Behavior/DP Question - WPF Discussion Boards

Re: Vertical text in WPF grid

6-Jul-20 23:43

That markup looks OK to me in Kaxaml[^].

Perhaps you need to use a layout transform instead of a render transform?

LayoutTransform vs. RenderTransform - What's the Difference?[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

kalberts7-Jul-20 5:03

kalberts

7-Jul-20 5:03

Aaah - thanks a lot!

I hadn't leaned the difference between LayoutTransform and RenderTransform. Although LayoutTransform is mentioned in my XAML textbook, it isn't illustrated in an XAML example, so I hadn't grasped the difference between the two concepts.

LayoutTransfor gives me code that looks a lot more like I want it, a lot more direct and maintaninable.

(I still think XAML often requires an extreme amount of red tape to do fairly simple things. That is an inherent "quality" of XAML, not of transforms in particular, but it certainly is clearly illustrated in transforms!)

Behavior/DP Question

Kevin Marois22-Jun-20 8:27

22-Jun-20 8:27

I have a behavior called SecurityBehavior that I'm using to control access to UI elements. I use it like this:

<TextBox Grid.Row="2" 
            Grid.Column="1"
            Text="{Binding EmployeeName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
            Height="32"
            Width="250"
            local:SecurityBehavior.SecurityTags="can_add_employees|can_edit_employees" 
            HorizontalAlignment="Left"
            VerticalAlignment="Top"
            Margin="5"/>

I set two tags that allows the field to be enabled if the user can Add or Edit the employee name.

Here's my Behavior class:

public static class SecurityBehavior
{
    #region Security Tags
    public static string GetSecurityTags(DependencyObject obj)
    {
        return (string)obj.GetValue(SecurityTagsProperty);
    }

    public static void SetSecurityTags(DependencyObject obj, string value)
    {
        obj.SetValue(SecurityTagsProperty, value);
    }

    public static readonly DependencyProperty SecurityTagsProperty =
                                DependencyProperty.RegisterAttached("SecurityTags",
                                typeof(string), typeof(SecurityBehavior),
                                new PropertyMetadata("", OnSecurityTagsChanged));

    private static void OnSecurityTagsChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        FrameworkElement element = (FrameworkElement)sender;

        bool canEnable = true;

        var tags = e.NewValue.ToString().Split('|').ToList();

        foreach (var tag in tags)
        {
            if (!string.IsNullOrEmpty(tag))
            {
                canEnable = canEnable & SecurityService.HasRights(tag);
            }
        }

        element.IsEnabled = canEnable;
    }
    #endregion
}

Pretty straightforward. But now I ned one more thing. The UI's are always disabled until the "Edit" button on the toolbar is clicked. So, I added another DP like this:

<h1>region Allow Enable</h1>

public static bool GetAllowEnable(DependencyObject obj)
{
    return (bool)obj.GetValue(AllowEnableProperty);
}

public static void SetAllowEnable(DependencyObject obj, bool value)
{
    obj.SetValue(AllowEnableProperty, value);
}

public static readonly DependencyProperty AllowEnableProperty =
                            DependencyProperty.RegisterAttached("AllowEnable",
                            typeof(bool), 
                            typeof(SecurityBehavior),
                            new PropertyMetadata(false, OnAllowEnableChanged));

private static void OnAllowEnableChanged(object sender, DependencyPropertyChangedEventArgs e)
{
    FrameworkElement element = (FrameworkElement)sender;
}
<h1>endregion

and use it like this:

<TextBox Grid.Row="2" 
            Grid.Column="1"
            Text="{Binding EmployeeName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
            Height="32"
            Width="250"
            local:SecurityBehavior.AllowEnable="{Binding AreFieldsEnabled, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
            local:SecurityBehavior.SecurityTags="can_add_employees|can_edit_employees" 
            HorizontalAlignment="Left"
            VerticalAlignment="Top"
            Margin="5"/>

The value of the VM's AreFieldsEnabled property is now passed to the DP AllowEnable. So far so good.

So I now tried to modify the OnSecurityTagsChanged method:

private static void OnSecurityTagsChanged(object sender, DependencyPropertyChangedEventArgs e)
{
    FrameworkElement element = (FrameworkElement)sender;

    // ************************ AllowEnable is a DP in this class. This won't compile. How do I check the AllowEnable DP?
    var allowEnable = AllowEnable; 

    bool canEnable = true;

    var tags = e.NewValue.ToString().Split('|').ToList();

    foreach (var tag in tags)
    {
        if (!string.IsNullOrEmpty(tag))
        {
            canEnable = canEnable & SecurityService.HasRights(tag);
        }
    }

    element.IsEnabled = canEnable;
}

I get a compilation error on the line with the commnent. How do I read the value of the other DP??

Thanks

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Richard Deeming23-Jun-20 4:44

23-Jun-20 4:44

It's an attached property, so you need to either call the attached property accessor, or call GetValue and pass in the dependency property.

Try something like this:

public static class SecurityBehavior
{
    private static readonly char[] TagSeparators = { '|' };
    
    public static readonly DependencyProperty SecurityTagsProperty =
        DependencyProperty.RegisterAttached("SecurityTags",
        typeof(string), typeof(SecurityBehavior),
        new PropertyMetadata("", OnSecurityChanged));
    
    public static string GetSecurityTags(DependencyObject obj)
    {
        return (string)obj.GetValue(SecurityTagsProperty);
    }

    public static void SetSecurityTags(DependencyObject obj, string value)
    {
        obj.SetValue(SecurityTagsProperty, value);
    }

    public static readonly DependencyProperty AllowEnableProperty =
        DependencyProperty.RegisterAttached("AllowEnable",
        typeof(bool), 
        typeof(SecurityBehavior),
        new PropertyMetadata(false, OnSecurityChanged));

    public static bool GetAllowEnable(DependencyObject obj)
    {
        return (bool)obj.GetValue(AllowEnableProperty);
    }

    public static void SetAllowEnable(DependencyObject obj, bool value)
    {
        obj.SetValue(AllowEnableProperty, value);
    }
    
    private static void OnSecurityChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        bool canEnable = GetAllowEnable(sender);
        if (canEnable)
        {
            string[] tags = GetSecurityTags(sender).Split(TagSeparators, StringSplitOptions.RemoveEmptyEntries);
            foreach (string tag in tags)
            {
                canEnable &= SecurityService.HasRights(tag);
            }
        }
    
        var element = (UIElement)sender;
        element.IsEnabled = canEnable;
    }

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Kevin Marois1-Jul-20 8:30

1-Jul-20 8:30

Ok, so I implemented your changes and the GetAllowEnable(sender) gets called fine. However, overall things still don't work right. Let me explain...

This is all in a small WPF test app. On the window I have a TextBox, and a ToggleButton called Enabled. When the Toggle is clicked, I set a property in the code behind called AreFieldsEnabled to True. This property is bound on the TextBox to the SecurityBehavior's AllowEnable DP:

<TextBox Grid.Row="2" 
            Grid.Column="1"
            Text="{Binding EmployeeName, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
            Height="32"
            Width="250"
            local:SecurityBehavior.AllowEnable="{Binding AreFieldsEnabled, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
            local:SecurityBehavior.SecurityTags="can_add_employees|can_edit_employees" 
            HorizontalAlignment="Left"
            VerticalAlignment="Top"
            Margin="5"/>

The problem is that the SecurityTags DP gets called first, which calls GetAllowEnable, which return False by default because AllowEnable hasn't yet been set to True (using the ToggleButton). Later, when I toggle the button and set AreFieldsEnabled to True, the SecurityTags property is never called again, so nothing is enabled. Here's all the code:

Behavior

public static class SecurityBehavior
{
    private static readonly char[] TagSeparators = { '|' };
    #region Allow Enable
    public static readonly DependencyProperty AllowEnableProperty =
                                DependencyProperty.RegisterAttached("AllowEnable",
                                typeof(bool),
                                typeof(SecurityBehavior),
                                new PropertyMetadata(false, OnAllowEnableChanged));
    public static bool GetAllowEnable(DependencyObject obj)
    {
        return (bool)obj.GetValue(AllowEnableProperty);
    }
    public static void SetAllowEnable(DependencyObject obj, bool value)
    {
        obj.SetValue(AllowEnableProperty, value);
    }
    private static void OnAllowEnableChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        FrameworkElement element = (FrameworkElement)sender;
    }
    #endregion
    #region Security Tags
    public static readonly DependencyProperty SecurityTagsProperty =
            DependencyProperty.RegisterAttached("SecurityTags",
            typeof(string), typeof(SecurityBehavior),
            new PropertyMetadata("", OnSecurityChanged));
    public static string GetSecurityTags(DependencyObject obj)
    {
        return (string)obj.GetValue(SecurityTagsProperty);
    }
    public static void SetSecurityTags(DependencyObject obj, string value)
    {
        obj.SetValue(SecurityTagsProperty, value);
    }
    private static void OnSecurityChanged(DependencyObject sender, DependencyPropertyChangedEventArgs e)
    {
        bool canEnable = GetAllowEnable(sender); //<=============== Returns FALSE by default
        if (canEnable)
        {
            string[] tags = GetSecurityTags(sender).Split(TagSeparators, StringSplitOptions.RemoveEmptyEntries);
            foreach (string tag in tags)
            {
                canEnable &= SecurityService.HasRights(tag);
            }
        }
        var element = (UIElement)sender;
        element.IsEnabled = canEnable;
    }
    #endregion
}

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Richard Deeming1-Jul-20 23:32

1-Jul-20 23:32

If you look at my code again, both DPs call the same "property changed" method. Your AllowEnable property is calling an almost empty method instead.

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Kevin Marois2-Jul-20 8:49

Re: 2 xaml windows question

2-Jul-20 8:49

Yup, I'm an idiot.

Thanks!

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

2 xaml windows question

Michele Smith26-May-20 7:10

Michele Smith

26-May-20 7:10

Hi, I have a need to link two xaml windows due to a constraint on xml processing. Instead of sending one xml request, I have to send two.

I have some some research, and there is not a whole lot on doing this. I found an article that discussed:

How can i combine multiple XAML files using C# in WPF? - Stack Overflow[^]

Can anyone steer me in the right direction? I just want to run one xaml window then the next.

I put them into my project and nothing happened. I did not receive an error, but nothing happened.

#realJSOP26-May-20 7:43

#realJSOP

26-May-20 7:43

If you're displaying the 2nd window from within the first one, just create an overloaded constructor in the 2nd window, and instantiate it with the necessary data.

".45 ACP - because shooting twice is just silly" - JSOP, 2010
-----
You can never have too much ammo - unless you're swimming, or on fire. - JSOP, 2010
-----
When you pry the gun from my cold dead hands, be careful - the barrel will be very hot. - JSOP, 2013

modified 21-Jun-20 7:40am.

Create DataGrid From List<T> With Properties As Columns

Kevin Marois18-May-20 7:14

Re: Create DataGrid From List<T> With Properties As Columns

18-May-20 7:14

I have a bit of a challenge here.

I'm working on an app that manages home building projects. A house can have floors, and this is a BuildingTypeEntity. Examples are "1 Story", "2 Story", etc. Parts, supplies, and equipment are delivered to the job site periodcally. Generally every few days. These deliveries are called "Schedule Packs", and that's represented by the SchedulePackEntity

These two entities are shown below:

public class BuildingTypeEntity : _EntityBase
{
    private string _Caption;
    public string Caption
    {
        get { return _Caption; }
        set
        {
            SetProperty<string>("Caption", ref _Caption, value);
        }
    }
    private int _NumberOfFloors;
    public int NumberOfFloors
    {
        get { return _NumberOfFloors; }
        set
        {
            SetProperty<int>("NumberOfFloors", ref _NumberOfFloors, value);
        }
    }
    private ObservableCollection<SchedulePackEntity> _SchedulePacks;
    public ObservableCollection<SchedulePackEntity> SchedulePacks
    {
        get { return _SchedulePacks; }
        set
        {
            if (_SchedulePacks != value)
            {
                _SchedulePacks = value;
                RaisePropertyChanged("SchedulePacks");
            }
        }
    }
}

public class SchedulePackEntity : _EntityBase
{
    private int _BuildingTypeId;
    public int BuildingTypeId
    {
        get { return _BuildingTypeId; }
        set
        {
            if (_BuildingTypeId != value)
            {
                _BuildingTypeId = value;
                RaisePropertyChanged("BuildingTypeId");
            }
        }
    }
    private string _Caption;
    public string Caption
    {
        get { return _Caption; }
        set
        {
            if (_Caption != value)
            {
                _Caption = value;
                RaisePropertyChanged("Caption");
            }
        }
    }
    private int _Sequence;
    public int Sequence
    {
        get { return _Sequence; }
        set
        {
            if (_Sequence != value)
            {
                _Sequence = value;
                RaisePropertyChanged("Sequence");
            }
        }
    }
    private int _Floor;
    public int Floor
    {
        get { return _Floor; }
        set
        {
            if (_Floor != value)
            {
                _Floor = value;
                RaisePropertyChanged("Floor");
            }
        }
    }
    private int _Days;
    public int Days
    {
    get { return _Days; }
    set
    {
        if (_Days != value)
        {
        _Days = value;
        RaisePropertyChanged("Days");
        }
    }
    }
}

The

Packs has a property called Days, which is the number of days past the project start date when the delivery will be made.

Ok, now the problem:

There is one part of the UI where the user can select which Packs they need for a project. Then, the pack data needs to become a "horizontal version" of the data represented as a DataGrid. Please see this screenshot.

On the left side is a list of Building Types built as Expanders with DataGrids inside. This part works fine.

The right side is what I need to build. Notice that there are expanders, and in each are one DataGrid for each floor. So on the right side, under 2 Story, are 1st Floor with its selected packs as columns of a grid, and next to that is 2nd Story with its selected packs as columns of a grid. There needs to be one grid for each floor, arranged horizontally. Only the packs that are checked on the left side should appear as columns in their respective DataGrids on the right side.

The summary of the problem is how to turn a vertical list of classes, 1 to however many there are in the list, to a DataGrid with those ojects as columns.

I'm open to suggestion on a different approach, or if someone has done this, I'd like to hear how.

Thanks

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Richard Deeming18-May-20 8:47

Re: Create DataGrid From List<T> With Properties As Columns

18-May-20 8:47

I suspect you're going to need a CustomTypeDescriptor for the floor view-model.
CustomTypeDescriptor Class (System.ComponentModel) | Microsoft Docs[^]

Perhaps something like this:

public class BuildingTypeViewModel
{
    public BuildingTypeViewModel(BuildingTypeEntity buildingType)
    {
        Caption = buildingType.Caption;
        
        var floors = new List<BuildingFloorViewModel>(buildingType.NumberOfFloors);
        for (int floorNumber = 1; floorNumber <= buildingType.NumberOfFloors; floorNumber++)
        {
            var floor = new BuildingFloorViewModel(buildingType, floorNumber);
            if (!floor.Packs.SchedulePacks.IsEmpty) floors.Add(floor);
        }
        
        Floors = floors;
    }
    
    public string Caption { get; }
    public IReadOnlyList<BuildingFloorViewModel> Floors { get; }
}

public class BuildingFloorViewModel
{
    public BuildingFloorViewModel(BuildingTypeEntity buildingType, int floorNumber)
    {
        Floor = floorNumber;
        Packs = new BuildingFloorPacksViewModel(buildingType, floorNumber);
    }
    
    public int Floor { get; }
    public BuildingFloorPacksViewModel Packs { get; }
}

public class BuildingFloorPacksViewModel : CustomTypeDescriptor, System.Collections.IEnumerable
{
    public BuildingFloorPacksViewModel(BuildingTypeEntity buildingType, int floorNumber)
    {
        SchedulePacks = buildingType.SchedulePacks.Where(p => p.Floor == floorNumber).ToDictionary(p => p.Caption);
        
        var properties = SchedulePacks.Keys.Select(name => new SchedulePackPropertyDescriptor(name)).ToArray();
        PropertyDescriptors = new PropertyDescriptorCollection(properties);
    }
    
    internal bool IsEmpty => SchedulePacks.Count == 0;
    private IReadOnlyDictionary<string, SchedulePackEntity> SchedulePacks { get; }
    private PropertyDescriptorCollection PropertyDescriptors { get; }
    
    public override PropertyDescriptorCollection GetProperties() => PropertyDescriptors;
    public override PropertyDescriptorCollection GetProperties(Attribute[] attributes) => PropertyDescriptors;
    
    public System.Collections.IEnumerator GetEnumerator()
    {
        // Need to implement IEnumerable to give you a single row in the grid:
        yield return this;
    }
    
    private sealed class SchedulePackPropertyDescriptor : PropertyDescriptor
    {
        public SchedulePackPropertyDescriptor(string name) : base(name, Array.Empty<Attribute>())
        {
        }
        
        public override Type ComponentType => typeof(BuildingFloorPacksViewModel);
        public override Type PropertyType => typeof(int);
        public override bool IsReadOnly => false;
        
        public override bool CanResetValue (object component) => false;
        public override void ResetValue (object component) => throw new NotSupportedException();
        public override bool ShouldSerializeValue (object component) => true;
        
        public override object GetValue (object component)
        {
            var parent = (BuildingFloorPacksViewModel)component;
            return parent.SchedulePacks[Name].Days;
        }
        
        public override void SetValue (object component, object value)
        {
            var parent = (BuildingFloorPacksViewModel)component;
            parent.SchedulePacks[Name].Days = (int)value;
        }
    }
}

Bind your right-hand view to a list of BuildingTypeViewModel objects. Within each expander, bind an ItemsControl to the Floors property. Within the data template for the ItemsControl, display the Floor, and bind the grid to the Packs property. Let WPF auto-generate the columns for the grid, and it should work.

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

Kevin Marois18-May-20 8:52

18-May-20 8:52

Thanks Richard. I'll give it a try

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

WPF ListBox

michaelbarb7-May-20 10:03

michaelbarb

7-May-20 10:03

ListBox is basically a list of ListBoxItem. How can you access this list in C#?

You can access parts of ListBoxItem threw SelectedItem but no the full item. For example you cannot get to background color of an item with SelectedItem.

So many years of programming I have forgotten more languages than I know.

Richard Deeming10-May-20 21:52

10-May-20 21:52

You need to use the ItemContainerGenerator[^] to get the ListBoxItem for a specific index:
How to: Get a ListBoxItem - WPF | Microsoft Docs[^]

NB: This can return null if the item has not been shown yet.

If you're trying to modify the style of the selected item, you should consider using declarative WPF styles instead.
ItemsControl.ItemContainerStyle Property (System.Windows.Controls) | Microsoft Docs[^]

"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer

michaelbarb11-May-20 19:11

michaelbarb

11-May-20 19:11

This seems to be one way. It can get a ListBoxItem but not return it to the ListBox after it is edited.

To be more exact about what I want to do. Given a ListBox and search key, I want to highlight or change the color of items that contain the search key. I do not want to edit the text in the list. I want to keep the list browsable and still contain all items. Change the search key: a)highlight different items in the ListBox b)clearing those that are no longer contain the search key.

So many years of programming I have forgotten more languages than I know.

Mycroft Holmes11-May-20 21:33

Mycroft Holmes

11-May-20 21:33

Try
Add a property to your listbox data source - IsMatched (probably a string with the colour name)
bind the back colour of your ListBoxItemTemplate to the IsMatched property of your data item
During the search event change the IsMatched value
Reset event should clear the IsMatched value back to the default, ptobably Transparent

Never underestimate the power of human stupidity -
RAH
I'm old. I know stuff - JSOP

Gerry Schmitz11-May-20 12:42

Gerry Schmitz

11-May-20 12:42

Depends on your "templating". The "contents" are the things you load (.Items). The item template, default or custom, deals with the visuals. The default "data" is via ToString().

.net - Default ItemTemplate of Controls like ListBox/ListView - Stack Overflow

It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food

Design Question

Kevin Marois18-Apr-20 15:26

18-Apr-20 15:26

I'm working on an automatic updater for my WPF app. When I do a publish, it copies those files that changed to my server. Then, when the user double-clicks the icon, it checks my server for changes, downloads them, starts the app. Everything works great.

What I'd like to do now is set it up for a test environment. This means that I want it to target a copy of the production DB. It will copy the changed files to an alternate location, different than the production location, but target the Test DB instead of Production. All the code files will be the same.

The question is, what's the best way to tell the code to go look at the test DB versus the production db? One idea I was considering was using the existance of a file to trigger test mode. So, if file "TestMode.txt" was in the EXE's location, then start in test mode, else start in production mode.

Anyone have any better ideas?

Thanks

If it's not broken, fix it until it is.
Everything makes sense in someone's mind.
Ya can't fix stupid.

Re: Design Question

Mycroft Holmes19-Apr-20 12:20

Mycroft Holmes

19-Apr-20 12:20

You are reinventing the wheel - clickonce deployment with different config files and different compile directives. You have 2 distinct deployments, UAT and production.

Alternatively if you just want to allow the user to change DBs then change the connection string when the user decides.

Caveat - change the background colour of the UAT version. You do not want the user to have any doubt which version they are entering their data into.

Never underestimate the power of human stupidity -
RAH
I'm old. I know stuff - JSOP

Re: Design Question

Kevin Marois19-Apr-20 14:09