[英]how to draw drawings in picture box
在图片中绘制图片使用c#拖动鼠标
将PictureBox放在窗体上,并将其BackColor设置为White。 然后将此代码添加到您的表单中(您必须实际连接下面的鼠标事件,即您不能将此代码复制并粘贴到您的表单中):
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;
}
然后抽离!
如果您愿意,可以通过设置Graphics
对象的SmoothingMode
属性来稍微提高绘制图像的质量。
更新: .Net CF没有Pens
集合,而且MoustEventArgs
没有Location
,所以这里是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;
}
这里,pictureBox1 ==签名。 我以这种方式翻译成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
您可以通过捕获图片框的mousemove事件然后从图片框中获取图片来实现。
图形g = pictureBox.CreateGraphics(); 那么你可以使用这个图形对象绘制你想要绘制的任何东西
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