TypeConverter in PropertyGrid & Datagrid

来源：互联网发布：舒尔特训练软件编辑：程序博客网时间：2024/04/30 14:51

自定义TypeConverter：可以用在Propertygrid或者Datagrid中

1. public class UnitTypeConverter : TypeConverter

{
public override bool CanConvertTo(ITypeDescriptorContext context, Type destinationType)
{
return true;
}

public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
{
return true;
}

public override Object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, Object value)
{
if (context.PropertyDescriptor.PropertyType == typeof(double))
{
string str = value.ToString();
double ret;
if (double.TryParse(str, out ret))
{
Validate(context, culture, ret);
return ret;
}
return null;
}

if (context.PropertyDescriptor.PropertyType == typeof(int))
{
string str = value.ToString();
double ret;
if (double.TryParse(str, out ret))
{
Validate(context, culture, (int)ret);
return (int)ret;
}
return null;
}
else
{
var valueStr = value as string;
double valueDouble;
if (double.TryParse(valueStr, out valueDouble))
{
valueStr = AppendUnitString(valueStr, context);
}

Validate(context, culture, valueStr);
Object ret = Quantity.Parse(valueStr, context.PropertyDescriptor.PropertyType);

return ret;
}
}

protected virtual string AppendUnitString(string text, ITypeDescriptorContext context)
{
return text;
}

protected static object GetNewValue(object value, Type dstType)
{
object newValue;
if (dstType.IsQuantity())
{
newValue = Quantity.Parse(value.ToString(), dstType);
}
else if (dstType.IsDouble())
{
newValue = double.Parse(value.ToString());
}
else if (dstType.IsInteger())
{
newValue = int.Parse(value.ToString());
}
else
{
newValue = value;
}
return newValue;
}

protected static void Validate(ITypeDescriptorContext context, CultureInfo culture, Object value)
{
var type = context.PropertyDescriptor.ComponentType;
var propertyInfo = type.GetProperty(context.PropertyDescriptor.Name);

if (propertyInfo != null)
{
object newValue = GetNewValue(value, propertyInfo.PropertyType);
var validationAttributes = propertyInfo.GetAttributes<ValidationAttribute>();
foreach (var validationAttribute in validationAttributes)
{
if (!validationAttribute.IsValid(newValue))
{
string error = validationAttribute.FormatErrorMessage(propertyInfo.GetDescriptionName());
throw new NmcpException(error);
}
}

if (context.Instance is object[])
{
var objs = context.Instance as object[];
foreach (object obj in objs)
{
ValidateInstance(obj, propertyInfo, newValue);
}
}
else
{
ValidateInstance(context.Instance, propertyInfo, newValue);
}
}
}

private static void ValidateInstance(object obj, PropertyInfo propertyInfo, object newValue)
{
if (obj is IValidate)
{
object oldValue = propertyInfo.GetValue(obj, null);
var validator = obj as IValidate;

try
{
propertyInfo.SetValue(obj, newValue, null);
validator.Validate();
}
finally
{
propertyInfo.SetValue(obj, oldValue, null);
}
}
}
}

2.定义对象，属性（每个属性上apply TypeConverter），以及列表（for datagrid）

public class DieselEngineParameters
{
public DieselEngineParameters()
{
_comPressure = new Pressure(0);
_maxPressure = new Pressure(0);
MIP = new Pressure(0);
SpeedMCR = new RotationalSpeed(0);
PowerMCR = new RateOfEnergy(0);
PowerPerCyl = new RateOfEnergy(0);
}

public Guid OID { get; set; }
public double Load { get; set; }

[TypeConverter(typeof(TvcTypeConverter)), TvcDisplayFormatAttribute(DisplayFormat = "F0")]
public RotationalSpeed SpeedMCR { get; set; }

[TypeConverter(typeof(TvcTypeConverter)), TvcDisplayFormatAttribute(DisplayFormat = "F1")]
public Pressure MIP { get; set; }

[TypeConverter(typeof(TvcTypeConverter)), TvcDisplayFormatAttribute(DisplayFormat = "F2")]
public RateOfEnergy PowerMCR { get; set; }

[TypeConverter(typeof(TvcTypeConverter)), TvcDisplayFormatAttribute(DisplayFormat = "F2")]
public RateOfEnergy PowerPerCyl { get; set; }

private Pressure _maxPressure;
[TypeConverter(typeof(TvcTypeConverter)), TvcDisplayFormatAttribute(DisplayFormat = "F1")]
public Pressure MaxPressure
{
get { return _maxPressure; }
set
{
if (_maxPressure == value || value.Amount < 0 || value < ComPressure)
{
return;
}
_maxPressure = value;
}
}

private Pressure _comPressure;
[TypeConverter(typeof(TvcTypeConverter)), TvcDisplayFormatAttribute(DisplayFormat = "F1")]
public Pressure ComPressure
{
get { return _comPressure; }
set
{
if (_comPressure == value || value.Amount < 0 || value > MaxPressure)
{
return;
}
_comPressure = value;
}
}
}

public class LoadCaseDieselEngineParameters
{
public List<DieselEngineParameters> ListDieselEngineParameters { get; set; }

public LoadCaseDieselEngineParameters()
{
ListDieselEngineParameters = new List<DieselEngineParameters>();
}
}

4. datagrid/databinding用法.

this.dgvGensetSettings.DataSource = this.gensetBindingSource;

gensetBindingSource.DataSource = new BindingList<DieselEngineParameters>(_lc.ListDieselEngineParameters.FindAll(t => t.OID == diesel.Oid));

Datagrid处理一些非法的输入

private void dgvGensetSettings_CellBeginEdit(object sender, DataGridViewCellCancelEventArgs e)
{
oldCellValue = dgvGensetSettings.CurrentCell.Value;
}

Occurs when a cell leaves edit mode if the cell value has been modified.

private void dgvGensetSettings_CellParsing(object sender, DataGridViewCellParsingEventArgs e)
{
if (e != null)
{
if (e.Value != null)
{
try
{
e.Value = Quantity.Parse(e.Value.ToString(), e.DesiredType);
}
catch
{
e.Value = oldCellValue;
}
e.ParsingApplied = true;
}
}
}

5. BindingSource.Filter fails when datasource derives from List(Of T)

不起作用；BindingSource只有为DataView或者实现了IBindingListView接口。Filter功能才气作用；

Please also make sure that you BindingSource is bound to a DataView or a data list which implements the IBindingListView interface. Like

Code Snippet

BindingSource bs1 = new BindingSource();

bs1.DataSource = myDataView;