1 Graphic Device Interface (GDI)

2 Class Form A Form is a representation of any window displayed in your application. The Form class can be used to create standard, tool, borderless, and floating windows. The events of the Form class allow you to respond to actions performed on the form. You can use the Activated event to perform operations such as updating the data displayed in the controls of the form when the form is activated. You can use a form as the starting class in your application by placing a method called Main() in the class. In the Main() method add code to create and show the form.

3 Some Event functions of Form protected override void OnClick( EventArgs e ) protected override void OnKeyDown( KeyEventArgs e) protected override void OnMouseDown( MouseEventArgs e) protected override void OnMouseEnter( MouseEventArgs e) protected override void OnMouseHove( MouseEventArgs e) protected override void OnMouseMove( MouseEventArgs e) protected override void OnMouseUp( MouseEventArgs e) protected override void OnMouseLeave( MouseEventArgs e) protected override void OnPaint( PaintEventArgs e ) protected override void OnResize(EventArgs e) Note: EventArgs is parent class of all other *** EventArgs

4 Class Point Namespace: System.Drawing Constructor Point p = new Point(int x, int y ); x y

5 Class Rectangle Constructor Rectangle r = new Rectangle( Point( x, y ), Size( w, h )); Rectangle r = new Rectangle( int x, int y, int w, int h ); x y w h

6 class Color Some static Color objects Color.Red Color.Yellow Color.Blue Color object can be obtained from RGB formation Color c1 = Color.FromArgb(200, 128, 48); We also can use 0   255 to control color  means opaque,  means transparent    means half transparent  For example: Color c2 = Color.FromArgb( , c1); Color c2 = Color.FromArgb( , 200, 128, 48);

7 Class Pen Namespace: System.Drawing Pen object draws a line of specified width and style. Constructor Pen(Color object, int width); Pen p = new (Color.Red, 3) Some Pen objects can be got from class Pens Pens.Red Pens.Yellow Pens.Blue They all have width 1

8 Class Font Constructor Font( FontFamily family, float Size, FontStyle style ); Example Font f = new Font("Arial", 36, FontStyle.Bold|FontStyle.Italic );

9 Class Brush Namespace: System.Drawing Brush object used to fill the interiors of graphical shapes such as rectangles, ellipses, pies, polygons, and paths. This is an abstract class. Use derived classes such as : SolidBrush(Color object) TextureBrush(Image object) (In Namespace: System.Drawing.Drawing2D) LinearGradientBrush(Point1, Point1, Color1, Color2) HatchBrush(HatchStyle, Color1, Color2)

10 Class Graphics Namespace: System.Drawing The Graphics class provides methods for drawing objects to the display device. A Graphics object is associated with a specific device context, which means every Form has a built- in Graphics object. The following method is wrong: Graphics g = new Graphics()

11 Some Methods of Graphics public void DrawArc(Pen, Rectangle, float angle1, float angle2); public void DrawLine(Pen, Point p1, Point p2); public void DrawLine(Pen, int x1, int y1, int x2, int y2); public void DrawRectangle(Pen, Rectangle); public void DrawRectangle(Pen, int x, int y, int w, int h); public void DrawEllipse(Pen, Rectangle); public void DrawImage(Image, Point); public void DrawString(string, Font, Brush, Point); public void FillEllipse(Brush, Rectangle); public void FillRectangle(Brush, Rectangle);

12 Operations in OnPaint() All code inside OnPaint() will be executed when the application window is showing to the screen. protected override void OnPaint(PaintEventArgs e) { Graphics g = e.Graphics ; Pen blackPen = new Pen(Color.Black, 3); Rectangle rect = new Rectangle( 0, 0, 200, 100); g.DrawEllipse(blackPen, rect);

13 Pen redPen = new Pen(Color.Red, 3); Point p1 = new Point(150, 150); Point p2 = new Point(500, 300); g.DrawLine(redPen, p1, p2); g.FillEllipse(new SolidBrush(Color.FromArgb (180,Color.Green)), new Rectangle(50,50, 200,200)) ; g.FillRectangle(new SolidBrush(Color.Red), 20, 20, 50, 50); g.FillRectangle(new SolidBrush(Color.FromArgb(180, Color.Yellow)), 40, 40, 50, 50); HatchBrush hb= new HatchBrush(HatchStyle.ForwardDiagonal, Color.Green, Color.FromArgb(100, Color.Yellow)); g.FillEllipse(hb, 250, 10, 100, 100); Image newImage = Image.FromFile("dog.gif"); g.DrawImage(newImage, new Point( 300, 100));

14 string drawString = "UH Sugarland"; Font drawFont = new Font("Arial", 36, FontStyle.Bold|FontStyle.Italic ); SolidBrush drawBrush = new SolidBrush(Color.Red); PointF drawPoint = new Point(50, 300); g.DrawString(drawString, drawFont, drawBrush, drawPoint); LinearGradientBrush lb = new LinearGradientBrush ( new Point(200,200), new Point(400,300), Color.Yellow, Color.Blue); g.FillRectangle(lb, 200, 200, 200, 100); }

15 Output