How to erase rectangle graphis from picture box

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Hello

how to remove the rectangle graphics from picture box, I am able to draw a rectangle graphics using this code:

Dim g As System.Drawing.Graphics
Dim cyan As New SolidBrush(Color.Yellow)
Dim rect As New Rectangle(x1, y1, 15, 15)
g.FillRectangle(cyan, rect)

Is it possible to remove this rectangle graphics i had draw, Please tell me how to do so.

Thanks.

Posted 21-Dec-15 6:53am

MinhajAli

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Dave Kreskowiak · Answer 1 · 2015-12-21T07:42:00

Solution 1

You simply call Invalidate on the PictureBox control and NOT draw your box on it.

This will force the control to redraw itself without the box you drew.

Posted 21-Dec-15 7:42am

Dave Kreskowiak

Comments

Sergey Alexandrovich Kryukov 21-Dec-15 14:16pm

This time, my 4. It would be better to say that PictureBox should not be used at all. It does not make any sense. Please see Solution 2.
—SA

MinhajAli 22-Dec-15 10:14am

Thanks for reply.
But Picturebox.Invalidate is not forcing to redraw in my case.
actually i am loading an image in picturebox and on that image i am drawing the rectangle on MouseDown event.

Dave Kreskowiak 22-Dec-15 11:54am

From the code you posted, it's impossible to be sure what you're actually drawing on. You never show what g is set to, other than saying it's going to hold a Graphics object.

If you are drawing directly on the Bitmap image itself, you cannot remove the pixels once drawn without having the original copy of the Bitmap somewhere. Once you draw on the Bitmap object, that's it, you cannot get the original pixels back unless you reload the Bitmap from it's original source data.

If you're drawing on the surface of the PictureBox, you simply Invalidate it and do NOT draw your rectangle on the control in the Paint event of the PictureBox. It's that simple.

Sergey Alexandrovich Kryukov · Answer 2 · 2015-12-21T08:15:00

Solution 2

With your code, you should not use PictureBox at all — it does nothing useful for you, nothing at all, only adds some pain in the… let's say, in the neck and steals some of your development time. What to do instead? Something a lot more simple. Please see my past answers:
Append a picture within picturebox[^],
draw a rectangle in C#[^],
What kind of playful method is Paint? (DataGridViewImageCell.Paint(...))[^],
capture the drawing on a panel[^],
How to speed up my vb.net application?[^].

And yes, you need to have some data model which may include, say, a Boolean flag named "clear". If it's "clear", just don't do any rendering. When you call Control.Invalidate(), your graphics will be refreshed, and your rendering method will be called not drawing anything.

—SA

Posted 21-Dec-15 8:15am

Sergey Alexandrovich Kryukov

Comments

MinhajAli 22-Dec-15 11:39am

Thanks for your reply.

i follow your given link but no luck.

In my case i am loading an image on pucturebox and counting the mouse click on that image for finding specific thing on image.Suppose i am loading the image of Hair and the user want to count the hair. for user information i am drawing rectangle on it that which hair user had already count.
if user mistakenly click on wrong place than there is a button to undo so how to remove that particular rectangle.

is there any other solution..?

Sergey Alexandrovich Kryukov 22-Dec-15 11:45am

This is not a "reply"; this is a comprehensive answer. I have no idea what you are missing, but you can ask follow-up questions. "Click on wrong place" is unrelated to your original question. Implement undo. "How to remove" question suggests that you did not get the simple idea of how rendering is done.
Other solution? Why? It simply makes no sense. All rendering is done in the same way. It's based on Windows API (GDI+), the whole library.
—SA