基于C#一个制作图像的特写窗口

// Save the original image.
private Bitmap OriginalImage, ShadedImage;
private int SmallWidth, SmallHeight;
private float ScaleX, ScaleY;
private void Form1_Load(object sender, EventArgs e)
{
    OriginalImage = picWhole.Image as Bitmap;
    picCloseup.Image = OriginalImage;
    picCloseup.SizeMode = PictureBoxSizeMode.AutoSize;
 
    // Make a shaded version of the image.
    ShadedImage = new Bitmap(OriginalImage);
    using (Graphics gr = Graphics.FromImage(ShadedImage))
    {
        using (Brush br =
            new SolidBrush(Color.FromArgb(128, 255, 255, 255)))
        {
            Rectangle rect = new Rectangle(0, 0,
                ShadedImage.Width, ShadedImage.Height);
            gr.FillRectangle(br, rect);
        }
    }
 
    // Get scale factors to map from big scale to small scale.
    ScaleX = (float)panCloseup.ClientSize.Width /
        OriginalImage.Width;
    ScaleY = (float)panCloseup.ClientSize.Height /
        OriginalImage.Height;
 
    // See how big the closeup is on the small scale.
    SmallWidth = (int)(ScaleX * picWhole.ClientSize.Width);
    SmallHeight = (int)(ScaleY * picWhole.ClientSize.Height);
}

// Use the shaded background image.
private void picWhole_MouseEnter(object sender, EventArgs e)
{
    picWhole.Image = ShadedImage;
    panCloseup.Visible = true;
}
 
// Use the regular image.
private void picWhole_MouseLeave(object sender, EventArgs e)
{
    picWhole.Image = OriginalImage;
    panCloseup.Visible = false;
}

// Display a closeup of this area.
private Rectangle ViewingRectangle;
private void picWhole_MouseMove(object sender, MouseEventArgs e)
{
    // Position picCloseup inside its parent Panel.
    float x = (float)e.X / picWhole.ClientSize.Width *
        OriginalImage.Width -
        (float)panCloseup.ClientSize.Width / 2;
    float y = (float)e.Y / picWhole.ClientSize.Height *
        OriginalImage.Height -
        (float)panCloseup.ClientSize.Height / 2;
    if (x < 0) x = 0;
    if (y < 0) y = 0;
    if (x > OriginalImage.Width - panCloseup.ClientSize.Width)
        x = OriginalImage.Width - panCloseup.ClientSize.Width;
    if (y > OriginalImage.Height - panCloseup.ClientSize.Height)
        y = OriginalImage.Height - panCloseup.ClientSize.Height;
    picCloseup.Location = new Point(-(int)x, -(int)y);
 
    // Record the position we are viewing.
    ViewingRectangle = new Rectangle((int)x, (int)y,
        panCloseup.ClientSize.Width, 
        panCloseup.ClientSize.Height);
 
    // Draw the closeup area.
    picWhole.Invalidate();
}

// Draw the viewing area.
private void picWhole_Paint(object sender, PaintEventArgs e)
{
    // Scale so we can draw in the full scale coordinates.
    e.Graphics.ScaleTransform(ScaleX, ScaleY);
 
    // Draw the viewing area using the original image.
    e.Graphics.DrawImage(OriginalImage, ViewingRectangle, 
        ViewingRectangle, GraphicsUnit.Pixel);
    //e.Graphics.DrawRectangle(Pens.Red, ViewingRectangle);
}