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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Collections.Specialized;
using System.ComponentModel;
using System.Globalization;
namespace System.Windows.Forms;
/// <summary>
/// ImageIndexConverter is a class that can be used to convert
/// image index values one data type to another.
/// </summary>
public class ImageKeyConverter : StringConverter
{
private string _parentImageListProperty = "Parent";
protected virtual bool IncludeNoneAsStandardValue
{
get
{
return true;
}
}
/// <summary>
/// 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 ToolStripItem, the ImageList is on
/// the ToolStripItem.Owner property.
/// </summary>
internal string ParentImageListProperty
{
get
{
return _parentImageListProperty;
}
set
{
_parentImageListProperty = value;
}
}
/// <summary>
/// Gets a value indicating whether this converter can convert an object in the
/// given source type to a string using the specified context.
/// </summary>
public override bool CanConvertFrom(ITypeDescriptorContext? context, Type sourceType)
{
if (sourceType == typeof(string))
{
return true;
}
return base.CanConvertFrom(context, sourceType);
}
/// <summary>
/// Converts the specified value object to a string object.
/// </summary>
public override object? ConvertFrom(ITypeDescriptorContext? context, CultureInfo? culture, object value)
{
if (value is string s)
{
return s;
}
if (value is null)
{
return string.Empty;
}
return base.ConvertFrom(context, culture, value);
}
/// <summary>
/// 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 destination type, this will
/// throw a NotSupportedException.
/// </summary>
public override object? ConvertTo(ITypeDescriptorContext? context, CultureInfo? culture, object? value, Type destinationType)
{
ArgumentNullException.ThrowIfNull(destinationType);
if (destinationType == typeof(string) && value is not null && value is string stringValue && stringValue.Length == 0)
{
return SR.toStringNone;
}
else if (destinationType == typeof(string) && (value is null))
{
return SR.toStringNone;
}
return base.ConvertTo(context, culture, value, destinationType);
}
/// <summary>
/// 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.
/// </summary>
public override StandardValuesCollection GetStandardValues(ITypeDescriptorContext? context)
{
if (context is not null && context.Instance is not null)
{
object? instance = context.Instance;
PropertyDescriptor? imageListProp = ImageListUtils.GetImageListProperty(context.PropertyDescriptor, ref instance);
while (instance is not null && imageListProp is null)
{
PropertyDescriptorCollection props = TypeDescriptor.GetProperties(instance);
foreach (PropertyDescriptor prop in props)
{
if (typeof(ImageList).IsAssignableFrom(prop.PropertyType))
{
imageListProp = prop;
break;
}
}
if (imageListProp is 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 is not null)
{
instance = parentProp.GetValue(instance);
}
else
{
// Stick a fork in us, we're done.
instance = null;
}
}
}
if (imageListProp is not null)
{
ImageList? imageList = (ImageList?)imageListProp.GetValue(instance);
if (imageList is not null)
{
// Create array to contain standard values
object[] values;
int nImages = imageList.Images.Count;
if (IncludeNoneAsStandardValue)
{
values = new object[nImages + 1];
values[nImages] = string.Empty;
}
else
{
values = new object[nImages];
}
// Fill in the array
StringCollection imageKeys = imageList.Images.Keys;
for (int i = 0; i < imageKeys.Count; i++)
{
string? key = imageKeys[i];
if (!string.IsNullOrEmpty(key))
{
values[i] = key;
}
}
return new StandardValuesCollection(values);
}
}
}
if (IncludeNoneAsStandardValue)
{
return new StandardValuesCollection(new object[] { "" });
}
else
{
return new StandardValuesCollection(Array.Empty<object>());
}
}
/// <summary>
/// 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.
/// </summary>
public override bool GetStandardValuesExclusive(ITypeDescriptorContext? context)
{
return true;
}
/// <summary>
/// Determines if this object supports a standard set of values
/// that can be picked from a list.
/// </summary>
public override bool GetStandardValuesSupported(ITypeDescriptorContext? context)
{
return true;
}
}
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