How to automatically scale child controls' font sizes when form size changes?

Question

I am using a TableLayoutPanel to contain controls that I would like to have automatically resize when the form is resized. I would like to know how to make a form's child controls "scale" in size proportional to the form when the form itself is resized? Although the TableLayoutPanel automatically adjusts the sizes of the contained controls, those controls keep the same font size.

Have you ever seen a program that makes its font smaller when the window gets smaller? It is just not the way it is done. — Hans Passant

gonzobrains gonzobrains · Accepted Answer · 2013-01-14T23:36:19

This is the best method I have come up with so far. I use two scale factors and I iterate through all the controls to selectively choose which ones I want to scale:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace TestTableLayoutPanel
{
    public partial class Form2 : Form
    {
        private const float LARGER_FONT_FACTOR = 1.5f;
        private const float SMALLER_FONT_FACTOR = 0.8f;

        private int _lastFormSize;

        public Form2()
        {
            InitializeComponent();

            this.Resize += new EventHandler(Form2_Resize);
            _lastFormSize = GetFormArea(this.Size);
        }

        private int GetFormArea(Size size)
        {
            return size.Height * size.Width;
        }

        private void Form2_Resize(object sender, EventArgs e)
        {

            var bigger = GetFormArea(this.Size) > _lastFormSize;
            float scaleFactor = bigger ? LARGER_FONT_FACTOR : SMALLER_FONT_FACTOR;

            ResizeFont(this.Controls, scaleFactor);

            _lastFormSize = GetFormArea(this.Size);

        }

        private void ResizeFont(Control.ControlCollection coll, float scaleFactor)
        {
            foreach (Control c in coll)
            {
                if (c.HasChildren)
                {
                    ResizeFont(c.Controls, scaleFactor);
                }
                else
                {
                    //if (c.GetType().ToString() == "System.Windows.Form.Label")
                    if (true)
                    {
                        // scale font
                        c.Font = new Font(c.Font.FontFamily.Name, c.Font.Size * scaleFactor);
                    }
                }
            }
        }
    }
}

How to automatically scale child controls' font sizes when form size changes?

2 Answers