如何在该图像上使用鼠标位置放大

Question

我有一个 userControl 库，它由主 Panel 和 PictureBox 组成，我想做一个可缩放的 PictureBox 工具，我使用主 Panel 的 mouseWheel 事件放大和缩小，我想不通的问题如何通过鼠标在图像上的位置进行放大，所以每当我放大时，缩放都会转到面板的左上角，那么我该如何解决呢？

private double ZOOMFACTOR = 1.15;   // = 15% smaller or larger
private int MINMAX = 5;
void picPanel_MouseWheel(object sender, MouseEventArgs e)
    {
        if (e.Delta > 0)
        {
            ZoomIn();
        }
        else
        {
            ZoomOut();
        }
    }

    private void ZoomIn()
    {
        if ((picBox.Width < (MINMAX * this.Width)) &&
            (picBox.Height < (MINMAX * this.Height)))
        {
            picBox.Width = Convert.ToInt32(picBox.Width * ZOOMFACTOR);
            picBox.Height = Convert.ToInt32(picBox.Height * ZOOMFACTOR);
        }
    } 
    private void picBox_MouseEnter(object sender, EventArgs e)
    {
        if (picBox.Focused) return;
        picBox.Focus();
    }

更新：

我已经尝试过了，它看起来可以工作，但不完全是应该的！有什么想法吗？

    private void ZoomIn()
    {
        if ((picBox.Width < (MINMAX * this.Width)) &&
            (picBox.Height < (MINMAX * this.Height)))
        {
            picBox.Width = Convert.ToInt32(picBox.Width * ZOOMFACTOR);
            picBox.Height = Convert.ToInt32(picBox.Height * ZOOMFACTOR);

            Point p = this.AutoScrollPosition;
            int deltaX = e.X - p.X;
            int deltaY = e.Y - p.Y;
            this.AutoScrollPosition = new Point(deltaX, deltaY);
        }
    } 

Answer 1

这是在鼠标位置缩放图像的示例.... 测试验证。

protected override void OnMouseWheel(MouseEventArgs ea)
{
    //  flag = 1;
    // Override OnMouseWheel event, for zooming in/out with the scroll wheel
    if (picmap1.Image != null)
    {
        // If the mouse wheel is moved forward (Zoom in)
        if (ea.Delta > 0)
        {
            // Check if the pictureBox dimensions are in range (15 is the minimum and maximum zoom level)
            if ((picmap1.Width < (15 * this.Width)) && (picmap1.Height < (15 * this.Height)))
            {
                // Change the size of the picturebox, multiply it by the ZOOMFACTOR
                picmap1.Width = (int)(picmap1.Width * 1.25);
                picmap1.Height = (int)(picmap1.Height * 1.25);

                // Formula to move the picturebox, to zoom in the point selected by the mouse cursor
                picmap1.Top = (int)(ea.Y - 1.25 * (ea.Y - picmap1.Top));
                picmap1.Left = (int)(ea.X - 1.25 * (ea.X - picmap1.Left));
            }
        }
        else
        {
            // Check if the pictureBox dimensions are in range (15 is the minimum and maximum zoom level)
            if ((picmap1.Width > (imagemappan.Width)) && (picmap1.Height > (imagemappan.Height)))
            {
                // Change the size of the picturebox, divide it by the ZOOMFACTOR
                picmap1.Width = (int)(picmap1.Width / 1.25);
                picmap1.Height = (int)(picmap1.Height / 1.25);

                // Formula to move the picturebox, to zoom in the point selected by the mouse cursor
                picmap1.Top = (int)(ea.Y - 0.80 * (ea.Y - picmap1.Top));
                picmap1.Left = (int)(ea.X - 0.80 * (ea.X - picmap1.Left));
            }
        }
    }
}

Answer 2

问题是你的控件就像一个视口——原点在左上角，所以每次你从那个角落拉伸图像时——结果就是你最终放大到左上角，您需要偏移拉伸的图像并将用户放大的点居中。

• 图像大小：200,200
• 用户点击 100,50 并放大 x2
• 拉伸图像
• 图像大小为 400,400，用户点击的位置现在有效为 200,100
• 您需要将图像向左滑动 100 像素并向上滑动 50 像素以更正调整图像大小

您需要覆盖paint 事件处理程序来绘制图像偏移：

 RectangleF BmpRect = new RectangleF((float)(Offset.X), (float)(Offset.Y), (float)(ZoomedWidth), (float)(ZoomedHeight));
  e.Graphics.DrawImage(Bmp, ViewPort , BmpRect, GraphicsUnit.Pixel);

Bmp 是你的形象； ViewPort 是一个由您的图片框控件定义的 Rectangle

这里是a thread，可能会有所帮助。