'CannyStill.vb
'
'Emgu CV 3.0.0
'
'put this code in your main form, for example frmMain.vb
'
'add the following components to your form:
'
'tlpOuter (TableLayoutPanel)
'tlpInner (TableLayoutPanel)
'btnOpenFile (Button)
'lblChosenFile (Label)
'ibOriginal (Emgu ImageBox)
'ibCanny (Emgu ImageBox)
'ofdOpenFile (OpenFileDialog)
'
'NOTE: Do NOT copy/paste the entire text of this file into Visual Studio !! It will not work if you do !!
'Follow the video on my YouTube channel to create the project and have Visual Studio write part of the code for you,
'then copy/pase the remaining text as needed

Option Explicit On      'require explicit declaration of variables, this is NOT Python !!
Option Strict On        'restrict implicit data type conversions to only widening conversions

Imports Emgu.CV                 'usual Emgu Cv imports
Imports Emgu.CV.CvEnum          '
Imports Emgu.CV.Structure       '
Imports Emgu.CV.UI              '

'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Public Class frmMain
    
    '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
    Private Sub btnOpenFile_Click(sender As Object, e As EventArgs) Handles btnOpenFile.Click
        Dim drChosenFile As DialogResult

        drChosenFile = ofdOpenFile.ShowDialog()                 'open file dialog
        
        If (drChosenFile <> DialogResult.OK Or ofdOpenFile.FileName = "") Then    'if user chose Cancel or filename is blank . . .
            lblChosenFile.Text = "file not chosen"              'show error message on label
            Return                                              'and exit function
        End If
        
        Dim imgOriginal As Mat

        Try
            imgOriginal = New Mat(ofdOpenFile.FileName, LoadImageType.Color)
        Catch ex As Exception                                                       'if error occurred
            lblChosenFile.Text = "unable to open image, error: " + ex.Message       'show error message on label
            Return                                                                  'and exit function
        End Try

        If (imgOriginal Is Nothing) Then                                  'if image could not be opened
            lblChosenFile.Text = "unable to open image"                 'show error message on label
            Return                                                      'and exit function
        End If

        Dim imgGrayscale As New Mat(imgOriginal.Size, DepthType.Cv8U, 1)
        Dim imgBlurred As New Mat(imgOriginal.Size, DepthType.Cv8U, 1)
        Dim imgCanny As New Mat(imgOriginal.Size, DepthType.Cv8U, 1)
        
        CvInvoke.CvtColor(imgOriginal, imgGrayscale, ColorConversion.Bgr2Gray)
        
        CvInvoke.GaussianBlur(imgGrayscale, imgBlurred, New Size(5, 5), 1.5)
        
        CvInvoke.Canny(imgBlurred, imgCanny, 100, 200)

        ibOriginal.Image = imgOriginal              'update image boxes
        ibCanny.Image = imgCanny                    '
    End Sub
    
End Class