private void btnParseQuery_Click(object sender, EventArgs e) { string inputString = txtSqlQuery.Text; var input = new ANTLRStringStream(inputString); var lexer = new EntityLexer(input); var tokens = new CommonTokenStream(lexer); var parser = new EntityParser(tokens); var result = parser.prog(); var tree = result.Tree; txtParseStringTree.Text = tree.ToStringTree(); var treeNodeDrawable = new ASTreeNode(tree); if (pictureBox1.Image != null) { pictureBox1.Image.Dispose(); pictureBox1.Image = null; } Image image = new VisualAST(treeNodeDrawable).Draw(); pictureBox1.Image = image; }