/// <include file='doc\ColorConverter.uex' path='docs/doc[@for="ColorConverter.ConvertTo"]/*' />
/// <devdoc>
/// Converts the given object to another type. The most common types to convert
/// are to and from a string object. The default implementation will make a call
/// to ToString on the object if the object is valid and if the destination
/// type is string. If this cannot convert to the desitnation type, this will
/// throw a NotSupportedException.
/// </devdoc>
public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
{
if (destinationType == null)
{
throw new ArgumentNullException("destinationType");
}
if (value is Color)
{
if (destinationType == typeof(string))
{
Color c = (Color)value;
if (c == Color.Empty)
{
return(string.Empty);
}
else
{
// If this is a known color, then Color can provide its own
// name. Otherwise, we fabricate an ARGB value for it.
//
if (ColorExt.IsKnownColor(c))
{
return(c.Name);
}
else if (c.IsNamedColor)
{
return("'" + c.Name + "'");
}
else
{
if (culture == null)
{
culture = CultureInfo.CurrentCulture;
}
string sep = culture.TextInfo.ListSeparator + " ";
TypeConverter intConverter = TypeDescriptor.GetConverter(typeof(int));
string[] args;
int nArg = 0;
if (c.A < 255)
{
args = new string[4];
args[nArg++] = intConverter.ConvertToString(context, culture, (object)c.A);
}
else
{
args = new string[3];
}
// Note: ConvertToString will raise exception if value cannot be converted.
args[nArg++] = intConverter.ConvertToString(context, culture, (object)c.R);
args[nArg++] = intConverter.ConvertToString(context, culture, (object)c.G);
args[nArg++] = intConverter.ConvertToString(context, culture, (object)c.B);
// Now slam all of these together with the fantastic Join
// method.
//
return(string.Join(sep, args));
}
}
}
if (destinationType == typeof(InstanceDescriptor))
{
MemberInfo member = null;
object[] args = null;
Color c = (Color)value;
if (c.IsEmpty)
{
member = typeof(Color).GetField("Empty");
}
else if (ColorExt.IsSystemColor(c))
{
member = typeof(SystemColors).GetProperty(c.Name);
}
else if (ColorExt.IsKnownColor(c))
{
member = typeof(Color).GetProperty(c.Name);
}
else if (c.A != 255)
{
member = typeof(Color).GetMethod("FromArgb", new Type[] { typeof(int), typeof(int), typeof(int), typeof(int) });
args = new object[] { c.A, c.R, c.G, c.B };
}
else if (c.IsNamedColor)
{
member = typeof(Color).GetMethod("FromName", new Type[] { typeof(string) });
args = new object[] { c.Name };
}
else
{
member = typeof(Color).GetMethod("FromArgb", new Type[] { typeof(int), typeof(int), typeof(int) });
args = new object[] { c.R, c.G, c.B };
}
//Debug.Assert(member != null, "Could not convert color to member. Did someone change method name / signature and not update Colorconverter?");
if (member != null)
{
return(new InstanceDescriptor(member, args));
}
else
{
return(null);
}
}
}
return(base.ConvertTo(context, culture, value, destinationType));
}
public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
{
string strValue = value as string;
if (strValue != null)
{
object obj = null;
string text = strValue.Trim();
if (text.Length == 0)
{
obj = Color.Empty;
}
else
{
// First, check to see if this is a standard name.
//
obj = GetNamedColor(text);
if (obj == null)
{
if (culture == null)
{
culture = CultureInfo.CurrentCulture;
}
char sep = culture.TextInfo.ListSeparator[0];
bool tryMappingToKnownColor = true;
TypeConverter intConverter = TypeDescriptor.GetConverter(typeof(int));
// If the value is a 6 digit hex number only, then
// we want to treat the Alpha as 255, not 0
//
if (text.IndexOf(sep) == -1)
{
// text can be '' (empty quoted string)
if (text.Length >= 2 && (text[0] == '\'' || text[0] == '"') && text[0] == text[text.Length - 1])
{
// In quotes means a named value
string colorName = text.Substring(1, text.Length - 2);
obj = Color.FromName(colorName);
tryMappingToKnownColor = false;
}
else if ((text.Length == 7 && text[0] == '#') ||
(text.Length == 8 && (text.StartsWith("0x") || text.StartsWith("0X"))) ||
(text.Length == 8 && (text.StartsWith("&h") || text.StartsWith("&H"))))
{
// Note: ConvertFromString will raise exception if value cannot be converted.
obj = Color.FromArgb(unchecked ((int)(0xFF000000 | (uint)(int)intConverter.ConvertFromString(context, culture, text))));
}
}
// Nope. Parse the RGBA from the text.
//
if (obj == null)
{
string[] tokens = text.Split(new char[] { sep });
int[] values = new int[tokens.Length];
for (int i = 0; i < values.Length; i++)
{
values[i] = unchecked ((int)intConverter.ConvertFromString(context, culture, tokens[i]));
}
// We should now have a number of parsed integer values.
// We support 1, 3, or 4 arguments:
//
// 1 -- full ARGB encoded
// 3 -- RGB
// 4 -- ARGB
//
switch (values.Length)
{
case 1:
obj = Color.FromArgb(values[0]);
break;
case 3:
obj = Color.FromArgb(values[0], values[1], values[2]);
break;
case 4:
obj = Color.FromArgb(values[0], values[1], values[2], values[3]);
break;
}
tryMappingToKnownColor = true;
}
if ((obj != null) && tryMappingToKnownColor)
{
// Now check to see if this color matches one of our known colors.
// If it does, then substitute it. We can only do this for "Colors"
// because system colors morph with user settings.
//
int targetARGB = ((Color)obj).ToArgb();
foreach (Color c in Colors.Values)
{
if (c.ToArgb() == targetARGB)
{
obj = c;
break;
}
}
}
}
if (obj == null)
{
//throw new ArgumentException(SR.GetString(SR.InvalidColor, text));
}
}
return(obj);
}
return(base.ConvertFrom(context, culture, value));
}
