add elements on existing bitmap

Question

1.00/5 (1 vote)

See more:

dear all
i have a picture box then draw a rectangle in it and make it permanent using a user form
then i add a circle to this rectangle by other user form and make it permanent also
the problem is when i try to modify the location of the circle it draw a new one and do not remove old one
and if i draw a new rectangle the all circles disappears
(i want to modify the circles location and remove old one, i want to modify the rectangle dimensions without remove the existing circles)

my code as follow:

VB

Module Module2
    Public canvas As Bitmap
    Public mygraphics As Graphics
    Public Sub draw_rec(ByVal points(,) As Double)

        Dim canavas_x As Integer = frm_main.pb_preview.Width
        Dim canavas_y As Integer = frm_main.pb_preview.Height / 2
        canvas = New Bitmap(canavas_x, canavas_y)
        mygraphics = Graphics.FromImage(canvas)
        Dim myPen As System.Drawing.Pen
        myPen = New System.Drawing.Pen(System.Drawing.Color.Black)
        myPen.Width = 0.0
        mygraphics.Clear(Color.White)
        mygraphics.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias
        For k = 0 To UBound(points, 1) - 1
            mygraphics.DrawLine(myPen, Convert.ToSingle(points(k, 0)), Convert.ToSingle(points(k, 1)), Convert.ToSingle(points(k + 1, 0)), Convert.ToSingle(points(k + 1, 1)))
        Next
        frm_main.pb_preview.Image = canvas 'make the image permenant
    End Sub
    Public Sub draw_cir()
        Dim myPen As System.Drawing.Pen
        myPen = New System.Drawing.Pen(System.Drawing.Color.Black)
        myPen.Width = 0.0
        Dim mygraphics1 = Graphics.FromImage(canvas)
        mygraphics1.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias

        For k = 0 To UBound(cicles, 1) - 1
            x = Convert.ToSingle(cicles(k, 1) - 0.5 * cicles(k, 3))
            y = Convert.ToSingle(cicles(k, 2) - 0.5 * cicles(k, 3))
            mygraphics1.DrawEllipse(myPen, x, y, Convert.ToSingle(cicles(k, 3)), Convert.ToSingle(cicles(k, 3)))
        Next
        frm_main.pb_preview.Image = canvas 'make the image permenant


    End Sub
End Module

Posted 21-Dec-13 9:56am

osama50000

Add a Solution

2 solutions

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

Sergey Alexandrovich Kryukov · Answer 1 · 2013-12-21T16:52:00

You complicate thing a lot by using PictureBox. It does not help you at all, only adds some hassles and consume extra resource and your development time, giving nothing in return. I'll explain what do to. Please see my past answers:
Append a picture within picturebox[^],
draw a rectangle in C#[^],
How do I clear a panel from old drawing[^].

And these answers should explain you how to do graphics rendering with changing images, such as interactive and/or animated:
capture the drawing on a panel[^],
What kind of playful method is Paint? (DataGridViewImageCell.Paint(...))[^],
Drawing Lines between mdi child forms[^],
How to speed up my vb.net application?[^],
any way to change a picture at run time with animation[^],
how to make a file from the content of e.graphics[^].

I hope you got the main ideas: 1) you render graphics keeping its model in memory, 2) you change graphics by changing the model and calling of of the Invalidate methods, 3) you avoid flicker by using double buffering.

—SA

osama50000 · Answer 2 · 2013-12-22T02:13:00

Solution 2

thanks Sergey, i will (try+learn) this Technic and till you when i had a problem

Posted 22-Dec-13 2:13am

osama50000

Comments

Nelek 22-Dec-13 9:15am

Please don't post solutions to chat with people asking or answering. The messages are not always sorted by date, so it can be a bit difficult to follow them correctly.
The best option is to use the "Have a question or comment?" (or the tiny "reply" on another comment). Another advantage is, that the person you write to will get a notification, otherwise it could be that he/she doesn't see your additional message.