根据文本内容创建图片并返回图片路径

//创建图片 
private string GetImagePath(string _text) 
{ 
Bitmap bitmap = new Bitmap(1, 1); 
Font font = new Font("Arial", 25, FontStyle.Regular, GraphicsUnit.Pixel); 
Graphics graphics = Graphics.FromImage(bitmap); 
int width = (int)graphics.MeasureString(_text, font).Width; 
int height = (int)graphics.MeasureString(_text, font).Height; 
bitmap = new Bitmap(bitmap, new Size(width, height)); 
graphics = Graphics.FromImage(bitmap); 
graphics.Clear(Color.White); 
graphics.SmoothingMode = SmoothingMode.AntiAlias; 
graphics.TextRenderingHint = TextRenderingHint.AntiAlias; 
graphics.DrawString(_text, font, new SolidBrush(Color.FromArgb(0, 0, 0)), 0, 0); 
graphics.Flush(); 
graphics.Dispose(); 
string fileName = Path.GetFileNameWithoutExtension(Path.GetRandomFileName()) + ".jpg"; 
bitmap.Save(Server.MapPath("~/ImageLib/") + fileName, ImageFormat.Jpeg); 
return "~/ImageLib/" + fileName; 
}