[IronPython] Databinding a color in the datagrid in Silverlight

Michael Foord fuzzyman at voidspace.org.uk
Mon Feb 8 21:20:32 CET 2010


Hello all,

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

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

-- 
http://www.ironpythoninaction.com/
http://www.voidspace.org.uk/blog

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-- 
http://www.ironpythoninaction.com/
http://www.voidspace.org.uk/blog

READ CAREFULLY. By accepting and reading this email you agree, on behalf of your employer, to release me from all obligations and waivers arising from any and all NON-NEGOTIATED agreements, licenses, terms-of-service, shrinkwrap, clickwrap, browsewrap, confidentiality, non-disclosure, non-compete and acceptable use policies ("BOGUS AGREEMENTS") that I have entered into with your employer, its partners, licensors, agents and assigns, in perpetuity, without prejudice to my ongoing rights and privileges. You further represent that you have the authority to release me from any BOGUS AGREEMENTS on behalf of your employer.


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