Visual Basic - Image Processing 3 (cropping)

Tutorial kemarin kita sudah membuat sebuah program yang dapat membaca nilai atau value RGB dan mengkoversinya menjadi sebuah image. Pada tutorial kali ini kita akan membuat sebuah program cropping atau pemotongan gambar.

Baru belajar Visual Basic? pahami artikel ini dulu,
Oke, langsung saja kita mulai tutorialnya,

Pertama, buat UI (User Interface) pada visual basic menggunakan tools OpenFileDialog dan SaveFileDialog  sehingga tampilannya akan tampak seperti ini,

Selanjutnya klik2 kali form UI-nya kemudian ketikkan codenya sehingga akan tampak seperti ini,

Public Class Form1
    Dim selection As Rectangle
    Dim down As Boolean
    Dim filedialog As New OpenFileDialog
    Dim imagebitmap As Bitmap
    Dim selectioncolour As Color = Color.Black
    Dim bordersize As Integer = 2

    Function changealpha(ByVal colour As Color, ByVal value As Integer) As Color
        Dim c As Color
        c = (Color.FromArgb((value), (colour)))
        Return (c)
    End Function
    Function cropimage(ByVal image As Bitmap) As Bitmap
        Dim cropped As Bitmap = image.Clone(selection, image.PixelFormat)
        Return cropped
    End Function

    Private Sub Form1_KeyDown(sender As Object, e As KeyEventArgs) Handles Me.KeyDown
        Select Case e.KeyCode
            Case Keys.O
                If Not filedialog.ShowDialog = Windows.Forms.DialogResult.Cancel Then imagebitmap = New Bitmap(filedialog.FileName)
                Me.BackgroundImage = imagebitmap
                Me.BackgroundImageLayout = ImageLayout.None
                Me.Invalidate()
            Case Keys.C
                'cropimage(imagebitmap).Save("C:\Data\")
                Try
                    SaveFileDialog1.Filter = "JPEG |*.jpeg"
                    If SaveFileDialog1.ShowDialog() = Windows.Forms.DialogResult.OK Then
                        cropimage(imagebitmap).Save(SaveFileDialog1.FileName, System.Drawing.Imaging.ImageFormat.Jpeg)
                    End If
                Catch ex As Exception
                End Try
            Case Keys.Space
                selection = New Rectangle(New Point(selection.X, selection.Y), New Size(InputBox("width", "", selection.Width), InputBox("height", "", selection.Height)))
                Me.Invalidate()
        End Select
    End Sub


    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        Me.SetStyle(ControlStyles.AllPaintingInWmPaint, True)
        Me.SetStyle(ControlStyles.OptimizedDoubleBuffer, True)
        selection = New Rectangle(New Point(0, 0), New Size(100, 100))
        Me.Invalidate()
    End Sub
    Private Sub Form1_MouseDown(sender As Object, e As MouseEventArgs) Handles Me.MouseDown
        down = True
    End Sub

    Private Sub Form1_MouseMove(sender As Object, e As MouseEventArgs) Handles Me.MouseMove
        If down = True Then
            selection = New Rectangle(e.Location, selection.Size)
            Me.Invalidate()
        End If
    End Sub

    Private Sub Form1_MouseUp(sender As Object, e As MouseEventArgs) Handles Me.MouseUp
        down = False
    End Sub

    Private Sub Form1_Paint(sender As Object, e As PaintEventArgs) Handles Me.Paint
        e.Graphics.FillRectangle((New SolidBrush((changealpha((selectioncolour), 100)))), selection)
        e.Graphics.DrawRectangle((New Pen((New SolidBrush((selectioncolour))), bordersize)), selection)
        e.Graphics.DrawString(selection.Width & "x" & selection.Height, New Font("arial", 10, FontStyle.Regular), Brushes.White, selection.X, selection.Y)
    End Sub
End Class

Sehingga tampilannya akan tampak seperti ini,

Untuk menggunakannya:

o     : Open file
c     : Crop+save
space : Ubah ukuran crop
mouse : Untuk memindahkan kotak cropping

===DONE!===