[PATCH v2] Implement DwmIsCompositionEnabled

[Zhiyi Zhang]

Hi Joel,

Just so you know, DwmIsCompositionEnabled always return TRUE on Windows 8.
So it shouldn't be that much of a problem only setting *enabled to TRUE.

If you are seriously thinking about a more complete implementation.
You should also consider implementing DwmEnableComposition and related
functions and some tests.

Thanks,
Zhiyi

On 10/3/19 8:14 PM, Joel Leclerc wrote:
> Signed-off-by: Joel Leclerc <meerkatanonymous at gmail.com>
> ---
> v2: Ensure the registry key is closed, small refactor
> ---
>  dlls/dwmapi/Makefile.in   |  1 +
>  dlls/dwmapi/dwmapi_main.c | 27 ++++++++++++++++++++-------
>  2 files changed, 21 insertions(+), 7 deletions(-)
>
> diff --git a/dlls/dwmapi/Makefile.in b/dlls/dwmapi/Makefile.in
> index 3a3691326f..ebdd3aae05 100644
> --- a/dlls/dwmapi/Makefile.in
> +++ b/dlls/dwmapi/Makefile.in
> @@ -1,5 +1,6 @@
>  MODULE    = dwmapi.dll
>  IMPORTLIB = dwmapi
> +IMPORTS   = advapi32
>  
>  EXTRADLLFLAGS = -mno-cygwin
>  
> diff --git a/dlls/dwmapi/dwmapi_main.c b/dlls/dwmapi/dwmapi_main.c
> index 6378a091f0..3a8a5ab856 100644
> --- a/dlls/dwmapi/dwmapi_main.c
> +++ b/dlls/dwmapi/dwmapi_main.c
> @@ -26,6 +26,7 @@
>  #include "winbase.h"
>  #include "wingdi.h"
>  #include "winuser.h"
> +#include "winreg.h"
>  #include "dwmapi.h"
>  #include "wine/debug.h"
>  
> @@ -51,16 +52,28 @@ BOOL WINAPI DllMain(HINSTANCE hInstDLL, DWORD fdwReason, LPVOID lpv)
>   */
>  HRESULT WINAPI DwmIsCompositionEnabled(BOOL *enabled)
>  {
> -    static int once;
> -    if (!once)
> +    static const WCHAR dwn_reg_keyW[] = {'S','o','f','t','w','a','r','e','\\',
> +                                         'M','i','c','r','o','s','o','f','t','\\',
> +                                         'W','i','n','d','o','w','s','\\',
> +                                         'D','W','M','\0'};
> +    static const WCHAR compositionW[] = {'C','o','m','p','o','s','i','t','i','o','n','\0'};
> +
> +    HKEY hkey;
> +    DWORD type, value, count = sizeof(value);
> +
> +    *enabled = FALSE;
> +
> +    if (RegOpenKeyW(HKEY_CURRENT_USER, dwn_reg_keyW, &hkey) == ERROR_SUCCESS)
>      {
> -        FIXME("%p\n", enabled);
> -        once = 1;
> +        if (RegQueryValueExW(hkey, compositionW, NULL, &type, &value, &count) == ERROR_SUCCESS &&
> +            type == REG_DWORD)
> +        {
> +            if (value == 1) *enabled = TRUE;
> +        }
> +        RegCloseKey(hkey);
>      }
> -    else
> -        TRACE("%p\n", enabled);
>  
> -    *enabled = FALSE;
> +    TRACE("*%p = %i\n", enabled, *enabled);
>      return S_OK;
>  }
>