C# Winforms Region.IsVisible

问题:

I want to detect mouse click on my custom created region.

1) I ve tried this code with rectangle and it worked, but with string it doesnt

 GraphicsPath gp = new GraphicsPath();
    Region reg = new Region();
        private void Form1_Load(object sender, EventArgs e)
    {

        gp.AddString("TEXT", new FontFamily("Arial"),0, 20.0f, new Point(300, 10), StringFormat.GenericDefault);
        gp.Widen(Pens.AliceBlue);
        reg = new Region(gp);
    }

and here is the part2

  private void panel1_MouseDown(object sender, MouseEventArgs e)
    {
        if (reg.IsVisible(e.Location))
        {
            MessageBox.Show("aaaa");
        }
    }

It doesnt show the message box. :)

EDIT :here is my Paint event to see where my string is

 private void panel1_Paint(object sender, PaintEventArgs e)
    {


        e.Graphics.DrawString("TEXT", new Font("Arial", 20), Brushes.Yellow, 300,100 );
    }

回答1:

The most basic error is a typo: One time you draw at y = 10, the other time at y = 100.

But there is another issue which is not so obvious at all:

Add

e.Graphics.FillPath(Brushes.Firebrick, gp);

to the Paint event and you'll see it: The fonts have quite a different size.

That is because when adding text to a GraphicsPath it is using a different scale (called 'emSize') than Graphics.DrawString does, which uses 'Point'.

To adapt you can use this:

float fontsize = 20.0f;
using (Graphics g = panel1.CreateGraphics()) fontsize *= g.DpiY / 72f;

Now you can build the GraphicsPath, best with the correct coordinates..:

gp.AddString("TEXT", new FontFamily("Arial"), 0, fontsize, 
             new Point(300, 100), StringFormat.GenericDefault);