在PropertyGrid中修改结构属性

本文介绍了在PropertyGrid中修改结构属性的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

为什么 SomeClass.ClassField.StructField 属性不会在的PropertyGrid 改变？ 看来，的PropertyGrid 不叫 SomeClass.ClassField.set 在 SomeStruct 的实例已被更改。但是，同样的code可以很好地点而不是 SomeStruct 。

[类型转换器（typeof运算（ExpandableObjectConverter））] 公共结构SomeStruct {     私人诠释structField;     公众诠释StructField     {         得到         {             返回structField;         }         组         {             structField =价值;         }     }     公共重写字符串的ToString（）     {         返回StructField：+ StructField;     } } [类型转换器（typeof运算（ExpandableObjectConverter））] 公共密封类SomeClass的 {     公共SomeStruct ClassField     {         得到;         组;     } } ... VAR SomeClass的=新SomeClass的 {     ClassField =新SomeStruct     {         StructField = 42     } }; propertyGrid.SelectedObject = SomeClass的;

解决方案

您需要一个特殊的类型转换器，它覆盖的 TypeConverter.GetCreateInstanceSupported ，因为以其他方式复制按值/拳击魔术发生在幕后的属性网格处理这一切的方式。

下面是一个应该适用于大多数值类型。您声明它是这样的：

[类型转换器（typeof运算（ValueTypeTypeConverter＆LT; SomeStruct＆GT;））] 公共结构SomeStruct {     公众诠释StructField {获得;组; } } 公共类ValueTypeTypeConverter＆LT; T＆GT; ：ExpandableObjectConverter其中T：结构 {     公众覆盖布尔GetCreateInstanceSupported（ITypeDescriptorContext上下文）     {         返回true;     }     公众覆盖对象的CreateInstance（ITypeDescriptorContext背景下，IDictionary的propertyValues​​）     {         如果（propertyValues​​ == NULL）             抛出新ArgumentNullException（propertyValues​​）;         牛逼RET =默认（T）;         反对盒装= RET;         的foreach（在propertyValues​​的DictionaryEntry项）         {             。的PropertyInfo PI = ret.GetType（）的getProperty（entry.Key.ToString（））;             如果（PI = NULL和放大器;！＆安培; pi.CanWrite）             {                 pi.SetValue（盒装，Convert.ChangeType（entry.Value，pi.PropertyType），NULL）;             }         }         返程（T）盒装;     } }

请注意它不支持纯粹的现场只结构，只有一个与属性，但ExpandableObjectConverter不支持这些或者说，它需要更多的code做到这一点。

Why SomeClass.ClassField.StructField property doesn't change in a propertyGrid? It seems, propertyGrid doesn't call SomeClass.ClassField.set after SomeStruct instance has been changed. But same code works well with Point instead of SomeStruct.

[TypeConverter(typeof(ExpandableObjectConverter))] public struct SomeStruct { private int structField; public int StructField { get { return structField; } set { structField = value; } } public override string ToString() { return "StructField: " + StructField; } } [TypeConverter(typeof(ExpandableObjectConverter))] public sealed class SomeClass { public SomeStruct ClassField { get; set; } } ... var someClass = new SomeClass { ClassField = new SomeStruct { StructField = 42 } }; propertyGrid.SelectedObject = someClass;

解决方案

You need a special TypeConverter that overrides TypeConverter.GetCreateInstanceSupported because otherwise copy-by-value/boxing magic happens behind the scene in the way the property grid handles all this.

Here is one that should work for most value types. You declare it like this:

[TypeConverter(typeof(ValueTypeTypeConverter<SomeStruct>))] public struct SomeStruct { public int StructField { get; set; } } public class ValueTypeTypeConverter<T> : ExpandableObjectConverter where T : struct { public override bool GetCreateInstanceSupported(ITypeDescriptorContext context) { return true; } public override object CreateInstance(ITypeDescriptorContext context, IDictionary propertyValues) { if (propertyValues == null) throw new ArgumentNullException("propertyValues"); T ret = default(T); object boxed = ret; foreach (DictionaryEntry entry in propertyValues) { PropertyInfo pi = ret.GetType().GetProperty(entry.Key.ToString()); if (pi != null && pi.CanWrite) { pi.SetValue(boxed, Convert.ChangeType(entry.Value, pi.PropertyType), null); } } return (T)boxed; } }

Note it doesn't support pure field-only structs, only the one with properties, but the ExpandableObjectConverter doesn't support these either, it would require more code to do it.