TextGraphics.cs :  » Game » RealmForge » System » Windows » Forms » C# / CSharp Open Source

// ---------------------------------------------------------
// Windows Forms CommandBar Control
// Copyright (C) 2001-2003 Lutz Roeder. All rights reserved.
// http://www.aisto.com/roeder
// roeder@aisto.com
// ---------------------------------------------------------
namespace System.Windows.Forms{
  using System;
  using System.Drawing;
  using System.Runtime.InteropServices;

  internal class TextGraphics : IDisposable
  {
    private Graphics graphics;
    private IntPtr graphicsHandle;

    public TextGraphics(Graphics graphics)
    {
      this.graphics = graphics;
      this.graphicsHandle = graphics.GetHdc();
    }

    public TextGraphics(IntPtr graphicsHandle)
    {
      this.graphics = null;
      this.graphicsHandle = graphicsHandle;
    }

    public void Dispose()
    {
      if (this.graphics != null)
      {
        this.graphics.ReleaseHdc(this.graphicsHandle);
        this.graphics = null;
      }

      this.graphicsHandle = IntPtr.Zero;
    }

    public Size MeasureText(string text, Font font)
    {
      IntPtr fontHandle = font.ToHfont();
      IntPtr oldFontHandle = NativeMethods.SelectObject(this.graphicsHandle, fontHandle);
      
      Size size = this.MeassureTextInternal(text);

      NativeMethods.SelectObject(this.graphicsHandle, oldFontHandle);
      NativeMethods.DeleteObject(fontHandle);

      return size;
    }

    public void DrawText(string text, Point point, Font font, Color foreColor)
    {
      IntPtr fontHandle = font.ToHfont();
      IntPtr oldFontHandle = NativeMethods.SelectObject(this.graphicsHandle, fontHandle);
    
      int oldBkMode = NativeMethods.SetBkMode(this.graphicsHandle, NativeMethods.TRANSPARENT);
      int oldTextColor = NativeMethods.SetTextColor(this.graphicsHandle, Color.FromArgb(0, foreColor.R, foreColor.G, foreColor.B).ToArgb());

      Size size = this.MeassureTextInternal(text);

      NativeMethods.RECT clip = new NativeMethods.RECT();
      clip.left = point.X;
      clip.top = point.Y;
      clip.right = clip.left + size.Width;
      clip.bottom = clip.top + size.Height;
    
      // ExtTextOut does not show Mnemonics highlighting.
      NativeMethods.DrawText(this.graphicsHandle, text, text.Length, ref clip, NativeMethods.DT_SINGLELINE | NativeMethods.DT_LEFT);

      NativeMethods.SetTextColor(this.graphicsHandle, oldTextColor);
      NativeMethods.SetBkMode(this.graphicsHandle, oldBkMode);
  
      NativeMethods.SelectObject(this.graphicsHandle, oldFontHandle);
      NativeMethods.DeleteObject(fontHandle);
    }


    private Size MeassureTextInternal(string text)
    {
      NativeMethods.RECT rect = new NativeMethods.RECT();
      rect.left = 0;
      rect.right = 0;
      rect.top = 0;
      rect.bottom = 0;
      
      // ExtTextOut does not show Mnemonics highlighting.
      NativeMethods.DrawText(this.graphicsHandle, text, text.Length, ref rect, NativeMethods.DT_SINGLELINE | NativeMethods.DT_LEFT | NativeMethods.DT_CALCRECT);

      return new Size(rect.right, rect.bottom);
    }

    private sealed class NativeMethods
    {
      private NativeMethods()
      {
      }

      public const int TRANSPARENT = 1;
      public const int OPAQUE = 2;

      [StructLayout(LayoutKind.Sequential)]
      public struct RECT
      {
        public int left;
        public int top;
        public int right;
        public int bottom;
      }

      [DllImport("gdi32.dll")]
      public extern static int SetBkMode(IntPtr hdc, int iBkMode);
  
      [DllImport("gdi32.dll")]
      public extern static int SetTextColor(IntPtr hdc, int crColor);
  
      [DllImport("gdi32.dll")]
      public extern static IntPtr SelectObject(IntPtr hdc, IntPtr hgdiobj);

      [DllImport("gdi32.dll", ExactSpelling=true)]
      public static extern bool DeleteObject(IntPtr hObject);

      public const int DT_SINGLELINE = 0x20;
      public const int DT_LEFT = 0x0;
      public const int DT_VCENTER = 0x4;
      public const int DT_CALCRECT = 0x400;

      [DllImport("user32.dll", CharSet=CharSet.Auto)]
      public extern static int DrawText(IntPtr hdc, string lpString, int nCount, ref RECT lpRect, int uFormat);
    }
  }
}