如何将文件从Explorer Shell拖放到Delphi应用程序中的VirtualTreeView控件中？ [英] How do you drag and drop a file from Explorer Shell into a VirtualTreeView control in a Delphi application?

问题描述

由Mike Lischke在VirtualTreeView中进行广泛的拖放支持，而且我使用的是TVirtualStringTree，它具有一些拖放事件，但是我无法弄清楚如何让它接受一个shell拖动，将某些文件从windows explorer shell下载到我的应用程序中。我想加载这些文件，当它们被拖到放置控件上时。

我尝试使用Anders Melander的第三方代码集来处理拖放，但是因为VirtualTreeView已经将自身注册为放置目标，所以我无法使用它。

编辑：我找到了一个简单的解决方法：在VT.TreeOptions中关闭toAcceptOLEDrop。杂项选项
如果有人知道使用VirtualTreeView的方式，而不使用第三方OLE-shell-drag-drop库，并使用其广泛的OLE拖放支持来提取从Shell拖入的文件名列表，那将是很酷的。

解决方案

我的实现（与Delphi 2010一起工作。必须添加ActiveX，ShellApi才能使用编译）：

  procedure TfMain.vstTreeDragDrop（发件人：TBaseVirtualTree;源：TObject; 
 DataObject：IDataObject;格式：TFormatArray; Shift：TShiftState; 
 Pt：TPoint; var Effect：Integer; Mode：TDropMode）; 
 var 
 I，j：整数; 
 MyList：TStringList; 
 AttachMode：TVTNodeAttachMode; 
 begin 
如果Mode = dmOnNode然后
 AttachMode：= amInsertBefore 
否如果Mode = dmAbove然后
 AttachMode：= amInsertBefore 
否如果Mode = dmBelow then 
 AttachMode：= amInsertAfter 
 else 
 AttachMode：= amAddChildLast; 
 
 MyList：= TStringList.Create; 
尝试
为i：= 0到高（格式） -  1 do 
开始
如果（格式[i] = CF_HDROP）然后
开始
 GetFileListFromObj（DataObject，MyList）; 
 
 //这里我们有所有文件名
为j：= 0到MyList.Count  -  1 do 
 begin 
 Sender.InsertNode（Sender.DropTargetNode，AttachMode） ; 
结束
结束
结束
 finally 
 MyList.Free; 
结束
结束
 
程序TfMain.GetFileListFromObj（const DataObj：IDataObject; 
 FileList：TStringList）; 
 var 
 FmtEtc：TFormatEtc; //指定所需的数据格式
中：TStgMedium; //包含文件列表的存储介质
 DroppedFileCount：Integer; //丢弃的文件数
 I：整数; //循环通过丢弃的文件
 FileNameLength：Integer; //删除文件名的长度
 FileName：string; //删除文件的名称
 begin 
 //从数据对象获取所需的存储介质
 FmtEtc.cfFormat：= CF_HDROP; 
 FmtEtc.ptd：= nil; 
 FmtEtc.dwAspect：= DVASPECT_CONTENT; 
 FmtEtc.lindex：= -1; 
 FmtEtc.tymed：= TYMED_HGLOBAL; 
 OleCheck（DataObj.GetData（FmtEtc，Medium））; 
尝试
尝试
 //获取丢弃的文件数
 DroppedFileCount：= DragQueryFile（
 Medium.hGlobal，$ FFFFFFFF，nil，0 
）; 
 //获取每个文件的名称并处理它
为I：= 0到Pred（DroppedFileCount）do 
 begin 
 //获取文件名的长度，然后命名自身
 FileNameLength：= DragQueryFile（Medium.hGlobal，I，nil，0）; 
 SetLength（FileName，FileNameLength）; 
 DragQueryFileW（
 Medium.hGlobal，I，PWideChar（FileName），FileNameLength + 1 
）; 
 //添加文件名以列出
 FileList.Append（FileName）; 
结束
 finally 
 //整理 - 释放放置句柄
 //在此
之后不再使用DropH DragFinish（Medium.hGlobal）; 
结束
 finally 
 ReleaseStgMedium（Medium）; 
结束
 
 end; 
  

There is extensive drag and drop support in VirtualTreeView by Mike Lischke, and I am using TVirtualStringTree, which has some on-drag-and-drop events, but I can not figure out how to get it to accept a shell drag-and-drop of some files from the windows explorer shell, into my application. I want to load the files, when they are dragged onto the drop control.

I tried using a third-party set of code from Anders Melander, to handle drag and drop, but because VirtualTreeView already registers itself as a drop target, I can't use that.

edit: I found a simple workaround: Turn off toAcceptOLEDrop in VT.TreeOptions.MiscOptions. It would be cool if anybody knows a way to use VirtualTreeView without using a third party OLE-shell-drag-drop library and using its extensive OLE drag/drop support to extract a list of filenames dragged in from the Shell.

解决方案

My implementation (Works very well with Delphi 2010. Must add ActiveX, ShellApi to uses to compile):

procedure TfMain.vstTreeDragDrop(Sender: TBaseVirtualTree; Source: TObject;
  DataObject: IDataObject; Formats: TFormatArray; Shift: TShiftState;
  Pt: TPoint; var Effect: Integer; Mode: TDropMode);
var
  I, j: Integer;
  MyList: TStringList;
  AttachMode: TVTNodeAttachMode;
begin
  if Mode = dmOnNode then
    AttachMode := amInsertBefore
  else if Mode = dmAbove then
    AttachMode := amInsertBefore
  else if Mode = dmBelow then
    AttachMode := amInsertAfter
  else
    AttachMode := amAddChildLast;

  MyList := TStringList.Create;
  try
    for i := 0 to High(formats) - 1 do
    begin
      if (Formats[i] = CF_HDROP) then
      begin
        GetFileListFromObj(DataObject, MyList);

        //here we have all filenames
        for j:=0 to MyList.Count - 1 do
        begin
          Sender.InsertNode(Sender.DropTargetNode, AttachMode);
        end; 
      end;  
    end;
  finally
    MyList.Free;
  end;
end;

procedure TfMain.GetFileListFromObj(const DataObj: IDataObject;
  FileList: TStringList);
var
  FmtEtc: TFormatEtc;                   // specifies required data format
  Medium: TStgMedium;                   // storage medium containing file list
  DroppedFileCount: Integer;            // number of dropped files
  I: Integer;                           // loops thru dropped files
  FileNameLength: Integer;              // length of a dropped file name
  FileName: string;                 // name of a dropped file
begin
  // Get required storage medium from data object
  FmtEtc.cfFormat := CF_HDROP;
  FmtEtc.ptd := nil;
  FmtEtc.dwAspect := DVASPECT_CONTENT;
  FmtEtc.lindex := -1;
  FmtEtc.tymed := TYMED_HGLOBAL;
  OleCheck(DataObj.GetData(FmtEtc, Medium));
  try
    try
      // Get count of files dropped
      DroppedFileCount := DragQueryFile(
        Medium.hGlobal, $FFFFFFFF, nil, 0
        );
      // Get name of each file dropped and process it
      for I := 0 to Pred(DroppedFileCount) do
        begin
          // get length of file name, then name itself
          FileNameLength := DragQueryFile(Medium.hGlobal, I, nil, 0);
          SetLength(FileName, FileNameLength);
          DragQueryFileW(
            Medium.hGlobal, I, PWideChar(FileName), FileNameLength + 1
            );
          // add file name to list
          FileList.Append(FileName);
        end;
    finally
      // Tidy up - release the drop handle
      // don't use DropH again after this
      DragFinish(Medium.hGlobal);
    end;
  finally
    ReleaseStgMedium(Medium);
  end;

end;

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