this is used to create a new Font from template font which is given by parameter Font, the parameter size show you a chance to redefine the Size.
if you want to zoom Size, you can get the size from your template font, and multiply it with the zoom factor you expected, which a new size you will got, for example named new size variable newSize, then use this constructor to create new Font: Font newFont = new Font(templateFont, newSize);
public class TestForm : Form { protected override void OnPaint(PaintEventArgs e) { base.OnPaint(e); IntPtr hDc = e.Graphics.GetHdc(); // create a font from default Form.Font (Microsoft Sans Serif, 8.25pt), size = 8.25 Gdi.Font font = new Gdi.Font(this.Font); IntPtr oldFont = SelectObject(hDc, font.Handle); string test1 = "1. This is drawing by GDI with GdiFont"; TextOut(hDc, 50, 50, test1, test1.Length); SelectObject(hDc, oldFont); // here I want to a font which size is as twice as current's Drawing.Gdi.Font font2 = new Drawing.Gdi.Font(font, 2 * font.Size); oldFont = SelectObject(hDc, font2.Handle); string test2 = "2. This is drawing by GDI with GdiFont"; TextOut(hDc, 50, 100, test2, test2.Length); font.Dispose(); font2.Dispose(); SelectObject(hDc, oldFont); e.Graphics.ReleaseHdc(hDc); } [DllImport("gdi32.dll", EntryPoint = "SelectObject")] public static extern IntPtr SelectObject( IntPtr hdc, IntPtr hObject ); [DllImport("gdi32.dll", EntryPoint = "TextOut")] public static extern int TextOut( IntPtr hdc, int x, int y, string lpString, int nCount ); }
public class TestForm : Form { protected override void OnPaint(PaintEventArgs e) { base.OnPaint(e); IntPtr hDc = e.Graphics.GetHdc(); // create a font from default Form.Font (Microsoft Sans Serif, 8.25pt), size = 8.25 Gdi.Font font = new Gdi.Font(this.Font); IntPtr oldFont = SelectObject(hDc, font.Handle); string test1 = "1. This is drawing by GDI with GdiFont"; TextOut(hDc, 50, 50, test1, test1.Length); SelectObject(hDc, oldFont); // here I want to a font which size is as twice as current's Drawing.Gdi.Font font2 = new Drawing.Gdi.Font(font, 2 * font.Size); oldFont = SelectObject(hDc, font2.Handle); string test2 = "2. This is drawing by GDI with GdiFont"; TextOut(hDc, 50, 100, test2, test2.Length); font.Dispose(); font2.Dispose(); SelectObject(hDc, oldFont); e.Graphics.ReleaseHdc(hDc); } [DllImport("gdi32.dll", EntryPoint = "SelectObject")] public static extern IntPtr SelectObject( IntPtr hdc, IntPtr hObject ); [DllImport("gdi32.dll", EntryPoint = "TextOut")] public static extern int TextOut( IntPtr hdc, int x, int y, string lpString, int nCount ); }