COMP 106

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COMP 106

• Review- C IDE
• The IDE
• Form
• Steps in making a program in C
• The Compute Salary Program

• Object-Orientation
• Object
• Class
• Properties and Methods
• C classes in Microsoft .NET framework

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COMP 106

• Introductory Graphics
• First Drawing program
• Common Methods to draw
• Assignment 1 (10 marks)

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IDE
Menu bar
Form
Toolbox
Solution Explorer
Properties
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Code window
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Program run
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A misspelled word in your code/instructions will
cause the compiler to display an error message
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When semi-colon is removed, the compiler says
expected
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What is an object

• an entity which has properties/variables/fields
• an entity which has methods- an action to be done
  by the object

properties
make size color date_manufactured date_shipped
methods
boot repair shutdown connect_to_net print
A Dell computer
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What is a class

• A class set of objects that share the same
  properties and methods

HP
Dell
Compaq
class computer
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Pop quiz ?

• Give me a class name of the following objects

Angelina
Bradd
Catherine
.5 bonus point to be added to your midterm test
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Pop quiz ?

• Give me some properties for the class Actor

class celebrity
methods
properties
screen_name real_name dateofbirth gross_income
hire sign_contract act takeholiday resign
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• An object is an instance of a class

className objectName new className

• To create an object from a class,

Example
Computer Dell new Computer
Pen pen new Pen(Color.Black)
How would you create objects Angelina? Bradd?
Catherine?
Celebrity Angelinenew Celebrity
Celebrity Braddnew Celebrity
Celebrity Catherinenew Celebrity
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• In C, the standard format to get the value of
  the property is

data object.propertyname
Example
its_color Dell.color c pen.Color
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• To set the value of the property,

object.propertyname data
Example
Dell.colorred pen.color black
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• To call or invoke the method of the object

object.methodname(arguments)
Example
Dell.Repair() Dell.Sell() Brad.Hire() Catherine
.Resign()
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Introductory Graphics

• C has existing classes buttons, labels, forms,
  etc
• The Microsoft .NET framework has hundreds of
  classes
• Programmers can make use of classes to
  instantiate objects

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Drawing..

• What object do we need?

• paper
• pen

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Lets draw a rectangle

• paper.DrawRectangle(pen to use, rectangle
  position, etc)

We invoke or call the method DrawRectangle
of object paper.
Arguments or parameters needed to make a rectangle
The method is called by placing a dot . between
the object name and the method
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Actual code to draw a rectangle..

• Draw a button, a picturebox inthe form
• Double click the button
• Enter the following code

Graphics paper paper
pictureBox1.CreateGraphics() Pen pen new
Pen(Color.Black) paper.DrawRectangle(pen
, 10,10,100,50) paper.DrawRectangle(pen,
10,75,100,100)
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Pixel coordinate in C
horizontal
form
picture box
0,0
vertical
100
0,0
200
shape in picture box
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Output after running the program
paper.DrawRectangle(pen, 10,10,100,50)
paper.DrawRectangle(pen, 10,75,100,100)
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C provides facilities to draw shapes

• lines
• ellipses (i.e. ovals,circles)
• filled rectangles and ellipses
• images from files.

You can change the color of the pens and use
brushes of a chosen color to fill shapes
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Methods for drawing shapes, lines, etc

• DrawRectangle
• a pen object
• the horizontal value of the top edge corner of
  the rectangle
• the vertical value of the top left corner of the
  rectangle
• the width of the rectangle
• the height of the rectangle

• DrawLine
• a pen object
• the horizontal value of the start of the line
• the vertical value of the start of the line
• the horizontal value of the end of the line
• the vertical value of the end of the line
• paper.Drawline(pen, 0,0,10,10)

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• DrawEllipse imagine the ellipse as an oval
  squeezed inside a rectangle
• a pen object
• the horizontal value of the top edge corner of
  the rectangle
• the vertical value of the top left corner of the
  rectangle
• the width of the rectangle
• the height of the rectangle

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• FillRectangle needs a brush object instead of a
  pen
• A brush object
• the horizontal value of the top edge corner of
  the rectangle
• the vertical value of the top left corner of the
  rectangle
• the width of the rectangle
• the height of the rectangle

Solidbrush myBrush new Solidbrush(Color.black)
paper.FillRectangle(myBrush,10,10,90,90)
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• DrawImage use to display a JPG or bitmap file
• A bitmap object containing an image from a file
• the horizontal value of the top edge corner of
  the rectangle
• the vertical value of the top left corner of the
  rectangle
• the width of the rectangle
• the height of the rectangle

Example code
Bitmap pic new Bitmap(_at_c\myphoto.jpg) paper.
DrawImage(pic,130,10,150,150)
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Assignment 1
Due date Friday, 18 Jan. email your program to
rtg4_at_cs.waikato.ac.nz

• Make a program that will draw the outer view of
  your flat/house. (put a picture of your own
  outside the house)
• Make a program that will draw the eye-birds
  (inner) view of your flat/house . Include
  appliances and furniture only. (shapes does not
  need to be filled with colors)