Delphi：模拟从剪贴板到EmbeddedWB的IHTMLElement的拖放 [英] Delphi: Simulating a drag and drop from the clipboard to EmbeddedWB’s IHTMLElement

问题描述

我有一个带有TEmbeddedWB的Delphi XE2应用程序，用于模拟用户操作。该应用程序导航到一个URL，使用数据填充相关的表单字段并提交数据。问题是，存在一个<输入类型=文件/> 字段，该字段接受上载的文件。

I have a Delphi XE2 application with a TEmbeddedWB that I use to simulate user actions. The application navigates to a URL, populates the relevant form fields with data and submits the data. The problem is that there is an <input type=file /> field which accepts files that are uploaded.

我已经了解了很多有关此程序的安全性问题，但发现有人建议将文件拖出剪贴板并放置到位。此后，我已经成功地将相关文件（jpeg图像）加载到剪贴板中（感谢CCR.Clipboard）并将它们放到我的EmbeddedWB上。但是，正如您最可能知道的那样，将图像拖放到TWebBrowser上将导致所显示的图像出现。

Having done a lot of reading on the matter I understand there is a security issue doing this programmatically but also found someone making a suggestion that the files could be ‘dragged’ from the clipboard and ‘dropped’ in place. I have since been successful in loading the relevant files (jpeg images) into the clipboard (thanks to CCR.Clipboard) and drop them onto my EmbeddedWB. However, as you are most likely aware, dropping an image on a TWebBrowser resorts to the image being displayed.

我的问题是我正在访问的网页有一个接受要删除文件的特​​定DIV元素。尽管我已经成功获取了该DIV的坐标作为IHTMLElement，甚至将鼠标光标移到了位置（用于视觉确认），但是将图像放到那里仍然可以打开它进行显示，而不是上传它。好像放置区域无法检测到放置，只有Web浏览器可以检测到。

My issue is that the web page I’m accessing has a specific DIV element that accepts files to be dropped. Although I have successfully obtained the coordinates of that DIV as an IHTMLElement and even moved the mouse cursor into position (for visual confirmation), dropping an image there still opens it for display instead of uploading it. It’s as though the drop area doesn’t detect the drop, only the web browser does.

任何有关此问题的指导将不胜感激。以下是相关代码。

Any guidance on this matter will be greatly appreciated. Following is the relevant code.

方法：

type
  TElementsArray = array of IHTMLElement;
...
    function TSiteRobot.FindElementByTagAttributeValue(const Document: IHTMLDocument2; TagName, Attribute, AttributeValue: String; out Info: String): IHTMLElement;
    var i:            integer;
        HTMLElem:     IHTMLElement;
        ElementCount: integer;
        OleElem:      OleVariant;
        ElementsArray:  TElementsArray;
    begin
      Result := nil; //initialise
      ElementsArray := GetElementsByTagName(Document, TagName);
      if Length(ElementsArray) = 0 then
      begin
        Info := 'No elements with "'+TagName+'" tag found.';
        Exit
      end;
      Info := 'No element found for tag "'+TagName+'" and attribute "'+Attribute+'" with Value "'+AttributeValue+'"';
      for i := Low(ElementsArray) to High(ElementsArray) do
      begin
        HTMLElem := ElementsArray[i];
        try
          OleElem := HTMLElem.getAttribute(Attribute,0);
          if (not varIsClear(OleElem)) and (OleElem <> null) then
          begin
            if (String(OleElem) = AttributeValue) then
            begin
              if HTMLElem <> nil then Result := HTMLElem;
              Break;
            end;
          end;
        except raise; end;
      end;
    end;

    function TSiteRobot.GetElementScreenPos(WebBrowser: TEmbeddedWB; HTMLElement: IHTMLElement): TPoint;
    var WinRect:        TRect;
        elTop, elLeft:  integer;
        HTMLElem2:      IHTMLElement2;
    begin
      HTMLElement.scrollIntoView(True);
      Application.ProcessMessages; //let the coordinates get updated since the page moved
      GetWindowRect(WebBrowser.Handle, WinRect);
      HTMLElem2 := (HTMLElement as IHTMLElement2);
      elLeft  := HTMLElem2.getBoundingClientRect.left + WinRect.Left;
      elTop   := HTMLElem2.getBoundingClientRect.top + WinRect.Top;
      Result  := Point(elLeft, elTop);
    end;

    procedure TfrmMain.DropFilesAtPoint(Area: TPoint; Wnd: HWND);
    var DropTarget:     IDropTarget;
        DataObj:        IDataObject;
        DropFiles:      PDropFiles;
        StgMed:         TSTGMEDIUM;
        FormatEtc:      TFORMATETC;
        EnumFormatEtc:  IEnumFORMATETC;
        dwEffect:       integer;
    begin
      DropTarget := IDropTarget(GetProp(Wnd, 'OleDropTargetInterface'));
      OleGetClipboard(dataObj);
      DataObj.EnumFormatEtc(DATADIR_GET, EnumFormatEtc);
      while (EnumFormatEtc.Next(1, FormatEtc,  nil) <> S_FALSE) do
      begin
        if (FormatEtc.cfFormat = CF_HDROP) and (DataObj.QueryGetData(FormatEtc) = S_OK) then
        begin
          DataObj.GetData(FormatEtc, StgMed);
          DropFiles := GlobalLock(StgMed.hGlobal);
          dwEffect := DROPEFFECT_COPY;
          DropTarget.Drop(DataObj, Integer(DropFiles), Area, dwEffect); // This is where the image opens in the web browser
          GlobalFree(StgMed.hGlobal);
          ReleaseStgMedium(StgMed);
        end;
      end; //while
      DataObj._Release;
    end;

呼叫代码：

    var  HTMLElem: IHTMLElement;
         dndArea:  TPoint;
    …
    HTMLElem := SiteRobot.FindElementByTagAttributeValue(Document, 'SPAN', 'id', 'dndArea', Info);
    dndArea := SiteRobot.GetElementScreenPos(WebBrowser, HTMLElem);
    dndArea.X := dndArea.X+24; //go ‘deeper’ into the drop area
    dndArea.Y := dndArea.Y+24;
    SetCursorPos(dndArea.X, dndArea.Y); //cursor moves onto the correct spot in the website every time
    (HTMLElem as IHTMLElement2).focus;
    DropFilesAtPoint(dndArea, webBrowser.Handle);

推荐答案

我已经找到了有关此问题的解决方案。我没有使用剪贴板，而是背负了Melander的拖放PIDLDemo。向表单添加一个TListView组件，并使其具有将文件拖放到Shell的能力就可以了。使用Windows的MOUSE_EVENT，我可以（以编程方式）将文件从TListView拖动到正确位置的TEmbeddedWB上。快点！文件被接受并上传到网站。

I have come to a solution regarding this problem. Rather than using the clipboard, I piggy-backed on Melander’s drag-and-drop PIDLDemo. Adding a TListView component to the form and giving it the ability to drag-and-drop files to the shell does the trick. Using Windows' MOUSE_EVENT I am able to (programmatically) drag the files from the TListView and drop them onto the TEmbeddedWB at the correct location. Presto! The files are accepted and uploaded to the website.

现在调用代码如下：

function TfrmMain.GetMickey(val: TPoint): TPoint;
begin
  {
    http://delphi.xcjc.net/viewthread.php?tid=43193
    Mouse Coordinates given are in "Mickeys", where their are 65535 "Mickeys"
    to a screen's width.
  }
  Result.X := Round(val.X * (65535 / Screen.Width));
  Result.Y := Round(val.Y * (65535 / Screen.Height));
end;

procedure TfrmMain.DropFilesAtPoint(const Area: TPoint; Wnd: HWND);
var Rect:               TRect;
    DropPoint,
    ListViewPoint,
    ListViewItemPoint:  TPoint;
begin
  GetWindowRect(ListView1.Handle, Rect);
  ListViewItemPoint := ListView1.Items.Item[0].GetPosition;
  ListViewPoint := Point(Rect.Left + ListViewItemPoint.X+10, 
                         Rect.Top + ListViewItemPoint.Y+10);
  ListView1.SelectAll; //ensures all files are dragged together

  SetCursorPos(ListViewPoint.X, ListViewPoint.Y);
  ListViewPoint := GetMickey(ListViewPoint);
  MOUSE_EVENT(MOUSEEVENTF_LEFTDOWN, 
              ListViewPoint.X, ListViewPoint.Y, 0, 0); //left mouse button down
  Sleep(500);

  DropPoint := ClientToScreen(Area);
  DropPoint := GetMickey(DropPoint);
  MOUSE_EVENT(MOUSEEVENTF_ABSOLUTE or MOUSEEVENTF_MOVE or 
              MOUSEEVENTF_LEFTDOWN or MOUSEEVENTF_LEFTUP, 
              DropPoint.X, DropPoint.Y, 0, 0); //move and drop
  Application.ProcessMessages;
end;

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