Chapter 18, Problem 18.39PE

Program Plan Intro

Drag the tree

Program Plan:

• Import required packages.
• Define the main class “E39” that extends the “Application” class.
  • The method “start ()” overrides the start method in the “Application” class.
    • Create a tree pane
    • Create a text field.
    • Set the depth.
    • Set the value of the property using “setPrefColumnCount (4)”.
    • Set the alignment to bottom right.
    • Create a HBox pane
    • Add the label and text field to the pane.
    • Set the hbox alignment to center.
    • Create a border pane
    • Set the pane to the center location.
    • Set the border pane at the bottom.
    • Create a scene and place it on the stage.
    • Display the stage using “show ()” method.
    • Set the width and height.
  • Declare a static class “TreePane” that extends Pane.
    • Declare required variables.
    • Give the constructor for this class.
      • Set the mouse handler
      • Call the function “paint ()”.
    • Function definition to set depth of the tree.
      • Set the depth and call the function “paint()”.
    • Give function definition for “paint ()”.
      • Clear the pane.
      • Check the condition “(startX == 0 && startY == 0)”.
        • Update the values.
      • Paint the branch by calling the function “paint_Branch ()”.
    • Give function definition for “paint_Branch ()”.
      • Check if the depth is greater than 0.
        • Calculate, create and add the line to the pane.
        • Draw the left branch of the tree.
        • Draw the right branch of the tree.
  • Declare a “main ()” function.
    • Launch the application.