win32-UpdateLayeredWindow -云博客

win32-UpdateLayeredWindow

# windos 2024-05-05 09:13 0 44 来源：云博客

创建半透明的窗口，以及在窗口上绘制不透明的文本

方法：

创建Bitmap具有PixelFormat32bppPARGB像素格式的GDI + 对象。
创建一个Graphics对象以绘制该Bitmap对象。
使用GDI +将所有图形绘制到该对象中。
销毁Graphics在步骤2中创建的对象。
GetHBITMAP在Bitmap对象上调用方法以获取Windows HBITMAP。
销毁Bitmap对象。
使用创建内存DC，CreateCompatibleDC然后HBITMAP从步骤5中选择。
使用内存DC作为源调用UpdateLayeredWindow。
选择以前的位图并删除内存DC。
销毁HBITMAP在步骤5中创建的。

代码示例：

#include <Windows.h>#include <stdio.h>#include <iostream>#include <ObjIdl.h>#include <gdiplus.h>#include <gdiplusheaders.h>using namespace Gdiplus;#pragma comment (lib,"Gdiplus.lib")#define MAX_WIDTH 800#define MAX_HEIGHT 600using namespace std;void Drawtext(HWND hwnd, HDC hdc);LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) { if (message == WM_DESTROY) { PostQuitMessage(0); } return DefWindowProc(hwnd, message, wParam, lParam);};HINSTANCE hinst;int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevinstance, PSTR szCmdLine, int iCmdShow) { HWND hWnd; GdiplusStartupInput gdiplusStartupInput; ULONG_PTR gdiplusToken; //Initialize GDI+ GdiplusStartup(&gdiplusToken, &gdiplusStartupInput, NULL); hinst = GetModuleHandle(NULL); // create a window class: WNDCLASS wc = {}; wc.lpfnWndProc = WndProc; wc.hInstance = hinst; wc.lpszClassName = L"win32"; // register class with operating system: RegisterClass(&wc); // create and show window: hWnd = CreateWindowExW( WS_EX_LAYERED | WS_EX_TOPMOST, L"win32", L"WinSoup", WS_POPUP, 0, 0, 1000, 500, nullptr, nullptr, hInstance, nullptr ); if (hWnd == NULL) { return 0; } Drawtext(hWnd, GetDC(hWnd)); ShowWindow(hWnd, SW_SHOW); MSG msg = {}; while (GetMessage(&msg, NULL, 0, 0)) { TranslateMessage(&msg); DispatchMessage(&msg); }}void Drawtext(HWND hwnd, HDC hdc){ FontFamily fontFamily(L"Times New Roman"); Font font(&fontFamily, 32, FontStyleRegular, UnitPixel); PointF pointF(30.0f, 10.0f); SolidBrush solidBrush(Color(255, 0, 0, 0)); Bitmap softwareBitmap(MAX_WIDTH, MAX_HEIGHT, PixelFormat32bppARGB); Graphics g(&softwareBitmap); g.Clear(Gdiplus::Color(30, 0, 0, 0)); // 30: alpha value  g.DrawString(L"Hello Hello Hello Hello Hello Hello Hello Hello", -1, &font, pointF, &solidBrush); HBITMAP bmp; softwareBitmap.GetHBITMAP(Color(0, 0, 0, 0), &bmp); HDC memdc = CreateCompatibleDC(hdc); HGDIOBJ original = SelectObject(memdc, bmp); BLENDFUNCTION blend = { 0 }; blend.BlendOp = AC_SRC_OVER; blend.SourceConstantAlpha = 255; blend.AlphaFormat = AC_SRC_ALPHA; POINT ptLocation = { 200, 300 }; SIZE szWnd = { MAX_WIDTH, MAX_HEIGHT }; POINT ptSrc = { 0, 0 }; BOOL l = UpdateLayeredWindow(hwnd, hdc, &ptLocation, &szWnd, memdc, &ptSrc, 0, &blend, ULW_ALPHA); int err = GetLastError(); SelectObject(hdc, original); DeleteObject(bmp); DeleteObject(memdc);}