ARTICLE

Getting and Setting Line Caps and Styles in GDI+

Posted by Dinesh Beniwal in Articles | GDI+ in VB.NET on May 28, 2010

Tags: GDI+, Getting and Setting Line Caps and Styles

In this article I will explain about Getting and Setting Line Caps and Styles in GDI+.

Tweet
1076
0

Reader Level: Beginner

HTML clipboard

We create aWindowsapplication

and a MainMenu control with three menu items on the form. We call these menu items GetCapStyle, LineDashStyle, and LineDashCap, respectively, and write menu click event handlers by double-clicking on them. On the GetCapStyle menu item click event handler, we will read different line caps and generate output using these line caps; on the LineDashStyle menu item click event handler, we will generate lines with different dash styles; and on the LineDashCap menu item click event handler, we will generate output with different line dash caps.

The GetCapStyle menu item click event handler is shown in Listing 9.2. We create a pen and set the starting and ending caps using the StartCap and EndCap properties of the Pen Object, and then we draw a line.

LISTING 9.2: Getting line caps

Imports System
Imports System.Collections.Generic
Imports System.ComponentModel
Imports System.Data
Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Linq
Imports System.Text
Imports System.Windows.Forms

Namespace GettingSetting_Line_CapsStyles
    Partial Public Class Form1
        Inherits Form
        Public Sub New()
            InitializeComponent()
        End Sub

        Private Sub Form1_Paint(ByVal sender As Object,ByVal e As PaintEventArgs)
           Dim g As Graphics = Me.CreateGraphics()
            g.Clear(Me.BackColor)
            ' Create a pen
            Dim blackPenAs New Pen(Color.Black, 10)
            ' Set line styles
            blackPen.StartCap = LineCap.Triangle
            blackPen.EndCap = LineCap.Triangle
            g.DrawLine(blackPen, 20, 10, 200, 10)
            blackPen.StartCap = LineCap.Square
            blackPen.EndCap = LineCap.AnchorMask
            g.DrawLine(blackPen, 20, 50, 200, 50)
            blackPen.StartCap = LineCap.DiamondAnchor
            blackPen.EndCap = LineCap.DiamondAnchor
            g.DrawLine(blackPen, 20, 70, 200, 70)
            blackPen.StartCap = LineCap.Flat
            blackPen.EndCap = LineCap.Flat
            g.DrawLine(blackPen, 20, 110, 200, 110)
            blackPen.StartCap = LineCap.RoundAnchor
            blackPen.EndCap = LineCap.RoundAnchor
            g.DrawLine(blackPen, 20, 130, 200, 130)
            blackPen.StartCap = LineCap.Square
            blackPen.EndCap = LineCap.Square
            g.DrawLine(blackPen, 20, 150, 200, 150)
            blackPen.StartCap = LineCap.SquareAnchor
            blackPen.EndCap = LineCap.SquareAnchor
            g.DrawLine(blackPen, 20, 170, 200, 170)
            blackPen.StartCap = LineCap.Flat
            blackPen.EndCap = LineCap.Flat
            g.DrawLine(blackPen, 20, 190, 200, 190)
            ' Dispose of objects
            blackPen.Dispose()
            g.Dispose()
        End Sub
    End Class
End Namespace

The output of Listing 9.2 looks like Figure 9.4, in which the lines have different caps.

The LineDashStyle menu item click event handler code is given in Listing 9.3. We create a pen and set the dash style and dash offset values using the DashStyle and DashOffset properties of the Pen object, and then we draw lines.

FIGURE 9.4: Reading line caps

LISTING 9.3: Getting line dash styles

Namespace GettingSetting_Line_CapsStyles
    Partial Public Class Form1
        Inherits Form
        Public Sub New()
            InitializeComponent()
        End Sub

FIGURE 9.5: Reading line dash styles

Figure 9.5 shows the output from Listing 9.3. The lines have different dash styles.

The GetCapStyle menu item click event handler code is given in Listing 9.4. We create a pen and set the dash cap styles using the DashCap property of the Pen object.

LISTING 9.4: Getting dash caps

Namespace GettingSetting_Line_CapsStyles
    Partial Public Class Form1
        Inherits Form
        Public Sub New()
            InitializeComponent()
        End Sub

        Private Sub Form1_Paint(ByVal sender As Object, ByVal e As PaintEventArgs)
            Dim g As Graphics = Me.CreateGraphics()
            g.Clear(Me.BackColor)
            ' Create a pen
            Dim blackPen As New Pen(Color.Black, 10)
            ' Set DashCap styles
            blackPen.DashStyle = DashStyle.DashDotDot
            blackPen.DashPattern = New Single() {10}
            blackPen.DashCap = DashCap.Triangle
            g.DrawLine(blackPen, 20, 10, 500, 10)
            blackPen.DashCap = DashCap.Flat
            g.DrawLine(blackPen, 20, 30, 500, 30)
            blackPen.DashCap = DashCap.Round
            g.DrawLine(blackPen, 20, 50, 500, 50)
            ' Dispose of objects
            blackPen.Dispose()
        End Sub
    End Class
End Namespace