我的程序中有一个分层窗口,它在视觉上似乎工作正常,但是UpdateLayeredWindow
的返回值应该是一个非零值表示成功。在我的情况下,它是0,而GetLastError
返回87,这是一个不正确的参数。请问我的设置是否有问题?以下是完整的函数,窗口样式为WS_EX_LAYERED|WS_EX_TOPMOST
和WS_POPUP
。
bool SplashScreen(HWND hwnd, HINSTANCE m_hinstance)
{
HBITMAP hBitmap = (HBITMAP)LoadImage(m_hinstance, "splash.bmp", IMAGE_BITMAP, 640, 640, LR_LOADFROMFILE);
PAINTSTRUCT ps;
HDC hdc;
BITMAP bitmap;
HDC hdcMem;
HGDIOBJ oldBitmap;
int result=0;
if(!SetLayeredWindowAttributes(hwnd, 0, (255 * 100) / 100, LWA_ALPHA))
{
char msg[255];
sprintf(msg,"Error SetLayeredWindowAttributes: %d",GetLastError());
MessageBox(hwnd,msg,"System",MB_OK);
return false;
}
hdc = BeginPaint(hwnd, &ps);
if(!hdc)
{
char msg[255];
sprintf(msg,"Error BeginPaint: %d",GetLastError());
MessageBox(hwnd,msg,"System",MB_OK);
return false;
}
hdcMem = CreateCompatibleDC(hdc);
if(!hdcMem)
{
char msg[255];
sprintf(msg,"Error CreateCompatibleDC: %d",GetLastError());
MessageBox(hwnd,msg,"System",MB_OK);
return false;
}
oldBitmap = SelectObject(hdcMem, hBitmap);
GetObject(hBitmap, sizeof(bitmap), &bitmap);
result=BitBlt(hdc, 0, 0, 640, 640, hdcMem, 0, 0, SRCCOPY);
if(result==0)
{
char msg[255];
sprintf(msg,"Error BitBlt: %d",GetLastError());
MessageBox(hwnd,msg,"System",MB_OK);
return false;
}
BLENDFUNCTION blend = { 0 };
blend.BlendOp = AC_SRC_OVER;
blend.SourceConstantAlpha = 255;
blend.AlphaFormat = AC_SRC_ALPHA;
result=UpdateLayeredWindow(hwnd,GetDC(NULL),NULL,NULL,hdcMem,NULL, RGB(0,0,0),&blend, ULW_ALPHA);// Returns non-zero on success(!), in reality works when 0 is returned.
if(result==0)
{
char msg[255];
sprintf(msg,"Error UpdateLayeredWindow: %d",GetLastError());// Error UpdateLayeredWindow: 87
MessageBox(hwnd,msg,"System",MB_OK);
return false;
}
result=SetLayeredWindowAttributes(hwnd, RGB(255,255,255), 0, ULW_COLORKEY);
if(result==0)
{
char msg[255];
sprintf(msg,"Error SetLayeredWindowAttributes: %d",GetLastError());
MessageBox(hwnd,msg,"System",MB_OK);
return false;
}
result=EndPaint(hwnd, &ps);
if(result==0)
{
char msg[255];
sprintf(msg,"Error EndPaint: %d",GetLastError());
MessageBox(hwnd,msg,"System",MB_OK);
return false;
}
SelectObject(hdcMem, oldBitmap);
DeleteDC(hdc);
DeleteObject(hdcMem);
return true;
}