Implemented GdiPlus bindings for text measurement.

Source/OpenTK/GdiPlus.cs

@@ -0,0 +1,130 @@
+#region --- License ---
+/* Licensed under the MIT/X11 license.
+ * Copyright (c) 2006-2008 the OpenTK Team.
+ * This notice may not be removed from any source distribution.
+ * See license.txt for licensing details.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+using System.Runtime.InteropServices;
+using System.Drawing;
+using System.Reflection;
+using System.Diagnostics;
+
+namespace OpenTK.Platform
+{
+    internal static class GdiPlus
+    {
+        const string gdi_plus_library = "gdiplus.dll";
+        static readonly PropertyInfo native_graphics_property, native_font_property;
+        static readonly FieldInfo native_string_format_field;
+
+        #region --- Constructors ---
+
+        static GdiPlus()
+        {
+            native_graphics_property =
+                typeof(System.Drawing.Graphics).GetProperty("NativeGraphics", BindingFlags.Instance | BindingFlags.NonPublic);
+
+            native_font_property =
+                typeof(System.Drawing.Font).GetProperty("NativeFont", BindingFlags.Instance | BindingFlags.NonPublic);
+
+            native_string_format_field =
+                typeof(System.Drawing.StringFormat).GetField("nativeFormat", BindingFlags.Instance | BindingFlags.NonPublic);
+        }
+
+        #endregion
+
+        #region --- Reflection ---
+
+        public static IntPtr GetNativeGraphics(System.Drawing.Graphics graphics)
+        {
+            return (IntPtr)native_graphics_property.GetValue(graphics, null);
+        }
+
+        public static IntPtr GetNativeFont(Font font)
+        {
+            return (IntPtr)native_font_property.GetValue(font, null);
+        }
+
+        public static IntPtr GetNativeStringFormat(StringFormat format)
+        {
+            return (IntPtr)native_string_format_field.GetValue(format);
+        }
+
+        public static int MaxMeasurableCharacterRanges
+        {
+            get
+            {
+                return 32;    // This is a GDI+ limitation. TODO: Can we query this somehow? 
+            }
+        }
+
+        #endregion
+
+        #region --- Methods ---
+
+        [DllImport(gdi_plus_library, CharSet = CharSet.Unicode, SetLastError = true, ExactSpelling = true, EntryPoint="GdipSetStringFormatMeasurableCharacterRanges")]
+        public static extern int SetStringFormatMeasurableCharacterRanges(HandleRef format, int rangeCount, [In, Out] CharacterRange[] range);
+
+        [DllImport(gdi_plus_library, CharSet = CharSet.Unicode, SetLastError = true, ExactSpelling = true, EntryPoint = "GdipGetStringFormatMeasurableCharacterRangeCount")]
+        public static extern int GetStringFormatMeasurableCharacterRangeCount(HandleRef format, out int count);
+
+        [DllImport(gdi_plus_library, CharSet = CharSet.Unicode, SetLastError = true, ExactSpelling = true, EntryPoint = "GdipMeasureCharacterRanges")]
+        public static extern int MeasureCharacterRanges(HandleRef graphics, string textString, int length, HandleRef font, ref RectangleF layoutRect, HandleRef stringFormat, int characterCount, [In, Out] IntPtr[] region);
+
+        [DllImport("gdiplus.dll", CharSet = CharSet.Unicode, SetLastError = true, ExactSpelling = true, EntryPoint = "GdipGetRegionBounds")]
+        public static extern int GetRegionBounds(IntPtr region, HandleRef graphics, ref RectangleF gprectf);
+
+        [DllImport("gdiplus.dll", EntryPoint = "GdipCreateRegion", CharSet = CharSet.Unicode, SetLastError = true, ExactSpelling = true)]
+        public static extern int CreateRegion(out IntPtr region);
+
+        [DllImport("gdiplus.dll", EntryPoint = "GdipDeleteRegion", CharSet = CharSet.Unicode, SetLastError = true, ExactSpelling = true)]
+        public static extern int DeleteRegion(IntPtr region);
+
+        #endregion
+
+        [StructLayout(LayoutKind.Sequential)]
+        internal struct GPRECTF
+        {
+            internal float X;
+            internal float Y;
+            internal float Width;
+            internal float Height;
+            internal GPRECTF(float x, float y, float width, float height)
+            {
+                this.X = x;
+                this.Y = y;
+                this.Width = width;
+                this.Height = height;
+            }
+
+            internal GPRECTF(RectangleF rect)
+            {
+                this.X = rect.X;
+                this.Y = rect.Y;
+                this.Width = rect.Width;
+                this.Height = rect.Height;
+            }
+
+            internal SizeF SizeF
+            {
+                get
+                {
+                    return new SizeF(this.Width, this.Height);
+                }
+            }
+            internal RectangleF ToRectangleF()
+            {
+                return new RectangleF(this.X, this.Y, this.Width, this.Height);
+            }
+        }
+
+
+    }
+
+
+}