pictureBox image scalling

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I have a code that draws over pictureBox but after draw the line shifts the image loaded into pictureBox. I wish the image loaded in pictureBox whole time he was properly scaled. For example picture 3000x2000 visible in the 800x600 pictureBox.

Thank you for any help.

I have code to draw lines

C#

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);

               // New line!
               offScreenDC.DrawImage(pictureBox1.Image, new Point());
               offScreenDC.DrawLines(PenSpikes, CurrentpointArray);
               pictureBox1.Image = canvas;
               offScreenDC.Dispose();
           }

       }

Posted 13-Jul-13 1:38am

stockCoders

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Ravimal Bandara · Answer 1 · 2013-07-13T04:04:00

I think you need to draw set of lines while you put points on a picture_Box by clicking on it. What you do with this code is, you collect the set of points as the mouse clicks, copy the set of points in to a local array, create an image with drawing lines with the local array and then set the image to the pictureBox1.

I think the best way is to do this is drawing lines with in the "Paint" event of the picture box.

change the mouse event as the follow.

C#

private void pictureBox1_MouseClick(object sender, MouseEventArgs e)
{
    pointArray[iNumberofClicks].X = e.X;
    pointArray[iNumberofClicks].Y = e.Y;
    iNumberofClicks++;
    pictureBox1.Refresh();
}

//this is the registered paint event of the pictureBox1
private void pictureBox1_Paint(object sender, PaintEventArgs e)
{
    if(iNumberofClicks >1)
    {
        Pen PenSpikes = new Pen(Color.Green);
        Graphics g = e.Graphics;
        g.DrawLines(PenSpikes, pointArray);
    }
}

When ever you put a new point, you can see the new line. If you need to scale up the drawing you can simply multiply the x and y coordinates of the points in the array by the scale factor you need and then call pictureBox1.Refresh().

C#

private void scaleDrawing(double factor)
{
    for (int i = 0; i < iNumberofClicks; i++)
    {
        pointArray[i].X = (int)pointArray[i].X*factor;
        pointArray[i].Y = (int)pointArray[i].Y*factor;
    }
    pictureBox1.Refresh();
}

This is how I understand your question. Please clarify if I'm wrong.