Create an Aquarium using graphics.^*

• Copy the Graphics Demo project you created in the Lab Entrance Assignment and the AquaFish folder (from the Creating Fish in An Aquarium Mini-Lab) from your floppy to the Temp folder on the C: drive. Open the Graphics Demo project (graphics-prj).

• Double-click on ABhouse.cpp in the project window to open it for editing. Immediately do a Save As (under the File menu) to create a new file in which you will draw an aquarium instead of a house. Make sure that the name of your new file ends in ".cpp", for example "newfile.cpp". Notice that the project will now list your new file rather than ABhouse.cpp. You can run the project, if you like, to see that CodeWarrior will now compile the project with the new file. Since the new file is still identical to ABhouse.cpp, you should get the same results as before.

• Modify your new main function to draw an aquarium rather than a house. The aquarium should have visible left and right walls and a visible bottom, but no line across the top.
  HINT: Modify the house body to become the water in the aquarium. You may use DEEPSKYBLUE for the water color, or you can test various colors from the colors.h file in the CMU graphics library. Use the roof lines of the house as a template for drawing the three walls of the aquarium. You can remove all references to the doors and windows, but be sure NOT to remove the call to function WaitNClear at the bottom of main. You can also remove any references to the midpoint of the house or aquarium, since you no longer need this.
  You may wish to run the program after each substantive change you make to see (and correct) the results, rather than wait until you have made many changes to discover that the program won't even compile.

• You may wish to print your program at this point. Remove the object code from the project (there is an option under the Project Menu to do this), so that you will be able to copy the folder to your floppy later. Do NOT, however, remove the Graphics Demo folder from the Temp folder on the C: drive yet, as you will be using it again.

Switch to a graphical display in the Aquarium program.⁺

• Open the "AquaGraphics" project in your AquaFish folder in Temp.

• In the CodeWarrior project window, double-click on the display.h file in the Aquarium folder. Modify the file to:
  • Uncomment the #include statement for the CMU graphics library.
  • Move the comments around the constructors so that the one-parameter constructor is commented out and the constructor that knows about a graphics window is not commented out.
  • Uncomment the lines that represent, according to the comment above them, "private data members used for graphical display only." We will explore what these lines do in a later lab.
  Save your changes to display.h.

• In the CodeWarrior project window, double-click on the file containing the main function. Modify the file to:
  • Add a #include statement to include waitnclear.h.
  • Construct a graphics window object by copying and pasting the appropriate line from the main function you created above into your Aquarium main function before the statements that construct the aquarium and the display.
  • Review the change to the Display constructor in your display.h file. Change the way you create the Display variable in main to correspond to the constructor declaration in the interface.
  • Copy and paste the lines that set the window title and adjust the "WaitClose" property of a window from the main function you created above into your Aquarium main function.
  • Add a call to WaitNClear after each set of display statements in main. (You no longer need to print an extra newline after displaying the initial configuration of fish.)

• Note that the file called display.cpp in the project has been replaced with a file called grdisplay.cpp. This file contains the graphics-based implementation of the Display class.

• Test your changes to the Aquarium demonstration program. You should see the three fish move on an empty white background. (You may sometimes see fewer fish if two or more fish were created in the same location.)

Add a graphical aquarium to the Aquarium program.⁺

• The obvious place to add the graphics code for displaying the aquarium is in the ShowAquarium function in the Display class. We have not yet seen how to implement class member functions, however, so for now we will write the code to display the aquarium as client code in a free function, one that is not tied to any particular object or class. A skeleton version of this free function, called TempShowAquarium because we will remove it in a later lab, can be found at the very bottom of grdisplay.cpp. You will be adding a modified version of the code produced in the first part of this lab to this function.

• Open the grdisplay.cpp file in the Aquarium folder. Scroll down to the bottom, where you will find the skeleton implementation of the TempShowAquarium function.

• Copy and paste the code you wrote in the first part of this lab for drawing the aquarium water and walls (but not the code for creating the window or calling WaitNClear) into TempShowAquarium.

• Note that the names of the values available to you are slightly different. More importantly, you have not been given the pixel width and height of the Aquarium as constants. Research the interface for Aquarium to discover how to determine the height and width of an aquarium. These are not the pixel width and height of an aquarium when displayed, however. The pixel width of the graphical display of the Aquarium should be proportional to the width of the Aquarium, not exactly the same as it. You should use local variables provided in TempShowAquarium, in conjunction with the width and height of the aquarium, to calculate aquaRight and aquaBottom.

• Adjust the names of the arguments to DrawRectangle and DrawLine to use the actual variables available to you in the TempShowAquarium function.

• Research the Display interface to determine how to display an aquarium. In your main function, add a command that displays the aquarium at the beginning of each sequence of fish display statements.

• Now run the program (CodeWarrior will automatically do any necessary compilation and linking) and make sure that it works.

Print and save your modifications.

• Print out your modified versions of grdisplay.cpp and the main function. Remove the object code from the project (there is an option under the Project Menu to do this). You may also need to remove the executable file(s) from both the Graphics Demo and AquaFish folders (named GraphicsApp ..., unless you changed the name of the Target File) to fit everything on your floppy disk. Copy the Graphics Demo and AquaFish folders from the Temp folder to your floppy disk. You should then remove the folders from the Temp folder on the C: drive.

• Be sure to turn in the printouts of the modified grdisplay.cpp file and your modified main function.

^*The CMU Graphics Library was created by the Carnegie Mellon University School of Computer Science and is used in their introductory programming courses. It is available from Mark Stehlik's Advanced Placement page.

⁺The Aquarium series of labs is loosely based on the Advanced Placement Computer Science Marine Biology Simulation Case Study, available from the College Board for face-to-face teaching purposes.