Make an image transparent : Image Operation « 2D Graphics « VB.Net Tutorial






Make an image transparent
Imports System.Drawing
Imports System.Drawing.Imaging

Imports System.Windows.Forms

public class BitmapTransparent
   public Shared Sub Main
        Application.Run(New TransparencyForm)
   End Sub
End class

Public Class TransparencyForm
    Inherits System.Windows.Forms.Form

#Region " Windows Form Designer generated code "

    Public Sub New()
        MyBase.New()

        'This call is required by the Windows Form Designer.
        InitializeComponent()

        'Add any initialization after the InitializeComponent() call
        Me.SetStyle(ControlStyles.ResizeRedraw, True)
        Me.SetStyle(ControlStyles.DoubleBuffer, True)
        Me.SetStyle(ControlStyles.AllPaintingInWmPaint, True)
    End Sub

    'Form overrides dispose to clean up the component list.
    Protected Overloads Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing Then
            If Not (components Is Nothing) Then
                components.Dispose()
            End If
        End If
        MyBase.Dispose(disposing)
    End Sub

    'Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    'NOTE: The following procedure is required by the Windows Form Designer
    'It can be modified using the Windows Form Designer.  
    'Do not modify it using the code editor.
    Friend WithEvents splitter2 As System.Windows.Forms.Splitter
    Friend WithEvents splitter1 As System.Windows.Forms.Splitter
    Friend WithEvents groupBox1 As System.Windows.Forms.GroupBox
    Friend WithEvents panel1 As System.Windows.Forms.Panel
    Friend WithEvents groupBox3 As System.Windows.Forms.GroupBox
    Friend WithEvents panel3 As System.Windows.Forms.Panel
    Friend WithEvents groupBox2 As System.Windows.Forms.GroupBox
    Friend WithEvents panel2 As System.Windows.Forms.Panel
    <System.Diagnostics.DebuggerStepThrough()> Private Sub InitializeComponent()
        Me.splitter2 = New System.Windows.Forms.Splitter()
        Me.splitter1 = New System.Windows.Forms.Splitter()
        Me.groupBox1 = New System.Windows.Forms.GroupBox()
        Me.panel1 = New System.Windows.Forms.Panel()
        Me.groupBox3 = New System.Windows.Forms.GroupBox()
        Me.panel3 = New System.Windows.Forms.Panel()
        Me.groupBox2 = New System.Windows.Forms.GroupBox()
        Me.panel2 = New System.Windows.Forms.Panel()
        Me.groupBox1.SuspendLayout()
        Me.groupBox3.SuspendLayout()
        Me.groupBox2.SuspendLayout()
        Me.SuspendLayout()
        '
        'splitter2
        '
        Me.splitter2.Location = New System.Drawing.Point(232, 0)
        Me.splitter2.Name = "splitter2"
        Me.splitter2.Size = New System.Drawing.Size(3, 102)
        Me.splitter2.TabIndex = 9
        Me.splitter2.TabStop = False
        '
        'splitter1
        '
        Me.splitter1.Location = New System.Drawing.Point(229, 0)
        Me.splitter1.Name = "splitter1"
        Me.splitter1.Size = New System.Drawing.Size(3, 102)
        Me.splitter1.TabIndex = 6
        Me.splitter1.TabStop = False
        '
        'groupBox1
        '
        Me.groupBox1.Controls.AddRange(New System.Windows.Forms.Control() {Me.panel1})
        Me.groupBox1.Dock = System.Windows.Forms.DockStyle.Left
        Me.groupBox1.Location = New System.Drawing.Point(117, 0)
        Me.groupBox1.Name = "groupBox1"
        Me.groupBox1.Size = New System.Drawing.Size(300, 102)
        Me.groupBox1.TabIndex = 5
        Me.groupBox1.TabStop = False
        Me.groupBox1.Text = "Original Colors"
        '
        'panel1
        '
        Me.panel1.BackColor = System.Drawing.Color.White
        Me.panel1.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.panel1.Dock = System.Windows.Forms.DockStyle.Fill
        Me.panel1.Location = New System.Drawing.Point(3, 16)
        Me.panel1.Name = "panel1"
        Me.panel1.Size = New System.Drawing.Size(106, 83)
        Me.panel1.TabIndex = 0
        '
        'groupBox3
        '
        Me.groupBox3.Controls.AddRange(New System.Windows.Forms.Control() {Me.panel3})
        Me.groupBox3.Dock = System.Windows.Forms.DockStyle.Fill
        Me.groupBox3.Location = New System.Drawing.Point(117, 0)
        Me.groupBox3.Name = "groupBox3"
        Me.groupBox3.Size = New System.Drawing.Size(235, 102)
        Me.groupBox3.TabIndex = 8
        Me.groupBox3.TabStop = False
        Me.groupBox3.Text = "Made Transparent"
        '
        'panel3
        '
        Me.panel3.BackColor = System.Drawing.Color.White
        Me.panel3.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.panel3.Dock = System.Windows.Forms.DockStyle.Fill
        Me.panel3.Location = New System.Drawing.Point(3, 16)
        Me.panel3.Name = "panel3"
        Me.panel3.Size = New System.Drawing.Size(229, 83)
        Me.panel3.TabIndex = 0
        '
        'groupBox2
        '
        Me.groupBox2.Controls.AddRange(New System.Windows.Forms.Control() {Me.panel2})
        Me.groupBox2.Dock = System.Windows.Forms.DockStyle.Left
        Me.groupBox2.Name = "groupBox2"
        Me.groupBox2.Size = New System.Drawing.Size(117, 102)
        Me.groupBox2.TabIndex = 7
        Me.groupBox2.TabStop = False
        Me.groupBox2.Text = "White Background"
        '
        'panel2
        '
        Me.panel2.BackColor = System.Drawing.Color.White
        Me.panel2.BorderStyle = System.Windows.Forms.BorderStyle.Fixed3D
        Me.panel2.Dock = System.Windows.Forms.DockStyle.Fill
        Me.panel2.Location = New System.Drawing.Point(3, 16)
        Me.panel2.Name = "panel2"
        Me.panel2.Size = New System.Drawing.Size(111, 83)
        Me.panel2.TabIndex = 0
        '
        'TransparencyForm
        '
        Me.AutoScaleBaseSize = New System.Drawing.Size(5, 13)
        Me.ClientSize = New System.Drawing.Size(352, 102)
        Me.Controls.AddRange(New System.Windows.Forms.Control() {Me.groupBox1})
        Me.Name = "TransparencyForm"
        Me.Text = "TransparencyForm"
        Me.groupBox1.ResumeLayout(False)
        Me.groupBox3.ResumeLayout(False)
        Me.groupBox2.ResumeLayout(False)
        Me.ResumeLayout(False)

    End Sub

#End Region


    Dim backgroundString As String = "the quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\nthe quick brown fox jumps over the lazy dog\n"


    Private Sub panel1_Paint(ByVal sender As Object, ByVal e As PaintEventArgs) Handles panel1.Paint
        Dim g As Graphics = e.Graphics
        Dim bmp As Bitmap = New Bitmap("yourfile.jpg")
        g.DrawString(backgroundString, Me.Font, Brushes.Black, Me.ClientRectangle.Left, Me.ClientRectangle.Top)

        bmp.MakeTransparent(bmp.GetPixel(10, 10))
        Dim rect As Rectangle = New Rectangle(0, 0, bmp.Width, bmp.Height)
        rect.Offset((Me.panel1.ClientRectangle.Width - rect.Width) / 2, (Me.panel1.ClientRectangle.Height - rect.Height) / 2)
        g.DrawImage(bmp, rect)
    End Sub

    Private Sub TransparencyForm_Layout(ByVal sender As Object, ByVal e As LayoutEventArgs) Handles MyBase.Layout
        panel1.Refresh()
    End Sub
End Class








17.49.Image Operation
17.49.1.Rotate an Image
17.49.2.Mirror an Image
17.49.3.Move an image and paintMove an image and paint
17.49.4.Scale an imageScale an image
17.49.5.Scale image with different Graphics UnitsScale image with different Graphics Units
17.49.6.Skew imageSkew image
17.49.7.Make an image transparentMake an image transparent
17.49.8.Invert an ImageInvert an Image
17.49.9.Invert an Image unsafeInvert an Image unsafe
17.49.10.Zoom ImageZoom Image
17.49.11.Zoom and Skew an ImageZoom and Skew an Image
17.49.12.Skew an ImageSkew an Image