[VB.Net/Graphics] Drawing arrows on the picturebox

[kalp suth via DotNetMonster.com]

I want to create arrows using lines on a picture in the picture box.
On clicking the button "btnShowAll ", the image is loaded and the lines drawn. "RGSShowAll ()" calls "DrawObjs() " which does the actual drawing work.

But after displaying all the arrows in a flick, the arrows disappers.
I have debugged and came to know that the "Paint" event of the picturebox is refreshing the image, so the work done on the CreateGraphics created object is lost!

============== a trimmed-up code from the actual module...====== =======

Private bzrPen As New Pen(Color.Navy)
Private Location As String = "c:\test.jp g"

Private Sub btnShowAll_Clic k(ByVal sender As System.Object, ByVal e As System.EventArg s) Handles btnShowAll.Clic k

pcbMarkupImage. Image = CType(New Bitmap(Location ), Image)
RGSShowAll(pcbM arkupImage)
End Sub

Public Sub RGSShowAll(ByVa l PicBox As PictureBox)
Dim g As Graphics = Graphics.FromIm age(i)

DrawObjs(g)

End Sub

Public Sub DrawObjs(ByRef objGrpahics As Graphics)
Try
Dim I, X1, Y1, X2, Y2 As Integer
' assigned values to the above line coordinates
X1 = 100
Y1 = 200
X2 = 150
Y2 = 300

objGrpahics.Dra wLine(bzrPen, X1, Y1, X1, Y2)
objGrpahics.Dra wLine(bzrPen, X1, Y1, X2, Y1)
objGrpahics.Dra wLine(bzrPen, X2, Y2, X2, Y1)
objGrpahics.Dra wString("title1 ", Me.Font, strBrush, x1 -5 , y1 + 5 )
Catch ex As Exception
MessageBox.Show (ex.Message)
End Try
End Sub
=============== =============== =============== =============== ========

--
Message posted via http://www.dotnetmonster.com

[Robby]

You must also call your piant routine in the Picturebox.Pain t event.

Robby

"kalp suth via DotNetMonster.c om" <fo***@DotNetMo nster.com> wrote in message
news:13******** *************** *******@DotNetM onster.com...

I want to create arrows using lines on a picture in the picture box.
On clicking the button "btnShowAll ", the image is loaded and the lines
drawn. "RGSShowAll ()" calls "DrawObjs() " which does the actual drawing
work.

But after displaying all the arrows in a flick, the arrows disappers.
I have debugged and came to know that the "Paint" event of the picturebox
is refreshing the image, so the work done on the CreateGraphics created
object is lost!

============== a trimmed-up code from the actual module...====== =======

Private bzrPen As New Pen(Color.Navy)
Private Location As String = "c:\test.jp g"

Private Sub btnShowAll_Clic k(ByVal sender As System.Object, ByVal e As
System.EventArg s) Handles btnShowAll.Clic k

pcbMarkupImage. Image = CType(New Bitmap(Location ), Image)
RGSShowAll(pcbM arkupImage)
End Sub

Public Sub RGSShowAll(ByVa l PicBox As PictureBox)
Dim g As Graphics = Graphics.FromIm age(i)

DrawObjs(g)

End Sub

Public Sub DrawObjs(ByRef objGrpahics As Graphics)
Try
Dim I, X1, Y1, X2, Y2 As Integer
' assigned values to the above line coordinates
X1 = 100
Y1 = 200
X2 = 150
Y2 = 300

objGrpahics.Dra wLine(bzrPen, X1, Y1, X1, Y2)
objGrpahics.Dra wLine(bzrPen, X1, Y1, X2, Y1)
objGrpahics.Dra wLine(bzrPen, X2, Y2, X2, Y1)
objGrpahics.Dra wString("title1 ", Me.Font, strBrush, x1 -5 , y1 + 5 )
Catch ex As Exception
MessageBox.Show (ex.Message)
End Try
End Sub
=============== =============== =============== =============== ========

--
Message posted via http://www.dotnetmonster.com

[Peter Proost]

this piece of code works for me, place it inside a button click event, what
it does is creates a bitmap based on the image in the picturebox, the it
draws the lines on this bitmap and place the new bitmap in the picturebox:

Dim g As Graphics
b = New Bitmap(PictureB ox1.Image)
g = Graphics.FromIm age(b)
g.DrawLine(Pens .Yellow, 100, 10, 110, 20)
g.DrawLine(Pens .Yellow, 110, 20, 100, 30)
g.DrawLine(Pens .Yellow, 90, 20, 110, 20)
PictureBox1.Ima ge = b
g.Dispose()

hth Peter

"Robby" <ed****@not.my. email.com> wrote in message
news:et******** ******@TK2MSFTN GP15.phx.gbl...

You must also call your piant routine in the Picturebox.Pain t event.

Robby

"kalp suth via DotNetMonster.c om" <fo***@DotNetMo nster.com> wrote in message news:13******** *************** *******@DotNetM onster.com...

I want to create arrows using lines on a picture in the picture box.
On clicking the button "btnShowAll ", the image is loaded and the lines
drawn. "RGSShowAll ()" calls "DrawObjs() " which does the actual drawing
work.

But after displaying all the arrows in a flick, the arrows disappers.
I have debugged and came to know that the "Paint" event of the picturebox is refreshing the image, so the work done on the CreateGraphics created
object is lost!

============== a trimmed-up code from the actual module...====== =======

Private bzrPen As New Pen(Color.Navy)
Private Location As String = "c:\test.jp g"

Private Sub btnShowAll_Clic k(ByVal sender As System.Object, ByVal e As
System.EventArg s) Handles btnShowAll.Clic k

pcbMarkupImage. Image = CType(New Bitmap(Location ), Image)
RGSShowAll(pcbM arkupImage)
End Sub

Public Sub RGSShowAll(ByVa l PicBox As PictureBox)
Dim g As Graphics = Graphics.FromIm age(i)

DrawObjs(g)

End Sub

Public Sub DrawObjs(ByRef objGrpahics As Graphics)
Try
Dim I, X1, Y1, X2, Y2 As Integer
' assigned values to the above line coordinates
X1 = 100
Y1 = 200
X2 = 150
Y2 = 300

objGrpahics.Dra wLine(bzrPen, X1, Y1, X1, Y2)
objGrpahics.Dra wLine(bzrPen, X1, Y1, X2, Y1)
objGrpahics.Dra wLine(bzrPen, X2, Y2, X2, Y1)
objGrpahics.Dra wString("title1 ", Me.Font, strBrush, x1 -5 , y1 + 5 )
Catch ex As Exception
MessageBox.Show (ex.Message)
End Try
End Sub
=============== =============== =============== =============== ========

--
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