C++屏幕水印实现遇到问题

没有必要用 std::wstring ，直接写 const wchar_t* watermarkText 即可。
CreateWindow 改成 CreateWindowExW ，第一个参数直接写 WS_EX_LAYERED | WS_EX_TRANSPARENT ，不需要 SetWindowLong 。
不应该用 SetLayeredWindowAttributes ，而应该用 UpdateLayeredWindow ，大致方法参见 https://www.cnblogs.com/strive-sun/p/13073015.html 。后续就不用管了，WM_PAINT 那块删掉。

”程序无法正常关闭退出“ 这是缺少 WM_CLOSE 。

你多问几次 GPT ，复杂代码一次成型几乎不太可能。多问几次就可以了。

保证 GdiplusShutdown 前 graphics 析构就可以了

参考下这个 https://github.com/3150601355/VideoWallPaperDemo

感谢各位。 @ysc3839 参考你提供的方案，解决了很多问题。放出最终版本，还有一些小问题，但是可以正常运行了，欢迎大家指正。
```
#include <Windows.h>
#include <gdiplus.h>
#include <string>
#include <thread>

using namespace Gdiplus;
#pragma comment(lib, "gdiplus.lib")

const wchar_t* watermarkText = L"Your Watermark Text";
const int watermarkFOntSize= 38;
const int watermarkSpacing = 100;

void DrawWatermarkToBitmap(HWND hwnd, HDC hdc, int width, int height)
{
// 创建位图上下文
HDC memDC = CreateCompatibleDC(hdc);
HBITMAP hBitmap = CreateCompatibleBitmap(hdc, width, height);
HBITMAP hOldBitmap = static_cast<HBITMAP>(SelectObject(memDC, hBitmap));

// 创建 Graphics 对象
Graphics graphics(memDC);

// 创建字体
FontFamily fontFamily(L"Arial");
Font font(&fontFamily, watermarkFontSize, FontStyleRegular, UnitPixel);

// Create a SolidBrush with the text color
SolidBrush textBrush(Color(128, 255, 0, 0));

// 获取文本尺寸
RectF layoutRect;
graphics.MeasureString(watermarkText, -1, &font, PointF(0, 0), &layoutRect);

// 计算水印文本块的总数以填满整个位图
int numBlocksX = (width + watermarkSpacing) / (static_cast<int>(layoutRect.Width) + watermarkSpacing);
int numBlocksY = (height + watermarkSpacing) / (static_cast<int>(layoutRect.Height) + watermarkSpacing);

// 计算实际的间距
int actualSpacingX = (width - numBlocksX * static_cast<int>(layoutRect.Width)) / (numBlocksX - 1);
int actualSpacingY = (height - numBlocksY * static_cast<int>(layoutRect.Height)) / (numBlocksY - 1);

// 绘制水印文本块
for (int y = 0; y < numBlocksY; y++) {
for (int x = 0; x < numBlocksX; x++) {
int textX = x * (static_cast<int>(layoutRect.Width) + actualSpacingX);
int textY = y * (static_cast<int>(layoutRect.Height) + actualSpacingY);

// 移动 Graphics 对象到文本块位置
graphics.ResetTransform();
graphics.TranslateTransform(static_cast<float>(textX), static_cast<float>(textY));
graphics.RotateTransform(-45.0f);

// 绘制水印文本
graphics.DrawString(watermarkText, -1, &font, PointF(0, 0), &textBrush);
}
}

// 渲染位图到窗口
BLENDFUNCTION blend = { AC_SRC_OVER, 0, 255, AC_SRC_ALPHA };
POINT ptSrc = { 0, 0 };
SIZE sizeWnd = { width, height };
POINT ptDst = { 0, 0 };
UpdateLayeredWindow(hwnd, hdc, &ptDst, &sizeWnd, memDC, &ptSrc, 0, &blend, ULW_ALPHA);

// 清理资源
SelectObject(memDC, hOldBitmap);
DeleteObject(hBitmap);
DeleteDC(memDC);

//ReleaseDC(hwnd, hdc);
}

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message)
{
case WM_CREATE:
SetTimer(hwnd, 1, 1000, NULL); // 创建定时器，每秒更新水印
break;
case WM_TIMER:
{
DrawWatermarkToBitmap(hwnd, GetDC(hwnd), GetSystemMetrics(SM_CXSCREEN), GetSystemMetrics(SM_CYSCREEN));
break;
}
case WM_SIZE:
// 窗口大小改变时重新绘制
{
DrawWatermarkToBitmap(hwnd, GetDC(hwnd), GetSystemMetrics(SM_CXSCREEN), GetSystemMetrics(SM_CYSCREEN));
break;
}
case WM_CLOSE:
DestroyWindow(hwnd);
break;
case WM_DESTROY:
{
PostQuitMessage(0);
break;
}
default:
return DefWindowProc(hwnd, message, wParam, lParam);
}

return 0;
}

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow)
{


// 注册窗口类
WNDCLASSEX wcex;
ZeroMemory(&wcex, sizeof(WNDCLASSEX));
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.lpfnWndProc = WndProc;
wcex.hInstance = hInstance;
wcex.lpszClassName = L"WatermarkWindowClass";
RegisterClassEx(&wcex);

HWND hwnd = CreateWindowExW(WS_EX_LAYERED | WS_EX_TRANSPARENT | WS_EX_TOPMOST, L"WatermarkWindowClass", L"Watermark Window", WS_POPUP, 0, 0, GetSystemMetrics(SM_CXSCREEN), GetSystemMetrics(SM_CYSCREEN), NULL, NULL, hInstance, NULL);

if (hwnd == NULL)
{
return 0;
}

GdiplusStartupInput gdiplusStartupInput;
ULONG_PTR gdiplusToken;
GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL);

ShowWindow(hwnd, nCmdShow);

MSG msg;
while (GetMessage(&msg, NULL, 0, 0))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}

// 关闭 GDI+
GdiplusShutdown(gdiplusToken);

return static_cast<int>(msg.wParam);
}
```

@ysc3839 感谢，参考你的方案，已解决问题。