CaseKeyBox.ViewModel.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / NetFx40 / Tools / System.Activities.Core.Presentation / System / Activities / Core / Presentation / CaseKeyBox.ViewModel.cs / 1305376 / CaseKeyBox.ViewModel.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------

namespace System.Activities.Core.Presentation 
{
    using System; 
    using System.Collections.ObjectModel; 
    using System.Windows;
    using System.Linq; 
    using System.ComponentModel;
    using System.Runtime;
    using System.Diagnostics.CodeAnalysis;
    using System.Globalization; 
    using System.Activities.Presentation.Model;
 
    class CaseKeyBoxViewModel : DependencyObject 
    {
        static readonly string Null = "(null)"; 
        static readonly string Empty = "(empty)";

        public static readonly DependencyProperty ComboBoxIsEditableProperty =
            DependencyProperty.Register("ComboBoxIsEditable", typeof(bool), typeof(CaseKeyBoxViewModel), new UIPropertyMetadata(false)); 

        public static readonly DependencyProperty ComboBoxVisibilityProperty = 
            DependencyProperty.Register("ComboBoxVisibility", typeof(Visibility), typeof(CaseKeyBoxViewModel), new UIPropertyMetadata(Visibility.Collapsed)); 

        public static readonly DependencyProperty ComboBoxItemsProperty = 
            DependencyProperty.Register("ComboBoxItems", typeof(ObservableCollection), typeof(CaseKeyBoxViewModel));

        public static readonly DependencyProperty DataTemplateNameProperty =
            DependencyProperty.Register("DataTemplateName", typeof(string), typeof(CaseKeyBoxViewModel), new UIPropertyMetadata("Label")); 

        public static readonly DependencyProperty TextProperty = 
            DependencyProperty.Register("Text", typeof(string), typeof(CaseKeyBoxViewModel), new UIPropertyMetadata(String.Empty)); 

        public static readonly DependencyProperty TextBoxVisibilityProperty = 
            DependencyProperty.Register("TextBoxVisibility", typeof(Visibility), typeof(CaseKeyBoxViewModel), new UIPropertyMetadata(Visibility.Visible));

        public const string BoxesTemplate = "Boxes";
        public const string LabelTemplate = "Label"; 

        string oldText = String.Empty; 
 
        public CaseKeyBoxViewModel(ICaseKeyBoxView view)
        { 
            this.View = view;
        }

        public bool ComboBoxIsEditable 
        {
            get { return (bool)GetValue(ComboBoxIsEditableProperty); } 
            set { SetValue(ComboBoxIsEditableProperty, value); } 
        }
 
        public ObservableCollection ComboBoxItems
        {
            get { return (ObservableCollection)GetValue(ComboBoxItemsProperty); }
            set { SetValue(ComboBoxItemsProperty, value); } 
        }
 
        public Visibility ComboBoxVisibility 
        {
            get { return (Visibility)GetValue(ComboBoxVisibilityProperty); } 
            set { SetValue(ComboBoxVisibilityProperty, value); }
        }

        public string DataTemplateName 
        {
            get { return (string)GetValue(DataTemplateNameProperty); } 
            set { SetValue(DataTemplateNameProperty, value); } 
        }
 
        public string Text
        {
            get { return (string)GetValue(TextProperty); }
            set { SetValue(TextProperty, value); } 
        }
 
        public Visibility TextBoxVisibility 
        {
            get { return (Visibility)GetValue(TextBoxVisibilityProperty); } 
            set { SetValue(TextBoxVisibilityProperty, value); }
        }

        public bool IsBoxOnly 
        {
            get; 
            set; 
        }
 
        public bool OnEnterPressed()
        {
            return this.CommitChanges();
        } 

        public void OnEscapePressed() 
        { 
            this.Text = oldText;
            if (!this.IsBoxOnly) 
            {
                this.DataTemplateName = CaseKeyBoxViewModel.LabelTemplate;
            }
            this.View.OnEditCancelled(); 
        }
 
        public void OnLabelGotFocus() 
        {
            this.DataTemplateName = CaseKeyBoxViewModel.BoxesTemplate; 
        }

        public bool OnLostFocus()
        { 
            return CommitChanges();
        } 
 
        public void OnValueChanged()
        { 
            if (this.Value is ModelItem)
            {
                // Since Value is a DP, this code will trigger OnValueChanged once more.
                this.Value = ((ModelItem)this.Value).GetCurrentValue(); 
                return;
            } 
 
            if (this.DataTemplateName != LabelTemplate && !this.IsBoxOnly)
            { 
                this.DataTemplateName = LabelTemplate;
            }

            if (this.DisplayHintText) 
            {
                this.Text = string.Empty; 
                return; 
            }
            if (this.ValueType == null) 
            {
                return;
            }
            if (this.ValueType.IsValueType) 
            {
                if (this.Value == null) 
                { 
                    this.Value = Activator.CreateInstance(this.ValueType);
                } 
            }
            if (this.Value == null)
            {
                this.Text = Null; 
            }
            else if ((this.ValueType == typeof(string)) && string.Equals(this.Value, String.Empty)) 
            { 
                this.Text = Empty;
            } 
            else
            {
                TypeConverter converter = XamlUtilities.GetConverter(this.ValueType);
                Fx.Assert(converter != null, "TypeConverter is not available"); 
                try
                { 
                    this.Text = converter.ConvertToString(this.Value); 
                }
                catch (ArgumentException) 
                {
                    this.Text = this.Value.ToString();
                }
            } 
        }
 
        public void OnValueTypeChanged() 
        {
            if (this.ValueType == null) 
            {
                return;
            }
            bool isBool = this.ValueType == typeof(bool); 
            bool isEnum = this.ValueType.IsEnum;
            if (isBool || isEnum) 
            { 
                this.ComboBoxVisibility = Visibility.Visible;
                this.TextBoxVisibility = Visibility.Collapsed; 
                this.ComboBoxIsEditable = false;
                if (isBool)
                {
                    this.ComboBoxItems = new ObservableCollection { "True", "False" }; 
                }
                else 
                { 
                    this.ComboBoxItems = new ObservableCollection(Enum.GetNames(this.ValueType).ToList());
                } 
            }
            else if (this.ValueType.IsValueType)
            {
                this.ComboBoxVisibility = Visibility.Collapsed; 
                this.TextBoxVisibility = Visibility.Visible;
                this.ComboBoxIsEditable = false; 
            } 
            else
            { 
                this.ComboBoxVisibility = Visibility.Visible;
                this.TextBoxVisibility = Visibility.Collapsed;
                this.ComboBoxIsEditable = true;
                this.ComboBoxItems = new ObservableCollection { Null }; 
                if (this.ValueType == typeof(string))
                { 
                    this.ComboBoxItems.Add(Empty); 
                }
            } 
            OnValueChanged();
        }

        public void SaveOldText() 
        {
            this.oldText = this.Text; 
        } 

        [SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes", 
            Justification = "If conversion fails, the exception type is System.Exception.So we must catch all types of exceptions here.")]
        [SuppressMessage("Reliability", "Reliability108:IsFatalRule",
            Justification = "Catch all exceptions to prevent crash.")]
        bool CommitChanges() 
        {
            object result = null; 
 
            try
            { 
                result = ResolveInputText();
            }
            catch
            { 
                // ---- all
                Fx.Assert(false, "Result should have been valid. Preview event handler should have handled the validation."); 
                return false; 
            }
 
            this.Value = result;
            if (this.DataTemplateName != CaseKeyBoxViewModel.LabelTemplate && !this.IsBoxOnly)
            {
                // this is for the case when setting this.Value to null. It looks like 
                // OnValueChanged won't get called because NULL is a default value for
                // the CaseKeyBox instance in SwitchDesigner. 
                this.DataTemplateName = CaseKeyBoxViewModel.LabelTemplate; 
            }
            this.View.OnValueCommitted(); 

            return true;
        }
 
        object ResolveInputText()
        { 
            object result = null; 
            if (this.ValueType == typeof(string))
            { 
                if (this.Text.Equals(Null))
                {
                    result = null;
                } 
                else if (this.Text.Equals(Empty))
                { 
                    result = string.Empty; 
                }
                else 
                {
                    result = this.Text;
                }
            } 
            else if (!this.ValueType.IsValueType && this.Text.Equals(Null))
            { 
                result = null; 
            }
            else 
            {
                TypeConverter converter = XamlUtilities.GetConverter(this.ValueType);
                Fx.Assert(converter != null, "TypeConverter is not available");
 
                if (!converter.CanConvertFrom(typeof(string)) || !converter.CanConvertTo(typeof(string)))
                { 
                    throw FxTrace.Exception.AsError(new NotSupportedException(SR.NotSupportedCaseKeyStringConversion)); 
                }
 
                result = converter.ConvertFromString(this.Text);
                // See if the result can be converted back to a string.
                // For example, we have a enum Color {Black, White}.
                // String "3" can be converted to integer 3, but integer 3 
                // cannot be converted back to a valid string for enum Color.
                // In this case, we disallow string "3". 
                converter.ConvertToString(result); 
            }
 
            string reason;
            if (this.CaseKeyValidationCallback != null && !this.CaseKeyValidationCallback(result, out reason))
            {
                throw FxTrace.Exception.AsError(new ArgumentException(reason)); 
            }
 
            return result; 
        }
 
        [SuppressMessage("Microsoft.Design", "CA1031:DoNotCatchGeneralExceptionTypes",
            Justification = "If conversion fails, the exception type is System.Exception.So we must catch all types of exceptions here.")]
        [SuppressMessage("Reliability", "Reliability108:IsFatalRule",
            Justification = "Catch all exceptions to prevent crash.")] 
        public bool CanResolveInputText(out string reason)
        { 
            reason = string.Empty; 
            try
            { 
                ResolveInputText();
                return true;
            }
            catch (Exception e) 
            {
                reason = e.Message; 
                return false; 
            }
        } 

        public bool TextHasBeenChanged()
        {
            string normalizedOldText = this.oldText; 
            string normalizedNewText = this.Text;
 
            // Tricky: this.DisplayHintText = false => This CaseKeyBox is in CaseDesigner 
            // Here, when changing value of string value type from "(empty)" to "", we must
            // consider the text hasn't been changed, such that we don't do commit-change. 
            // We normalize the strings for empty-string situation before we do comparison.
            if (this.ValueType == typeof(string) && !this.DisplayHintText)
            {
                normalizedOldText = normalizedOldText == Empty ? string.Empty : normalizedOldText; 
                normalizedNewText = normalizedNewText == Empty ? string.Empty : normalizedNewText;
            } 
 
            return normalizedOldText != normalizedNewText;
        } 

        ICaseKeyBoxView View { get; set; }

        bool DisplayHintText 
        {
            get { return this.View.DisplayHintText; } 
        } 

        object Value 
        {
            get { return this.View.Value; }
            set { this.View.Value = value; }
        } 

        Type ValueType 
        { 
            get { return this.View.ValueType; }
        } 

        CaseKeyValidationCallbackDelegate CaseKeyValidationCallback
        {
            get { return this.View.CaseKeyValidationCallback;  } 
        }
 
        public void ResetText() 
        {
            this.Text = string.Empty; 
            this.oldText = string.Empty;
        }
    }
} 

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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CaseKeyBox.ViewModel.cs source code in C# .NET

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