ImageKeyConverter.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / WinForms / Managed / System / WinForms / ImageKeyConverter.cs / 1 / ImageKeyConverter.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
//----------------------------------------------------------------------------- 

/* 
 */ 
namespace System.Windows.Forms {
 
    using Microsoft.Win32;
    using System.Collections;
    using System.ComponentModel;
    using System.Drawing; 
    using System.Diagnostics;
    using System.Globalization; 
    using System.Reflection; 
    using System.Collections.Specialized;
 
    /// 
    /// 
    /// ImageIndexConverter is a class that can be used to convert
    /// image index values one data type to another. 
    /// 
    public class ImageKeyConverter : StringConverter { 
 
        private string parentImageListProperty  = "Parent";
 
        /// 
        protected virtual bool IncludeNoneAsStandardValue {
            get {
                return true; 
            }
        } 
 
        /// 
        /// this is the property to look at when there is no ImageList property 
        /// on the current object.  For example, in ToolBarButton - the ImageList is
        /// on the ToolBarButton.Parent property.  In WinBarItem, the ImageList is on
        /// the WinBarItem.Owner property.
        ///  
        internal string ParentImageListProperty {
            get { 
                return parentImageListProperty; 
            }
            set { 
                parentImageListProperty = value;
            }
        }
        ///  
        /// 
        /// Gets a value indicating whether this converter can convert an object in the 
        /// given source type to a string using the specified context. 
        /// 
        public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType) { 
            if (sourceType == typeof(string)) {
                return true;
            }
            return base.CanConvertFrom(context, sourceType); 
        }
 
        ///  
        /// 
        /// Converts the specified value object to a string object. 
        /// 
        public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value) {
            if (value is string) {
                return (string)value; 
            }
            if (value == null) { 
                return ""; 
            }
            return base.ConvertFrom(context, culture, value); 
        }


 
        /// 
        ///  
        /// Converts the given object to another type.  The most common types to convert 
        /// are to and from a string object.  The default implementation will make a call
        /// to ToString on the object if the object is valid and if the destination 
        /// type is string.  If this cannot convert to the desitnation type, this will
        /// throw a NotSupportedException.
        /// 
        public override object ConvertTo(ITypeDescriptorContext context, CultureInfo culture, object value, Type destinationType) { 
            if (destinationType == null) {
                throw new ArgumentNullException("destinationType"); 
            } 

            if (destinationType == typeof(string) && value != null && value is string && ((string)value).Length == 0) { 
                return SR.GetString(SR.toStringNone);
            }
            else if (destinationType == typeof(string) && (value == null)) {
                return SR.GetString(SR.toStringNone); 
            }
 
            return base.ConvertTo(context, culture, value, destinationType); 
        }
 

        /// 
        /// 
        /// Retrieves a collection containing a set of standard values 
        /// for the data type this validator is designed for.  This
        /// will return null if the data type does not support a 
        /// standard set of values. 
        /// 
        public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext context) { 
            if (context != null && context.Instance != null) {
                object instance = context.Instance;
                PropertyDescriptor imageListProp = ImageListUtils.GetImageListProperty(context.PropertyDescriptor, ref instance);
 
                while (instance != null && imageListProp == null) {
                    PropertyDescriptorCollection props = TypeDescriptor.GetProperties(instance); 
 
                    foreach (PropertyDescriptor prop in props) {
                        if (typeof(ImageList).IsAssignableFrom(prop.PropertyType)) { 
                            imageListProp = prop;
                            break;
                        }
                    } 

                    if (imageListProp == null) { 
 
                        // We didn't find the image list in this component.  See if the
                        // component has a "parent" property.  If so, walk the tree... 
                        //
                        PropertyDescriptor parentProp = props[ParentImageListProperty];
                        if (parentProp != null) {
                            instance = parentProp.GetValue(instance); 
                        }
                        else { 
                            // Stick a fork in us, we're done. 
                            //
                            instance = null; 
                        }
                    }
                }
 
                if (imageListProp != null) {
                    ImageList imageList = (ImageList)imageListProp.GetValue(instance); 
 
                    if (imageList != null) {
 
                        // Create array to contain standard values
                        //
                        object[] values;
                        int nImages = imageList.Images.Count; 
                        if (IncludeNoneAsStandardValue) {
                            values = new object[nImages + 1]; 
                            values[nImages] = ""; 
                        }
                        else { 
                            values = new object[nImages];
                        }

 
                        // Fill in the array
                        // 
                        StringCollection imageKeys = imageList.Images.Keys; 
                        for (int i = 0; i < imageKeys.Count; i++) {
                            if ((imageKeys[i] != null) && (imageKeys[i].Length != 0)) 
                                values[i] = imageKeys[i];
                        }

                        return new StandardValuesCollection(values); 
                    }
                } 
            } 

            if (IncludeNoneAsStandardValue) { 
                return new StandardValuesCollection(new object[] {""});
            }
            else {
                return new StandardValuesCollection(new object[0]); 
            }
        } 
 
        /// 
        ///  
        /// Determines if the list of standard values returned from
        /// GetStandardValues is an exclusive list.  If the list
        /// is exclusive, then no other values are valid, such as
        /// in an enum data type.  If the list is not exclusive, 
        /// then there are other valid values besides the list of
        /// standard values GetStandardValues provides. 
        ///  
        public override bool GetStandardValuesExclusive(ITypeDescriptorContext context) {
            return true; 
        }

        /// 
        ///  
        /// Determines if this object supports a standard set of values
        /// that can be picked from a list. 
        ///  
        public override bool GetStandardValuesSupported(ITypeDescriptorContext context) {
             return true; 
        }
    }
}
 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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ImageKeyConverter.cs source code in C# .NET

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