Microsoft Word and Visual Studio have one very cool feature in common — squiggly underlining of errors. As of richedit 3.0 (distributed with Windows 2000 and higher, possibly also with ME) we can get these in the RichTextBox. Actually, we can get a lot more underline styles than that…
Underlining
Once again we are going to have to communicate with the underlying richedit control. This time we need to set the character format, so we’ll need to add some extra stuff to our class:
+ Code to interface with the Win32 CHARFORMAT2 structure.
private const int CFM_UNDERLINETYPE = 8388608;
private const int EM_SETCHARFORMAT = 1092;
private const int EM_GETCHARFORMAT = 1082;
[StructLayout(LayoutKind.Sequential)]
private struct CHARFORMAT {
public int cbSize;
public uint dwMask;
public uint dwEffects;
public int yHeight;
public int yOffset;
public int crTextColor;
public byte bCharSet;
public byte bPitchAndFamily;
[MarshalAs(UnmanagedType.ByValArray, SizeConst = 32)]
public char[] szFaceName;
// CHARFORMAT2 from here onwards.
public short wWeight;
public short sSpacing;
public int crBackColor;
public int LCID;
public uint dwReserved;
public short sStyle;
public short wKerning;
public byte bUnderlineType;
public byte bAnimation;
public byte bRevAuthor;
}
[DllImport("user32", CharSet = CharSet.Auto)]
private static extern int SendMessage(HandleRef hWnd, int msg, int wParam,
ref CHARFORMAT lp);Underline Style
The underline style and colour are both set with the same message, so we must be careful to preserve the colour while changing the underline style. We’ll use a property again so that we remain consistent with the original RichTextBox:
/// <summary>
/// Gets or sets the underline style to apply to the
/// current selection or insertion point.
/// </summary>
/// <remarks>
/// Underline styles can be set to any value of the
/// <see cref="UnderlineStyle"/> enumeration.
/// </remarks>
public UnderlineStyle SelectionUnderlineStyle {
get {
CHARFORMAT fmt = new CHARFORMAT();
fmt.cbSize = Marshal.SizeOf(fmt);
// Get the underline style.
SendMessage(new HandleRef(this, Handle), EM_GETCHARFORMAT, SCF_SELECTION,
ref fmt);
// Default to no underline.
if ((fmt.dwMask & CFM_UNDERLINETYPE) == 0)
return UnderlineStyle.None;
byte style = (byte)(fmt.bUnderlineType & 0x0F);
return (UnderlineStyle)style;
}
set {
// Ensure we don't alter the color by accident.
UnderlineColor color = SelectionUnderlineColor;
// Ensure we don't show it if it shouldn't be shown.
if (value == UnderlineStyle.None)
color = UnderlineColor.Black;
CHARFORMAT fmt = new CHARFORMAT();
fmt.cbSize = Marshal.SizeOf(fmt);
fmt.dwMask = CFM_UNDERLINETYPE;
fmt.bUnderlineType = (byte)((byte)value | (byte)color);
// Set the underline type.
SendMessage(new HandleRef(this, Handle), EM_SETCHARFORMAT, SCF_SELECTION,
ref fmt);
}
}Once again, this has not been fully tested so you use it at your own risk. Let me know if there are any problems, etc. The UnderlineStyle enumeration is also fairly straightforward:
+ UnderlineStyle enumeration.
/// <summary>
/// Specifies the style of underline that should be
/// applied to the text.
/// </summary>
public enum UnderlineStyle {
/// <summary>
/// No underlining.
/// </summary>
None = 0,
/// <summary>
/// Standard underlining across all words.
/// </summary>
Normal = 1,
/// <summary>
/// Standard underlining broken between words.
/// </summary>
Word = 2,
/// <summary>
/// Double line underlining.
/// </summary>
Double = 3,
/// <summary>
/// Dotted underlining.
/// </summary>
Dotted = 4,
/// <summary>
/// Dashed underlining.
/// </summary>
Dash = 5,
/// <summary>
/// Dash-dot ("-.-.") underlining.
/// </summary>
DashDot = 6,
/// <summary>
/// Dash-dot-dot ("-..-..") underlining.
/// </summary>
DashDotDot = 7,
/// <summary>
/// Wave underlining (like spelling mistakes in MS Word).
/// </summary>
Wave = 8,
/// <summary>
/// Extra thick standard underlining.
/// </summary>
Thick = 9,
/// <summary>
/// Extra thin standard underlining.
/// </summary>
HairLine = 10,
/// <summary>
/// Double thickness wave underlining.
/// </summary>
DoubleWave = 11,
/// <summary>
/// Thick wave underlining.
/// </summary>
HeavyWave = 12,
/// <summary>
/// Extra long dash underlining.
/// </summary>
LongDash = 13
}Note that some of these styles may not display correctly. This is a common problem with the richedit control, often you will apply some formatting only to find that it will not display at all. The formatting is usually stored though, so cutting and pasting into Word will show the text correctly.
Underline Colour
We can also change the underline colour. Notice how the set method of underline colour retrieves the underline style in order to maintain consistency.
/// <summary>
/// Gets or sets the underline color to apply to the
/// current selection or insertion point.
/// </summary>
/// <remarks>
/// Underline colors can be set to any value of the
/// <see cref="UnderlineColor"/> enumeration.
/// </remarks>
public UnderlineColor SelectionUnderlineColor {
get {
CHARFORMAT fmt = new CHARFORMAT();
fmt.cbSize = Marshal.SizeOf(fmt);
// Get the underline color.
SendMessage(new HandleRef(this, Handle), EM_GETCHARFORMAT, SCF_SELECTION,
ref fmt);
// Default to black.
if ((fmt.dwMask & CFM_UNDERLINETYPE) == 0)
return UnderlineColor.Black;
byte style = (byte)(fmt.bUnderlineType & 0xF0);
return (UnderlineColor)style;
}
set {
// Ensure we don't alter the style.
UnderlineStyle style = SelectionUnderlineStyle;
// Ensure we don't show it if it shouldn't be shown.
if (style == UnderlineStyle.None)
value = UnderlineColor.Black;
CHARFORMAT fmt = new CHARFORMAT();
fmt.cbSize = Marshal.SizeOf(fmt);
fmt.dwMask = CFM_UNDERLINETYPE;
fmt.bUnderlineType = (byte)((byte)style | (byte)value);
// Set the underline color.
SendMessage(new HandleRef(this, Handle), EM_SETCHARFORMAT, SCF_SELECTION,
ref fmt);
}
}Unfortunately there are not many colours available to this property. They are defined by the UnderlineColor enumeration:
+ UnderlineColor enumeration.
/// me if you feel one should be changed.
/// </remarks>
public enum UnderlineColor {
/// <summary>Black.</summary>
Black = 0x00,
/// <summary>Blue.</summary>
Blue = 0x10,
/// <summary>Cyan.</summary>
Cyan = 0x20,
/// <summary>Lime green.</summary>
LimeGreen = 0x30,
/// <summary>Magenta.</summary>
Magenta = 0x40,
/// <summary>Red.</summary>
Red = 0x50,
/// <summary>Yellow.</summary>
Yellow = 0x60,
/// <summary>White.</summary>
White = 0x70,
/// <summary>DarkBlue.</summary>
DarkBlue = 0x80,
/// <summary>DarkCyan.</summary>
DarkCyan = 0x90,
/// <summary>Green.</summary>
Green = 0xA0,
/// <summary>Dark magenta.</summary>
DarkMagenta = 0xB0,
/// <summary>Brown.</summary>
Brown = 0xC0,
/// <summary>Olive green.</summary>
OliveGreen = 0xD0,
/// <summary>Dark gray.</summary>
DarkGray = 0xE0,
/// <summary>Gray.</summary>
Gray = 0xF0
}If you set the underline colour to anything other than black it will not serialise correctly. I don’t know if this is by design or not. Any text with a non-black underline that is cut and pasted into Word (or any other application) will lose it’s underlining all together. I don’t know if the underline is still stored in the actual rich text or not when this happens.
Conclusion
Well that’s it for part two. In my next post in this series I will cover setting the background colour.
