How to use Mouse_Wheel to zoom in & out

ghasem deh

How to use Mouse_Wheel to zoom in & out pictureBox ...

i use this code :

namespace Test_Code_Csharp
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
            pictureBox1.MouseWheel += new MouseEventHandler(pictureBox1_MouseWheel);
        }

        void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
        {
            pictureBox1.Height += e.Delta / 60;
            pictureBox1.Width += e.Delta / 60;
            pictureBox1.Top -= e.Delta / 120;
            pictureBox1.Left -= e.Delta / 120;
        }

But no happen ! no error ! and no ...

5 Replies

Know the answer? Post it — somebody with the same question will find it here.

Vulpes12y ago
Accepted answer
Doh, I know now what's happened here!

When I tried it myself, I added the MouseEnter event through the Properties Box at design time.

When I subsequently posted it, I added the event dynamically instead as that's what you'd done for the MouseWheel event. Unfortunately, I forgot that MouseEnter is an EventHandler rather than a MouseEventHandler delegate.

If you change:

pictureBox1.MouseEnter += new MouseEventHandler(pictureBox1_MouseEnter);

to:

pictureBox1.MouseEnter += new EventHandler(pictureBox1_MouseEnter);

then it should now compile and work.
ghasem deh12y ago
this : Error 1 Cannot implicitly convert type 'System.Windows.Forms.MouseEventHandler' to 'System.EventHandler'
Vulpes12y ago
I tried it before posting and it worked fine (VS 2010 .NET 4.0).

What error are you getting?
ghasem deh12y ago
hi my friend ...
use this But : error in MouseEnter Method ...
and when use just pictureBox1.Focus ...
not happen !
Vulpes12y ago
A control's MouseWheel event fires if the mouse wheel is moved while the control has focus.

The problem with pictureboxes is that they don't normally receive focus even when they're clicked so the trick is to force focus onto them when (say) the mouse moves over them. The MouseWheel event will then fire.

You also need to set the picturebox's SizeMode property to zoom when its size changes.

Try this:

namespace Test_Code_Csharp
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
pictureBox1.MouseEnter += new MouseEventHandler(pictureBox1_MouseEnter);
pictureBox1.MouseWheel += new MouseEventHandler(pictureBox1_MouseWheel);
pictureBox1.SizeMode = PictureBoxSizeMode.Zoom;
}

void pictureBox1_MouseWheel(object sender, MouseEventArgs e)
{
pictureBox1.Height += e.Delta / 60;
pictureBox1.Width += e.Delta / 60;
pictureBox1.Top -= e.Delta / 120;
pictureBox1.Left -= e.Delta / 120;
}

void pictureBox1_MouseEnter(object sender, EventArgs e)
{
pictureBox1.Focus();
}