Draw a Circle in Asp.net

Introduction

Welcome to the second (and most probable, the concluding) installment of my resizing Drawn objects series. In Part 1, "Creating Resizable Drawings in Visual Basic.Cyberspace, Part 1: Rectangles," I covered how to set things upward nicely so that you accept a resizable Rectangular object. Today, I volition take it a step farther and show you how to resize circular shapes and odd shapes.

Luckily, there are a lot of similarities from the previous installment, but manifestly there is still some work ahead. Let's get started!

If yous haven't still read the first part, delight practice then. The first part also contains all the code every bit well as a downloadable file containing the code. You lot volition need this project for this article.

Let's start with the new design. Design your project to resemble Figure 1.

Figure i: New Blueprint

I take enlarged the PictureBox area and added three buttons. The buttons will be used for Rectangle, Circumvolve, and Odd Shape, respectively.

Add a new Component to your projection. Name it something practical, such as clsMain, for example. Add together the following code into clsMain:

          Public Enum Shape       Rect       Circle       Odd     End Enum        

This Enum simply represents the blazon of object to be drawn. Move the NodePos Enum from clsObject to clsMain:

          Public Enum NodePos        TopLeft       TopMiddle       TopRight        BottomLeft       BottomMiddle       BottomRight        LeftMiddle       RightMiddle        None     End Enum        

This identifies the position of the Nodes on the drawn object. Your whole clsMain now should look like the following:

Public Class clsMain    Public Enum Shape       Rect       Circle       Odd     Finish Enum     Public Enum NodePos        TopLeft       TopMiddle       TopRight        BottomLeft       BottomMiddle       BottomRight        LeftMiddle        RightMiddle        None     Terminate Enum   Terminate Class        

The move was needed considering these two Enums volition be used from inside the Object class besides as the class.

Figure 2: Add together Component

You now need to import this course into both:

clsObject

Imports ResizableObject_HTG.clsMain

All the imports for clsObject should include the following:

Imports Organization.Drawing.Drawing2D Imports ResizableObject_HTG.clsMain        

frmResizeObject

Imports ResizableObject_HTG.clsMain

Add the following variables to clsObject:

          Individual shShape As Shape    Private grShape As Graphics        

shShape will identify the shape you want to describe, and grShape is a Graphics object to draw with. Edit your clsObject's constructor to include more parameters:

Public Sub New(ByVal rctTemp Every bit Rectangle,          ByVal sh Every bit Shape, _       ByVal moving-picture show As PictureBox)     rectObject = rctTemp          shShape = sh          blnClick = False     Me.picObject = moving-picture show     AddHandler picObject.MouseDown, AddressOf picObject_MouseDown    AddHandler picObject.MouseMove, AddressOf picObject_MouseMove    AddHandler picObject.MouseUp, AddressOf picObject_MouseUp          'AddHandler picObject.Paint, AddressOf picObject_Paint'          Try          grShape = pic.CreateGraphics()          Create(grShape, shShape)          Grab ex Every bit Exception        MessageBox.Evidence(ex.Message)     End Try  End Sub        

I have added the Shape and then that information technology can be instantiated when this grade gets called. Besides, I accept removed the Pigment event handler, because you lot will be using the grShape graphics object to draw. Edit the Create Sub to also include the Shape parameter:

          Public Sub Create(ByVal thou Every bit Graphics, sh Equally Shape)          Select Example sh          Case Shape.Rect          one thousand.DrawRectangle(New Pen(Color.Green), rectObject)          Instance Shape.Circle          g.DrawEllipse(New Pen(Colour.Orangish), rectObject)          Case Shape.Odd          DrawSpiral(g)          End Select          For Each npPos As NodePos In             [Enum].GetValues(GetType(NodePos))           g.DrawRectangle(New Pen(Color.Blue), GetObject(npPos))        Next     End Sub        

Y'all also will notice the Select statement to determine which shape has been chosen. If information technology is a Rectangle, depict a rectangle using the built-in Graphics capabilities; the aforementioned holds truthful with a circle that will draw an Ellipse. With the Odd shape, a sub named DrawSpiral gets called that draws a spiral, which follows side by side:

          Public Sub DrawSpiral(ByVal yard As Graphics)        Dim PI Equally Double = iii.14159265358979       'Dim Orientation Equally Double = three.356987413'       '2.718281828 orientation'       Dim Orientation Every bit Double = 2.718281828    'orientation'        Dim penSpiral As New Pen(Color.Maroon)        Dim cx As Integer       Dim ten As Integer       Dim cy As Integer       Dim y As Integer        Dim rectSprial As New Rectangle(ten, 10, 250, 250)        cx = rectSprial.Width / 2       cy = rectSprial.Height / 2        Dim a As Single       Dim b Every bit Single       Dim i Every bit Long       Dim ang Equally Double        a = 0.xv    'shape'       b = 0.15    'shape'        For i = 0 To 10000    'size of spiral'           ang = (PI / 720) * i           x = cx + (a * (Math.Cos(ang)) *          (Orientation ^ (b * ang)))          y = cy - (a * (Math.Sin(ang)) *          (Orientation ^ (b * ang)))           'The higher the + number, the thicker the lines'          g.DrawLine(penSpiral, ten, y, x + ane, y + 1)        Next i     End Sub        

I also have commented out the Pigment issue for the PictureBox. You already will be using a Graphics object to draw with:

          'Private Sub picObject_Paint(ByVal sender Equally Object,'    'ByVal due east As PaintEventArgs)'        'Effort'           'Create(east.Graphics, shShape)'        'Take hold of ex As Exception'           'MessageBox.Show(ex.Message)'        'Stop Effort'     'Finish Sub'        

The remainder of the lawmaking in clsObject remains the same. Add the following variable to frmResizeObject:

          Private shShape Every bit Shape

Add together the following code to all three buttons:

          Private Sub Button1_Click(sender As Object, e As EventArgs) _          Handles Button1.Click        objRect = Nothing       shShape = Shape.Rect       objRect = New clsObject(New Rectangle(5, v, 350, 350), _                 shShape, picCanvas)     End Sub     Private Sub Button2_Click(sender As Object, eastward As EventArgs) _          Handles Button2.Click       objRect = Zero       shShape = Shape.Circle       objRect = New clsObject(New Rectangle(5, v, 350, 350), _                 shShape, picCanvas)     End Sub     Individual Sub Button3_Click(sender Equally Object, eastward Equally EventArgs) _          Handles Button3.Click       objRect = Nothing       shShape = Shape.Odd       objRect = New clsObject(New Rectangle(5, 5, 350, 350), _                 shShape, picCanvas)    End Sub        

That's it! It is non perfect, but it works and can exist made even more flexible. Running the program results in the following outputs:

Figure 3: Rectangle

Effigy 4: Circle

Figure 5: Spiral

The lawmaking for this article is available on GitHub.

Determination

As y'all can see: If y'all take set up your application properly the first time, it is like shooting fish in a barrel to aggrandize and build onto it to provide better functionality. Savor playing around with your drawing application programming skills!

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Source: https://www.codeguru.com/visual-basic/resizing-drawn-objects-with-vb-net-part-2-circles-and-odd-shapes/

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