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Tebjan Halm authoredae333749
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Threading;
namespace Svg
{
/// <summary>
/// Converts string representations of colours into <see cref="Color"/> objects.
/// </summary>
public class SvgColourConverter : System.Drawing.ColorConverter
{
/// <summary>
/// Converts the given object to the converter's native type.
/// </summary>
/// <param name="context">A <see cref="T:System.ComponentModel.TypeDescriptor"/> that provides a format context. You can use this object to get additional information about the environment from which this converter is being invoked.</param>
/// <param name="culture">A <see cref="T:System.Globalization.CultureInfo"/> that specifies the culture to represent the color.</param>
/// <param name="value">The object to convert.</param>
/// <returns>
/// An <see cref="T:System.Object"/> representing the converted value.
/// </returns>
/// <exception cref="T:System.ArgumentException">The conversion cannot be performed.</exception>
/// <PermissionSet>
/// <IPermission class="System.Security.Permissions.FileIOPermission, mscorlib, Version=2.0.3600.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" version="1" Unrestricted="true"/>
/// </PermissionSet>
public override object ConvertFrom(System.ComponentModel.ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value)
{
string colour = value as string;
if (colour != null)
{
var oldCulture = Thread.CurrentThread.CurrentCulture;
Thread.CurrentThread.CurrentCulture = System.Globalization.CultureInfo.InvariantCulture;
colour = colour.Trim();
if (colour.StartsWith("rgb"))
{
try
{
int start = colour.IndexOf("(") + 1;
//get the values from the RGB string
string[] values = colour.Substring(start, colour.IndexOf(")") - start).Split(new char[]{',', ' '}, StringSplitOptions.RemoveEmptyEntries);
//determine the alpha value if this is an RGBA (it will be the 4th value if there is one)
int alphaValue = 255;
if (values.Length > 3)
{
//the alpha portion of the rgba is not an int 0-255 it is a decimal between 0 and 1
//so we have to determine the corosponding byte value
var alphastring = values[3];
if(alphastring.StartsWith("."))
{
alphastring = "0" + alphastring;
}
var alphaDecimal = decimal.Parse(alphastring);
if(alphaDecimal <= 1)
{
alphaValue = (int)(alphaDecimal * 255);
}
else
{
alphaValue = (int)alphaDecimal;
}
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}
Color colorpart = System.Drawing.Color.FromArgb(alphaValue, int.Parse(values[0]), int.Parse(values[1]), int.Parse(values[2]));
return colorpart;
}
catch
{
throw new SvgException("Colour is in an invalid format: '" + colour + "'");
}
}
else if (colour.StartsWith("#") && colour.Length == 4)
{
colour = string.Format(culture, "#{0}{0}{1}{1}{2}{2}", colour[1], colour[2], colour[3]);
return base.ConvertFrom(context, culture, colour);
}
Thread.CurrentThread.CurrentCulture = oldCulture;
}
return base.ConvertFrom(context, culture, value);
}
public override bool CanConvertFrom(System.ComponentModel.ITypeDescriptorContext context, Type sourceType)
{
if (sourceType == typeof(string))
{
return true;
}
return base.CanConvertFrom(context, sourceType);
}
public override bool CanConvertTo(System.ComponentModel.ITypeDescriptorContext context, Type destinationType)
{
if (destinationType == typeof(string))
{
return true;
}
return base.CanConvertTo(context, destinationType);
}
public override object ConvertTo(System.ComponentModel.ITypeDescriptorContext context, System.Globalization.CultureInfo culture, object value, Type destinationType)
{
if (destinationType == typeof(string))
{
var colour = (Color)value;
return ColorTranslator.ToHtml(colour);
}
return base.ConvertTo(context, culture, value, destinationType);
}
}
}