TTreeViewCanvas (Delphi)

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Description

The following code uses ClientRect to find and draw a line from the upper left to the lower right of the current control. Select a TControl in the ListBox list. This example assumes that the current object is a descendant of TControl and has a public Canvas property.

Code

  if (ListBox1.Items.Objects[Index] is TTreeView) then
  begin
    myTreeView:= (ListBox1.Items.Objects[Index] as TTreeView);
    with myTreeView.ClientRect do
    begin // Make sure you are using the canvas of the TControl, and not the from's canvas
      myTreeView.Canvas.MoveTo(Left, Top);
      myTreeView.Canvas.LineTo(Right, Bottom);
    end;
  myTreeView:= nil;
  end;

Uses