public partial class Form1 : Form
    {
        Bitmap memBmp = new Bitmap(150, 50);
        public Form1()
        {
            // 准备一个字符串图形
             //
            using (Graphics g = Graphics.FromImage(memBmp))
            {
                g.DrawString("Hello world", new Font("Times New Roman", 16), Brushes.Black, 10, 10);
            }
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            using (Graphics g = e.Graphics)
            {
                // 原样画图
                //
                g.DrawImageUnscaled(memBmp, 0, 0);

                // 放大，采用最近点取样，突出失真的效果
                //
                g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.NearestNeighbor;                       //<---
                g.DrawImage(memBmp, new Rectangle(0, 50, 600, 200), new Rectangle(0, 0, 150, 50), GraphicsUnit.Pixel);  //<---
            }
        }
    }

------解决方案--------------------

C# code

public Bitmap CreateFontBmp(Font font, string text, float zoom)
        {
            if (string.IsNullOrEmpty(text))
                return null;
            Size size = TextRenderer.MeasureText(text, font);
            Rectangle rect = new Rectangle(0,0,size.Width,size.Height);
            Bitmap bmp = new Bitmap(size.Width, size.Height);
            Graphics graphics = Graphics.FromImage(bmp);
            TextRenderer.DrawText(
                graphics,
                text,
                font,
                rect,
                SystemColors.ControlText);

            if (zoom > 0 && zoom != 1)
            {
                int width = (int)Math.Ceiling(size.Width * zoom);
                int height = (int)Math.Ceiling(size.Height * zoom);
                Rectangle tmpRect = new Rectangle(0,0,width,height);
                Bitmap tmpBmp = new Bitmap(width, height);
                graphics = Graphics.FromImage(tmpBmp);
                graphics.DrawImage(
                    bmp,
                    tmpRect,
                    rect,
                    GraphicsUnit.Pixel);
                graphics.Flush();
                graphics.Dispose();
                bmp.Dispose();
                return tmpBmp;
            }
            graphics.Flush();
            graphics.Dispose();
            return bmp;
        }

------解决方案--------------------

参考:

C# code
Graphics g = this.pictureBox1.CreateGraphics();
            g.SmoothingMode = Smoothi