1. Graphics and Multimedia
Lecture 9

2. Outline
Drawing Polygons and Polylines
Advanced Graphics Capabilities

3. Drawing Polygons and Polylines
Multisided shapes
Graphics methods used to draw polygons
DrawLines, DrawPolygon, and FillPolygon

4. Drawing Polygons and Polylines

5. Drawing a Triangle
Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
Dim myGraphics As Graphics = e.Graphics
Dim myPen As Pen
Dim A As New Point(10, 10)
Dim B As New Point(100, 50)
Dim C As New Point(60, 150)
Dim myPoints As Point() = {A, B, C}
myPen = New Pen(Drawing.Color.Blue, 5)
myGraphics.DrawPolygon(myPen, myPoints)
End Sub

6. Advanced Graphics Capabilities
Visual Basic offers many additional graphics capabilities
Examples
Brush hierarchy also includes:
HatchBrush, LinearGradientBrush, PathGradientBrush and TextureBrush
Additional graphics features
Dashed lines, thick lines, filling shapes with patterns, etc

7. Advanced Graphics Capabilities
Bitmap Class
Produce images in color and gray scale with a particular width and height.
Used to work with images defined by pixel data.
How to use…
Dim graphicsObject As Graphics = e.Graphics
Dim BitmapVar As Bitmap = New Bitmap(width, height) .
Dim BrushVar As TextureBrush = New TextureBrush(BitmapVar)
graphicsObject.FillRectangle(BrushVar, X, Y, width, height)

8. Texture Brush
Dim pts() As Point = { _ New Point(20, 5), _ New Point(100, 30), _ New Point(80, 100), _ New Point(120, 120), _ New Point(60, 140), _ New Point(5, 60) _ } ' Fill a polygon with a textured brush. e.Graphics.FillPolygon(New Drawing.TextureBrush(picFace.Image), pts) ' Make a pen. Dim a_pen As New Pen(Color.Tomato, 3) a_pen.DashStyle = Drawing.Drawing2D.DashStyle.Dash ' Outline the polygon. e.Graphics.DrawPolygon(a_pen, pts)