问题描述
下一个代码使您可以使用鼠标单击在窗体中绘制矩形.为什么不呢,或者如何在PictureBox上绘制呢?
The next code lets you draw Rectangles in the Form with mouse clics.Why not, or how can be draw over a PictureBox?
Public Class Form1
Dim SelectRect As Rectangle = New Rectangle()
Dim ps As Point = New Point()
Dim pe As Point = New Point()
这会捕获矩形的第一个点击,起点或角点
This catch the first click, starting point or corner of the rectangle
Private Sub Form1_MouseDown(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseDown
SelectRect.Width = 0
SelectRect.Height = 0
SelectRect.X = e.X
SelectRect.Y = e.Y
ps.X = e.X
ps.Y = e.Y
pe = ps
End Sub
这部分确定矩形的宽度和高度:
This part determine the width and height of the rectangle:
Private Sub Form1_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseMove
If (e.Button = MouseButtons.Left) Then
ControlPaint.DrawReversibleFrame(Me.RectangleToScreen(SelectRect), Color.Black, FrameStyle.Dashed)
SelectRect.Width = e.X - SelectRect.X
SelectRect.Height = e.Y - SelectRect.Y
ControlPaint.DrawReversibleFrame(Me.RectangleToScreen(SelectRect), Color.Black, FrameStyle.Dashed)
End If
End Sub
这部分确定最后一个坐标,即矩形的第二个角:
This part determine the last coordinate, the second corner of the rectangle:
Private Sub Form1_MouseUp(ByVal sender As System.Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles MyBase.MouseUp
Dim g As Graphics = Me.CreateGraphics()
Dim p As Pen = New Pen(Color.Blue, 2)
ControlPaint.DrawReversibleFrame(Me.RectangleToScreen(SelectRect), Color.Black, FrameStyle.Dashed)
g.DrawRectangle(p, SelectRect)
g.Dispose()
End Sub
End Class
推荐答案
您的代码在Control.DrawReversibleFrame()
提供的准则的帮助下,使用控件(在这种情况下为Form)鼠标事件来启用矩形形状的绘制. .
您只需要定义一个不同的可绘制控件(例如PictureBox)的相同事件,并(在清理之后)或多或少地重复相同的过程即可.
Your code uses a control (a Form in this case) mouse events to enable the drawing of rectangular shapes, with the help of guidelines, provided by Control.DrawReversibleFrame()
.
You just have to define the same events of a different, drawable, control - like a PictureBox - and repeat, more or less, the same procedure (after a cleanup).
我已经添加了一个事件处理程序,用于检查是否按下了
Control Key
.如果按下
Control
,则添加一个矩形,否则,将仅绘制一个矩形.作为示例,我还包含了填充矩形的一行代码.我认为这很有趣,因为您必须控制无效Region的大小.
注释掉以下代码行以仅绘制框架:
I've adden an event handler that checks if
Control Key
is pressed.If
Control
is pressed, you add a rectangle, if not, only one rectangle is drawn.I've also included, as an example, a line of code that fills the rectangle. I think it's interesting, because you have to control the size of the invalidated Region.
Comment out these lines of code to draw just the frame:
SelectRect.Inflate(CInt(-_pen.Width / 2), CInt(-_pen.Width / 2))
e.Graphics.FillRectangle(_brush, SelectRect)
Dim SelectRect As Rectangle = New Rectangle()
Dim _pen As Pen = New Pen(Color.Green, 4)
Dim _brush As SolidBrush = New SolidBrush(Color.Orange)
Dim _ControlPressed As Boolean = False
Private Sub Form1_KeyDown(sender As Object, e As KeyEventArgs) Handles MyBase.KeyDown
_ControlPressed = (e.Modifiers And Keys.Control) = Keys.Control
End Sub
Private Sub Form1_KeyUp(sender As Object, e As KeyEventArgs) Handles Me.KeyUp
_ControlPressed = (e.Modifiers And Keys.Control) = Keys.Control
End Sub
Private Sub PictureBox1_MouseDown(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseDown
SelectRect.Location = e.Location
SelectRect.Size = New Size(0, 0)
End Sub
Private Sub PictureBox1_MouseMove(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseMove
If (e.Button = MouseButtons.Left) Then
ControlPaint.DrawReversibleFrame(PictureBox1.RectangleToScreen(SelectRect), PictureBox1.BackColor, FrameStyle.Dashed)
SelectRect.Width = e.X - SelectRect.X
SelectRect.Height = e.Y - SelectRect.Y
ControlPaint.DrawReversibleFrame(PictureBox1.RectangleToScreen(SelectRect), PictureBox1.BackColor, FrameStyle.Dashed)
End If
End Sub
Private Sub PictureBox1_MouseUp(sender As Object, e As MouseEventArgs) Handles PictureBox1.MouseUp
If (e.Y < SelectRect.Y) Then
SelectRect.Location = If(SelectRect.Location.X > e.X,
New Point(e.X, e.Y), New Point(SelectRect.X, e.Y))
SelectRect.Size = New Size(Math.Abs(SelectRect.Width), Math.Abs(SelectRect.Height))
Else
If SelectRect.Location.X > SelectRect.Right Then
SelectRect.Location = New Point(e.X, SelectRect.Y)
SelectRect.Size = New Size(Math.Abs(SelectRect.Width), Math.Abs(SelectRect.Height))
End If
End If
If _ControlPressed Then
Dim _InflatedRect As Rectangle = New Rectangle(SelectRect.Location, SelectRect.Size)
_InflatedRect.Inflate(CInt(_pen.Width / 2), CInt(_pen.Width / 2))
PictureBox1.Invalidate(_InflatedRect)
Else
PictureBox1.Invalidate()
End If
End Sub
Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
'Draw the outer rectangle with the color of _pen
e.Graphics.DrawRectangle(_pen, SelectRect)
'Fill the rectangle with the color of _brush
'It's half Pen.Width smaller so it doesn't erase the contour
SelectRect.Inflate(CInt(-_pen.Width / 2), CInt(-_pen.Width / 2))
e.Graphics.FillRectangle(_brush, SelectRect)
End Sub
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