[IronPython] Databinding a color in the datagrid in Silverlight

[Dino Viehland]

On the IValueConverter side of things: I haven't debugged through this but I have a guess as to what could be going on.  When we emit a type via reflection I don't believe it's available via Type.GetType - which is the way types usually get loaded by name.  If you attach a debugger I think you'd probably see an exception when trying to load the type.

The usual solution for this would be to combine pre-compiled subtypes and then save the generated type to disk and re-load it.  You need the pre-compiled subtypes because you can't reference a transient assembly (which our in-memory subtypes are) from a non-transient one.  But that's not going to be immediately viable in Silverlight because the pre-compiled type will be a desktop CLR type.  So you could use pre-compiled types on the desktop and try to re-write the generated assembly but it seems like that's never worked for anyone in the past.

I have no clue on the PARSER_BAD_PROPERTY_VALUE error.

From: users-bounces at lists.ironpython.com [mailto:users-bounces at lists.ironpython.com] On Behalf Of Michael Foord
Sent: Monday, February 08, 2010 12:21 PM
To: Discussion of IronPython
Subject: [IronPython] Databinding a color in the datagrid in Silverlight

Hello all,

We've been successfully using clrtype with IronPython 2.6 and Silverlight for databinding, based on the example provided by Lukáš:

    http://gui-at.blogspot.com/2009/11/inotifypropertychanged-and-databinding.html

We create the binding when we create the datagrid columns programatically.

Today I've been trying (and failing) to get a column in the grid show different colors based on databinding.

I've got the colored bubble *showing* in the grid, but can't get databinding to the color to work.  First the basics.

This is the xaml for the bubble with a fixed color:

<DataTemplate xmlns='http://schemas.microsoft.com/client/2007'
 xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
    <Ellipse Stroke="#FF222222" Height="15" Width="15">
        <Ellipse.Fill>
           <LinearGradientBrush EndPoint="0.5,1" StartPoint="0.5,0">
              <GradientStop x:Name="bubbleColor" Offset="0.694"
               Color="#FF00FF40" />
              <GradientStop Color="#FFE6E6E6"/>
           </LinearGradientBrush>
        </Ellipse.Fill>
    </Ellipse>
</DataTemplate>

I can add a column based on this template very simply:

        from com_modules.loadxaml import loadXaml
        from System.Windows.Controls import DataGridTemplateColumn
        column = DataGridTemplateColumn()
        column.CellTemplate = loadXaml('templatecolumn')
        column.Header = 'Bubble'

        grid.Columns.Add(column)

If I try to naively specify a binding in the xaml then I get a PARSER_BAD_PROPERTY_VALUE when I attempt to load the xaml (so no hope of setting up the binding after load):

    <GradientStop x:Name="bubbleColor" Offset="0.694" Color="{Binding color}" />


One approach I tried was to create a ValueConverter. Here is the skeleton of the class I created:

from System import Type
from System.Globalization import CultureInfo
from System.Windows.Data import IValueConverter

class ColorConverter(IValueConverter):
    _clrnamespace = "Converters"
    __metaclass__ = clrtype.ClrClass

    @clrtype.accepts(object, Type, object, CultureInfo)
    @clrtype.returns(object)
    def Convert(self, value, targetType, parameter, culture):
        pass

    @clrtype.accepts(object, Type, object, CultureInfo)
    @clrtype.returns(object)
    def ConvertBack(self, value, targetType, parameter, culture):
        pass

As there is a _clrnamespace specified I thought I might then be able to use this converter in xaml. Trying to reference the ColorConverter class in the Converters namespace in a resources dictionary again causes blow ups when loading the xaml.

Setting this up programatically would be ideal. Anyone got any ideas?

All the best,

Michael



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http://www.ironpythoninaction.com/

http://www.voidspace.org.uk/blog



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--

http://www.ironpythoninaction.com/

http://www.voidspace.org.uk/blog



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