步骤 10：编写其他按钮和复选框的代码

  • 项目

现在，您可以完成其他四个方法了。虽然您可以复制并粘贴此代码，但是若想从此教程中学些到最多的内容，那么请键入代码并使用 IntelliSense。

链接到视频有关本主题的视频版本，请参见 Tutorial 1: Create a Picture Viewer in Visual Basic - Video 5 或 Tutorial 1: Create a Picture Viewer in C# - Video 5。

说明说明

最佳做法是始终对您的代码进行注释。注释是供用户阅读的信息，花些时间使您的代码易于理解是值得的。程序会忽略注释行上的所有内容。在 Visual C# 中，通过在开头键入两个正斜杠 (//) 来注释一行；在 Visual Basic 中，通过以单引号 (') 开头来注释一行。

对其他按钮和复选框编写代码

  • 添加下列代码。

    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

    private void clearButton_Click(object sender, EventArgs e)
{
    // Clear the picture.
    pictureBox1.Image = null;
}

private void backgroundButton_Click(object sender, EventArgs e)
{
    // 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)
        pictureBox1.BackColor = colorDialog1.Color;
}

private void closeButton_Click(object sender, EventArgs e)
{
    // Close the form.
    this.Close();
}

private void checkBox1_CheckedChanged(object sender, EventArgs e)
{
    // 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)
        pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
    else
        pictureBox1.SizeMode = PictureBoxSizeMode.Normal;
}

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