我需要在另一个应用程序窗口的顶部绘制边框（主要目的是突出显示用户从运行的应用程序列表中选择的窗口）。我试图在本机窗口边框的顶部绘制边框，但未绘制边框。这是代码：
HPEN framePen = ::CreatePen(PS_SOLID, 5, RGB(255, 0, 0));
HWND handle = FindWindow(L"ConsoleWindowClass", L"C:\\WINDOWS\\system32\\cmd.exe");
WINDOWPLACEMENT winPlacement;
GetWindowPlacement(handle, &winPlacement);
if (winPlacement.showCmd == SW_SHOWMINIMIZED)
{
ShowWindow(handle, SW_RESTORE);
}
SetWindowPos(handle, HWND_TOP, 0, 0, 0, 0, SWP_ASYNCWINDOWPOS | SWP_SHOWWINDOW | SWP_NOMOVE | SWP_NOSIZE);
SetForegroundWindow(handle);
PAINTSTRUCT ps;
RECT rect = {};
::GetClientRect(handle, &rect);
HDC hdc = ::BeginPaint(handle, &ps);
::SelectObject(hdc, framePen);
::Rectangle(hdc, rect.left, rect.top, rect.right, rect.bottom);
::EndPaint(handle, &ps);
在此示例中，使用了cmd窗口的句柄，但实际上并不重要。 您能告诉我为什么没有画边框以及如何画边框吗？ 谢谢。
答案 0 :(得分：3)
您不能直接在另一个窗口上绘图，因为系统可能会随时刷新该窗口，从而覆盖您的绘图。
要使您的图形具有持久性，请在另一个窗口的顶部创建一个layered window。
WS_EX_LAYERED标志创建窗口。SetLayeredWindowAttributes()。WM_PAINT处理程序中，使用颜色键（通过将其用于画笔）绘制矩形的内部。使用色键绘制的所有内容都将变为透明。用所需的颜色（通过将其用于笔）绘制矩形的边框。这是一个入门的最小示例。可以通过拖放操作来移动框架。
请注意，没有错误处理可使示例代码保持简洁。您应该检查每个Windows API调用的返回值。
#include <windows.h>
const COLORREF MY_COLOR_KEY = RGB( 255, 0, 255 );
int APIENTRY wWinMain(
HINSTANCE hInstance, HINSTANCE /*hPrevInst*/, LPWSTR /*lpCmdLine*/, int nCmdShow )
{
WNDCLASSW wc{ sizeof( wc ) };
wc.hInstance = hInstance;
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.hCursor = LoadCursor( nullptr, IDC_ARROW );
wc.hbrBackground = reinterpret_cast<HBRUSH>( COLOR_BTNFACE + 1 );
wc.lpszClassName = L"MyTransparentFrame";
wc.lpfnWndProc = []( HWND hwnd, UINT msg, WPARAM wp, LPARAM lp ) -> LRESULT
{
switch( msg )
{
case WM_PAINT:
{
PAINTSTRUCT ps{};
HDC hdc = BeginPaint( hwnd, &ps );
RECT rc{}; GetClientRect( hwnd, &rc );
HPEN hPen = CreatePen( PS_SOLID, 20, GetSysColor( COLOR_HIGHLIGHT ) );
HBRUSH hBrush = CreateSolidBrush( MY_COLOR_KEY );
HGDIOBJ hOldPen = SelectObject( hdc, hPen );
HGDIOBJ hOldBrush = SelectObject( hdc, hBrush );
Rectangle( hdc, rc.left, rc.top, rc.right, rc.bottom );
if( hOldPen )
SelectObject( hdc, hOldPen );
if( hOldBrush )
SelectObject( hdc, hOldBrush );
if( hPen )
DeleteObject( hPen );
if( hBrush )
DeleteObject( hBrush );
EndPaint( hwnd, &ps );
}
break;
case WM_DESTROY:
PostQuitMessage( 0 );
break;
case WM_NCHITTEST:
return HTCAPTION; // to be able to drag the window around
break;
default:
return DefWindowProcW( hwnd, msg, wp, lp );
}
return 0;
};
RegisterClassW( &wc );
HWND hwnd = CreateWindowExW( WS_EX_LAYERED, wc.lpszClassName, L"", WS_POPUP,
200, 200, 800, 600, nullptr, nullptr, hInstance, nullptr );
SetLayeredWindowAttributes( hwnd, MY_COLOR_KEY, 255, LWA_COLORKEY );
ShowWindow( hwnd, nCmdShow );
MSG msg;
while( GetMessage( &msg, nullptr, 0, 0 ) )
{
TranslateMessage( &msg );
DispatchMessage( &msg );
}
return (int) msg.wParam;
}
答案 1 :(得分：0)
最后，我设法通过以下代码解决了这个问题：
const COLORREF MY_COLOR_KEY = RGB(255, 128, 0);
HWND cmdHanlde = NULL;
constexpr unsigned int timerIdWindowUpdate = 1;
constexpr unsigned int timerIdFrameColor = 2;
bool tick = false;
bool minimized = false;
int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
_In_opt_ HINSTANCE hPrevInstance,
_In_ LPWSTR lpCmdLine,
_In_ int nCmdShow)
{
WNDCLASSEX wc = {};
wc.cbSize = sizeof(WNDCLASSEX);
wc.style = CS_HREDRAW | CS_VREDRAW;
wc.lpszClassName = L"MyTransparentFrame";
wc.hCursor = ::LoadCursor(NULL, IDC_ARROW);
wc.hbrBackground = NULL;
wc.lpfnWndProc = [](HWND hwnd, UINT msg, WPARAM wp, LPARAM lp) -> LRESULT
{
switch (msg)
{
case WM_PAINT:
{
PAINTSTRUCT ps{};
HDC hdc = BeginPaint(hwnd, &ps);
RECT rc{}; GetClientRect(hwnd, &rc);
HPEN hPen = CreatePen(PS_SOLID, 5, tick ? RGB(255, 128, 1) : RGB(255, 201, 14));
HBRUSH hBrush = CreateSolidBrush(MY_COLOR_KEY);
HGDIOBJ hOldPen = SelectObject(hdc, hPen);
HGDIOBJ hOldBrush = SelectObject(hdc, hBrush);
Rectangle(hdc, rc.left, rc.top, rc.right, rc.bottom);
if (hOldPen)
SelectObject(hdc, hOldPen);
if (hOldBrush)
SelectObject(hdc, hOldBrush);
if (hPen)
DeleteObject(hPen);
if (hBrush)
DeleteObject(hBrush);
EndPaint(hwnd, &ps);
}
break;
case WM_TIMER:
{
if (wp == timerIdWindowUpdate)
{
WINDOWPLACEMENT windowPlacement = { sizeof(WINDOWPLACEMENT), };
if (::GetWindowPlacement(cmdHanlde, &windowPlacement))
{
if (windowPlacement.showCmd == SW_SHOWMINIMIZED
|| !IsWindowVisible(cmdHanlde))
{
ShowWindow(hwnd, SW_HIDE);
minimized = true;
}
else
{
RECT rect = {};
DwmGetWindowAttribute(cmdHanlde, DWMWA_EXTENDED_FRAME_BOUNDS, &rect, sizeof(rect));
MONITORINFO monInfo;
monInfo.cbSize = sizeof(MONITORINFO);
GetMonitorInfoW(MonitorFromWindow(cmdHanlde, MONITOR_DEFAULTTONEAREST), &monInfo);
if (cmdHanlde != NULL && ::IsZoomed(cmdHanlde))
{
rect.left = monInfo.rcWork.left;
rect.top = monInfo.rcWork.top;
rect.bottom = monInfo.rcWork.bottom > rect.bottom ? rect.bottom : monInfo.rcWork.bottom;
rect.right = monInfo.rcWork.right > rect.right ? rect.right : monInfo.rcWork.right;
}
if (minimized)
{
::SetWindowPos(hwnd, cmdHanlde, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE);
minimized = false;
}
else
{
::SetWindowPos(cmdHanlde, hwnd, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE);
::SetWindowPos(hwnd, 0, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top,
SWP_SHOWWINDOW);
}
}
}
}
else if (wp == timerIdFrameColor)
{
tick = !tick;
::RedrawWindow(hwnd, NULL, NULL, RDW_INVALIDATE);
}
break;
}
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProcW(hwnd, msg, wp, lp);
}
return 0;
};
RegisterClassEx(&wc);
HWND hwnd = CreateWindowExW(WS_EX_TOOLWINDOW | WS_EX_NOACTIVATE | WS_EX_LAYERED | WS_EX_TRANSPARENT, wc.lpszClassName, L"", WS_POPUP | WS_VISIBLE | WS_DISABLED,
0, 0, 0, 0, nullptr, nullptr, nullptr, nullptr);
::SetTimer(hwnd, timerIdWindowUpdate, 50, NULL);
::SetTimer(hwnd, timerIdFrameColor, 500, NULL);
SetLayeredWindowAttributes(hwnd, MY_COLOR_KEY, 255, LWA_COLORKEY);
ShowWindow(hwnd, SW_SHOW);
cmdHanlde = FindWindow(L"ConsoleWindowClass", L"C:\\WINDOWS\\system32\\cmd.exe");
MSG msg;
while (GetMessage(&msg, nullptr, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
return (int)msg.wParam;
}
可能不是最佳解决方案，但对我有用。您能否看一下，并说是否有什么需要改进的地方？