[Bug 54271] WeChat has graphical artifacts displaying animated GIFs

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=54271

--- Comment #6 from [e-mail] ---
(In reply to Bartosz from comment #1)
> How I could reproduce the issue?
> Please provide step by step instruction.

A relatively new clue: I commented out everything in get_gif_background_color
and used the following writeup, and the background color no longer shows up as
solid black (or various other strange colors)

Is there a problem with reading in the data

'''

/* Get window handle by pid */
HWND GetHwndByPid(DWORD dwProcessID)
{
    HWND h = GetTopWindow(0);
    HWND retHwnd = NULL;
    while (h)
    {
        DWORD pid = 0;
        DWORD dwTheardId = GetWindowThreadProcessId(h, &pid);
        if (dwTheardId != 0)
            if (pid == dwProcessID && GetParent(h) == NULL &&
IsWindowVisible(h))
                retHwnd = h;
        h = GetNextWindow(h, GW_HWNDNEXT);
    }
    return retHwnd;
}

/* Get the default background color of the window */
static DWORD get_win_default_background_color(void)
{
    DWORD pid = GetCurrentProcessId();
    if(pid)
    {
        HWND hwnd = GetHwndByPid(pid);
        if(hwnd)
            return GetClassLongW(hwnd,GCLP_HBRBACKGROUND);
    }
    return 0xffffffff;
}

static DWORD get_gif_background_color(GpBitmap *bitmap)
{
    BYTE bgcolor_idx = 0;
    UINT i;

//    for(i=0; i<bitmap->prop_count; i++) {
//        if(bitmap->prop_item[i].id == PropertyTagIndexBackground) {
//            bgcolor_idx = *(BYTE*)bitmap->prop_item[i].value;
//            break;
//        }
//    }
//
//    for(i=0; i<bitmap->prop_count; i++) {
//        if(bitmap->prop_item[i].id == PropertyTagIndexTransparent) {
//            BYTE transparent_idx;
//            transparent_idx = *(BYTE*)bitmap->prop_item[i].value;
//
//            if(transparent_idx == bgcolor_idx)
//                return 0;
//        }
//    }
//
//    for(i=0; i<bitmap->prop_count; i++) {
//        if(bitmap->prop_item[i].id == PropertyTagGlobalPalette) {
//            if(bitmap->prop_item[i].length/3 > bgcolor_idx) {
//                BYTE *color =
((BYTE*)bitmap->prop_item[i].value)+bgcolor_idx*3;
//                return color[2] + (color[1]<<8) + (color[0]<<16) +
(0xffu<<24);
//            }
//            break;
//        }
//    }

FIXME("can't get gif background color\n");
    return get_win_default_background_color();
}

'''