How to crop (make a rectangular hole in) a panel in C#

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hello morning everyone
anyone know how to crop (make a rectangular hole in) a control?

i try to crop a square in the middle of the panel
for an example
if the size of my panel was

C#

Panel myPanel = new Panel() { Size = new Size(300, 800), Location = new Point(0,0); BackColor = Color.FromArgb(0,0,0); }

i would like to crop a square with a size of 250, 250 and located at point 25,25

What I have tried:

C#

GraphicsPath graphicPath = new GraphicPath();
Rectangle myRec = new Rectangle(new point(25,25), new Size(250,250));
Panel myPanel = new Panel() { Size = new Size(300, 800), Location = new Point(0,0); BackColor = Color.FromArgb(0,0,0); }
myPanel.Region = new Region(myRec);

i know by doing this,
it just set the original panel to a new region.
but is there any method to crop the rectangle in the middle of panel..
thank you

Posted 31-Aug-17 16:04pm

newbie1992

Updated 1-Sep-17 13:33pm

BillWoodruff

v2

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Graeme_Grant 31-Aug-17 23:40pm

Are you trying to crop an image???

newbie1992 1-Sep-17 0:29am

Hello sir
Nope.. i m not croping an image..

I try to crop my panel..so that there is an empty space in the middle of the panel

Graeme_Grant 1-Sep-17 0:31am

Do you mean resize the panel?

newbie1992 1-Sep-17 1:57am

Nope.. not resizebut i try to drill a 'hole' on the panel
The hole is in rectangle size..
It was like a card.. i draw a rectangle on it..
The i cut the rectangle..
I will get a card with a hole in the middle of the card

Ralf Meier 1-Sep-17 2:41am

Sorry ... I didn't understand your issue.
Please try to explain it once more - perhaps improve your question with some pictures ...

Graeme_Grant 1-Sep-17 2:47am

[moved to solution 2 below]

newbie1992 4-Sep-17 20:26pm

have everyone
I am very sorry that I am late in return a feedback cause I just came back from holiday
I would like to say thank you for all of the comments and answers
sorry for make an unclear question.
Will research on the suggestion given below :) thanks..

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RickZeeland · Answer 1 · 2017-08-31T21:14:00

In addition to the nice article mentioned by Graeme (which deserves points really) Making Transparent Controls - No Flickering[^] , the following:

If you want to "punch a hole", this article might be of interest: Phil Wright : Component Factory: .NET2, Transparent controls[^]
Also using WS_EX_TRANSPARENT might be of interest: c# - Any trick to use opacity on a panel in Visual Studio Window Form? - Stack Overflow[^]

Graeme_Grant · Answer 2 · 2017-08-31T21:47:00

Solution 2

[moved from comments - thanks for the suggestion RickZeeland]

Is the hole suppose to show objects behind it? Like a transparent hole? Something like this: Making Transparent Controls - No Flickering[^][^]???

Posted 31-Aug-17 21:47pm

Graeme_Grant

Comments

RickZeeland 1-Sep-17 6:14am

Your helping hand in CP land :)

Graeme_Grant 1-Sep-17 7:39am

;)

BillWoodruff · Answer 3 · 2017-09-01T13:28:00

using System.Drawing;
using System.Windows.Forms;

namespace PathStuff
{
    public static class PathExtensions
    {
        public static void MakeHole(this Control cntrl, Rectangle xrect)
        {
            var region = new Region(cntrl.ClientRectangle);
            region.Exclude(xrect);

            cntrl.Region = region;
        }

        public static void MakeHoleCenteredProportional(this Control cntrl, int scaleX, int scaleY)
        {
            var rect = new Rectangle();
            rect.Size = cntrl.ClientRectangle.Size;
            Region region = new Region(rect);

            rect.Inflate(cntrl.Width / (scaleX * -2), cntrl.Height / (scaleY * -2));

            region.Exclude(rect);

            cntrl.Region = region;
        }
    }
}

Sample uses in a Form:

using PathStuff;
namespace YourForm
{
    private void Form1_Load(object sender, EventArgs e)
    {
         PathExtensions.MakeHole(this, new Rectangle(100,100, 100, 100));

        // or
        PathExtensions.MakeHoleCenteredProportional(this Control cntrl, (this, 2, 2);
    
    }
};

Note the 'MakeHoleCenteredProportional method makes a hole centered in the Control; its size is determined by the ratios supplied: a value of #2 will create length, or width, of half the size of the corresponding dimension of the Control.

Suggestion: use double-buffering with Forms, or UserControls with this.

How to crop (make a rectangular hole in) a panel in C#

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