propertygrid - user selectable unit

[Lee]

Hi,

Using the propertygrid, is it possible to have a user selectable 'unit
of measure' for a field.

For example, I am looking at using a propertygrid for defining inputs
into a calculation. Some of the inputs can be either monetary or
percantage. The ideal scenario is where the user enters the value and
immediately to the right of the value field is a drop down, defaulted
to %,which allows a currency to be selected.

I'm very new to c# so apologies if this is straightforward .

Thanks
Lee

[Marc Gravell]

Hard to do "all in one", as the PropertyGrid uses the TypeConverter,
which allows for text conversions [inclusive or] list of available
options.

What you can do, however, is to split the two, and have the
TypeConverter be able to parse the entire string, else enter the value
and unit on separate lines in the grid.

See enclosed example (just add a CurrencyAmount property to your class
;-p).

Marc

using System;
using System.Componen tModel;

public enum UnitOfCurrency { GBP, USD, INR, EUR } // etc
public class CurrencyAmountC onverter : TypeConverter
{
public override bool CanConvertFrom( ITypeDescriptor Context context,
Type sourceType)
{
return sourceType == typeof(string) ||
base.CanConvert From(context, sourceType);
}
public override object ConvertFrom(ITy peDescriptorCon text context,
System.Globaliz ation.CultureIn fo culture, object value)
{
string text = value as string;
if (text == null) return base.ConvertFro m(context, culture,
value);
return CurrencyAmount. Parse(text);
}
public override bool
GetCreateInstan ceSupported(ITy peDescriptorCon text context)
{
return true;
}
public override object CreateInstance( ITypeDescriptor Context
context, System.Collecti ons.IDictionary propertyValues)
{
decimal amount = (decimal)proper tyValues["Amount"];
UnitOfCurrency unit = (UnitOfCurrency )propertyValues["Unit"];
return new CurrencyAmount( unit, amount);
}
public override bool GetPropertiesSu pported(ITypeDe scriptorContext
context)
{
return true;
}
public override PropertyDescrip torCollection
GetProperties(I TypeDescriptorC ontext context, object value, Attribute[]
attributes)
{
return TypeDescriptor. GetProperties(t ypeof(CurrencyA mount),
attributes).Sor t(new string[] { "Amount", "Unit" });
}
}

[TypeConverter(t ypeof(CurrencyA mountConverter) )]
[ImmutableObject (true)]
public struct CurrencyAmount : IEquatable<Curr encyAmount>, IComparable,
IComparable<Cur rencyAmount>
{
public static CurrencyAmount operator *(CurrencyAmoun t lhs, decimal
rhs)
{
return new CurrencyAmount( lhs.Unit, lhs.Amount * rhs);
}
public int CompareTo(Curre ncyAmount other)
{
int result = this.Unit.Compa reTo(other.Unit );
if (result == 0) result = this.Amount.Com pareTo(other.Am ount);
return result;
}
int IComparable.Com pareTo(object other)
{
return CompareTo((Curr encyAmount)othe r);
}
public override int GetHashCode()
{
return _amount.GetHash Code() * 7 + _unit.GetHashCo de();
}
public override bool Equals(object obj)
{
return base.Equals((Cu rrencyAmount)ob j);
}
public bool Equals(Currency Amount amount)
{
return (amount == this);
}
public static bool operator <(CurrencyAmoun t lhs, CurrencyAmount
rhs)
{
return lhs.Unit == rhs.Unit && lhs.Amount < rhs.Amount;
}
public static bool operator >(CurrencyAmoun t lhs, CurrencyAmount
rhs)
{
return lhs.Unit == rhs.Unit && lhs.Amount rhs.Amount;
}
public static bool operator <=(CurrencyAmou nt lhs, CurrencyAmount
rhs)
{
return lhs.Unit == rhs.Unit && lhs.Amount <= rhs.Amount;
}
public static bool operator >=(CurrencyAmou nt lhs, CurrencyAmount
rhs)
{
return lhs.Unit == rhs.Unit && lhs.Amount >= rhs.Amount;
}
public static bool operator ==(CurrencyAmou nt lhs, CurrencyAmount
rhs)
{
return lhs.Unit == rhs.Unit && lhs.Amount == rhs.Amount;
}
public static bool operator !=(CurrencyAmou nt lhs, CurrencyAmount
rhs)
{
return lhs.Unit != rhs.Unit || lhs.Amount != rhs.Amount;
}
private readonly decimal _amount;
private readonly UnitOfCurrency _unit;
public decimal Amount { get { return _amount; } }
public UnitOfCurrency Unit { get { return _unit; } }
public CurrencyAmount( UnitOfCurrency unit, decimal amount)
{
_amount = amount;
_unit = unit;
}
public override string ToString()
{
return _unit.ToString( ) + ": " + _amount;
}
public static CurrencyAmount Parse(string value)
{
if (value != null) value = value.Trim();
if (string.IsNullO rEmpty(value)) throw new
ArgumentNullExc eption();
string[] parts = value.Split(':' );
if (parts.Length != 2) throw new ArgumentExcepti on();
return new CurrencyAmount(
(UnitOfCurrency )Enum.Parse(typ eof(UnitOfCurre ncy),
parts[0].Trim(), true),
decimal.Parse(p arts[1].Trim()));

}
}

[Marc Gravell]

I forgot to say; if the drop-down is runtime (not simply an enum) then
you need a type converter for that too ;-p Specifically, you'd look at
the GetStandardValu es, ...Supported and ...Exclusive methods. Note that
the context gives you the parent object, so you should be able to do
some clever "likely options" code if you want...

Marc

[Marc Gravell]

An alternative answer (sorry; brain not firing 100% this evening ;-p):
look into UITypeEditor implementations ; this is basically a way of
providing a drop-down UI.

This would allow you to place a custom control or two on the drop down,
with the appropriate values into the screen. Look at:
http://msdn2.microsoft.com/en-us/lib...ypeeditor.aspx
In particular, think GetEditStyle() returning DropDown, EditValue
showing your control. You can also do "Modal", which displays the
elipsis.

In terms of what this looks like : think "dock", "anchor" etc; it can
look like whatever you want...

Marc

[Nico]

Hello Lee,

Marc already gave you some pointers for workarounds. This is a fact
that you won't be able to have an editable number + its unit in the
same property row with the Microsoft PropertyGrid. So I have no other
solution to give you. However, if representing your data in a single
row is a strong requirement for you and you can consider a commercial
package, you can try Smart PropertyGrid.Ne t. There is a screenshot of
this value+unit property in action at
http://www.visualhint.com/visualhint...etfeature6.gif. I can tell
you that from the end-user point of view this is very practical. If you
have any question, you can contact me there
(http://www.visualhint.com/helpdesk).

Best regards,

Nicolas Cadilhac @ VisualHint (http://www.visualhint.com)
Home of Smart PropertyGrid for .Net and MFC

Lee wrote:

Hi,

Using the propertygrid, is it possible to have a user selectable 'unit
of measure' for a field.

For example, I am looking at using a propertygrid for defining inputs
into a calculation. Some of the inputs can be either monetary or
percantage. The ideal scenario is where the user enters the value and
immediately to the right of the value field is a drop down, defaulted
to %,which allows a currency to be selected.

I'm very new to c# so apologies if this is straightforward .

Thanks
Lee

[Lee]

Marc,

Many thanks for the responses. I will investigate the UITypeEditor
class which sounds very promising..

Lee