Homework 4: Constraints & window management

Description

In this homework assignment, you are asked to implement some of the window managment techniques in the QuickSpace system (by Hutchings and Stasko) using constraints.  The techniques you must implement are the expand , friendly expand and shove operations.  More detail on QuickSpace and the full set of techniques can be found in the following papers:
http://www.gvu.gatech.edu/ii/space/hutchings-stasko-quickspace.pdf


The toolkit you must use to implement the following homework assignment is the subArctic toolkit (by Hudson and Smith).  While subArctic is a fully implemented GUI toolkit, you will only need to work with the portion of the toolkit that deals with constraints.  More information on this toolkit can be found at the following URL:
http://www.cc.gatech.edu/gvu/ui/sub_arctic


To minimize the amount of programming using subArctic you will need to be exposed to, we provide you with two Java files.  The quick_space.java file handles the reading of test case files, rendering it appropriately and invoking different method functions based on user input through the interface.  Rather than actually working with windows on the desktop, assume that the canvas rendered in the quick_space application is the desktop and the objects contained in it are the windows.  These objects are defined by the labeled_object.java file (you will not need to modify this file).

You are provided with different test cases (discussed in the remainder of this homework assignment):
    hw4-test1.txt
    hw4-test2.txt
    hw4-test3.txt

You can also create your own test cases.  The test file contains a description of the labeled_objects (representing windows) to render in the following format:
    object_name: x_position y_position width height

The quick_space application can be launched using the following command:    java quick_space test-filename

Each labeled_object described in the test file is added to the labeled_objects Vector (and you can access each of these objects through this Vector).


quick_space (figure 1)

Figure 1. The quick_space application, after it is launched and the child_2 labeled_object is given the focus.

Expand
Once the application has been launched, any labeled_object can be given the focus (see Figure 1, where child_2 is given the focus), different window management operations can be performed on that object --allowing it to consume more space on the desktop canvas.

The first operation expands an object in each direction until it encounters another object.  In Figure 2, child_2 is expanded to the right until it runs into child_3.  It expands to the bottom until it hits the parent's border.  It cannot expand to the left or to the top because of child_1.

expand

Figure 2. child_2 expanded to the right and to the bottom until it encounters child_3 and the bottom of the parent_obj's boundary.

To support this operation, you must implement the expand( ) method in the quick_space application.  This operation can be performed without the use of constraints.  It is recommended you implement this operation first to get accustomed with the quick_space.java and labeled_object.java files.

Friendly Expand
In a friendly expand, those components immediately touching the object with the focus (known as friends) can slide along with the focused object until the focused object or the friend encounters another object or the parent's boundary.  Referring to Figure 1, child_1 is a friend with child_2.  If a friendly expand is performed on Figure 1, again, child_2 expands to the right and to the bottom until it encounters child_3 and the parent_obj's boundary.  However, now it can expand to the left and to the top by sliding child_1 until the friend encounters the parent_obj's top and left boundaries (see Figure 3).

friendly expand

Figure 3. child_2 expanded to the right and to the bottom until it encounters child_3 and the bottom of the parent_obj 's boundary, but also slides it's friend (child_1) to the top and to the left until child_1 encounters the parent_obj's top and left boundaries.

Note that the friendly expand only affects the layout relationship between the object in focus and objects it overlaps.  If an object is overlapping two objects, that also overlap each other, these two friends do not necessarily need to remain overlapping after the friendly expansion is completed.

Also note, the portion of the amount of surface area the friend has exposed under the focused object remains the same after the friendly expansion is completed.  For example, if the focused object exists completely inside of a friend's borders by 30 pixels in  every direction, the friend is still larger than the focused object by 30 pixels in every direction after the friendly expansion.

To support this operation, you must implement the friendly_expand( ) method in the quick_space application.

Shove
During a shove, a focused object and its friends will grow to form neighborhoods.  When a new object is encountered, it becomes part of the focused object's neighborhood.  This new relationship allows the focused object to continue to grow in each direction until it or its friends or neighbors encounters the parent's boundary.

From Figure 3, after the friendly expansion, child_3 becomes child_2's neighbor.  The focus object can then shove this neighbor right until it touches the parent's right boundary (see Figure 4).

shove

Figure 4. child_2 shoves child_3 to the right.

Note, in this operation relationships can now exist between objects when they start touching.  Figure 5, shows child_1 expanding and shoving child_2 into child_3 and then child_4, continuing to shove these neighbors until child_3 touches child_5.  The shove is completed once child_5 touches the parent_obj's right boundary.

pre-shove     post-shove

Figure 5. child_1 expands and then shoves all the neighbors to the right.

Note, each neighbor may have friends that will need to be preserved.  In Figure 6, child_3 is a friend of child_2.  This relationship is preserved during the shove operation.

shove     shove

Figure 6. child_1 expands and then shoves all the neighbors to the right.  Note that friend relationship between child_2 and child_3 is preserved.

To support this operation, you must implement the shove( ) method in the quick_space application.

Deliverables

These techniques MUST be implemented  inside the provided quick_space.java file and should work with the included labeled_object.java file. You must use constraints in the friendly_expand( ) and shove( ) methods.

Please work on this homework assignment alone; please do not consult others.

This homework assignment should be done using the subArctic toolkit.
Please zip up your source code and mail the zip file to the TA ( khai@cc.gatech.edu ) when you have completed the assignment (and remember to CC yourself on the email).  Please include in the email instructions on how to run your application.

The due date and time for both parts of this assignment is:  October 7, 2002, 12:00 PM EST.