execcommand

This example shows how to use the execCommand and pasteHTML method to put an alternative text to an image in TWebBrowser control in Delphi.

procedure TForm1.Button1Click(Sender: TObject);
var
  HtmlDoc: IHTMLDocument2;
  HtmlSelObj: IHTMLSelectionObject;
  HtmlTxtRng: IHTMLTxtRange;
begin
  HtmlDoc := WebBrowser1.Document as IHTMLDocument2;
  HtmlDoc.execCommand('InsertImage', False, '');
  HtmlSelObj := HtmlDoc.selection;
  if HtmlSelObj.type_ = 'Control' then
    HtmlSelObj.Clear;
  HtmlTxtRng := HtmlSelObj.createRange as IHTMLTxtRange;
  HtmlTxtRng.pasteHTML('This is the alternative text ');
end;

Note that the function HtmlDoc.execCommand('InsertImage', False, ''), when the second parameter is set to true, the TWebBrowser document will prompt a dialog for select an image to insert.