gm82alpha.c

#include <windows.h>
#include <dwmapi.h>

#pragma comment(lib, "Dwmapi.lib")

#define GMREAL __declspec(dllexport) double __cdecl
#define GMSTR __declspec(dllexport) char* __cdecl

GMREAL __gm82alpha_setcomposite(double whandle, double enable) {  
    HWND window_handle = (HWND)(int)whandle;
    if (enable>=0.5) {    
        SetWindowLong(window_handle,GWL_EXSTYLE,GetWindowLong(window_handle,GWL_EXSTYLE) | WS_EX_COMPOSITED); 
        MARGINS margins = {-1,-1,-1,-1};
        DwmExtendFrameIntoClientArea(window_handle,&margins);
    } else {
        SetWindowLong(window_handle,GWL_EXSTYLE,GetWindowLong(window_handle,GWL_EXSTYLE) & ~WS_EX_COMPOSITED);    
        MARGINS margins = {0,0,0,0};
        DwmExtendFrameIntoClientArea(window_handle,&margins);
    }
    return 0;
}

GMREAL __gm82alpha_setchromakey(double handle, double enable, double color) {  
    HWND window_handle = (HWND)(int)handle;
    
    if (enable>=0.5) {    
        //SetParent(window_handle,NULL);
        SetWindowLong(window_handle,GWL_EXSTYLE,GetWindowLong(window_handle,GWL_EXSTYLE) | WS_EX_LAYERED); 
        SetLayeredWindowAttributes(window_handle,((DWORD)color)&0x00ffffff,0xff,LWA_COLORKEY);          
    } else {
        SetWindowLong(window_handle,GWL_EXSTYLE,GetWindowLong(window_handle,GWL_EXSTYLE) & ~WS_EX_LAYERED);
    }
    return 0;
}