在桌面背景上绘图(WIN32)

Question

有没有办法在WIN32中绘制桌面背景,并在重新绘制桌面背景时接收通知？

我试过这个:

desk = GetDesktopWindow();
dc = GetDC(desk);
MoveToEx(dc,0,0,NULL);
LineTo(dc,1680,1050);
ReleaseDC(desk,dc);

但它在整个屏幕上绘制,甚至在屏幕上的窗口上.

Answer 1

您可以使用Spy ++查找哪个窗口是桌面背景窗口.

在我的系统上,我看到以下层次结构:

• 窗口000100098"程序管理器"Progman
  • 窗口0001009E""SHELLDLL_DefView
    • 窗口00100A0"FolderView"SysListView32

我猜你指的是SysListView32--带有所有图标的窗口.您可以使用FindWindowEx查找此窗口.

编辑 您应该使用FindWindowEx和EnumerateChildWindows的组合.下面的代码可以在命令行框中编译,如下所示:cl /EHsc finddesktop.cpp /DUNICODE /link user32.lib

#include <windows.h>
#include <iostream>
#include <string>

BOOL CALLBACK EnumChildProc(HWND hwnd, LPARAM lParam)
{
  std::wstring windowClass;
  windowClass.resize(255);

  unsigned int chars = ::RealGetWindowClass(hwnd, &*windowClass.begin(), windowClass.size());
  windowClass.resize(chars);

  if (windowClass == L"SysListView32")
  {
    HWND* folderView = reinterpret_cast<HWND*>(lParam);
    *folderView = hwnd;

    return FALSE;
  }

  return TRUE;
}

int wmain()
{
  HWND parentFolderView = ::FindWindowEx(0, 0, L"Progman", L"Program Manager");
  if (parentFolderView == 0)
  {
    std::wcout << L"Couldn't find Progman window, error: 0x" << std::hex << GetLastError() << std::endl;
  }

  HWND folderView = 0;
  ::EnumChildWindows(parentFolderView, EnumChildProc, reinterpret_cast<LPARAM>(&folderView));

  if (folderView == 0)
  {
    std::wcout << L"Couldn't find FolderView window, error: 0x" << std::hex << GetLastError() << std::endl;
  }
  HWND desktopWindow = ::GetDesktopWindow();

  std::wcout << L"Folder View: " << folderView << std::endl;
  std::wcout << L"Desktop Window: " << desktopWindow << std::endl;

  return 0;
}

以下是运行finddesktop.exe后的结果

Folder View: 000100A0
Desktop Window: 00010014

正如您所看到的,窗口把手是完全不同的.