How to Create an On-Screen Dimension Calculator in Visual Basic

Submitted by Yorkiebar on Sunday, October 13, 2013 - 09:28.

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Introduction: Welcome to my tutorial on how to create a on-screen dimensions calculator. Steps of Creation: Step 1: First we want to create a form with a button to begin the process. We also want to make two labels, one to say "Console:" and label2 to contain the current console status, set the default to "Idle...". We then want to Import System.Threading because we will be using a one second delay multiple times. If we used a one second delay within the main program thread the entire program UI would freeze.

Imports System.Threading

Step 2: Now that we have imported we are ready to create a new thread, on button1 click lets create a new thread and give it the starting address of a new custom function called getx...

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    Dim trd As thread = New thread(AddressOf getx)
    trd.isbackground = True
    trd.start()
End Sub

We also want to disable checking for illegal crossthread calls on form load otherwise we would get an error when trying to update our console line in the UI from a new thread.

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
    CheckForIllegalCrossThreadCalls = False
End Sub

Step 3: Now we want to tell the user to position their mouse in the correct location and give them a few seconds to perform the step. We then take note of the x and y co-ordinates of the mouse. (twice).

Private Function getx()
    Dim i As Integer = 3
    Do Until i <= 0
        Label2.Text = "Position mouse over the top, left corner of the image... {" & i & " Seconds}"
        thread.sleep(1000)
        i -= 1
    Loop
    Dim x1 As Integer = MousePosition.X
    Dim y1 As Integer = MousePosition.Y
    i = 3
    Do Until i <= 0
        Label2.Text = "Position mouse over the bottom, right corner of the image... {" & i & " Seconds}"
        thread.sleep(1000)
        i -= 1
    Loop
End Function

Step 4: Once we have the top (left and right) and bottom (left and right) positions of the image, we want to create a new couple of integers which has the biggest co-ords minus the lowest co-ords (get the size of the image). We then output the result in a message. Done!

Dim x2 As Integer = MousePosition.X
Dim y2 As Integer = MousePosition.Y
Dim x3 As Integer = x2 - x1
Dim y3 As Integer = y2 - y1
MsgBox("On-screen dimensions of the image are: " & x3 & "x" & y3)

Project Complete! Below is the full source code and download to the project files.

Imports System.Threading
Public Class Form1
    Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Dim trd As thread = New thread(AddressOf getx)
        trd.isbackground = True
        trd.start()
    End Sub
 
    Private Function getx()
        Dim i As Integer = 3
        Do Until i <= 0
            Label2.Text = "Position mouse over the top, left corner of the image... {" & i & " Seconds}"
            thread.sleep(1000)
            i -= 1
        Loop
        Dim x1 As Integer = MousePosition.X
        Dim y1 As Integer = MousePosition.Y
        i = 3
        Do Until i <= 0
            Label2.Text = "Position mouse over the bottom, right corner of the image... {" & i & " Seconds}"
            thread.sleep(1000)
            i -= 1
        Loop
        Dim x2 As Integer = MousePosition.X
        Dim y2 As Integer = MousePosition.Y
        Dim x3 As Integer = x2 - x1
        Dim y3 As Integer = y2 - y1
        MsgBox("On-screen dimensions of the image are: " & x3 & "x" & y3)
    End Function
 
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        CheckForIllegalCrossThreadCalls = False
    End Sub
End Class

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