Define polygon over image

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5.00/5 (1 vote)

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Hello,

I am trying to define polygon over Image Dynamically....i.e. User will define polygon points on mouse click and after that defined area's color will change..

please please help me ...

Thanks in advance

Posted 27-Mar-12 22:01pm

rahulbhadouria

Updated 27-Mar-12 22:02pm

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OriginalGriff · Accepted Answer · 2012-03-27T23:00:00

Solution 1

Create a class level GraphicsPath object:

C#

GraphicsPath path = new GraphicsPath();

In your mouse Down event, add lines to the path:

C#

path.AddLine(oldPoint, newPoint);

Where 0old point is the previous mouse click location.
Handle the Paint event for whatever object holds your image, and construct a Region from the GraphicsPath. You can then draw as needed within the region:

C#

Region r = new Region(path);
e.Graphics.FillRegion(Brushes.Red, r);

Posted 27-Mar-12 23:00pm

OriginalGriff

Comments

ProEnggSoft 28-Mar-12 5:41am

To the point. +5

rahulbhadouria 28-Mar-12 6:11am

I am still unable to do this ...because I am new to "system.drawing" .So please tell me some details so that I can do this.

Thanks a lot for helping...

Thanks

OriginalGriff 28-Mar-12 6:18am

Which bit do you need more details for?

rahulbhadouria 28-Mar-12 8:16am

I want that user will select polygon and the vertices of selected polygon are stored either in DB or any where.

OriginalGriff 28-Mar-12 9:48am

So instead of just adding them to the GraphicsPath, add them to your store.

Vinay Swa · Accepted Answer · 2012-03-28T00:58:00

Hi,
drawing is the basic programming for C#;

First create a sample of windows form, and drop the picture box on that.

and replace the code to application

* this is for total form class.

* and add the required events (pictureBox1_MouseClick).

****************************************************************
public partial class Form1 : Form
{
int iNumberofClicks = 0;
Point[] pointArray = new Point[100];
public Form1()
{
InitializeComponent();
}
private void pictureBox1_MouseClick(object sender, MouseEventArgs e)
{
pointArray[iNumberofClicks].X = e.X;
pointArray[iNumberofClicks].Y = e.Y;
Pen PenSpikes = new Pen(Color.Green);
SolidBrush solidBrush = new SolidBrush(Color.Blue);
iNumberofClicks++;
if (iNumberofClicks > 1)
{
Point[] CurrentpointArray = new Point[iNumberofClicks];

for (int i = 0; i < iNumberofClicks; i++)
{
CurrentpointArray[i].X = pointArray[i].X;
CurrentpointArray[i].Y = pointArray[i].Y;
}

Bitmap canvas = new Bitmap(pictureBox1.Width, pictureBox1.Height);
Graphics offScreenDC = Graphics.FromImage(canvas);
// offScreenDC.DrawPolygon(PenSpikes, CurrentpointArray);
offScreenDC.FillPolygon(solidBrush, CurrentpointArray);
pictureBox1.Image = canvas;
offScreenDC.Dispose();
}
}
}

**********************************************************
Regards

Vinay