mirror of https://github.com/encounter/SDL.git
WinRT: workaround a possible Windows bug, whereby hiding cursors, disables mouse-moved events
This workaround, unfortunately, requires that apps directly link to a set of Win32-style cursor resource files (that contain a transparent cursor image). Copies of suitable resource files are in src/core/winrt/, and should be included directly in an app's MSVC project. A rough explanation of this workaround/hack, and why it's needed (and seemingly can't be done through programmatic means), is in this change's code.
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@ -159,7 +159,9 @@ following, at a high-level:
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the linker, and will copy SDL's .dll files to your app's final output.
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4. adjust your app's build settings, at minimum, telling it where to find SDL's
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header files.
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5. add a file that contains a WinRT-appropriate main function.
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5. add files that contains a WinRT-appropriate main function, along with some
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data to make sure mouse-cursor-hiding (via SDL_ShowCursor(SDL_DISABLE) calls)
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work properly.
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6. add SDL-specific app code.
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7. build and run your app.
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@ -267,33 +269,27 @@ To change these settings:
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10. close the dialog, saving settings, by clicking the "OK" button
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### 5. Add a WinRT-appropriate main function to the app. ###
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### 5. Add a WinRT-appropriate main function, and a blank-cursor image, to the app. ###
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C/C++-based WinRT apps do contain a `main` function that the OS will invoke when
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the app starts launching. The parameters of WinRT main functions are different
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than those found on other platforms, Win32 included. SDL/WinRT provides a
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platform-appropriate main function that will perform these actions, setup key
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portions of the app, then invoke a classic, C/C++-style main function (that take
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in "argc" and "argv" parameters). The code for this file is contained inside
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SDL's source distribution, under `src/main/winrt/SDL_winrt_main_NonXAML.cpp`.
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You'll need to add this file, or a copy of it, to your app's project, and make
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sure it gets compiled using a Microsoft-specific set of C++ extensions called
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C++/CX.
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A few files should be included directly in your app's MSVC project, specifically:
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1. a WinRT-appropriate main function (which is different than main() functions on
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other platforms)
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2. a Win32-style cursor resource, used by SDL_ShowCursor() to hide the mouse cursor
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(if and when the app needs to do so). *If this cursor resource is not
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included, mouse-position reporting may fail if and when the cursor is
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hidden, due to possible bugs/design-oddities in Windows itself.*
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**NOTE: C++/CX compilation is currently required in at least one file of your
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app's project. This is to make sure that Visual C++'s linker builds a 'Windows
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Metadata' file (.winmd) for your app. Not doing so can lead to build errors.**
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To include `SDL_winrt_main_NonXAML.cpp`:
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To include these files:
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1. right-click on your project (again, in Visual C++'s Solution Explorer),
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navigate to "Add", then choose "Existing Item...".
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2. open `SDL_winrt_main_NonXAML.cpp`, which is found inside SDL's source
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distribution, under `src/main/winrt/`. Make sure that the open-file dialog
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closes, either by double-clicking on the file, or single-clicking on it and
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then clicking Add.
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3. right-click on the file (as listed in your project), then click on
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"Properties...".
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2. navigate to the directory containing SDL's source code, then into its
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subdirectory, 'src/main/winrt/'. Select, then add, the following files:
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- `SDL_winrt_main_NonXAML.cpp`
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- `SDL2-WinRTResources.rc`
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- `SDL2-WinRTResource_BlankCursor.cur`
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3. right-click on the file `SDL_winrt_main_NonXAML.cpp` (as listed in your
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project), then click on "Properties...".
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4. in the drop-down box next to "Configuration", choose, "All Configurations"
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5. in the drop-down box next to "Platform", choose, "All Platforms"
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6. in the left-hand list, click on "C/C++"
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@ -301,6 +297,11 @@ To include `SDL_winrt_main_NonXAML.cpp`:
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8. click the OK button. This will close the dialog.
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**NOTE: C++/CX compilation is currently required in at least one file of your
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app's project. This is to make sure that Visual C++'s linker builds a 'Windows
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Metadata' file (.winmd) for your app. Not doing so can lead to build errors.**
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### 6. Add app code and assets ###
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At this point, you can add in SDL-specific source code. Be sure to include a
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@ -465,3 +466,13 @@ section.
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/nodefaultlib:vccorlibd /nodefaultlib:msvcrtd vccorlibd.lib msvcrtd.lib
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#### Mouse-motion events fail to get sent, or SDL_GetMouseState() fails to return updated values
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This may be caused by a bug in Windows itself, whereby hiding the mouse
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cursor can cause mouse-position reporting to fail.
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SDL provides a workaround for this, but it requires that an app links to a
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set of Win32-style cursor image-resource files. A copy of suitable resource
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files can be found in `src/main/winrt/`. Adding them to an app's Visual C++
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project file should be sufficient to get the app to use them.
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After Width: | Height: | Size: 326 B |
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#include "winres.h"
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LANGUAGE LANG_ENGLISH, SUBLANG_ENGLISH_US
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5000 CURSOR "SDL2-WinRTResource_BlankCursor.cur"
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@ -26,6 +26,7 @@
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* Windows includes:
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*/
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#include <Windows.h>
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#include <windows.ui.core.h>
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using namespace Windows::UI::Core;
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using Windows::UI::Core::CoreCursor;
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@ -116,11 +117,69 @@ WINRT_ShowCursor(SDL_Cursor * cursor)
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return 0;
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}
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CoreWindow ^ coreWindow = CoreWindow::GetForCurrentThread();
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if (cursor) {
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CoreCursor ^* theCursor = (CoreCursor ^*) cursor->driverdata;
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CoreWindow::GetForCurrentThread()->PointerCursor = *theCursor;
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coreWindow->PointerCursor = *theCursor;
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} else {
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CoreWindow::GetForCurrentThread()->PointerCursor = nullptr;
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// HACK ALERT: TL;DR - Hiding the cursor in WinRT/UWP apps is weird, and
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// a Win32-style cursor resource file must be directly included in apps,
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// otherwise hiding the cursor will cause mouse-motion data to never be
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// received.
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//
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// Here's the lengthy explanation:
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//
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// There are two ways to hide a cursor in WinRT/UWP apps.
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// Both involve setting the WinRT CoreWindow's (which is somewhat analogous
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// to a Win32 HWND) 'PointerCursor' property.
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//
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// The first way to hide a cursor sets PointerCursor to nullptr. This
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// is, arguably, the easiest to implement for an app. It does have an
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// unfortunate side-effect: it'll prevent mouse-motion events from being
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// sent to the app (via CoreWindow).
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//
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// The second way to hide a cursor sets PointerCursor to a transparent
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// cursor. This allows mouse-motion events to be sent to the app, but is
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// more difficult to set up, as:
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// 1. WinRT/UWP, while providing a few stock cursors, does not provide
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// a completely transparent cursor.
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// 2. WinRT/UWP allows apps to provide custom-built cursors, but *ONLY*
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// if they are linked directly inside the app, via Win32-style
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// cursor resource files. APIs to create cursors at runtime are
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// not provided to apps, and attempting to link-to or use Win32
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// cursor-creation APIs could cause an app to fail Windows Store
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// certification.
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//
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// SDL can use either means of hiding the cursor. It provides a Win32-style
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// set of cursor resource files in its source distribution, inside
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// src/main/winrt/. If those files are linked to an SDL-for-WinRT/UWP app
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// (by including them in a MSVC project, for example), SDL will attempt to
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// use those, if and when the cursor is hidden via SDL APIs. If those
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// files are not linked in, SDL will attempt to hide the cursor via the
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// 'set PointerCursor to nullptr' means (which, if you recall, causes
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// mouse-motion data to NOT be sent to the app!).
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//
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// Tech notes:
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// - SDL's blank cursor resource uses a resource ID of 5000.
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// - SDL's cursor resources consist of the following two files:
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// - src/main/winrt/SDL2-WinRTResource_BlankCursor.cur -- cursor pixel data
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// - src/main/winrt/SDL2-WinRTResources.rc -- declares the cursor resource, and its ID (of 5000)
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//
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const unsigned int win32CursorResourceID = 5000;
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CoreCursor ^ blankCursor = ref new CoreCursor(CoreCursorType::Custom, win32CursorResourceID);
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// Set 'PointerCursor' to 'blankCursor' in a way that shouldn't throw
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// an exception if the app hasn't loaded that resource.
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ABI::Windows::UI::Core::ICoreCursor * iblankCursor = reinterpret_cast<ABI::Windows::UI::Core::ICoreCursor *>(blankCursor);
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ABI::Windows::UI::Core::ICoreWindow * icoreWindow = reinterpret_cast<ABI::Windows::UI::Core::ICoreWindow *>(coreWindow);
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HRESULT hr = icoreWindow->put_PointerCursor(iblankCursor);
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if (FAILED(hr)) {
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// The app doesn't contain the cursor resource, or some other error
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// occurred. Just use the other, but mouse-motion-preventing, means of
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// hiding the cursor.
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coreWindow->PointerCursor = nullptr;
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}
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}
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return 0;
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}
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