C# 如何在绘制的矩形区域上使用鼠标滚轮进行放大或缩小？

这是我用来在图片上绘制矩形的代码B：

private void DrawRectangle(Graphics e)
{
    using (Pen pen = new Pen(Color.Red, 2))
    {
        e.DrawRectangle(pen, mRect);
    }
}

private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
    mRect = new Rectangle(e.X, e.Y, 0, 0);
    pictureBox1.Invalidate();
}


private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
    if (e.Button == MouseButtons.Left)
    {
        mRect = new Rectangle(mRect.Left, mRect.Top, e.X - mRect.Left, e.Y - mRect.Top);
        pictureBox1.Invalidate();
    }
}

在我画了一个矩形后，当我向上或向下移动鼠标滚轮时，它将调整图片框中图像上绘制的矩形区域的大小，我该怎么做？

---

不调整所有图像的大小，但仅对矩形绘制区域进行放大/缩小。

熟悉鼠标滚轮事件

可以手动添加鼠标滚轮事件，如下所示，当然您可以根据需要进行设置：

this.MouseWheel += new MouseEventHandler(Form1_MouseWheel);

private void Form1_MouseWheel(object sender, MouseEventArgs e)
{
    e.Delta;
    // e.Delta: Represents the amount the wheel has changed. This value is positive if the mouse wheel is 
    // rotated in an upward direction (away from the user) or negative if the mouse wheel
    // is rotated in a downward direction (toward the user).
}

您可以使用

Graphics

class'

ScaleTransform

缩放绘制的矩形