Using a Grid as an ItemsPanel

Ed Poore

Is is possible to use a Grid in the following situation:

I've been trying the previous to no avail, the textblocks just won't sit in the appropriate row. I've got a feeling as to why this is happening but not how to solve it (note that using a UniformGrid without setting the rows and columns explicitly works). Is it something to do with binding to an attached property?

Pete OHanlon

Ed - sorry I haven't got round to looking at this before, but wouldn't a StackPanel with it's Orientation set to Horizontal do the job?

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Ed Poore

Nope, sorry. What I'm actually trying to do is create a schedule-like component (think Outlook week view). If you imagine the following class which stores the "Event information:

public class Event
{
    public string Summary { get; set; }
    public DateTime Start { get; set; }
    public DateTime End { get; set; }
}

Then the following XAML:

Hope that makes things a bit clearer, to be honest I was surprised when it didn't work but maybe it's something to do with the Grid.Row etc being an attached property? The UniformGrid works but I think that's something to do with the fact that you can just set the rows and columns and add children controls and they're each added to a cell in the order in which they appear in the XAML, whereas this does not happen with the normal Grid. I'd really appreciate not having to go off and write a custom control just to manage what seemingly seems so simple. :rolleyes:

Pete OHanlon

Ed. I'm off for the weekend now, but I'll try to knock something together early on next week for you if that's OK with you. Pete

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Ed Poore

Thanks, that'd be great, I'm not planning on doing anything on it over the weekend apart from go to a shoot tomorrow and then being re-wiring my Land Rover on Sunday. To give you a bit more perspective on it, apart from learning what I had thought it'd be useful for would be something involved: WPF, LINQ, Visual Studio Tools for Office and plain old C#. I was thinking off getting an add-in for Outlook (or perhaps a service / tray app of some kind) to pull off by calendar from Outlook / Google Calendar (they're synced), use LINQ to select the current week (because it's so easy with that thing) and then use WPF to layout a view of the week like in outlook. Capture that to an image, do some fancy alpha blending with a background image and then set that as my desktop background. Ambitious I know but hey :rolleyes:, might be useful to someone else, would be interesting articles if I get the time. I had thought of just using GDI+ for the rendering but when I came across a blog entry that said the Calendar Printing Assistant for Outlook uses WPF I thought what a good idea, much nicer for rendering it than loads of tedious calculations.

Pete OHanlon

Have a look at this:

<Window.Resources>
<XmlDataProvider x:Key="SummaryData" d:IsDataSource="True"
Source="D:\wpf\OutlookWeekView\Events.xml"/>
<DataTemplate x:Key="EventTemplate">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition/>
<ColumnDefinition/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition/>
<RowDefinition/>
</Grid.RowDefinitions>
<TextBlock Padding="2"
Grid.Column="1"
Grid.RowSpan="2"
Text="{Binding Mode=OneWay, XPath=Summary}"/>
<TextBlock Grid.Row="0" Padding="2"
Grid.Column="0" Text="{Binding Mode=OneWay, XPath=Start}"/>
<TextBlock Grid.Row="1" Padding="2"
Grid.Column="0" Text="{Binding Mode=OneWay, XPath=End}"/>
</Grid>
</DataTemplate>
</Window.Resources>

Does it help in any way?

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Ed Poore

I don't think I explained it well enough, what you've got works fine so to speak, if you set the Grid.Row and Grid.Column of the TextBlocks (in this instance) explicitly then it does arrange them in the appropriate "cell". However if you try and set them through binding then it doesn't work. E.g.

Where DateToRowConverter returns say the hour of the event and the DateToColConverter returns the day of week. (Sorry hit the wrong key so you won't get the full post).

Pete OHanlon

Sorry - I get it now (to quote American teens, "My bad"). OK - this is a more complicated issue and one that I can't see off the top of my head how you'd accomplish this. Potentially you could do this by setting the Grid.Row and Grid.Column in the converters.

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Ed Poore

Pete O'Hanlon wrote:

Potentially you could do this by setting the Grid.Row and Grid.Column in the converters.

Hadn't thought of it that way. Any idea why it doesn't work with a "normal" binding expression? Perhaps it's time to dig out Reflector...

Pete OHanlon

The problem that you have is that you are returning the wrong type of value here. I've just been playing around with a sample of this, and here's a converter sample that you might want to take a look at:

[ValueConversion(typeof(DateTime), typeof(int))]
public class ColDateFormatter : IValueConverter
{
#region IValueConverter Members

public object Convert(object value, Type targetType, 
    object parameter, System.Globalization.CultureInfo culture)
{
    DateTime startDate = DateTime.Today; // This is just a test to get a date to compare to.
    TimeSpan off = startDate.Subtract(DateTime.Parse(value as string));

    return off.Days + 1;
}

public object ConvertBack(object value, Type targetType, object parameter,
    System.Globalization.CultureInfo culture)
{
    throw new NotImplementedException();
}

#endregion

}

Here's a sample of the XAML that you'll need:

Obviously, you'll need to have added an appropriate number of RowDefinition and ColumnDefinition items. Hmmm. I'm almost tempted to turn this into an article. :-D

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Ed Poore

Pete O'Hanlon wrote:

The problem that you have is that you are returning the wrong type of value here

My converter was constructed as such:

public class DateToRowConverter : IValueConverter
{
    public object ConvertTo(object value, Type targetType, object parameter, CultureInfo culture)
    {
       // No checking for simplicity
       return ((DateTime)value).Hour - 8; // Grid starts at 08:00 for example so this provides the necessary offset
    }
// Rest of class...
}

I didn't have those attributes so perhaps that was what was missing. I'll see if I can get a sample project made up for you to illustrate the point...

Pete OHanlon

And do you have enough RowDefinition and ColumnDefinition items in the XAML? This is important.

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Ed Poore

Yep. Check out a quick project I've put together here[^]. [edit] Seems I can't add TextBlocks for rows and column headers either if I'm using it as an ItemsPanel. Makes sense, perhaps I need to do something with the ItemsPresenter? [/edit]

Ed Poore

Sorted it out, ;P Thanks to someone on the WPF forum @ MSDN (god I miss the CP forums compared to those). Basically everything I was doing was correct but didn't realise that the TextBlock / ItemTemplate is bound by a ListItem so you have to set the Grid.Row and Grid.Column from there. E.g.

Pete OHanlon

:doh: I should have realised that. Stoopid stoopid me.

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Ed Poore

Ah well we all learn something (me particularly). You can see a screenshot of the "finished" WpfCalendar[^] and the corresponding outlook[^] calendars.

My Blog[^]

Pete OHanlon

Very nice.

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Ed Poore

Why thank you, pretty chuffed so far considering my design skills are non-existant... Now trying to sort out some issues with saving it to a bitmap.

My Blog[^]