Code:
/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Base / MS / Internal / ComponentModel / AttachInfo.cs / 1305600 / AttachInfo.cs
namespace MS.Internal.ComponentModel { using System; using System.Collections.Generic; using System.ComponentModel; using System.Diagnostics; using System.Reflection; using System.Windows; ////// This class contains information about an attached property. It can /// tell you if the property can be attached to a given object. /// /// This class is thread-safe. /// internal class AttachInfo { //------------------------------------------------------ // // Internal Constructors // //----------------------------------------------------- internal AttachInfo(DependencyProperty dp) { _dp = dp; } //----------------------------------------------------- // // Private Properties // //----------------------------------------------------- // // Returns the static Get method associated with this attached // property. This can return null if the attached property // has no static get method. // private MethodInfo AttachMethod { get { if (!_getMethodChecked) { _getMethod = DependencyObjectPropertyDescriptor.GetAttachedPropertyMethod(_dp); _getMethodChecked = true; } return _getMethod; } } // // Returns an array of attributes of type AttachedPropertyBrowsableAttribute. // private AttachedPropertyBrowsableAttribute[] Attributes { get { if (!_attributesChecked) { MethodInfo m = AttachMethod; object[] attributes = null; if (m != null) { AttachedPropertyBrowsableAttribute[] browsableAttributes = null; // No need to inherit attributes here because the method is static attributes = m.GetCustomAttributes(DependencyObjectPropertyDescriptor.AttachedPropertyBrowsableAttributeType, false); // Walk attributes and see if there is a AttachedPropertyBrowsableForTypeAttribute // present. If there isn't, fabricate one, but only if there is // at least one AttachedPropertyBrowsableAttribute. We require at // least one attribute to consider an attached property. bool seenTypeAttribute = false; for (int idx = 0; idx < attributes.Length; idx++) { if (attributes[idx] is AttachedPropertyBrowsableForTypeAttribute) { seenTypeAttribute = true; break; } } if (!seenTypeAttribute && attributes.Length > 0) { browsableAttributes = new AttachedPropertyBrowsableAttribute[attributes.Length + 1]; for(int idx = 0; idx < attributes.Length; idx++) { browsableAttributes[idx] = (AttachedPropertyBrowsableAttribute)attributes[idx]; } browsableAttributes[attributes.Length] = ParameterTypeAttribute; } else { browsableAttributes = new AttachedPropertyBrowsableAttribute[attributes.Length]; for(int idx = 0; idx < attributes.Length; idx++) { browsableAttributes[idx] = (AttachedPropertyBrowsableAttribute)attributes[idx]; } } // Update the _attributes last, this is how we maintain thread-safety. There's a slight chance // that this routine will run simultaneously on two threads, but they will produce the same result // anyway. _attributes = browsableAttributes; } _attributesChecked = true; } return _attributes; } } // // Returns a custom attached property browsable attribute that // verifies the parameter type is compatible. This may return null // if we've done the work and verified that there is no need for // such an attribute. // private AttachedPropertyBrowsableAttribute ParameterTypeAttribute { get { if (!_paramTypeAttributeChecked) { MethodInfo m = AttachMethod; if (m != null) { ParameterInfo[] parameters = m.GetParameters(); // The AttachMethod property should have already done the correct // work to ensure this method has the right signature. Assert here // that we assume this is the case. Debug.Assert(parameters != null && parameters.Length == 1, "GetAttachedPropertyMethod should return a method with one parameter."); TypeDescriptionProvider typeProvider = TypeDescriptor.GetProvider(_dp.OwnerType); _paramTypeAttribute = new AttachedPropertyBrowsableForTypeAttribute(typeProvider.GetRuntimeType(parameters[0].ParameterType)); } _paramTypeAttributeChecked = true; } return _paramTypeAttribute; } } //------------------------------------------------------ // // Internal Methods // //----------------------------------------------------- // // Returns true if the DP can logically be attached to the // given instance. This will return false if the property // is not an attached property or if the property's // AttachedPropertyBrowsableAttributes are not compatible with // this instance. // internal bool CanAttach(DependencyObject instance) { Debug.Assert(instance != null, "Caller should validate non-null instance before calling CanAttach."); if (AttachMethod != null) { int numAttrs = 0; AttachedPropertyBrowsableAttribute[] attrs = Attributes; if (attrs != null) { numAttrs = attrs.Length; for(int idx = 0; idx < numAttrs; idx++) { AttachedPropertyBrowsableAttribute attr = attrs[idx]; if (!attr.IsBrowsable(instance, _dp)) { // The attribute isn't browsable. If UnionResults is turned on, we must // look for another matching attribute of the same type. I don't expect // a very large list of attributes here, so I'd rather go n^2 than // create a list of UnionResults attributes somewhere I need to reconcile. bool isBrowsable = false; if (attr.UnionResults) { Type attrType = attr.GetType(); for(int idx2 = 0; idx2 < numAttrs; idx2++) { AttachedPropertyBrowsableAttribute subAttr = attrs[idx2]; if (attrType == subAttr.GetType() && subAttr.IsBrowsable(instance, _dp)) { isBrowsable = true; break; } } } if (!isBrowsable) { return false; } } } } // We got through all matches, this property can be attached // to the given instance provided we found at least one // attribute. If we didn't, that means the property should // be treated as non-visible. return numAttrs > 0; } // No AttachMethod means this property is not an attached // property, so it cannot be attached elsewhere. return false; } //------------------------------------------------------ // // Private Fields // //------------------------------------------------------ private readonly DependencyProperty _dp; private MethodInfo _getMethod; private AttachedPropertyBrowsableAttribute[] _attributes; private AttachedPropertyBrowsableAttribute _paramTypeAttribute; private bool _attributesChecked; private bool _getMethodChecked; private bool _paramTypeAttributeChecked; } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007. // Copyright (c) Microsoft Corporation. All rights reserved.
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