下面是支持应用缩放能力的图片框子不仅对图片还要图形绘制在其表面。

Here is a PictureBox subclass that supports the ability to apply zooming not only to the Image but also to graphics you draw onto its surface.

它包括 SetZoom 功能通过缩放本身和矩阵放大

It includes a SetZoom function to zoom in by scaling both itself and a Matrix.

它也有，你可以用它来计算 ScalePoint 功能来自像素的缩放的坐标，坐标，你的鼠标事件接收。

It also has a ScalePoint function you can use to calculate the unscaled coordinates from the pixel coordinates you receive in the mouse events.

我们的想法是使用变换矩阵缩放图形对象将在油漆画事件的任何像素。

The idea is to use a Transformation Matrix to scale any pixels the Graphics object will draw in the Paint event.

我包括形式测试一些代码

I include a little code for the form for testing.

public partial class ScaledPictureBox : PictureBox
{
    public Matrix ScaleM { get; set; }

    float Zoom { get; set; }
    Size ImgSize { get; set; }

    public ScaledPictureBox()
    {
        InitializeComponent();
        ScaleM = new Matrix();
        SizeMode = PictureBoxSizeMode.Zoom;
    }

    public void InitImage()
    {
        if (Image != null)
        {
            ImgSize = Image.Size;
            Size = ImgSize;
            SetZoom(100);
        }
    }

    public void SetZoom(float zoomfactor)
    {
        if (zoomfactor <= 0) throw new Exception("Zoom must be positive");
        float oldZoom = Zoom;
        Zoom = zoomfactor / 100f;
        ScaleM.Reset();
        ScaleM.Scale(Zoom , Zoom );
        if (ImgSize != Size.Empty) Size = new Size((int)(ImgSize.Width * Zoom), 
                                                   (int)(ImgSize.Height * Zoom));

    }

    public PointF ScalePoint(PointF pt)
    {   return new PointF(pt.X / Zoom , pt.Y / Zoom );     }

}

下面是该做的测试代码的形式

Here is the code in the Form that does the testing:

public List<PointF> somePoints = new List<PointF>();

private void scaledPictureBox1_MouseClick(object sender, MouseEventArgs e)
{
    somePoints.Add(scaledPictureBox1.ScalePoint(e.Location) );
    scaledPictureBox1.Invalidate();
}

private void scaledPictureBox1_Paint(object sender, PaintEventArgs e)
{
    // here we apply the scaling matrix to the graphics object:
    e.Graphics.MultiplyTransform(scaledPictureBox1.ScaleM);
    using (Pen pen = new Pen(Color.Red, 10f))
    {
        PointF center = new PointF(scaledPictureBox1.Width / 2f, 
                                   scaledPictureBox1.Height / 2f);
        center = scaledPictureBox1.ScalePoint(center);
        foreach (PointF pt in somePoints)
        {
            DrawPoint(e.Graphics, pt, pen);
            e.Graphics.DrawLine(Pens.Yellow, center, pt);
        }
    }
}

public void DrawPoint(Graphics G, PointF pt, Pen pen)
{
    using (SolidBrush brush = new SolidBrush(pen.Color))
    {
        float pw = pen.Width;
        float pr = pw / 2f;
        G.FillEllipse(brush, new RectangleF(pt.X - pr, pt.Y - pr, pw, pw));
    }
}

下面是绘制出了几个点后的结果在四个不同的变焦设置相同点;在 ScaledPictureBox 显然是放置在自动滚屏面板英寸该行显示了如何使用常规的绘图命令。

Here are the results after drawing a few points showing the same points in four different zoom settings; the ScaledPictureBox is obviously placed in an AutoScroll-Panel. The lines show how to use the regular drawing commands..