so easy

控件ID：IDC_BUTTON
图片：IDB_BITMAP (.bmp图片)
控件句柄：hwnd
实现：
HBITMAP bmp1 = LoadBitmap(GetModuleHandle(NULL), MAKEINTRESOURCE(IDB_BITMAP));
按钮要有BS_BITMAP样式
SetWindowLong(hwnd, GWL_STYLE, GetWindowLong(hwnd, GWL_STYLE) + BS_BITMAP);
SendMessage(hwnd, BM_SETIMAGE, IMAGE_BITMAP, (LPARAM)bmp1);