我有点困惑。当文件被拖动到WS_EX_ACCEPTFILES标记的窗口上时,它将PostMessage放入WndProc函数,该函数将UINT消息设置为WM_DROPFILES,并根据
https://msdn.microsoft.com/en-us/library/windows/desktop/bb774303(v=vs.85).aspx
WPARAM =(WPARAM)(HDROP)hDrop;所以我错误地假设我可以使用WPARAM来初始化HDROP或者只是将它传递给DragQueryFile吗?
LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam) {
switch (message) {
case WM_CREATE:
return 0;
case WM_DROPFILES:
TCHAR* FilePath;
HDROP hDrop = wParam; //wParam cannot be used to ini. an entity of type HDROP
//HDROP hdrop = (HDROP)wParam; initialization of hDrop is skipped by case label
DragQueryFile(wParam, 0, FilePath, 0); //wParam not compatible
return 0;
case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, message, wParam, lParam);
}
感谢各种帮助。
答案 0 :(得分:1)
您需要将wparam转换为HDROP,然后迭代提供缓冲区的已删除文件路径。
case WM_DROPFILES:
{
auto const drop_handle{reinterpret_cast< ::HDROP >(wParam)};
auto const dropped_files_count
{
::DragQueryFileW(drop_handle, 0xFFFFFFFF, nullptr, 0)
};
::std::vector< wchar_t > buffer;
for(::UINT dropped_file_index{0}; dropped_files_count != dropped_file_index; ++dropped_file_index)
{
auto const file_path_symbols_count_excluding_terminating_null
{
::DragQueryFileW(drop_handle, dropped_file_index, nullptr, 0)
};
if(0 < file_path_symbols_count_excluding_terminating_null)
{
auto const buffer_size{file_path_symbols_count_excluding_terminating_null + 1};
buffer.resize(buffer_size);
auto const copied_symbols_count_excluding_terminating_null
{
::DragQueryFileW(drop_handle, dropped_file_index, buffer.data(), buffer_size)
};
if(copied_symbols_count_excluding_terminating_null == file_path_symbols_count_excluding_terminating_null)
{
buffer.back() = L'\0'; // just in case....
// buffer now contains file path...
}
}
}
break;
}
但请注意,即使处理WM_DROPFILES
应该有效,处理拖放的优先方法是为您的应用程序实施IDropTarget
interface和register it as drop target handler。
答案 1 :(得分:0)
你快到了。您有正确的答案,但由于与您使用case
标签有关的不同错误,您对其进行了评论。不应该使用HDROP
和WPARAM
向后移动,而应该修复不同的错误;)
演员阵容是正确的,但你需要确定你的案例范围&#34; body&#34; (因为,事实上,案件没有任何主体或自己的范围),这就是错误告诉你的:
case WM_DROPFILES: {
TCHAR FilePath[MAX_PATH];
HDROP hdrop = (HDROP)wParam;
DragQueryFile(hdrop, 0, FilePath, 0);
return 0;
}
此处我添加了{
和}
来介绍块范围。
答案 2 :(得分:0)
添加已回答的VTT。
您可以将::std::vector< wchar_t > buffer;
替换为std::wstring buffer
代码
case WM_DROPFILES:
{
auto const drop_handle{ reinterpret_cast<::HDROP>(wParam) };
auto const dropped_files_count
{
::DragQueryFileW(drop_handle, 0xFFFFFFFF, nullptr, 0)
};
::std::wstring buffer;
for (::UINT dropped_file_index{ 0 }; dropped_files_count != dropped_file_index; ++dropped_file_index)
{
auto const file_path_symbols_count_excluding_terminating_null
{
::DragQueryFileW(drop_handle, dropped_file_index, nullptr, 0)
};
if (0 < file_path_symbols_count_excluding_terminating_null)
{
auto const buffer_size{ file_path_symbols_count_excluding_terminating_null + 1 };
buffer.resize(buffer_size);
auto const copied_symbols_count_excluding_terminating_null
{
::DragQueryFileW(drop_handle, dropped_file_index, &buffer[0], buffer_size)
};
if (copied_symbols_count_excluding_terminating_null == file_path_symbols_count_excluding_terminating_null)
{
buffer.back() = L'\0'; // just in case....
// buffer now contains file path...
MessageBox(0, buffer.c_str(), buffer.c_str(), MB_OK);
}
}
}
break;
}