如何在圖片框中繪制圖紙

Question

在圖片中繪制圖片使用c＃拖動鼠標

Answer 1

將PictureBox放在窗體上，並將其BackColor設置為White。 然后將此代碼添加到您的表單中（您必須實際連接下面的鼠標事件，即您不能將此代碼復制並粘貼到您的表單中）：

private Point? _Previous = null;
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
    _Previous = e.Location;
    pictureBox1_MouseMove(sender, e);
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
    if (_Previous != null)
    {
        if (pictureBox1.Image == null)
        {
            Bitmap bmp = new Bitmap(pictureBox1.Width, pictureBox1.Height);
            using (Graphics g = Graphics.FromImage(bmp))
            {
                g.Clear(Color.White);
            }
            pictureBox1.Image = bmp;
        }
        using (Graphics g = Graphics.FromImage(pictureBox1.Image))
        {
            g.DrawLine(Pens.Black, _Previous.Value, e.Location);
        }
        pictureBox1.Invalidate();
        _Previous = e.Location;
    }
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
    _Previous = null;
}

然后抽離！

如果您願意，可以通過設置Graphics對象的SmoothingMode屬性來稍微提高繪制圖像的質量。

更新： .Net CF沒有Pens集合，而且MoustEventArgs沒有Location ，所以這里是CF友好版本：

private Point? _Previous = null;
private Pen _Pen = new Pen(Color.Black);
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
    _Previous = new Point(e.X, e.Y);
    pictureBox1_MouseMove(sender, e);
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
    if (_Previous != null)
    {
        if (pictureBox1.Image == null)
        {
            Bitmap bmp = new Bitmap(pictureBox1.Width, pictureBox1.Height);
            using (Graphics g = Graphics.FromImage(bmp))
            {
                g.Clear(Color.White);
            }
            pictureBox1.Image = bmp;
        }
        using (Graphics g = Graphics.FromImage(pictureBox1.Image))
        {
            g.DrawLine(_Pen, _Previous.Value.X, _Previous.Value.Y, e.X, e.Y);
        }
        pictureBox1.Invalidate();
        _Previous = new Point(e.X, e.Y);
    }
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
    _Previous = null;
}

Answer 2

這里，pictureBox1 ==簽名。 我以這種方式翻譯成vb：

全球：

Dim _previous As Point = Nothing
Dim _pen As Pen = New Pen(Color.Black)
Dim drawing As Boolean = False


''' <summary>
''' This handles the signature drawing events (drawing)
''' </summary>
''' <param name="sender"></param>
''' <param name="e"></param>
''' <remarks></remarks>
Private Sub signature_MouseMove(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles signature.MouseMove
    If drawing = True Then
        If signature.Image Is Nothing Then
            Dim bmp As Bitmap = New Bitmap(signature.Width, signature.Height)

            Using g As Graphics = Graphics.FromImage(bmp)
                g.Clear(Color.White)
            End Using

            signature.Image = bmp
        End If

        Using g As Graphics = Graphics.FromImage(signature.Image)
            g.DrawLine(_pen, _previous.X, _previous.Y, e.X, e.Y)
        End Using
        signature.Invalidate()
        _previous = New Point(e.X, e.Y)
    End If
End Sub

''' <summary>
''' this indicates somebody is going to write a signature
''' </summary>
''' <param name="sender"></param>
''' <param name="e"></param>
''' <remarks></remarks>
Private Sub signature_MouseDown(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles signature.MouseDown
    _previous = New Point(e.X, e.Y)
    drawing = True
    signature_MouseMove(sender, e)

End Sub

''' <summary>
''' the signature is done.
''' </summary>
''' <param name="sender"></param>
''' <param name="e"></param>
''' <remarks></remarks>
Private Sub signature_MouseUp(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles signature.MouseUp
    _previous = Nothing
    drawing = False
End Sub

Answer 3

您可以通過捕獲圖片框的mousemove事件然后從圖片框中獲取圖片來實現。

圖形g = pictureBox.CreateGraphics（）; 那么你可以使用這個圖形對象繪制你想要繪制的任何東西