[PATCH v2] Implement DwmIsCompositionEnabled

[Joel Leclerc]

Signed-off-by: Joel Leclerc 
---
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;
 }

[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
> 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;
>
> }

[Anonymous Meerkat]

> 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.

Thank you, I forgot to check MSDN's documentation before writing the
patch. I've submitted v3.
> You should also consider implementing DwmEnableComposition

According to MSDN however, DwmEnableComposition has no effect under Windows 8?

As for the others, I agree, I'll try to get around to it if I can find
more programs using it to test. Enabling it will cause some programs
to assume various functions will exist, so I think at least stubbing
the DLL is likely going to be important.

Thanks for the review.