为什么裁剪后的矩形不适合pictureBox sizemode？

Question

In my program i did that on the listBox i have items when i select an item i see a screenshot image in the picturebox on the right. Then i can draw a rectangle on the pictureBox and with a button click i can crop the rectangle. The problem is that i need to make the pictureBox in the form1 designer SizeMode proprty to be zoom or stretch image if not when i select an item i see the screenshot in pictureBox too large. Only if it's zoom or stretch i see it good. But then when i crop the rectangle it's not fitting and i need the pictureBox sizemode to be Normal. How can i fix it ?

This is my form1 code:

Form1.cs

This is how i select and item and display the image of it:

private void listBoxSnap_SelectedIndexChanged(object sender, EventArgs e)
        {

            WindowSnap snap = this.listBoxSnap.SelectedItem as WindowSnap;
            selectedIndex = this.listBoxSnap.SelectedIndex.ToString();
            this.pictureBoxSnap.Image = snap.Image;
            for (int i = 0; i < rectangles.Length; i++)
            {
                if (rectangles[i] != RectClone)
                {
                    ClearGraphics = false;
                }
                else
                {
                    ClearGraphics = true;
                }
            }

        }

And this is the paint event:

private void pictureBoxSnap_Paint(object sender, PaintEventArgs e)
        {

            if (pictureBoxSnap.Image != null)
            {
                {
                    if (ClearGraphics == false)
                    {

                            if (rectangles[listBoxSnap.SelectedIndex] != Rectangle.Empty)
                            {
                                e.Graphics.DrawRectangle(Pens.Firebrick, rectangles[listBoxSnap.SelectedIndex]);
                            }




                    }
                    if (cropRect == true)
                    {
                        if (recttest.Width > 10 && recttest.Height > 10)
                        {
                            e.Graphics.Clear(Color.White);

                            e.Graphics.DrawImage(pictureBoxSnap.Image, new Rectangle(rect.X, rect.Y, rect.Width, rect.Height), rect, GraphicsUnit.Pixel);

                        }
                    }
                }
            }           
        }

The drawimage line draw the cropped rectangle.

The problem is that if SizeMode set to Normal i see good the cropped rectangle but then the screenshot/image when i select an item dosent fit the pictureBox too large. And if i change the sizemode to zoom i see the selected item image good but the cropped image is not fitting.

EDITED:

When it set to Normal i see the cropped image in the rectangle good but then the screenshot of a selected item look like zoom in very big/wide in the pictureBox. And if it set to zoom i see the image of a item good but then the rectangle i draw i see the cropped image inside not what i marked with the rectangle but more like the image 0,0 area part.

This is a link with 4 images i took and explained each one what SizeMode the pictureBox is and what is the problem. I can't upload here images so i did an album in my facebook

Answer 1

....
....
if (cropRect == true){
    if (recttest.Width > 10 && recttest.Height > 10){
        e.Graphics.FillRectangle(Brushes.White, 0, 0, pictureBoxSnap.Width, rect.Y);
        e.Graphics.FillRectangle(Brushes.White, 0, rect.Y, rect.X, rect.Height);
        e.Graphics.FillRectangle(Brushes.White, rect.X + rect.Width, rect.Y, pictureBoxSnap.Width - rect.X - rect.Width, rect.Height);
        e.Graphics.FillRectangle(Brushes.White, 0, rect.Y + rect.Height, pictureBoxSnap.Width, pictureBoxSnap.Height - rect.Y - rect.Height);
     }
}    

or better

private void pictureBoxSnap_Paint(object sender, PaintEventArgs e){
    Point pnt;

    ....
    ....
    if (cropRect == true){
        if (recttest.Width > 10 && recttest.Height > 10){
            pnt = PointToScreen(pictureBoxSnap.Location);

            e.Graphics.Clear(Color.White);
            e.Graphics.CopyFromScreen(pnt.X + rect.X, pnt.Y + rect.Y, rect.X, rect.Y, New Size(rect.Width, rect.Height));
        }
    }

valter