我有一个asp:TextBox，我可以通过以下方式设置width：
<asp:TextBox runat="server" ID="TextBox1" Width="100"></asp:TextBox>
或
<asp:TextBox runat="server" ID="TextBox1" Width="100%"></asp:TextBox>
在 Codebehind 中我只能设置
TextBox1.Width = 100; // remember, Width is type of Unit, not int
不可能是这样的：
TextBox1.Width = "100%";
我的期望
TextBox1.Width = new Unit.. ;
问题：为什么nUnit 会这样？为什么int 可能但string 不可能，为什么不期望Unit 的新对象？
【问题讨论】：
标签： c# asp.net web-controls
你可以这样设置百分比。
TextBox1.Width = System.Web.UI.WebControls.Unit.Percentage(90);
【讨论】：
TextBox 是一个WebControl，其中 Width 是一个虚拟属性，定义为：
[DefaultValue(typeof(Unit), "")]
[WebCategory("Layout")]
[WebSysDescription("WebControl_Width")]
public virtual Unit Width
{
get
{
if (!this.ControlStyleCreated)
{
return Unit.Empty;
}
return this.ControlStyle.Width;
}
set
{
this.ControlStyle.Width = value;
}
}
Unit 是一个结构（这是您问题的答案）：
[Serializable]
[TypeConverter(typeof(UnitConverter))]
public struct Unit
{
internal const int MaxValue = 32767;
internal const int MinValue = -32768;
public readonly static Unit Empty;
private readonly UnitType type;
private readonly double @value;
public bool IsEmpty
{
get
{
return (int)this.type == 0;
}
}
public UnitType Type
{
get
{
if (this.IsEmpty)
{
return UnitType.Pixel;
}
return this.type;
}
}
public double Value
{
get
{
return this.@value;
}
}
static Unit()
{
Unit.Empty = new Unit();
}
public Unit(int value)
{
if (value < -32768 || value > 32767)
{
throw new ArgumentOutOfRangeException("value");
}
this.@value = (double)value;
this.type = UnitType.Pixel;
}
public Unit(double value)
{
if (value < -32768 || value > 32767)
{
throw new ArgumentOutOfRangeException("value");
}
this.@value = (double)((int)value);
this.type = UnitType.Pixel;
}
public Unit(double value, UnitType type)
{
if (value < -32768 || value > 32767)
{
throw new ArgumentOutOfRangeException("value");
}
if (type != UnitType.Pixel)
{
this.@value = value;
}
else
{
this.@value = (double)((int)value);
}
this.type = type;
}
public Unit(string value) : this(value, CultureInfo.CurrentCulture, UnitType.Pixel)
{
}
public Unit(string value, CultureInfo culture) : this(value, culture, UnitType.Pixel)
{
}
internal Unit(string value, CultureInfo culture, UnitType defaultType)
{
if (string.IsNullOrEmpty(value))
{
this.@value = 0;
this.type = (UnitType)0;
return;
}
if (culture == null)
{
culture = CultureInfo.CurrentCulture;
}
string lower = value.Trim().ToLower(CultureInfo.InvariantCulture);
int length = lower.Length;
int num = -1;
for (int i = 0; i < length; i++)
{
char chr = lower[i];
if ((chr < '0' || chr > '9') && chr != '-' && chr != '.' && chr != ',')
{
break;
}
num = i;
}
if (num == -1)
{
object[] objArray = new object[] { value };
throw new FormatException(SR.GetString("UnitParseNoDigits", objArray));
}
if (num >= length - 1)
{
this.type = defaultType;
}
else
{
this.type = Unit.GetTypeFromString(lower.Substring(num + 1).Trim());
}
string str = lower.Substring(0, num + 1);
try
{
TypeConverter singleConverter = new SingleConverter();
this.@value = (double)((float)singleConverter.ConvertFromString(null, culture, str));
if (this.type == UnitType.Pixel)
{
this.@value = (double)((int)this.@value);
}
}
catch
{
object[] objArray1 = new object[] { value, str, this.type.ToString("G") };
throw new FormatException(SR.GetString("UnitParseNumericPart", objArray1));
}
if (this.@value < -32768 || this.@value > 32767)
{
throw new ArgumentOutOfRangeException("value");
}
}
public override bool Equals(object obj)
{
if (obj == null || !(obj is Unit))
{
return false;
}
Unit unit = (Unit)obj;
if (unit.type == this.type && unit.@value == this.@value)
{
return true;
}
return false;
}
public override int GetHashCode()
{
return HashCodeCombiner.CombineHashCodes(this.type.GetHashCode(), this.@value.GetHashCode());
}
private static string GetStringFromType(UnitType type)
{
switch (type)
{
case UnitType.Pixel:
{
return "px";
}
case UnitType.Point:
{
return "pt";
}
case UnitType.Pica:
{
return "pc";
}
case UnitType.Inch:
{
return "in";
}
case UnitType.Mm:
{
return "mm";
}
case UnitType.Cm:
{
return "cm";
}
case UnitType.Percentage:
{
return "%";
}
case UnitType.Em:
{
return "em";
}
case UnitType.Ex:
{
return "ex";
}
}
return string.Empty;
}
private static UnitType GetTypeFromString(string value)
{
if (string.IsNullOrEmpty(value))
{
return UnitType.Pixel;
}
if (value.Equals("px"))
{
return UnitType.Pixel;
}
if (value.Equals("pt"))
{
return UnitType.Point;
}
if (value.Equals("%"))
{
return UnitType.Percentage;
}
if (value.Equals("pc"))
{
return UnitType.Pica;
}
if (value.Equals("in"))
{
return UnitType.Inch;
}
if (value.Equals("mm"))
{
return UnitType.Mm;
}
if (value.Equals("cm"))
{
return UnitType.Cm;
}
if (value.Equals("em"))
{
return UnitType.Em;
}
if (!value.Equals("ex"))
{
throw new ArgumentOutOfRangeException("value");
}
return UnitType.Ex;
}
public static bool operator ==(Unit left, Unit right)
{
if (left.type != right.type)
{
return false;
}
return left.@value == right.@value;
}
public static implicit operator Unit(int n)
{
return Unit.Pixel(n);
}
public static bool operator !=(Unit left, Unit right)
{
if (left.type != right.type)
{
return true;
}
return left.@value != right.@value;
}
public static Unit Parse(string s)
{
return new Unit(s, CultureInfo.CurrentCulture);
}
public static Unit Parse(string s, CultureInfo culture)
{
return new Unit(s, culture);
}
public static Unit Percentage(double n)
{
return new Unit(n, UnitType.Percentage);
}
public static Unit Pixel(int n)
{
return new Unit(n);
}
public static Unit Point(int n)
{
return new Unit((double)n, UnitType.Point);
}
public override string ToString()
{
return this.ToString((IFormatProvider)CultureInfo.CurrentCulture);
}
public string ToString(CultureInfo culture)
{
return this.ToString((IFormatProvider)culture);
}
public string ToString(IFormatProvider formatProvider)
{
string str;
if (this.IsEmpty)
{
return string.Empty;
}
str = (this.type != UnitType.Pixel ? ((float)this.@value).ToString(formatProvider) : ((int)this.@value).ToString(formatProvider));
return string.Concat(str, Unit.GetStringFromType(this.type));
}
}
它定义了一个UnitConverter:
public class UnitConverter : TypeConverter
{
public UnitConverter()
{
}
public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
{
if (sourceType == typeof(string))
{
return true;
}
return base.CanConvertFrom(context, sourceType);
}
public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
{
if (destinationType == typeof(string) || destinationType == typeof(InstanceDescriptor))
{
return true;
}
return base.CanConvertTo(context, destinationType);
}
public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
{
if (value == null)
{
return null;
}
string str = value as string;
if (str == null)
{
return base.ConvertFrom(context, culture, value);
}
string str1 = str.Trim();
if (str1.Length == 0)
{
return Unit.Empty;
}
if (culture != null)
{
return Unit.Parse(str1, culture);
}
return Unit.Parse(str1, CultureInfo.CurrentCulture);
}
public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType)
{
if (destinationType == typeof(string))
{
if (value == null || ((Unit)value).IsEmpty)
{
return string.Empty;
}
return ((Unit)value).ToString(culture);
}
if (destinationType != typeof(InstanceDescriptor) || value == null)
{
return base.ConvertTo(context, culture, value, destinationType);
}
Unit unit = (Unit)value;
MemberInfo constructor = null;
object[] objArray = null;
if (!unit.IsEmpty)
{
Type type = typeof(Unit);
Type[] typeArray = new Type[] { typeof(double), typeof(UnitType) };
constructor = type.GetConstructor(typeArray);
object[] objArray1 = new object[] { unit.Value, unit.Type };
objArray = objArray1;
}
else
{
constructor = typeof(Unit).GetField("Empty");
}
if (constructor == null)
{
return null;
}
return new InstanceDescriptor(constructor, objArray);
}
}
在此代码中，您可以找到问题的答案。
【讨论】：
Unit 是一个结构体，如果你的意思是Unit
public Unit(int value) 转换回来。我认为这应该会有所帮助。
【讨论】：