vb.net 教程 5-10 Graphics类- VB

版权声明：本文为博主原创文章，转载请在显著位置标明本文出处以及作者网名，未经作者允许不得用于商业目的。
个人觉得Graphics就像是画布，要作画，就必须先建立Graphics对象，在这上面实现图像的操作。
能够在表面作图的控件，都支持CreateGraphics()方法
例如：
PictureBox1.CreateGraphics()
Me.CreateGraphics()
等等

如果是绘制图形，那么要用的工具主要是Pen类和Brush类
Pen主要用于线条图形类的，Brush主要用于填充图形类
声明一个Pen对象：
Dim myPen As New Pen(Color.Blue, 1)

声明一个Brush对象：
Dim myBrush As New SolidBrush(Color.Red)

Brush类是一个抽象类，实际使用中需要用Brush的派生类：
SolidBrush、HatchBrush、PathGrdientBrush、TextureBrush和LinearGradientBrush。

画线：Graphics.DrawLine
画矩形：Graphics.DrawRectangles
画椭圆：Graphics.DrawEllipse
画弧线：Graphics.DrawArc
画多边形：Graphics.DrawPolygon
。。。。

填充椭圆：Graphics.FillEllipse
填充扇形：Graphics.FillPie
填充多边形：Graphics.FillPolygon
填充矩形：Graphics.FillRectangle

一个简单的例子：

代码如下：

Public Class Form1

Dim gCanvas As Graphics

Private Sub btnLine_Click(sender As Object, e As EventArgs) Handles btnLine.Click
Dim myPen As New Pen(Color.Red, 2) '红色，宽度2的画笔
gCanvas.DrawLine(myPen, New Point(10, 10), New Point(10, 200)) '画线
End Sub

Private Sub btnRectangle_Click(sender As Object, e As EventArgs) Handles btnRectangle.Click
Dim myPen As New Pen(Color.Blue, 2) '蓝色，宽度2的画笔
gCanvas.DrawRectangle(myPen, New Rectangle(20, 10, 150, 200)) '画矩形
End Sub

Private Sub btnArc_Click(sender As Object, e As EventArgs) Handles btnArc.Click
Dim myPen As New Pen(Color.Green, 2) '绿色，宽度2的画笔
gCanvas.DrawArc(myPen, New Rectangle(240, 10, 150, 200), 0, 180) '画弧线
End Sub

Private Sub btnFillRectangle_Click(sender As Object, e As EventArgs) Handles btnFillRectangle.Click
Dim myBrush As New SolidBrush(Color.Red) '红色画刷
gCanvas.FillRectangle(myBrush, New Rectangle(21, 11, 148, 198)) '填充矩形
End Sub

Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
gCanvas = Me.CreateGraphics()
End Sub

Private Sub btnFillEllipse_Click(sender As Object, e As EventArgs) Handles btnFillEllipse.Click
Dim myBrush As New SolidBrush(Color.Red) '红色画刷
gCanvas.FillEllipse(myBrush, New Rectangle(241, 11, 148, 198)) '填充椭圆
End Sub
End Class