Data Structures with C Using STL

1
Data Structures with CUsing STL

• Chapter Thirteen
• Inheritance and Abstract
• Classes Example

2
EZDraw Functions

• // initialize drawing surface
• void openWindow()
• // wait until a key is pressed
• void viewWindow()
• // erase the drawing window
• void eraseWindow()
• // close the drawing surface
• void closeWindow()

3
EZDraw Functions

• // wait secs seconds before executing next
• // instruction
• void delayWindow(double secs)
• // return true if a key pressed else, return
  false
• bool keyPress()

4
Building a graphics system

• Graphics window

x
(0,0)
10 units
length
8 u n i t s
radius
y
width
Base point
Base point (x,y)
5
Shapes in graphics package

• Circle
• Rectangle
• Square
• Polygon

6
Common characteristics of shapes

• Base point - although the base point may be in
  different locations depending on the shape all
  shapes have one.
• Fill color - valid values are
• white blue teal green turquoise dark
  grey brown purple light blue light grey
  gold red orange pink yellow black

7
shapeColor Class

• include "d_draw.h"
• // colors of the shapes
• enum drawing_color
• white, blue, teal, green, turquoise, darkgray,
  brown, purple, lightblue, lightgray, gold, red,
  orange, pink, yellow, black

8
shapeColor Class - cont.

• // wrapper class for the colors
• class shapeColor
• private
• drawing_color color
• // table defining conversion from simple
  colors
• // to necessary Windows definitions
• static const ezdColor g_aColors

9
shapeColor Class - cont.

• public
• // constructor
• shapeColor(drawing_color c blue)
• // increment and decrement operators
• shapeColor operator (int)
• shapeColor operator ()
• shapeColor operator-- (int)
• shapeColor operator-- ()

10
shapeColor Class - cont.

• // relational operators
• friend bool operator (const shapeColor lhs,
• const
  shapeColor rhs)
• friend bool operator! (const shapeColor lhs,
• const
  shapeColor rhs) friend bool operatorlt (const
  shapeColor lhs,
• const shapeColor
  rhs)
• friend bool operatorlt (const shapeColor lhs,
• const
  shapeColor rhs)

11
shapeColor Class - cont.

• friend bool operatorgt (const shapeColor lhs,
• const
  shapeColor rhs)
• friend bool operatorgt (const shapeColor lhs,
• const
  shapeColor rhs)
• // convert to Windows definition for colors
• ezdColor convertToEzdColor()

12
Implementation of shapeColor Class

• // color conversion lookup table
• const ezdColor shapeColorg_aColors
• ezdWhite, ezdBlue, ezdTeal, ezdGreen,
  ezdTurquoise,
• ezdDarkGray, ezdBrown, ezdPurple,
  ezdLightBlue,
• ezdLightGray, ezdGold, ezdRed, ezdOrange,
  ezdPink,
• ezdYellow, ezdBlack

13
Implementation of shapeColor Class

• // constructor. initialize color
• shapeColorshapeColor(drawing_color c) color(c)
  
• // postfix increment
• shapeColor shapeColoroperator (int)
• drawing_color origColor color
• color drawing_color((color1) 16)
• return shapeColor(origColor)

14
Implementation of shapeColor Class

• // prefix increment
• shapeColor shapeColoroperator ()
• color drawing_color((color1) 16)
• return this
• // postfix decrement
• shapeColor shapeColoroperator-- (int)
• drawing_color origColor color
• if (color black) color white
• else color drawing_color(color-1) return
  shapeColor(origColor)

15
Implementation of shapeColor Class

• // prefix decrement
• shapeColor shapeColoroperator-- ()
• if (color black) color white
• else color drawing_color(color-1)
• return this
• // use lookup table to convert to Windows color
  definitions
• ezdColor shapeColorconvertToEzdColor()
• return g_aColorscolor

16
Implementation of shapeColor Class

• // relational operators
• bool operator (const shapeColor lhs,
• const shapeColor rhs)
• return lhs.color rhs.color
• bool operator! (const shapeColor lhs,
• const shapeColor rhs)
• return lhs.color ! rhs.color
• bool operatorlt (const shapeColor lhs,
• const shapeColor rhs)
• return lhs.color lt rhs.color

17
Implementation of shapeColor Class

• bool operatorlt (const shapeColor lhs,
• const shapeColor rhs)
• return lhs.color lt rhs.color
• bool operatorgt (const shapeColor lhs,
• const shapeColor rhs)
• return lhs.color gt rhs.color
• bool operatorgt (const shapeColor lhs,
• const shapeColor rhs)
• return lhs.color gt rhs.color

18
Hierarchy of shapes
19
Shape Class - base class

• // The graphics base class. Maintains the base
  point and fill
• // color. Has functions to access and change
  these
• // attributes. The graphics classes that draw
  specific
• // figures inherit this class.
• class shape
• protected
• double baseX, baseY // location of
  the base point
• shapeColor color // color of
  the shape
• EZDHANDLE shape_handle // handle to the
  shape

20
Shape Class - base class

• public
• // the arguments initialize the base point (x,y)
  and the
• // fill color c
• shape(double x, double y, shapeColor c)
• // virtual destructor may be necessary for
  derived class
• virtual shape()
• // returns the x coordinate of the base point
• double getX() const
• // returns the y coordinate of the base point
• double getY() const

21
Shape Class - base class

• // repositions the base point to the new
  coordinates (x,y)
• void move(double x, double y)
• // returns the current fill color for the figure
• shapeColor getColor() const
• // set the fill color of the figure to the value
  c from the
• // color palette
• void setColor(shapeColor c)
• // draw the shape. must be implemented in a
  derived class
• virtual void draw() 0

22
Shape Class - base class

• // removes the figure from the drawing surface
• void erase()
• // update the shape
• virtual void update()

23
Implementation of shape class

• // initialize basepoint coordinates and color.
  specify that no
• // shape has been drawn by setting shape_handle
  to 0
• shapeshape(double x, double y, shapeColor c)
• baseX(x), baseY(y), color(c),
  shape_handle(0)
• // shape class destructor
• shapeshape()
• // access base point
• double shapegetX() const
• return baseX
• double shapegetY() const
• return baseY

24
Implementation of shape class

• // retrieve shape color
• shapeColor shapegetColor() const
• return color
• // modify shape color
• void shapesetColor(shapeColor c)
• color c
• // change the position of the base point
• void shapemove(double x, double y)
• baseX x baseY y

25
Implementation of shape class

• void shapeerase()
• // shape_handle identifies the shape in the
  window.
• // the shape is defined if shape_handle is not 0
• if (shape_handle ! 0)
• ezdDeleteShape(shape_handle) // erase
  the shape
• shape_handle 0 // no shape
  defined
• void shapeupdate()
• erase()
• draw()

26
circleShape Class - Derived class

• include "d_shape.h"
• // declaration of circleShape class with base
  class shape
• class circleShape public shape
• private
• double radius // radius of the circle
• public
• // arguments for the base point, radius and
  color
• circleShape(double x 0.0, double y 0.0,
• double r 0.0, shapeColor c
  darkgray)

27
circleShape Class - Derived class

• // retrieve or set the radius
• double getRadius() const
• void setRadius(double r)
• // draw the circle
• virtual void draw()

28
Implementaton of circleShape

• // constructor
• circleShapecircleShape(double x, double y,
  double r,
• shapeColor c) shape(x,y,c),
  radius(r)
• // return value of private radius data
• double circleShapegetRadius() const
• return radius
• // change the radius value of the current object
• void circleShapesetRadius(double r)
• radius r // assign r as the new
  radius

29
Implementaton of circleShape

• // draw the circleShape with center at (x,y),
  given radius
• // and color
• void circleShapedraw()
• EZDCOLORVAL old_color
• old_color ezdSetColor(color.convertToEzdColor
  ())
• shape_handle ezdDrawCircle(baseX, baseY,
  radius)
• ezdSetColor(old_color)

30
rectShape Class - derived class

• include "d_shape.h"
• // declaration of rectShape class with base class
  shape
• class rectShape public shape
• private
• double length, width // rectangle
  dimensions
• public
• // constructor. has parameters for the base
  point,
• // length, width and color
• rectShape(double x 0.0, double y 0.0,
• double len 0.0, double
  wid 0.0,
• shapeColor c darkgray)

31
rectShape Class - derived class

• // retrieve or set rectangle dimensions
• double getLength() const
• double getWidth() const
• void setSides(double len, double wid)
• // draw the rectangle
• virtual void draw()

32
Implementation of rectShape

• // constructor
• rectShaperectShape(double x, double y, double
  len, double wid, shapeColor c) shape(x,y,c),
  length(len), width(wid)
• // retrieve length and width
• double rectShapegetLength() const
• return length
• double rectShapegetWidth() const
• return width

33
Implementation of rectShape

• // change size of rectangle
• void rectShapesetSides(double len, double wid)
• length len width wid
• void rectShapedraw()
• EZDCOLORVAL old_color
• old_color ezdSetColor(color.convertToEzdColor
  ())
• // execute primitive function and draw the
  rectangle
• shape_handle ezdDrawRectangle(baseX, baseY,
• 
  baseXlength,baseYwidth)
• ezdSetColor(old_color)

34
squareShape Class - derived class

• include "d_rectShape.h"
• // declaration of squaretShape class with base
  class rectshape
• class squareShapepublic rectShape
• public
• squareShape(double x 0.0, double y 0.0,
• double s 0.0,
  shapeColor c darkgray)
• // retrieve and store sides
• double getSides() const
• void setSides(double s)
• // draw the square
• virtual void draw()

35
Implement squareShape Class

• // constructor
• squareShapesquareShape(double x, double y,
  double s, shapeColor c) rectshape(x,y,s,s,c)
  
• // retrieve and store sides
• double squareShapegetSides() const
• return getLength()
• void squareShapesetSides(double s)
• setSides(s,s)
• // draw the square
• void squareShapedraw()
• rectShapedraw()

36
polyShape Class - derived class

• include ltvectorgt
• include ltcmathgt
• include "d_shape.h"
• // declaration of polygonShape class with base
  class shape
• class polyShape public shape
• private
• int numSides // number of sides
• double length // length of each side
• // x and y-coordinates of the vertices
• vectorltdoublegt point_X
• vectorltdoublegt point_Y
• void buildPoints() // construct the
  vertices

37
polyShape Class - derived class

• public
• // constructor. has arguments for the base
  point, number // of sides, the length of each
  side and the color
• polyShape(double x 0.0, double y 0.0, int n
  4, double len 0.0, shapeColor c
  darkgray)
• // retrieve or set length of a side
• double getLength() const
• void setLength(double len)

38
polyShape Class - derived class

• // retrieve or set number of sides
• int getN()
• void setN(int numsides)
• // draw the polygon
• virtual void draw()

39

• void polyShapebuildPoints()
• int side
• double theta, d
• const double PI 3.141592653589793,
• DELTA_THETA
  (2.0PI)/numSides
• // allocate space for the numSides coordinates
• point_X.resize(numSides)
• point_Y.resize(numSides)
• d length/(2.0sin(PI/numSides))
• theta 0.0
• for(side 0 side lt numSides side)
• point_Xside baseX dcos(theta)
• point_Yside baseY - dsin(theta)
• theta DELTA_THETA

40
Implementation of polyShape

• // initialize base class, the number of sides and
  the length
• // of each side
• polyShapepolyShape(double x, double y, int n,
  double len, shapeColor c) shape(x,y,c),
  numSides(n),
• length(len), point_X(0), point_Y(0)
• // retrieve the length of the sides
• double polyShapegetLength() const
• return length

41
Implementation of polyShape

• // change the length of a side
• void polyShapesetLength(double len)
• length len
• int polyShapegetN()
• return numSides
• void polyShapesetN(int n)
• numSides n

42
Implementation of polyShape

• void polyShapedraw()
• EZDCOLORVAL old_color
• // build the polygon's points and draw it
• buildPoints()
• old_color ezdSetColor(color.convertToEzdColor
  ())
• shape_handle ezdDrawPolygon(numSides,
  point_X0, point_Y0)
• ezdSetColor(old_color)

43
EZDraw functions

• include "ezdraw.h"
• void openWindow() // initialize drawing
  surface
• void viewWindow() // wait until a key is
  pressed
• void eraseWindow() // erase the drawing
  window
• void closeWindow() // close the drawing
  surface
• // wait secs seconds before executing next
  instruction
• void delayWindow(double secs)
• // return true if a key pressed otherwise,
  return false
• bool keyPress()

44
Program using graphics package

• include "squareshape.h" // squareShape class
• include "d_draw.h" // drawing functions
• int main()
• // begin with the large square at (2.5, 1.5),
  sides 5,
• // and color lightblue
• squareShape sq(2.5,1.5,5,lightblue)
• // use c to cycle through the colors
• shapeColor c lightblue
• // location and side of a square. set to the
  values
• // of the large square
• double x 2.5, y 1.5, side 5.0
• int i

45

• // create the drawing window
• openWindow()
• for (i0i lt 5i)
• sq.draw() // draw the current square shape
• c // move to the next color in the palette
• side - 1.0 // decrease the side by 1.0
• x 0.5 // increase x and y by 0.5
• y 0.5
• sq.setColor(c) // assign the new attributes
• sq.setSide(side)
• sq.move(x,y)
• viewWindow() // view the nested squares
• closeWindow() // close the window
• return 0