Accessing items in a TreeView of an external application

uses CommCtrl, StrUtils;
 
function GetTreeView(aHandle: THandle): TTreeView;
var
  Item: TTVItem;
  ItemId: HTreeItem;
begin
  Result := nil;
  ItemId := TreeView_GetRoot(aHandle);
  with Item do
  begin
    hItem := ItemId;
    mask := TVIF_PARAM;
  end;
  if TreeView_GetItem(aHandle, Item) then
    Result := TTreeView(TTreeNode(Item.lParam).TreeView);
end;
 
procedure TForm1.Button1Click(Sender: TObject);
var X: TTreeView;
begin
  X := GetTreeView(TreeView1.Handle);
  ShowMessage(IfThen(X.Selected <> nil, X.Selected.Text, 'nothing selected'));
end;

                                              

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function GetSelectedTreeItemV3(HwndTree) : TTreeView;
var
  TreeItem: TTVItem;
  ItemId: HTreeItem;
begin
  try
    FillChar(TreeItem, SizeOf(TreeItem), 0);
    result := nil;
    ItemId := TreeView_GetRoot(HwndTree);
    with TreeItem do
       begin
       mask := TVIF_PARAM;
       hItem := ItemId;
      end;
    if (TreeView_GetItem(HwndTree, TreeItem)) then
      begin
      UpdateLog('Successfull GetItem');
      result := TTreeView(TTreeNode(TreeItem.lParam).TreeView);
      end;
    else
      UpdateLog('Unsuccessful GetItem');
  except
    result := nil;
  end;
end;

                                              

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unit main;
 
interface
 
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, ComCtrls, ProcessMemory, CommCtrl;
 
type
  TForm1 = class(TForm)
    tvLocal: TTreeView;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
  private
    { Private declarations }
     FTreeMem:      TProcessMemory;
     FItem:         TProcessMemoryItem;
     FText:         TProcessMemoryItem;
  public
    { Public declarations }
     function       TreeItemHasChildren(hwndTree: HWND; RemoteNode: HTREEITEM): Boolean;
     function       TreeItemText(hwndTree: HWND; RemoteNode: HTREEITEM): String;
     procedure      LoadTreeItem(hwndTree: HWND; ParentNode: TTreeNode; RemoteParentNode, RemoteNode: HTREEITEM);
     function GetHwnd: Hwnd;
  end;
 
const
  TV_TEXTMAX        =  1024;
 
var
  Form1: TForm1;  
  WindowList : TList;   
 
implementation
 
{$R *.dfm}
 
procedure InitiateWindowsList;
begin
  WindowList := TList.Create;
end;
 
procedure ClosewindowsList;
begin
  WindowList.Free;
end;
 
function GetWindow (Handle: HWND; LParam: longint): bool; stdcall;
begin
  Result := true;
  { add each handle to the list }
  WindowList.Add (Pointer(Handle));
end;
 
procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
  ClosewindowsList;
end;
 
procedure TForm1.FormCreate(Sender: TObject);
begin
  InitiateWindowsList;
end;
 
procedure TForm1.LoadTreeItem(hwndTree: HWND; ParentNode: TTreeNode; RemoteParentNode, RemoteNode: HTREEITEM);
var  tvNode:        TTreeNode;
     htiChild:      HTREEITEM;
begin
 
  // Check remote node
  if Assigned(RemoteNode) then
  begin
     // Process messages
     Application.ProcessMessages;
     // Add local tree item
     tvNode:=tvLocal.Items.AddChild(ParentNode, TreeItemText(hwndTree, RemoteNode));
     // Determine if the tree item has children
     if (TreeItemHasChildren(hwndTree, RemoteNode)) then
     begin
        // Process messages
        Application.ProcessMessages;
        // Get first child
        htiChild:=TreeView_GetChild(hwndTree, RemoteNode);
        // Load the children
        while Assigned(htiChild) do
        begin
           // Load the child
           LoadTreeItem(hwndTree, tvNode, RemoteNode, htiChild);
           // Get next sibling
           htiChild:=TreeView_GetNextSibling(hwndTree, htiChild);
        end;
     end;
  end;
 
end;
 
function TForm1.TreeItemHasChildren(hwndTree: HWND; RemoteNode: HTREEITEM): Boolean;
var  tvItem:        TV_ITEM;
begin
 
  // Default result
  result:=False;
 
  // Check remote node
  if Assigned(RemoteNode) then
  begin
     // Clear local struct
     FillChar(tvItem, SizeOf(TV_ITEM), 0);
     // Set mask for what we want
     tvItem.mask:=TVIF_HANDLE or TVIF_CHILDREN;
     // Set handle
     tvItem.hItem:=RemoteNode;
     // Now copy local data to remote memory
     FItem.Write(tvItem, SizeOf(TV_ITEM));
     // Make the call
     if (SendMessage(hwndTree, TVM_GETITEM, 0, Integer(FItem.Memory)) <> 0) then
     begin
        // Copy the remote data back to local space
        Move(FItem.LocalMemory^, tvItem, SizeOf(TV_ITEM));
        // Now check the cChildren field of the struct (we wont deal with callbacks for child nodes)
        result:=(tvItem.cChildren = 1);
     end;
  end;
 
end;
 
function TForm1.TreeItemText(hwndTree: HWND; RemoteNode: HTREEITEM): String;
var  tvItem:        TV_ITEM;
begin
 
  // Default result
  result:='< Failure >';
 
  // Check remote node
  if Assigned(RemoteNode) then
  begin
     // Clear local struct
     FillChar(tvItem, SizeOf(TV_ITEM), 0);
     // Set mask for what we want
     tvItem.mask:=TVIF_HANDLE or TVIF_TEXT;
     // Set handle
     tvItem.hItem:=RemoteNode;
     // Set remote text pointer
     tvItem.pszText:=FText.Memory;
     tvItem.cchTextMax:=TV_TEXTMAX;
     // Now copy local data to remote memory
     FItem.Write(tvItem, SizeOf(TV_ITEM));
     // Make the call
     if (SendMessage(hwndTree, TVM_GETITEM, 0, Integer(FItem.Memory)) <> 0) then
     begin
        // We now need to get the string data which has been filled in on the remote side
        SetString(result, PChar(FText.LocalMemory), StrLen(FText.LocalMemory));
     end;
  end;
 
end;
 
procedure TForm1.Button1Click(Sender: TObject);
var
  hwndTree:      HWND;
  htiRoot:       HTREEITEM;
  htiNext:       HTREEITEM;
begin
  hwndTree := GetHwnd;
  tvLocal.Items.BeginUpdate;
  // Resource protection
  try
     // Clear items
     tvLocal.Items.Clear;
     // Convert string to window handle
     //hwndTree:=StrToIntDef(txtHwnd.Text, 0);
     // Check window
     if IsWindow(hwndTree) then
     begin
        // Attempt to get the root item
        htiRoot:=TreeView_GetRoot(hwndTree);
        // Check the root
        if Assigned(htiRoot) then
        begin
           // Create remote memory handler
           FTreeMem:=TProcessMemory.CreateFromHwnd(hwndTree);
           // Resource protection
           try
              // Allocate remote memory for getting tree item data
              FItem:=FTreeMem[FTreeMem.Add(SizeOf(TV_ITEM))];
              // Allocate remote memory for getting tree item text
              FText:=FTreeMem[FTreeMem.Add(TV_TEXTMAX)];
              // Seed load
              htiNext:=htiRoot;
              // While next
              while Assigned(htiNext) do
              begin
                 // Recursively load the tree items
                 LoadTreeItem(hwndTree, nil, nil, htiRoot);
                 // Get next
                 htiNext:=TreeView_GetNextSibling(hwndTree, htiNext);
              end;
           finally
              // Free and nil
              FreeAndNil(FTreeMem);
           end;
        end
        else
           // Failed to get root
           tvLocal.Items.Add(nil, '< Failed to get the root item >');
     end
     else
        // Not a valid window
        tvLocal.Items.Add(nil, '< Not a valid window handle >');
  finally
     // Unlock the tree
     tvLocal.Items.EndUpdate;
  end;
 
end;
 
function TForm1.GetHwnd : Hwnd;
var
  HwndPOS, HwndPOSChild : HWND;
  Buffer: array [0..255] of char;
  i : Integer;
begin
  WindowList.Clear;
  EnumWindows (@GetWindow, 0);
  // Lock the tree
    for i := 0 to WindowList.Count - 1 do begin
      HwndPOS := HWND (WindowList [i]);
      if IsWindowVisible (HwndPOS) then begin
        GetWindowText (HwndPOS, Buffer, SizeOf (Buffer) - 1);
        if Buffer [0] <> #0 then //if not empty
          if StrPas(Buffer) = 'TreeViewTest' then
            begin
            HwndPOSChild := FindWindowEx(HwndPOS, 0, 'TPanel', nil);
            if HwndPOSChild > 0 then
              begin
              HwndPOSChild := FindWindowEx(HwndPOSChild, 0, 'TTreeView', nil);  //Media Tree
              if HwndPOSChild > 0 then
                begin
                result := HwndPOSChild;//we found our TTreeView;
                exit;
                end;
              end;
            end;
      end;
    end;
end;
 
end.

                                              

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