build and run your app.
   176 
   177 
   178 Setup, Detailed Steps
   179 ---------------------
   180 
   181 ### 1. Create a new project ###
   182 
   183 Create a new project using one of Visual C++'s templates for a plain, non-XAML,
   184 "Direct3D App" (XAML support for SDL/WinRT is not yet ready for use).  If you
   185 don't see one of these templates, in Visual C++'s 'New Project' dialog, try
   186 using the textbox titled, 'Search Installed Templates' to look for one.
   187 
   188 
   189 ### 2. Remove unneeded files from the project ###
   190 
   191 In the new project, delete any file that has one of the following extensions:
   192 
   193 - .cpp
   194 - .h
   195 - .hlsl
   196 
   197 When you are done, you should be left with a few files, each of which will be a
   198 necessary part of your app's project.  These files will consist of:
   199 
   200 - an .appxmanifest file, which contains metadata on your WinRT app.  This is
   201   similar to an Info.plist file on iOS, or an AndroidManifest.xml on Android.
   202 - a few .png files, one of which is a splash screen (displayed when your app
   203   launches), others are app icons.
   204 - a .pfx file, used for code signing purposes.
   205 
   206 
   207 ### 3. Add references to SDL's project files ###
   208 
   209 SDL/WinRT can be built in multiple variations, spanning across three different
   210 CPU architectures (x86, x64, and ARM) and two different configurations
   211 (Debug and Release).  WinRT and Visual C++ do not currently provide a means
   212 for combining multiple variations of one library into a single file.
   213 Furthermore, it does not provide an easy means for copying pre-built .dll files
   214 into your app's final output (via Post-Build steps, for example).  It does,
   215 however, provide a system whereby an app can reference the MSVC projects of
   216 libraries such that, when the app is built:
   217 
   218 1. each library gets built for the appropriate CPU architecture(s) and WinRT
   219    platform(s).
   220 2. each library's output, such as .dll files, get copied to the app's build 
   221    output.
   222 
   223 To set this up for SDL/WinRT, you'll need to run through the following steps:
   224 
   225 1. open up the Solution Explorer inside Visual C++ (under the "View" menu, then
   226    "Solution Explorer")
   227 2. right click on your app's solution.
   228 3. navigate to "Add", then to "Existing Project..."
   229 4. find SDL/WinRT's Visual C++ project file and open it.  Different project
   230    files exist for different WinRT platforms.  All of them are in SDL's
   231    source distribution, in the following directories:
   232     * `VisualC-WinRT/UWP_VS2015/`        - for Windows 10 / UWP apps
   233     * `VisualC-WinRT/WinPhone81_VS2013/` - for Windows Phone 8.1 apps
   234     * `VisualC-WinRT/WinRT80_VS2012/`    - for Windows 8.0 apps
   235     * `VisualC-WinRT/WinRT81_VS2013/`    - for Windows 8.1 apps
   236 5. once the project has been added, right-click on your app's project and
   237    select, "References..."
   238 6. click on the button titled, "Add New Reference..."
   239 7. check the box next to SDL
   240 8. click OK to close the dialog
   241 9. SDL will now show up in the list of references.  Click OK to close that
   242    dialog.
   243 
   244 Your project is now linked to SDL's project, insofar that when the app is
   245 built, SDL will be built as well, with its build output getting included with
   246 your app.
   247 
   248 
   249 ### 4. Adjust Your App's Build Settings ###
   250 
   251 Some build settings need to be changed in your app's project.  This guide will
   252 outline the following:
   253 
   254 - making sure that the compiler knows where to find SDL's header files
   255 - **Optional for C++, but NECESSARY for compiling C code:** telling the
   256   compiler not to use Microsoft's C++ extensions for WinRT development.
   257 - **Optional:** telling the compiler not generate errors due to missing
   258   precompiled header files.
   259 
   260 To change these settings:
   261 
   262 1. right-click on the project
   263 2. choose "Properties"
   264 3. in the drop-down box next to "Configuration", choose, "All Configurations"
   265 4. in the drop-down box next to "Platform", choose, "All Platforms"
   266 5. in the left-hand list, expand the "C/C++" section
   267 6. select "General"
   268 7. edit the "Additional Include Directories" setting, and add a path to SDL's
   269    "include" directory
   270 8. **Optional: to enable compilation of C code:** change the setting for
   271    "Consume Windows Runtime Extension" from "Yes (/ZW)" to "No".  If you're 
   272    working with a completely C++ based project, this step can usually be 
   273    omitted.
   274 9. **Optional: to disable precompiled headers (which can produce 
   275    'stdafx.h'-related build errors, if setup incorrectly:** in the left-hand 
   276    list, select "Precompiled Headers", then change the setting for "Precompiled 
   277    Header" from "Use (/Yu)" to "Not Using Precompiled Headers".
   278 10. close the dialog, saving settings, by clicking the "OK" button
   279 
   280 
   281 ### 5. Add a WinRT-appropriate main function, and a blank-cursor image, to the app. ###
   282 
   283 A few files should be included directly in your app's MSVC project, specifically:
   284 1. a WinRT-appropriate main function (which is different than main() functions on
   285    other platforms)
   286 2. a Win32-style cursor resource, used by SDL_ShowCursor() to hide the mouse cursor
   287    (if and when the app needs to do so).  *If this cursor resource is not
   288    included, mouse-position reporting may fail if and when the cursor is
   289    hidden, due to possible bugs/design-oddities in Windows itself.*
   290 
   291 To include these files:
   292 
   293 1. right-click on your project (again, in Visual C++'s Solution Explorer), 
   294    navigate to "Add", then choose "Existing Item...".
   295 2. navigate to the directory containing SDL's source code, then into its
   296    subdirectory, 'src/main/winrt/'.  Select, then add, the following files:
   297    - `SDL_winrt_main_NonXAML.cpp`
   298    - `SDL2-WinRTResources.rc`
   299    - `SDL2-WinRTResource_BlankCursor.cur`
   300 3. right-click on the file `SDL_winrt_main_NonXAML.cpp` (as listed in your
   301    project), then click on "Properties...".
   302 4. in the drop-down box next to "Configuration", choose, "All Configurations"
   303 5. in the drop-down box next to "Platform", choose, "All Platforms"
   304 6. in the left-hand list, click on "C/C++"
   305 7. change the setting for "Consume Windows Runtime Extension" to "Yes (/ZW)".
   306 8. click the OK button.  This will close the dialog.
   307 
   308 
   309 **NOTE: C++/CX compilation is currently required in at least one file of your 
   310 app's project.  This is to make sure that Visual C++'s linker builds a 'Windows 
   311 Metadata' file (.winmd) for your app.  Not doing so can lead to build errors.**
   312 
   313 
   314 ### 6. Add app code and assets ###
   315 
   316 At this point, you can add in SDL-specific source code.  Be sure to include a 
   317 C-style main function (ie: `int main(int argc, char *argv[])`).  From there you 
   318 should be able to create a single `SDL_Window` (WinRT apps can only have one 
   319 window, at present), as well as an `SDL_Renderer`.  Direct3D will be used to 
   320 draw content.  Events are received via SDL's usual event functions 
   321 (`SDL_PollEvent`, etc.)  If you have a set of existing source files and assets, 
   322 you can start adding them to the project now.  If not, or if you would like to 
   323 make sure that you're setup correctly, some short and simple sample code is 
   324 provided below.
   325 
   326 
   327 #### 6.A. ... when creating a new app ####
   328 
   329 If you are creating a new app (rather than porting an existing SDL-based app), 
   330 or if you would just like a simple app to test SDL/WinRT with before trying to 
   331 get existing code working, some working SDL/WinRT code is provided below.  To 
   332 set this up:
   333 
   334 1. right click on your app's project
   335 2. select Add, then New Item.  An "Add New Item" dialog will show up.
   336 3. from the left-hand list, choose "Visual C++"
   337 4. from the middle/main list, choose "C++ File (.cpp)"
   338 5. near the bottom of the dialog, next to "Name:", type in a name for your 
   339 source file, such as, "main.cpp".
   340 6. click on the Add button.  This will close the dialog, add the new file to 
   341 your project, and open the file in Visual C++'s text editor.
   342 7. Copy and paste the following code into the new file, then save it.
   343 
   344 
   345     #include <SDL.h>
   346     
   347     int main(int argc, char **argv)
   348     {
   349         SDL_DisplayMode mode;
   350         SDL_Window * window = NULL;
   351         SDL_Renderer * renderer = NULL;
   352         SDL_Event evt;
   353     
   354         if (SDL_Init(SDL_INIT_VIDEO) != 0) {
   355             return 1;
   356         }
   357     
   358         if (SDL_GetCurrentDisplayMode(0, &mode) != 0) {
   359             return 1;
   360         }
   361     
   362         if (SDL_CreateWindowAndRenderer(mode.w, mode.h, SDL_WINDOW_FULLSCREEN, &window, &renderer) != 0) {
   363             return 1;
   364         }
   365     
   366         while (1) {
   367             while (SDL_PollEvent(&evt)) {
   368             }
   369     
   370             SDL_SetRenderDrawColor(renderer, 0, 255, 0, 255);
   371             SDL_RenderClear(renderer);
   372             SDL_RenderPresent(renderer);
   373         }
   374     }
   375 
   376 
   377 #### 6.B. Adding code and assets ####
   378 
   379 If you have existing code and assets that you'd like to add, you should be able 
   380 to add them now.  The process for adding a set of files is as such.
   381 
   382 1. right click on the app's project
   383 2. select Add, then click on "New Item..."
   384 3. open any source, header, or asset files as appropriate.  Support for C and 
   385 C++ is available.
   386 
   387 Do note that WinRT only supports a subset of the APIs that are available to 
   388 Win32-based apps.  Many portions of the Win32 API and the C runtime are not 
   389 available.
   390 
   391 A list of unsupported C APIs can be found at 
   392 <http://msdn.microsoft.com/en-us/library/windows/apps/jj606124.aspx>
   393 
   394 General information on using the C runtime in WinRT can be found at 
   395 <https://msdn.microsoft.com/en-us/library/hh972425.aspx>
   396 
   397 A list of supported Win32 APIs for WinRT apps can be found at 
   398 <http://msdn.microsoft.com/en-us/library/windows/apps/br205757.aspx>.  To note, 
   399 the list of supported Win32 APIs for Windows Phone 8.0 is different.  
   400 That list can be found at 
   401 <http://msdn.microsoft.com/en-us/library/windowsphone/develop/jj662956(v=vs.105).aspx>
   402 
   403 
   404 ### 7. Build and run your app ###
   405 
   406 Your app project should now be setup, and you should be ready to build your app.  
   407 To run it on the local machine, open the Debug menu and choose "Start 
   408 Debugging".  This will build your app, then run your app full-screen.  To switch 
   409 out of your app, press the Windows key.  Alternatively, you can choose to run 
   410 your app in a window.  To do this, before building and running your app, find 
   411 the drop-down menu in Visual C++'s toolbar that says, "Local Machine".  Expand 
   412 this by clicking on the arrow on the right side of the list, then click on 
   413 Simulator.  Once you do that, any time you build and run the app, the app will 
   414 launch in window, rather than full-screen.
   415 
   416 
   417 #### 7.A. Running apps on older, ARM-based, "Windows RT" devices ####
   418 
   419 **These instructions do not include Windows Phone, despite Windows Phone
   420 typically running on ARM processors.**  They are specifically for devices
   421 that use the "Windows RT" operating system, which was a modified version of
   422 Windows 8.x that ran primarily on ARM-based tablet computers.
   423 
   424 To build and run the app on ARM-based, "Windows RT" devices, you'll need to:
   425 
   426 - install Microsoft's "Remote Debugger" on the device.  Visual C++ installs and 
   427   debugs ARM-based apps via IP networks.
   428 - change a few options on the development machine, both to make sure it builds 
   429   for ARM (rather than x86 or x64), and to make sure it knows how to find the 
   430   Windows RT device (on the network).
   431 
   432 Microsoft's Remote Debugger can be found at 
   433 <https://msdn.microsoft.com/en-us/library/hh441469.aspx>.  Please note 
   434 that separate versions of this debugger exist for different versions of Visual 
   435 C++, one each for MSVC 2015, 2013, and 2012.
   436 
   437 To setup Visual C++ to launch your app on an ARM device:
   438 
   439 1. make sure the Remote Debugger is running on your ARM device, and that it's on 
   440    the same IP network as your development machine.
   441 2. from Visual C++'s toolbar, find a drop-down menu that says, "Win32".  Click 
   442    it, then change the value to "ARM".
   443 3. make sure Visual C++ knows the hostname or IP address of the ARM device.  To 
   444    do this:
   445     1. open the app project's properties
   446     2. select "Debugging"
   447     3. next to "Machine Name", enter the hostname or IP address of the ARM 
   448        device
   449     4. if, and only if, you've turned off authentication in the Remote Debugger,
   450        then change the setting for "Require Authentication" to No
   451     5. click "OK"
   452 4. build and run the app (from Visual C++).  The first time you do this, a 
   453    prompt will show up on the ARM device, asking for a Microsoft Account.  You 
   454    do, unfortunately, need to log in here, and will need to follow the 
   455    subsequent registration steps in order to launch the app.  After you do so, 
   456    if the app didn't already launch, try relaunching it again from within Visual 
   457    C++.
   458 
   459 
   460 Troubleshooting
   461 ---------------
   462 
   463 #### Build fails with message, "error LNK2038: mismatch detected for 'vccorlib_lib_should_be_specified_before_msvcrt_lib_to_linker'"
   464 
   465 Try adding the following to your linker flags.  In MSVC, this can be done by
   466 right-clicking on the app project, navigating to Configuration Properties ->
   467 Linker -> Command Line, then adding them to the Additional Options
   468 section.
   469 
   470 * For Release builds / MSVC-Configurations, add:
   471 
   472     /nodefaultlib:vccorlib /nodefaultlib:msvcrt vccorlib.lib msvcrt.lib
   473 
   474 * For Debug builds / MSVC-Configurations, add:
   475 
   476     /nodefaultlib:vccorlibd /nodefaultlib:msvcrtd vccorlibd.lib msvcrtd.lib
   477 
   478 
   479 #### Mouse-motion events fail to get sent, or SDL_GetMouseState() fails to return updated values
   480 
   481 This may be caused by a bug in Windows itself, whereby hiding the mouse
   482 cursor can cause mouse-position reporting to fail.
   483 
   484 SDL provides a workaround for this, but it requires that an app links to a
   485 set of Win32-style cursor image-resource files.  A copy of suitable resource
   486 files can be found in `src/main/winrt/`.  Adding them to an app's Visual C++
   487 project file should be sufficient to get the app to use them.
   488 
   489 
   490 #### SDL's Visual Studio project file fails to open, with message, "The system can't find the file specified."
   491 
   492 This can be caused for any one of a few reasons, which Visual Studio can
   493 report, but won't always do so in an up-front manner.
   494 
   495 To help determine why this error comes up:
   496 
   497 1. open a copy of Visual Studio without opening a project file.  This can be
   498    accomplished via Windows' Start Menu, among other means.
   499 2. show Visual Studio's Output window.  This can be done by going to VS'
   500    menu bar, then to View, and then to Output.
   501 3. try opening the SDL project file directly by going to VS' menu bar, then
   502    to File, then to Open, then to Project/Solution.  When a File-Open dialog
   503    appears, open the SDL project (such as the one in SDL's source code, in its
   504    directory, VisualC-WinRT/UWP_VS2015/).
   505 4. after attempting to open SDL's Visual Studio project file, additional error
   506    information will be output to the Output window.
   507 
   508 If Visual Studio reports (via its Output window) that the project:
   509 
   510 "could not be loaded because it's missing install components. To fix this launch Visual Studio setup with the following selections:
   511 Microsoft.VisualStudio.ComponentGroup.UWP.VC"
   512 
   513 ... then you will need to re-launch Visual Studio's installer, and make sure that
   514 the workflow for "Universal Windows Platform development" is checked, and that its
   515 optional component, "C++ Universal Windows Platform tools" is also checked.  While
   516 you are there, if you are planning on targeting UWP / Windows 10, also make sure
   517 that you check the optional component, "Windows 10 SDK (10.0.10240.0)".  After
   518 making sure these items are checked as-appropriate, install them.
   519 
   520 Once you install these components, try re-launching Visual Studio, and re-opening
   521 the SDL project file.  If you still get the error dialog, try using the Output
   522 window, again, seeing what Visual Studio says about it.