1 Chapter 26 D&D – Graphics Outline 26.1 Introduction 26.3 Graphics Contexts and Graphics Objects 26.4 Color Control 26.5 Font Control 26.6 Drawing Lines, Rectangles and Ovals 26.8 Drawing Polygons and Polylines Loading, Displaying and Scaling Images Animating a Series of Images

Introduction Graphical Device Interface –Two dimensional vector graphics Drawing capabilities –Pen or Brush object –Structure Color –Positioning in x,y coordinate system

Introduction Fig System.Drawing namespace’s classes and structures. structure class key System.Drawing Font FontFamily Graphics Icon Pen Region SolidBrush TextureBrush Image Brush HatchBrush LinearGradientBrush PathGradientBrush SolidBrush TextureBrush Color Point Rectangle Size

Graphics Contexts and Graphics Objects Fig. 26.2GDI+ coordinate system. Units are measured in pixels. x-axis y-axis (0, 0) +x +y (x, y)

Graphics Contexts and Graphics Objects Graphics context –Drawing surface Graphics object –control how information is drawn –Virtual OnPaint event handler –Method Invalidate Refreshes and repaints

Color Control Enhancing program appearance –Structure Color ARGB values Value range from 0 to 255 Run UsingColors.cs

ColorDialog // Create ColorDialog object private static ColorDialog myColorChooser = new ColorDialog(); //get chosen color DialogResult result = myColorChooser.ShowDialog(); if (result != DialogResult.Cancel) { // assign something’s color to result of dialog something’s color = myColorChooser.Color; } Demo UsingComplexColors 7

Font Control Methods and constants of font control –Creating Font Font’s metrics: –height, decent, ascent and leading Once created properties cannot be modified –Size property Return font size measured in design units xy1 Õ descent baseline ascent leading height Fig An illustration of font metrics.

Drawing Shapes: Lines, Rectangles and Ovals Graphics methods –Use for drawing lines, rectangles and ovals Shape outlines take Pen Solid shapes take Brush Int argument represent coordinates Last two int argument are for width and height Fig Ellipse bounded by a rectangle. (x, y) height width

Drawing Lines, Rectangles, and Ovals

11 LinesRectanglesO vals.cs 1 // Fig : LinesRectanglesOvals.cs 2 // Demonstrating lines, rectangles and ovals. 3 4 using System; 5 using System.Drawing; 6 using System.Collections; 7 using System.ComponentModel; 8 using System.Windows.Forms; 9 using System.Data; // draws shapes on the Form 12 public partial class LinesRectanglesOvals : Form 13 { 26 public LinesRectanglesOvals () 18 { 19 InitializeComponent(); 20 } 24 protected override void OnPaint( 25 PaintEventArgs paintEvent ) 26 { 27 // get graphics object 28 Graphics g = paintEvent.Graphics; 29 SolidBrush brush = new SolidBrush( Color.Blue ); 30 Pen pen = new Pen( Color.AliceBlue ); // create filled rectangle 33 g.FillRectangle( brush, 90, 30, 150, 90 ); 34 Drawing rectangle on the screen Drawing objectCoordinates for bounding rectangle Rectangle’s width and height

12 LinesRectanglesO vals.cs Program Output 35 // draw lines to connect rectangles 36 g.DrawLine( pen, 90, 30, 110, 40 ); 37 g.DrawLine( pen, 90, 120, 110, 130 ); 38 g.DrawLine( pen, 240, 30, 260, 40 ); 39 g.DrawLine( pen, 240, 120, 260, 130 ); // draw top rectangle 42 g.DrawRectangle( pen, 110, 40, 150, 90 ); // set brush to red 45 brush.Color = Color.Red; // draw base Ellipse 48 g.FillEllipse( brush, 280, 75, 100, 50 ); // draw connecting lines 51 g.DrawLine( pen, 380, 55, 380, 100 ); 52 g.DrawLine( pen, 280, 55, 280, 100 ); // draw Ellipse outline 55 g.DrawEllipse( pen, 280, 30, 100, 50 ); } // end method OnPaint } // end class LinesRectanglesOvals DrawLine takes a Pen and two pairs of ints Start and end point of the line Uses pen object to draw Overloaded methods DrawEllipse and FillEllipse Specify drawing objectCoordinates of the bounding rectangle for the ellipse Bounding rectangle’s width and height

Drawing Polygons and Polylines Polygons –Multisided shapes –DrawLines Series of connected points –DrawPolygon Closed polygon –FillPolygon Solid polygon

Drawing Polygons and Polylines

15 DrawPolygons.cs Program Output

Loading, Displaying and Scaling Images C#’s multimedia capabilities –Graphics –Images –Animations –video

17 DisplayLogoForm. cs

18 DisplayLogoForm. cs 1 // Fig : DisplayLogoForm.cs 2 // Displaying and resizing an image. 3 4 using System; 5 using System.Drawing; 6 using System.Collections; 7 using System.ComponentModel; 8 using System.Windows.Forms; 9 using System.Data; 14 private System.Windows.Forms.Button setButton; 15 private System.Windows.Forms.TextBox heightTextBox; 16 private System.Windows.Forms.Label heightLabel; 26 private System.Windows.Forms.TextBox widthTextBox; 18 private System.Windows.Forms.Label widthLabel; // displays an image and allows the user to resize it 12 public partial class DisplayLogoForm : Form 13 { 23 private Image image = Image.FromFile( "images/Logo.gif" ); 25 private Graphics graphicsObject; public DisplayLogoForm() 28 { 29 InitializeComponent(); graphicsObject = this.CreateGraphics(); 32 } 33 image is assign through method FromFile Method CreateGraphics to create a Graphics object associated with the Form

19 DisplayLogoForm. cs 42 private void setButton_Click( 43 object sender, System.EventArgs e ) 44 { 45 // get user input 46 int width = Convert.ToInt32( widthTextBox.Text ); 47 int height = Convert.ToInt32( heightTextBox.Text ); // if dimensions specified are too large 50 // display problem 51 if ( width > 375 || height > 225 ) 52 { 53 MessageBox.Show( "Height or Width too large" ); return; 56 } // clear Windows Form 59 graphicsObject.Clear( this.BackColor ); // draw image 62 graphicsObject.DrawImage( 63 image, 5, 5, width, height ); } // end method setButton_Click } // end class DisplayLogoForm When user select Set, test to validate they are in acceptable range Method Clear to paint entire Form in current background color Graphics method DrawImage is called to display image

Animating a Series of Images Animate series of images from an array Collision detection Regional invalidation

21 LogoAnimator.cs 1 // Fig : LogoAnimator.cs 2 // Program that animates a series of images. 3 4 using System; 5 using System.Drawing; 6 using System.Collections; 7 using System.ComponentModel; 8 using System.Windows.Forms; 9 using System.Data; private System.Windows.Forms.PictureBox logoPictureBox; 15 private System.Windows.Forms.Timer Timer; 16 private System.ComponentModel.IContainer components; 11 // animates a series of 30 images 12 public private class LogoAnimator : Form 13{ 18 private ArrayList images = new ArrayList(); 19 private int count = -1; public LogoAnimator() 22 { 23 InitializeComponent(); for ( int i = 0; i < 30; i++ ) 26 images.Add( Image.FromFile( "images/deitel" + i + 27 ".gif" ) ); // load first image 30 logoPictureBox.Image = ( Image ) images[ 0 ]; // set PictureBox to be the same size as Image 33 logoPictureBox.Size = logoPictureBox.Image.Size; } // end constructor PictureBox contain images to animate Timer to cycle through the image Count keeps track of current image Load each of 30 images and store in an ArrayList Places first image in the PictureBox Modify size if PictureBox to equal size of Image

22 45 private void Timer_Tick( 46 object sender, System.EventArgs e ) 47 { 48 // increment counter 49 count = ( count + 1 ) % 30; // load next image 52 logoPictureBox.Image = ( Image )images[count ]; } // end method Timer_Tick } // end class LogoAnimator LogoAnimator.cs Program Output