I am working on a program that displays the liveView image from a Nikon camera in a pictureBox. I want to be able to hover with the cursor over the image and display a zoomed in area around the cursor in another picturebox. I would also like to add a crosshair instead of mouse pointer. The only solution I have found so far is the following:
zoom an image in a second picturebox following cursor
It does exactly what I want, however I can not get it to work. More specifically, nothing is showing up in picZoom. In the example, images are loaded while in my case, a video stream is shown. That might be the reason why I am not getting it to work. I am relatively new to c#, and did not fully understand the example.
Lets say I have picBox where I receive the video stream. How do I show a portion of picBox around the cursor (let's say a rectangle around the cursor of dimensions x,y) in picZoom with a crosshair as in the example. I do not need to worry about differing dimensions of picBox and picZoom since they will not vary. I also want to be able to vary the degree of zoom by a factor zoomFactor.
If anyone could give me pointers or a solution, it would be greatly appreciated. Also, sorry if my question is poorly formatted, I am new to the forum.
Thank you!
Alexander
CodePudding user response:
I would approach it like this
using System;
using System.Drawing;
using System.Windows.Forms;
namespace MagnifierExample
{
class Magnifier : PictureBox
{
public Magnifier()
{
Visible = false;
}
PictureBox source;
private Point sourcePoint;
Cursor oldCursor;
public PictureBox Source
{
get
{
return source;
}
set
{
if (source != null)
{
source.MouseEnter -= Source_MouseEnter;
source.MouseLeave -= Source_MouseLeave;
source.MouseMove -= Source_MouseMove;
source.Cursor = oldCursor;
}
source = value;
if (source != null)
{
source.MouseEnter = Source_MouseEnter;
source.MouseLeave = Source_MouseLeave;
source.MouseMove = Source_MouseMove;
oldCursor = source.Cursor;
source.Cursor = Cursors.Cross;
}
}
}
private void Source_MouseEnter(object sender, EventArgs e)
{
Visible = true;
BringToFront();
}
private void Source_MouseLeave(object sender, EventArgs e)
{
Visible = false;
}
private void Source_MouseMove(object sender, MouseEventArgs e)
{
sourcePoint = e.Location;
Location = new Point(source.Location.X e.X - Width / 2, source.Location.Y e.Y - Height / 2);
Invalidate();
}
protected override void WndProc(ref Message m)
{
const int WM_NCHITTEST = 0x0084;
const int HTTRANSPARENT = (-1);
if (!DesignMode && m.Msg == WM_NCHITTEST)
{
m.Result = (IntPtr)HTTRANSPARENT;
}
else
{
base.WndProc(ref m);
}
}
protected override void OnPaint(PaintEventArgs pe)
{
if (!DesignMode && Source != null && Source.Image != null)
{
Rectangle destRect = new Rectangle(0, 0, Width, Height);
// IMPORTANT: This calculation will depend on the SizeMode of the source and the amount you want to zoom.
// This does 2x zoom and works with PictureBoxSizeMode.Normal:
Rectangle srcRect = new Rectangle(sourcePoint.X - Width / 4, sourcePoint.Y - Height / 4, Width / 2, Height / 2);
pe.Graphics.DrawImage(Source.Image, destRect, srcRect, GraphicsUnit.Pixel);
}
else
{
base.OnPaint(pe);
}
}
}
}
To hook it up all you have to do is add a Magnifier
to your form, give it a size, and set its Source
to the PictureBox
you want it to magnify.
this.magnifier1.Source = this.pictureBox1;
I used the approach in this answer to ignore messages from the magnifier window.
Importantly, I only coded up the zoom math for the PictureBoxSizeMode.Normal
SizeMode of the source PictureBox. But I think this is a pretty good start.
Not 100% sure what you wanted for crosshairs, but this uses the built-in crosshair cursor.
CodePudding user response:
thank you very much for your detailed answer. I am sure that the code works great, but I must admit that I am very new to c#, so I do not really understand how to use it. For example, I do not know what you mean by "add a Magnifier to my form" or even how to use this code. Is there a more simplified way of doing this, or could you give me a description on how to use it?
Sorry for the trouble, I have barely scratched the surface of c# programming.
Alexander