CODEWITHSUNDEEP
c#winformszoomingpanel
J-P
J-P

Reputation: 403

Panel Drawing zoom in C#

I have a Form that contain a panel, and in this panel I draw shapes, like rectangles and circles, I need to zoom into this shapes, I saw couple options but most of them using PictureBox. Should I use Bitmap creating the panel area as a bitmap and change the zooming factor ?? would this help me also further if I want to have Panning and not draw images not into the fit in the panel size.

Here is a snapshot of my code 

  private void panel1_Paint(object sender, PaintEventArgs e)
    {
        Graphics g = panel1.CreateGraphics();
        SolidBrush myBrush = new SolidBrush(Color.Black);
        Pen p = new Pen(Color.Black);
        int RecScale = 1;
        foreach (CircuitData.ResistorRow resistorRow in ResistorData.Resistor)
        {
            RectangleF rec = new RectangleF((float)(resistorRow.CenterX - resistorRow.Length / 2), (float)(resistorRow.CenterY - resistorRow.Width/ 2), (float)resistorRow.Length, (float)resistorRow.Width);
            float orientation = 360 - (float)resistorRow.Orientation;
            PointF center = new PointF((float)resistorRow.CenterX, (float)resistorRow.CenterY);
            PointF[] points = CreatePolygon(rec, center, orientation);
            if (!Double.IsNaN(resistorRow.HiX) && !Double.IsNaN(resistorRow.HiY))
            {
                g.FillEllipse(myBrush, (float)resistorRow.HiX - 5 , (float)resistorRow.HiY - 5, 10, 10);
                g.DrawLine(p, new PointF((float)resistorRow.HiX, (float)resistorRow.HiY), center);
            }
            g.FillPolygon(myBrush, points);
        }
    }

Can a sample code be provided. Many Thanks

Jp

Upvotes: 4

Views: 15924

Answers (2)

TaW
TaW

Reputation: 54453

Here is a way to scale the drawing by scaling the Graphics object:

private void panel1_Paint(object sender, PaintEventArgs e)
{
    Graphics g = e.Graphics;
    g.ScaleTransform(zoom, zoom);

    // some demo drawing:
    Rectangle rect = panel1.ClientRectangle;
    g.DrawEllipse(Pens.Firebrick, rect);
    using (Pen pen = new Pen(Color.DarkBlue, 4f)) g.DrawLine(pen, 22, 22, 88, 88);

}

Here we store the zoom level:

float zoom = 1f;

Here we set it and update the Panel:

private void trackBar1_Scroll(object sender, EventArgs e)
{
   // for zooming between, say 5% - 500%
   // let the value go from 50-50000, and initialize to 100 !
    zoom = trackBar1.Value / 100f;  
    panel1.Invalidate();
}

Two example screenshots:

enter image description hereenter image description here

Note how nicely this scales the Pen widths as well. Turning on antialiasing would be a good idea..: g.SmoothingMode = SmoothingMode.AntiAlias;

Upvotes: 9

Marlon
Marlon

Reputation: 1877

Since you're drawing from scratch, couldn't you resize you drawing base on zoom factor?

You could multiply your drawing dimensions by your zoom factor. Assuming your zoom factor would be:

  • 0.5 for 50 % zoom (which would reduce the drawing size)
  • 1.0 for 100% (Real size)
  • 1.5 for 150 % (bigger size), you could calc the width this way: 
object.Width = originalWidth * zoomFactor;

Upvotes: 0

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