VB 2008 Tutorial - Points, Sizes and Rectangles

Heres your chance to share your own tutorials with the community. Just post them on here. If your lucky they may even be posted on the main site.
4 posts Page 1 of 1
Contributors
User avatar
tvs praveen
Top Poster
Top Poster
Posts: 205
Joined: Tue Dec 08, 2009 6:20 am

Hi, Now i`m gonna show about Points, Sizes and Rectangles

A fundamental concept for any graphics system is the way that positions or sizes are represented. GDI+ uses specialist objects that enable you to specify a point in two dimensional space, a size or a complete rectangle having both location and size.
Points

Coordinates in GDI+ are represented by the Point or PointF structures. These both contain an X and Y member that hold the coordinates for the two axes of the drawing surface. Point structures store the values as integers and PointF structures store them as floating point values. Remember that GDI+ uses floating point values internally so the values in the Point structure will be interpreted by the drawing system as a float or a single for the purpose of creating the graphics.

Some drawing methods, such as DrawLine, are overloaded to accept either X,Y coordinate values or two Point or PointF structures as parameters. The following listing shows two line drawing directives that are functionally identical.
Code: Select all
myGraphics.DrawLine(Pens.Black,10,20,210,50);

Point p1=new Point(10,20);

Point p2=new Point(210,50);

myGraphics.DrawLine(Pens.Black,p1,p2);

myGraphics.DrawLine(Pens.Black,10,20,210,50)

Dim p1 As new Point(10,20)

Dim p2 As new Point(210,50)

myGraphics.DrawLine(Pens.Black,p1,p2)
You can see that the first line takes discrete values and the second directive takes points that were created earlier.
Sizes

Sizes in GDI+ are specified by Width and Height. Just like the Point and PointF, the size comes in two flavours, Size and SizeF with the first storing Width and Height as integers and the second storing them as floating point float or Single values.
Rectangles

Shapes drawn on GDI+ surfaces, such as ellipses or rectangles, are defined by their location which corresponds to the top-left corner of the shape and their width and height defined by a size structure. These two entities, Location and Size are most often used to create a single rectangle definition. Continuing the pattern seen in Points and Sizes, the rectangle too has integer and floating-point versions Rectangle and RectangleF. clapper;

Internally, the Rectangle stores the X and Y position of the top-left corner, the Width and the Height. These may be read or manipulated as Location and Size. The Rectangle will also return useful values such as Left, Right, Top and Bottom as individual values. :P

The code shown in listing 2 creates the effect shown in Figure 1.

Figure 1 [Screenshot of black and white checks made by GDI+ coding]

Image

You can make this checks using this code :)

Just copy and paste this code below Public Class Form1 and debug, You can see this black and white checks around a form ;)

You can make circles, squrea and more shapes with this code, You can change sizes of each checks, Colours and you can learn a lot to make GDI+ Points, Sizes and Rectangles wahooo;
Code: Select all
Private Sub Form1_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
        Dim smallSquareSize As New SizeF(0.1F * Me.ClientRectangle.Width, _
        0.1F * Me.ClientRectangle.Height)
        'create the brush
        Dim sb As New SolidBrush(Color.White)
        'toggle between black and white squares
        Dim toggle As Boolean = False
        'ten steps down
        Dim y As Integer
        For y = 0 To 9
            'ten steps across
            Dim x As Integer
            For x = 0 To 9
                'select the brush colour
                If toggle Then
                    sb.Color = Color.Black
                Else
                    sb.Color = Color.White
                End If 'create a rectangle
                Dim rc As New RectangleF(x * smallSquareSize.Width, _
       y * smallSquareSize.Height, smallSquareSize.Width, smallSquareSize.Height)
                'fill it with the colour
                e.Graphics.FillRectangle(sb, rc)
                'swop the colour
                toggle = Not toggle
            Next x
            'swop the colour at the line ends
            toggle = Not toggle
        Next y
        'recycle the brush
        sb.Dispose()
    End Sub 'Form1_Paint

*******************Thanks for reading my tutorial, I think this Tutorial will be most helpful to you!*******************

If you want any custom tutorial for you or you need any help in VS.NET, VB.NET, Software Coding, Designing and much more any help in Computer stuffs just ask me

Mostly i will help everyone in coding and design stuffs in on Computer

- Best regards hehaho;

- Tvs Praveen wahooo;

- Thanks CodeNStuff! for this amazing Website cooll;
Lewis
Coding God
Coding God
Posts: 1564
Joined: Sun Dec 20, 2009 2:12 pm

Another great tutorial!
Image
User avatar
Usman55
VIP - Site Partner
VIP - Site Partner
Posts: 2821
Joined: Thu Dec 24, 2009 7:52 pm

Great!
Image
Lewis
Coding God
Coding God
Posts: 1564
Joined: Sun Dec 20, 2009 2:12 pm

Checkers!!
Image
4 posts Page 1 of 1
Return to “Tutorials”