Advice needed for drawing program

[Martin Horn]

Hi all,

I'm adding basic drawing capability to an application that I am writing, and
I have been having problems with making the graphics output persist when the
application is re-sized,covered etc.

This is the solution I have come up with, but it seems a bit convoluted.
Before I get too far into the development of the program, could someone cast
an eye over my code and tell me if I have approached it in the correct way,
or suggest a better solution.

Many thanks,

Martin Horn. (See below for my code)

Imports System.Windows. Forms

Public Class ComplexInscript ionDesignerForm
Private Drawing As Boolean = False
Private OldX As Integer = 0
Private OldY As Integer = 0
Private PaintObject As Object
Private CanvasBM As System.Drawing. Bitmap
Private Canvas As Graphics

Private Sub PicCanvas_Mouse Down(ByVal sender As Object, _
ByVal e As System.Windows. Forms.MouseEven tArgs) _
Handles PicCanvas.Mouse Down

Drawing = True
OldX = e.X
OldY = e.Y
End Sub

Private Sub PicCanvas_Mouse Move(ByVal sender As Object, _
ByVal e As System.Windows. Forms.MouseEven tArgs) _
Handles PicCanvas.Mouse Move

If Drawing Then
Canvas.DrawLine (Pens.Black, OldX, OldY, e.X, e.Y)
OldX = e.X
OldY = e.Y
PicCanvas.Inval idate()
End If
End Sub

Private Sub PicCanvas_Mouse Up(ByVal sender As Object, _
ByVal e As System.Windows. Forms.MouseEven tArgs) _
Handles PicCanvas.Mouse Up

Drawing = False
End Sub

Private Sub PicCanvas_Paint (ByVal sender As Object, _
ByVal e As System.Windows. Forms.PaintEven tArgs) _
Handles PicCanvas.Paint

e.Graphics.Draw ImageUnscaled(C anvasBM, 0, 0)
End Sub

Private Sub ComplexInscript ionDesignerForm _Load _
(ByVal sender As System.Object, _
ByVal e As System.EventArg s) _
Handles MyBase.Load

CanvasBM = New System.Drawing. Bitmap( _
PicCanvas.Clien tSize.Width, _
PicCanvas.Clien tSize.Height)

Canvas = Graphics.FromIm age(CanvasBM)
End Sub
End Class

[Armin Zingler]

"Martin Horn" <mv****@theinte rnet.com> schrieb

I'm adding basic drawing capability to an application that I am
writing, and I have been having problems with making the graphics
output persist when the application is re-sized,covered etc.

This is the solution I have come up with, but it seems a bit
convoluted. Before I get too far into the development of the
program, could someone cast an eye over my code and tell me if I
have approached it in the correct way, or suggest a better solution.

The approach is really good, IMO. I guess the line shouldn't be drawn before
the mouse button is released. Therefore I'd store the line coordinates
(start and end) in variables and paint the line in PicCanvas_Paint (if
drawing=true) additionally to CanvasBM. When the button is released, the
line can be drawn persistently on the bitmap. Thus, I'd write a sub drawing
the line that can be called in mouse-up as well as in piccanvas_paint .

Armin

[Martin Horn]

Hi Armin,

thanks for the feedback and tips. It's the first time I've tried something
like this with VB.Net and it's reassuring to know that I'm starting off in
the right direction.

Kind regards,

Martin Horn.

"Armin Zingler" <az*******@free net.de> wrote in message
news:u%******** **********@tk2m sftngp13.phx.gb l...

"Martin Horn" <mv****@theinte rnet.com> schrieb

I'm adding basic drawing capability to an application that I am
writing, and I have been having problems with making the graphics
output persist when the application is re-sized,covered etc.

This is the solution I have come up with, but it seems a bit
convoluted. Before I get too far into the development of the
program, could someone cast an eye over my code and tell me if I
have approached it in the correct way, or suggest a better solution.

The approach is really good, IMO. I guess the line shouldn't be drawn
before the mouse button is released. Therefore I'd store the line
coordinates (start and end) in variables and paint the line in
PicCanvas_Paint (if drawing=true) additionally to CanvasBM. When the
button is released, the line can be drawn persistently on the bitmap.
Thus, I'd write a sub drawing the line that can be called in mouse-up as
well as in piccanvas_paint .

Armin