CODEWITHSUNDEEP
cvisual-studiowinapiwindows-runtime
Andrew
Andrew

Reputation: 849

Using WinRT from C?

Watching the //BUILD stuff, I saw that WinRT API's can be consumed by C code:

enter image description here

I am rather excited about a fresh C API available to Win32 developers.

Where can I find information on the C WinRT API? How is it better than the existing Win32 C API?

Upvotes: 52

Views: 13870

Answers (2)

DJm00n
DJm00n

Reputation: 1411

Wine have test code that can be used as example how to call WinRT from a C:

#define COBJMACROS
#include "initguid.h"
#include <stdarg.h>

#include "windef.h"
#include "winbase.h"
#include "winstring.h"

#include "roapi.h"

#define WIDL_using_Windows_Foundation
#define WIDL_using_Windows_Foundation_Collections
#include "windows.foundation.h"
#define WIDL_using_Windows_Devices_Bluetooth
#include "windows.devices.bluetooth.h"

#include "wine/test.h"

#define check_interface( obj, iid ) check_interface_( __LINE__, obj, iid )
static void check_interface_( unsigned int line, void *obj, const IID *iid )
{
    IUnknown *iface = obj;
    IUnknown *unk;
    HRESULT hr;

    hr = IUnknown_QueryInterface( iface, iid, (void **)&unk );
    ok_(__FILE__, line)( hr == S_OK, "got hr %#lx.\n", hr );
    IUnknown_Release( unk );
}

static void test_BluetoothAdapterStatics(void)
{
    static const WCHAR *default_res = L"System.Devices.InterfaceClassGuid:=\"{92383B0E-F90E-4AC9-8D44-8C2D0D0EBDA2}\" "
                                      L"AND System.Devices.InterfaceEnabled:=System.StructuredQueryType.Boolean#True";
    static const WCHAR *bluetoothadapter_statics_name = L"Windows.Devices.Bluetooth.BluetoothAdapter";
    IBluetoothAdapterStatics *bluetoothadapter_statics;
    IActivationFactory *factory;
    HSTRING str, default_str;
    HRESULT hr;
    INT32 res;
    LONG ref;

    hr = WindowsCreateString( bluetoothadapter_statics_name, wcslen( bluetoothadapter_statics_name ), &str );
    ok( hr == S_OK, "got hr %#lx.\n", hr );

    hr = RoGetActivationFactory( str, &IID_IActivationFactory, (void **)&factory );
    WindowsDeleteString( str );
    ok( hr == S_OK || broken( hr == REGDB_E_CLASSNOTREG ), "got hr %#lx.\n", hr );
    if (hr == REGDB_E_CLASSNOTREG)
    {
        win_skip( "%s runtimeclass not registered, skipping tests.\n", wine_dbgstr_w( bluetoothadapter_statics_name ) );
        return;
    }

    check_interface( factory, &IID_IUnknown );
    check_interface( factory, &IID_IInspectable );
    check_interface( factory, &IID_IAgileObject );

    hr = IActivationFactory_QueryInterface( factory, &IID_IBluetoothAdapterStatics, (void **)&bluetoothadapter_statics );
    ok( hr == S_OK, "got hr %#lx.\n", hr );

    hr = IBluetoothAdapterStatics_GetDeviceSelector( bluetoothadapter_statics, NULL );
    ok( hr == E_POINTER, "got hr %#lx.\n", hr );
    hr = IBluetoothAdapterStatics_GetDeviceSelector( bluetoothadapter_statics, &str );
    ok( hr == S_OK, "got hr %#lx.\n", hr );
    hr = WindowsCreateString( default_res, wcslen(default_res), &default_str );
    ok( hr == S_OK, "got hr %#lx.\n", hr );
    hr = WindowsCompareStringOrdinal( str, default_str, &res );
    ok( hr == S_OK, "got hr %#lx.\n", hr );
    ok( !res, "got unexpected string %s.\n", debugstr_hstring(str) );

    WindowsDeleteString( str );
    WindowsDeleteString( default_str );
    ref = IBluetoothAdapterStatics_Release( bluetoothadapter_statics );
    ok( ref == 2, "got ref %ld.\n", ref );
    ref = IActivationFactory_Release( factory );
    ok( ref == 1, "got ref %ld.\n", ref );
}

START_TEST(bluetooth)
{
    HRESULT hr;

    hr = RoInitialize( RO_INIT_MULTITHREADED );
    ok( hr == S_OK, "RoInitialize failed, hr %#lx\n", hr );

    test_BluetoothAdapterStatics();

    RoUninitialize();
}

https://gitlab.winehq.org/wine/wine/-/blob/master/dlls/windows.devices.bluetooth/tests/bluetooth.c

Upvotes: 0

Pavel Minaev
Pavel Minaev

Reputation: 101555

WinRT is fundamentally COM, so using WinRT components from C is like using COM components from C. Like before, you get .idl files for all WinRT components, and also .h files produced from those .idl files. The .h files include both C++ and C declarations (wrapped in #ifdef __cplusplus as needed). You can just #include them and start hacking away.

It's not exactly neat, though, e.g. something like this C++/CX:

Windows::UI::Xaml::Controls::TextBlock^ tb = ...;
tb->Text = "Foo";

which is equivalent to this vanilla C++:

Windows::UI::Xaml::Controls::ITextBlock* tb = ...;
HSTRING hs;
HRESULT hr = WindowsStringCreate(L"Foo", 3, &hs);
// check hr for errors
hr = tb->set_Text(hs);
// check hr for errors
tb->Release();

would be written in C as:

__x_Windows_CUI_CXaml_CControls_CITextBlock* tb = ...;
HRESULT hr;
HSTRING hs;
hr = WindowsCreateString(L"Foo", 3, &hs);
// check hr for errors
hr = __x_Windows_CUI_CXaml_CControls_CITextBlock_put_Text(tb, hs);
// check hr for errors
IUnknown_Release(tb);

Look inside "C:\Program Files (x86)\Windows Kits\8.0\Include\winrt" in Developer Preview to see the .idl and .h files.

Upvotes: 73

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