Step 10: Write Code for Additional Buttons and a Check Box

Now you're ready to complete the other four methods. You could copy and paste this code, but if you want to learn the most from this tutorial, type the code and use IntelliSense.

This code adds functionality to the buttons you added earlier. Without this code, the buttons don't do anything. The buttons use code in their Click events (and the check box uses the CheckChanged event) to do different things when you activate the controls. For example, the clearButton_Click event, which activates when you choose the Clear the picture button, erases the current image by setting its Image property to null (or, nothing). Each event in the code includes comments that explain what the code does.

link to videoFor a video version of this topic, see Tutorial 1: Create a Picture Viewer in Visual Basic - Video 5 or Tutorial 1: Create a Picture Viewer in C# - Video 5. These videos use an earlier version of Visual Studio, so there are slight differences in some menu commands and other user interface elements. However, the concepts and procedures work similarly in the current version of Visual Studio.

Note Note

As a best practice: Always comment your code. Comments are information for a person to read, and it's worth the time to make your code understandable. Everything on a comment line is ignored by the program. In Visual C#, you comment a line by typing two forward slashes at the beginning (//), and in Visual Basic you comment a line by starting with a single quotation mark (').

To write code for additional buttons and a check box

  • Add the following code to your Form1 code file (Form1.cs or Form1.vb). Choose the VB tab to view Visual Basic code.

    Private Sub clearButton_Click() Handles clearButton.Click
        ' Clear the picture.
        PictureBox1.Image = Nothing 
    End Sub 
    
    Private Sub backgroundButton_Click() Handles backgroundButton.Click
        ' Show the color dialog box. If the user clicks OK, change the 
        ' PictureBox control's background to the color the user chose. 
        If ColorDialog1.ShowDialog() = DialogResult.OK Then
            PictureBox1.BackColor = ColorDialog1.Color
        End If 
    End Sub 
    
    Private Sub closeButton_Click() Handles closeButton.Click
        ' Close the form.
        Close()
    End Sub 
    
    Private Sub CheckBox1_CheckedChanged() Handles CheckBox1.CheckedChanged
        ' If the user selects the Stretch check box, change  
        ' the PictureBox's SizeMode property to "Stretch". If the user  
        ' clears the check box, change it to "Normal". 
        If CheckBox1.Checked Then
            PictureBox1.SizeMode = PictureBoxSizeMode.StretchImage
        Else
            PictureBox1.SizeMode = PictureBoxSizeMode.Normal
        End If 
    End Sub
    

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