.net - 在 VB.NET 中用给定的大小和 X/Y POS 绘制一个圆会产生意想不到的结果
问题描述
我正在制作一个应用程序,当给定直径和圆的中心点X
和Y
通过的输入时,它会绘制一个圆。aTextBox
在 PictureBox 中。
当我运行应用程序并输入恒定的 X 和 Y 但缓慢增加/减小圆的直径时,即使 X 和 Y 的位置是恒定的,圆也会开始随机移动。有时,如果我在没有更改任何变量(X Pos、Y Pos 和 Diameter)时刷新,PictureBox
即使没有任何更改,圆圈也会无缘无故移动......
这是重现的代码:
这些变量已经被声明:
Dim beginSCircleXPos As Integer 'What the user put into as the circle's center for X
Dim beginSCircleYPos As Integer 'What the user put into as the circle's center for y
Dim sCircleXPos As Integer 'Top-Left point of the circle in X
Dim sCircleYPos As Integer 'Top-Left point of the circle in Y
Dim sCircleDiameter As Integer 'The diameter that user put into.
Dim sCenterPointX As Integer 'Variables will be updated later
Dim sCenterPointY As String
PictureBox
的Paint
事件
beginSCircleXPos = TextBox1.Text
beginSCircleYPos = TextBox2.Text
sCircleXPos = beginSCircleXPos - sCircleDiameter / 2
sCircleYPos = beginSCircleYPos - sCircleDiameter / 2
sCircleDiameter = TextBox3.Text
Using path As New GraphicsPath
path.AddEllipse(sCircleXPos, sCircleYPos, sCircleDiameter, sCircleDiameter)
sCenterPointX = sCircleXPos + sCircleDiameter / 2
sCenterPointY = sCircleYPos + sCircleDiameter / 2
Using brush As New PathGradientBrush(path)
brush.CenterPoint = New PointF(sCenterPointX, sCenterPointY)
brush.CenterColor = Color.FromArgb(0, Color.Orange)
brush.SurroundColors = {Color.Orange}
brush.FocusScales = PointF.Empty
e.Graphics.FillRectangle(brush, sCircleXPos, sCircleYPos, sCircleDiameter, sCircleDiameter)
End Using
End Using
值得注意的PictureBox
是,通过单击带有PictureBox1.Refresh()
命令的按钮来刷新。
我该如何解决这个问题,以便中心点的输入和 X/Y 值每次都会产生正确且恒定的答案?
编辑:
beginSCircleXPos = Convert.ToSingle(TextBox1.Text)
beginSCircleYPos = Convert.ToSingle(TextBox2.Text)
sCircleXPos = beginSCircleXPos - sCircleDiameter / 2
sCircleYPos = beginSCircleYPos - sCircleDiameter / 2
sCircleDiameter = Convert.ToSingle(TextBox3.Text)
Using path As New GraphicsPath
path.AddEllipse(sCircleXPos, sCircleYPos, sCircleDiameter, sCircleDiameter)
sCenterPointX = sCircleXPos + sCircleDiameter / 2
sCenterPointY = sCircleYPos + sCircleDiameter / 2
Using brush As New PathGradientBrush(path)
brush.CenterPoint = New PointF(sCenterPointX, sCenterPointY)
brush.CenterColor = Color.FromArgb(0, Color.Orange)
brush.SurroundColors = {Color.Orange}
brush.FocusScales = PointF.Empty
e.Graphics.FillRectangle(brush, sCircleXPos, sCircleYPos, sCircleDiameter, sCircleDiameter)
End Using
End Using
```
Variables:
将 beginSCircleXPos 调暗为单曲 将 beginSCircleYPos 调暗为单曲
Dim sCircleXPos As Single
Dim sCircleYPos As Single
Dim sCircleDiameter As Single
Dim sCenterPointX As Single
Dim sCenterPointY As Single
解决方案
我没有仔细看你的代码。我仍然有我提供的代码来回答你之前的问题,所以我以此为基础,只是像我自己做的那样修改它。我用 a每秒Timer
重绘PictureBox
一次以使其更简单。这就是我最终的结果:
Private Sub PictureBox1_Paint(sender As Object, e As PaintEventArgs) Handles PictureBox1.Paint
Dim centreX As Single
Dim centreY As Single
Dim diameter As Single
If Single.TryParse(TextBox1.Text, centreX) AndAlso
Single.TryParse(TextBox2.Text, centreY) AndAlso
Single.TryParse(TextBox3.Text, diameter) Then
Dim radius = diameter / 2.0F
Dim bounds As New RectangleF(centreX - radius,
centreY - radius,
diameter,
diameter)
Using path As New GraphicsPath
path.AddEllipse(bounds)
Using brush As New PathGradientBrush(path) With {.CenterPoint = New PointF(centreX, centreY),
.CenterColor = Color.FromArgb(0, Color.Orange),
.SurroundColors = {Color.Orange},
.FocusScales = PointF.Empty}
e.Graphics.FillRectangle(brush, bounds)
End Using
End Using
End If
End Sub
Private Sub Timer1_Tick(sender As Object, e As EventArgs) Handles Timer1.Tick
PictureBox1.Invalidate()
End Sub
It seemed to work just as expected for me. If one or more of the TextBoxes
didn't contain a valid number then nothing was drawn, otherwise a graded circle was drawn where and how expected. If I set the centre coordinates and then varied the diameter, the circle that was drawn maintained a constant centre but grew and shrunk as expected.
You can obviously use a Button.Click
instead of a Timer.Tick
if you want.
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