我试图用半透明像素创建非矩形窗口。该图像不是来自PNG,而是使用GDI +调用即时绘制的。使用UpdateLayeredWindow绘制部分透明的GDI +位图到无边框窗口
我创建窗口如下:
WNDCLASSEX wc = WNDCLASSEX();
wc.cbSize = sizeof(wc);
HINSTANCE instance = GetModuleHandle(nullptr);
std::wstring classname(L"gditest ui window class");
if (!GetClassInfoEx(instance, classname.c_str(), &wc)) {
//wc.cbSize;
//wc.style = CS_DROPSHADOW;
wc.lpfnWndProc = process_messages;
//wc.cbClsExtra;
//wc.cbWndExtra;
wc.hInstance = instance;
wc.hIcon;
wc.hCursor = LoadCursor(0, IDC_ARROW);
//wc.hbrBackground;
//wc.lpszMenuName;
wc.lpszClassName = classname.c_str();
wc.hIconSm;
if (!RegisterClassEx(&wc))
throw GetLastError();
}
m_window = CreateWindowEx(WS_EX_APPWINDOW | WS_EX_LAYERED,
classname.c_str(), L"User Interface",
WS_VISIBLE,
CW_USEDEFAULT, CW_USEDEFAULT, 640, 480,
HWND_DESKTOP, 0, instance, this);
if (!m_window)
throw GetLastError();
update_window();
的update_window()函数看起来像这样:
void user_interface::update_window()
{
RECT r;
GetClientRect(m_window, &r);
Bitmap buf(r.right - r.left, r.bottom - r.top, PixelFormat32bppARGB);
Graphics gfx(&buf);
Rect rect(r.left, r.top, r.right - r.left, r.bottom - r.top);
SolidBrush b(Color(0x7f00ff00));
gfx.FillRectangle(&b, rect);
/* CLSID clsid;
UINT numbytes = 0, numenc = 0;
GetImageEncodersSize(&numenc, &numbytes);
std::vector<char> encoders(numbytes, 0);
ImageCodecInfo *encoderptr = (ImageCodecInfo *)&encoders[0];
GetImageEncoders(numenc, numbytes, encoderptr);
clsid = encoderptr[4].Clsid;
buf.Save(L"test.png", &clsid);
*/
HDC gfxdc = gfx.GetHDC();
HDC scrndc = GetDC(HWND_DESKTOP);
BLENDFUNCTION blend;
blend.BlendOp = AC_SRC_OVER;
blend.BlendFlags = 0;
blend.SourceConstantAlpha = 255;
blend.AlphaFormat = AC_SRC_ALPHA;
POINT src = POINT(), dst;
SIZE size;
GetWindowRect(m_window, &r);
dst.x = r.left;
dst.y = r.top;
size.cx = buf.GetWidth();
size.cy = buf.GetHeight();
if (!UpdateLayeredWindow(m_window, scrndc, &dst, &size, gfxdc, &src, 0, &blend, ULW_ALPHA)) {
throw GetLastError();
}
ReleaseDC(HWND_DESKTOP, scrndc);
gfx.ReleaseHDC(gfxdc);
}
代码的注释片保存位图对象的PNG,其中我写只是为了确认位图是否正确绘制。
没有发生错误,但屏幕上的结果并不是我的意图。而不是一个很好的50%透明的绿色广场,我得到一个几乎看不见的白色正方形:。
另一个奇怪的是,在窗口坠落点击进入什么是下,尽管它已经是稍微可见......
我在做什么错在这里?