Is it normal that the COM vtbl structure cannot be aligned between Windows and Wine

[zhengxianwei]

In wine, Visual2Vtbl

```
typedef struct IDCompositionVisual2Vtbl {
    BEGIN_INTERFACE

    /*** IUnknown methods ***/
    HRESULT (STDMETHODCALLTYPE *QueryInterface)(
        IDCompositionVisual2 *This,
        REFIID riid,
        void **ppvObject);

    ULONG (STDMETHODCALLTYPE *AddRef)(
        IDCompositionVisual2 *This);

    ULONG (STDMETHODCALLTYPE *Release)(
        IDCompositionVisual2 *This);

    /*** IDCompositionVisual methods ***/
    HRESULT (STDMETHODCALLTYPE *SetOffsetX)(
        IDCompositionVisual2 *This,
        float offset_x);

    HRESULT (STDMETHODCALLTYPE *SetOffsetXAnimation)(
        IDCompositionVisual2 *This,
        IDCompositionAnimation *animation);

    HRESULT (STDMETHODCALLTYPE *SetOffsetY)(
        IDCompositionVisual2 *This,
        float offset_y);
```

setOffsetX (float *) at offset 0x18
[image: visual2vtbl.png]
But in windows 0x18 is setOffsetX (Animation *)

Is this correct?

[Zhiyi Zhang]

On 6/11/25 20:16, zhengxianwei wrote:
> In wine, Visual2Vtbl 
>
> ```
> typedef struct IDCompositionVisual2Vtbl {
>     BEGIN_INTERFACE
>
>     /*** IUnknown methods ***/
>     HRESULT (STDMETHODCALLTYPE *QueryInterface)(
>         IDCompositionVisual2 *This,
>         REFIID riid,
>         void **ppvObject);
>
>     ULONG (STDMETHODCALLTYPE *AddRef)(
>         IDCompositionVisual2 *This);
>
>     ULONG (STDMETHODCALLTYPE *Release)(
>         IDCompositionVisual2 *This);
>
>     /*** IDCompositionVisual methods ***/
>     HRESULT (STDMETHODCALLTYPE *SetOffsetX)(
>         IDCompositionVisual2 *This,
>         float offset_x);
>
>     HRESULT (STDMETHODCALLTYPE *SetOffsetXAnimation)(
>         IDCompositionVisual2 *This,
>         IDCompositionAnimation *animation);
>
>     HRESULT (STDMETHODCALLTYPE *SetOffsetY)(
>         IDCompositionVisual2 *This,
>         float offset_y);
> ```
>
> setOffsetX (float *) at offset 0x18
> visual2vtbl.png
> But in windows 0x18 is setOffsetX (Animation *)
>
> Is this correct?

No. This is a bug. It's addressed by https://gitlab.winehq.org/zhiyi/wine/-/commit/1ef17ccd021d7b549abeabdbcf9e14....
Please see https://gitlab.winehq.org/zhiyi/wine/-/commits/bug-23698-react-native if you want the latest dcomp work.

[zhengxianwei]

cool job, thank you

On Wed, Jun 11, 2025 at 8:51 PM Zhiyi Zhang <zzhang(a)codeweavers.com> wrote:
> On 6/11/25 20:16, zhengxianwei wrote:
> > In wine, Visual2Vtbl
> >
> > ```
> > typedef struct IDCompositionVisual2Vtbl {
> >     BEGIN_INTERFACE
> >
> > /*** IUnknown methods ***/
> >     HRESULT (STDMETHODCALLTYPE *QueryInterface)(
> >         IDCompositionVisual2 *This,
> >         REFIID riid,
> >         void **ppvObject);
> >
> > ULONG (STDMETHODCALLTYPE *AddRef)(
> >         IDCompositionVisual2 *This);
> >
> > ULONG (STDMETHODCALLTYPE *Release)(
> >         IDCompositionVisual2 *This);
> >
> > /*** IDCompositionVisual methods ***/
> >     HRESULT (STDMETHODCALLTYPE *SetOffsetX)(
> >         IDCompositionVisual2 *This,
> >         float offset_x);
> >
> > HRESULT (STDMETHODCALLTYPE *SetOffsetXAnimation)(
> >         IDCompositionVisual2 *This,
> >         IDCompositionAnimation *animation);
> >
> > HRESULT (STDMETHODCALLTYPE *SetOffsetY)(
> >         IDCompositionVisual2 *This,
> >         float offset_y);
> > ```
> >
> > setOffsetX (float *) at offset 0x18
> > visual2vtbl.png
> > But in windows 0x18 is setOffsetX (Animation *)
> >
> > Is this correct?
>
> No. This is a bug. It's addressed by
> https://gitlab.winehq.org/zhiyi/wine/-/commit/1ef17ccd021d7b549abeabdbcf9e14...
> .
> Please see
> https://gitlab.winehq.org/zhiyi/wine/-/commits/bug-23698-react-native if
> you want the latest dcomp work.

[Zhiyi Zhang]

On 6/11/25 20:16, zhengxianwei wrote:
> In wine, Visual2Vtbl 
>
> ```
> typedef struct IDCompositionVisual2Vtbl {
>     BEGIN_INTERFACE
>
>     /*** IUnknown methods ***/
>     HRESULT (STDMETHODCALLTYPE *QueryInterface)(
>         IDCompositionVisual2 *This,
>         REFIID riid,
>         void **ppvObject);
>
>     ULONG (STDMETHODCALLTYPE *AddRef)(
>         IDCompositionVisual2 *This);
>
>     ULONG (STDMETHODCALLTYPE *Release)(
>         IDCompositionVisual2 *This);
>
>     /*** IDCompositionVisual methods ***/
>     HRESULT (STDMETHODCALLTYPE *SetOffsetX)(
>         IDCompositionVisual2 *This,
>         float offset_x);
>
>     HRESULT (STDMETHODCALLTYPE *SetOffsetXAnimation)(
>         IDCompositionVisual2 *This,
>         IDCompositionAnimation *animation);
>
>     HRESULT (STDMETHODCALLTYPE *SetOffsetY)(
>         IDCompositionVisual2 *This,
>         float offset_y);
> ```
>
> setOffsetX (float *) at offset 0x18
> visual2vtbl.png
> But in windows 0x18 is setOffsetX (Animation *)

This screenshot is from disassembling native dcomp.dll. You are not allowed to do this if you want to
send your patches to Wine.
> Is this correct?

[zhengxianwei]

Due to some reasons, I may not submit patches to Wine, but thank you for
letting me know about this rule — I will follow it

On Wed, Jun 11, 2025 at 8:57 PM Zhiyi Zhang <zzhang(a)codeweavers.com> wrote:
> On 6/11/25 20:16, zhengxianwei wrote:
> > In wine, Visual2Vtbl
> >
> > ```
> > typedef struct IDCompositionVisual2Vtbl {
> >     BEGIN_INTERFACE
> >
> > /*** IUnknown methods ***/
> >     HRESULT (STDMETHODCALLTYPE *QueryInterface)(
> >         IDCompositionVisual2 *This,
> >         REFIID riid,
> >         void **ppvObject);
> >
> > ULONG (STDMETHODCALLTYPE *AddRef)(
> >         IDCompositionVisual2 *This);
> >
> > ULONG (STDMETHODCALLTYPE *Release)(
> >         IDCompositionVisual2 *This);
> >
> > /*** IDCompositionVisual methods ***/
> >     HRESULT (STDMETHODCALLTYPE *SetOffsetX)(
> >         IDCompositionVisual2 *This,
> >         float offset_x);
> >
> > HRESULT (STDMETHODCALLTYPE *SetOffsetXAnimation)(
> >         IDCompositionVisual2 *This,
> >         IDCompositionAnimation *animation);
> >
> > HRESULT (STDMETHODCALLTYPE *SetOffsetY)(
> >         IDCompositionVisual2 *This,
> >         float offset_y);
> > ```
> >
> > setOffsetX (float *) at offset 0x18
> > visual2vtbl.png
> > But in windows 0x18 is setOffsetX (Animation *)
>
> This screenshot is from disassembling native dcomp.dll. You are not
> allowed to do this if you want to
> send your patches to Wine.
> > Is this correct?