Resize from Center [Winforms]

问题

i have 2 forms (parent & child)
child form's properties are ControlBox:False, DoubleBuffer:True & FormBorderStyle:SizeableToolWindow (rest all are default values).
i want child form to resize from center (and not from top left)

In Child form Resize Event, i have following code

this.Location = System.Drawing.Point(x / 2 - this.Width / 2, y / 2 - this.Height / 2);
//tried this.CenterToParent();`

where x = parent form's width and y = parent form's height.

now after showing child form from parent form, while resizing it flickers a lot, child form tends to go back to its original location!
how to create smooth resize from center?
is there a way to change Form's resize origin to center?
this question is already posted here, but didn't understand solution

回答1:

using System;
using System.Windows.Forms;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        protected override void OnResize(EventArgs e)
        {
            this.Location = new System.Drawing.Point(this.Location.X / 2 - this.Width / 2, this.Location.Y / 2 - this.Height / 2);
            //tried this.CenterToParent();`
            base.OnResize(e);
        }

        const int WM_SYSCOMMAND = 0x112;
        const int SC_MAXIMIZE = 0xF030;
        const int SC_MAXIMIZE2 = 0xF032;

        protected override void WndProc(ref Message m)
        {
            if ((m.Msg == WM_SYSCOMMAND && m.WParam == new IntPtr(SC_MAXIMIZE)) || m.WParam == new IntPtr(SC_MAXIMIZE2))
            {
                this.Size = this.MaximumSize;
                m.Result = new IntPtr(0);
                //base.WndProc(ref m);
                //Eat the message so won't process further
            }
            else
            {
                m.Result = new IntPtr(0);
                base.WndProc(ref m);
            }
        }
    }
}

Here's the better link: https://msdn.microsoft.com/en-us/library/system.windows.forms.control.wndproc(v=vs.110).aspx

来源：https://stackoverflow.com/questions/43502292/resize-from-center-winforms