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CMPT 381 Assignment 2: Layout in JavaFX

Overview
You will build an interface using several JavaFX widgets and layout containers. You will also build a custom panel that does simulated
layout of a row of items. This assignment will demonstrate your ability to work with widgets and layout containers (and their APIs),
to implement basic elements of layout algorithms, and to implement simple 2D graphical representation of the layout simulation.
Part 1: An interface with basic layout
Build a simple interface using a BorderPane
layout that looks like the picture at right. The
interface must include:
 In the top area, a menu bar with three
menus, each containing ten items (choosing
a menu item does not have to do anything)
 In the right area, a list view with at least 25
items (i.e., so that the scroll bar is shown).
 In the bottom area, a label that fills the
width of the screen, and has the text
centred in the window. When the selection
changes in the list view, the selection is
shown in the label.
 In the left area, a FlowPane that contains 40
Circle objects (radius = 25) with random fill colours.
 In the centre area, a custom widget with a canvas draws a full-size white circle on a blue background. The custom widget should
use a similar approach to your custom widget from Assignment 1 (i.e., extend Pane, use a Canvas as a child of the custom class,
draw the blue background and circle using the canvas’s GraphicsContext object).
 When the window is resized, any extra space is given to the central area, and the canvas (and the circle) resizes.
Resources for part 1:
 Tutorial for JavaFX BorderPane and FlowPane: https://docs.oracle.com/javafx/2/layout/builtin_layouts.htm
 Tutorial for JavaFX ListView: https://docs.oracle.com/javafx/2/ui_controls/list-view.htm
 Tutorial for JavaFX menus: https://docs.oracle.com/javafx/2/ui_controls/menu_controls.htm
 Tutorial for the JavaFX Canvas: https://docs.oracle.com/javafx/2/canvas/jfxpub-canvas.htm
 An example layoutChildren() method for your custom widget (called by JavaFX when the window size changes) is:
@Override
public void layoutChildren() {
myCanvas.setWidth(this.getWidth());
myCanvas.setHeight(this.getHeight());
drawCanvasContents();
}
Part 2: Adding a layout simulator
In this part of the assignment you will add to the custom widget you built for the central panel of the BorderPane; the new version
of the widget will provide a live graphical simulation of a simple layout manager for a row of simulated widgets. An example is
shown in the figure below (and demonstrations of the working system will be shown in class).
Your custom widget will be a container widget that lays out a row of simulated widgets, as rectangles on a canvas. The container
responds to changes in the window’s size (use the same layoutChildren( ) method as above), and re-calculates the layout of the
simulated widgets with each change in size. In the examples below, three widgets have been added to the container (each with
different min, preferred, and max sizes, and each with different vertical position constraints.
Figure 2. Initial view of the layout simulator pane showing three simulated widgets, all at preferred size (and so are shown in green).
The left widget has a vertical position of centered, the middle widget has a vertical position of filled, and the right widget has a
vertical position of top. The white ovals indicate the bounds of the cells in the row.
Figure 3. View of the layout simulator after the window has been widened. The left widget’s max size means that it takes up the
available space (in purple because it is between preferred and max size); the middle and right widgets are at their max size (and so
are shown in blue).
Figure 4. View of the layout simulator after the window has been narrowed. All three widgets are at their minimum width, so the
pane clips the widgets at the right side. (The same behaviour occurs vertically: widgets are clipped when at their min height).
For the layout simulator, you will develop three main classes in addition to your application class:
 RowLayoutPane: a class that extends Pane and creates a canvas for showing the layout. The basic approach of this class is
similar to that used in part 1 (and in Assignment 1). In addition, the RowLayoutPane class will have methods for adding and
configuring a list of “widgets”, and doing the layout of these widgets. (See API specification below).
 RowCell: a class used to represent a rectangular region of the row-based layout. Each widget is positioned into a cell.
 Widget: a class to represent a simulated widget, with min, max, and preferred width and height.
Main RowLayoutPane methods (you may add others as needed, including constructors):
 addWidget(Widget w): adds a widget object to the list for this container, and creates a RowCell to hold the widget
 setVerticalPosition(Widget w, int position): sets the given widget’s vertical position as TOP, CENTER, or FILL
 doLayout(): calculates the positions and sizes of all widgets in the list
 drawRow(): draws the current layout to the canvas
Main RowCell methods:
 addWidget(Widget w): associates a widget object with this cell
 drawCell(GraphicsContext gc): draws an oval to indicate the bounds of this cell, then asks the widget to draw itself
 positionWidgetVertical(): sets the vertical position and height of the widget, given its positioning constraint
Main Widget methods:
 drawWidget(GraphicsContext gc): draws a rectangle to indicate the position and size of the widget. The rectangle is red if the
widget is at its min width, orange if between min and preferred width, green if at preferred width, purple if between preferred
and max width, and blue if at max width. In addition, draw lines from corner to corner (see figures above) to clearly show the
size of the widget rectangle.
 setMinSize(double newMinWidth, double newMinHeight): sets the widget’s min width and height
 setMaxSize(double newMaxWidth, double newMaxHeight): sets the widget’s max width and height
 setPrefSize(double newPrefWidth, double newPrefHeight): sets the widget’s preferred width and height
Notes on layout behaviour:
 Widget objects should be created and added to the RowLayoutPane from your application class
 the system should start up with all added widgets at their preferred width
 if all widgets are at their min width and the window gets smaller, the window should clip at the right side
 when the window gets wider, all widgets grow proportionally until they reach their max width
 if all widgets are at their max width, the canvas extends but the widgets do not change
 if vertical position is set to FILL, the widget’s pref and max height values are ignored
 when the window gets taller, only widgets with position of FILL should change height
 the widgets in the pictures above were created with the following values:
o left widget: setPrefSize(300,200); setMinSize(300,200); setMaxSize(Double.MAX_VALUE, Double.MAX_VALUE);
o middle widget: setPrefSize(300,400); setMinSize(250,200); setMaxSize(400,500);
o right widget: setPrefSize(00,200); setMinSize(100,200); setMaxSize(300,300);
Resources for part 2:
 General algorithms for a row-based layout container: Olsen text, pages 118-119.
This assignment is to be completed individually; each student will hand in an assignment.
What to hand in
 Java: a zip file of your NetBeans project folders for either part 1 (if that is as much as you have completed) or part 2. If you
have completed part 2, you do not have to hand in a project file for part 1.
 A readme.txt file that indicates exactly what the marker needs to do to run your code. (Systems for 381 should never
require the marker to install external libraries).
Where to hand in
Hand in your two files (one zip and one readme.txt) to the link on the course Moodle.
Evaluation
Marks will be given for producing a system that meets the requirements above, and compiles and runs without errors. Note that no
late assignments will be allowed, and no extensions will be given, without medical reasons.

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