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I'm using MVVM in which WPF controls are data bound to propertied in a "ViewModel". This all works fine. One of our main controls is an XY chart and it can only be update via code because it requires looping and other logic. i.e it's not adaptable to data binding.
Since I cannot bind the chart to data, I was forced to add a method to the XAML code behind that knows how to update the chart. To further muddy the MVVM design pattern, I had to pass the View down to the ViewModel, so that the ViewModel could explicitly call the UpdateChart method that is in the View code behind.
Instead of binding between the ViewModel and UI control, I would like to bind between the ViewModel and a method in the code behind. Then the method in the code behind could go thru its complex logic to update the chart control.
Thanks for any suggestions. I appreciate the benfits of DataBinding and MVVM, but I can't make it work with my WinForms control that is embedded in a WindowsFormsHost control.
Mitch
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barker770 wrote: pass the View down to the ViewModel
why would you do that ? You could bind in the view to change notification and update whenever there is a change?
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ABitSmart wrote: why would you do that ? You could bind in the view to change notification and update whenever there is a change?
The view is bound to the view model, and I have implemented INotifyChange. This works for binding to WPF controls, but not for binding to my chart control that is in the WinFormsHost.
So the question remains, can I bind a method in my View to the ViewModel without explicitly passing the view object down to the viewModel object.
Mitch
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barker770 wrote: Since I cannot bind the chart to data, I was forced to add a method to the XAML code behind that knows how to update the chart. To further muddy the MVVM design pattern, I had to pass the View down to the ViewModel, so that the ViewModel could explicitly call the UpdateChart method that is in the View code behind.
Why is this method not part of the ViewModel? If it's updating data, then it has no place in the view - the view should only be a visual representation.
"WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
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> Why is this method not part of the ViewModel? If it's updating data,
> then it has no place in the view - the view should only be a visual
> representation.
Agreed. And the procedural code in the View.xaml.cs code is really just to help transfer the data into the winforms control.
Yes, I would prefer to bind a chart property directly to a method in the ViewModel, but I need this procedural code to be somewhere. And it makes sense to make it part of the View. Just as somewhere in the standard WPF binding code there is some procedural code that does the actual display of the data.
It would be perfect if I could bind a method in the View.xaml.cs to my ViewModel In effect, encapsulating the logic needed to bind to the chart control inside the View (albeit the code behind for the View.
Mitch
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If you just need to use the host because you have a none WPF chart, why not take a look at this[^]?
"WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
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A native chart is of course the best solution. However, we have a lot of expertise with this third party chart control (ChartFx) that it would be too costly in terms of time to abandon it now. We have several WinForms products and we have layered on many custom interactive chart features. We're starting a new product and want to use WPF for all but the chart.
ChartFx is developing a WPF native chart, but it may not have the same feature set nor does it's release schedule match ours.
Anyway, I did find the "PropertyMap" property of the WinFormsHost, but it only maps to properties of the winForms host class. Is there some way to add a new property? For example, I would map a new property named "DataSeries" to a method in the xaml.cs code. Then I would bind the "DataSeries" property to my ViewModel. Any tips on doing this?
Thanks,
Mitch
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I think I answered my own question. Since the ViewModel implemented INotifyChangedProperty I just added an event handler in the view's code behind to listen for each event from the viewModel. When it's the even I want, I update the winforms chart.
This pseudo binding still relies on both the View and ViewModel to agree on a property name. But that's the nature of binding anyway.
Mitch
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Congratulations. It's just a shame you've had to use the Interop Helpers; they are such a bind. Pun unintended.
"WPF has many lovers. It's a veritable porn star!" - Josh Smith As Braveheart once said, "You can take our freedom but you'll never take our Hobnobs!" - Martin Hughes.
My blog | My articles | MoXAML PowerToys | Onyx
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That was actually what I meant. I should have put in more details.
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Hello!
I have such task - to create control that union two controls (DataGrid from WPFToolkit and standard Toolbar). On a large scale, it doesn't matter what particular controls it unions, I need to find out the common practices that can be used to build what I need. At first glance, I need something like user control, i.e composition of controls, that I can implement as a whole and reuse then. But, my task requires me to have possibility to tune my composite control in XAML. So, if I compose Toolbar and DataGrid, I want properties and events of both them would be exposed. So I could set in XAML both, for example, columns of datagrid and bars of toolbar:
(I put spaces in tag names intentionally, because loacal parser didn't type them for some reason)
< MyDataGridToolBarControl ><br />
< DataGrid ><br />
< DataGrid.Columns ><br />
< DataGridTextColumn Header="firstColumn" ><br />
< /DataGridTextColumn ><br />
< DataGridTextColumn Header="secondColumn" /><br />
< /DataGrid.Columns ><br />
< /DataGrid ><br />
< ToolBar Background="{x:Null}" > <br />
<button tooltip="New"><br />
<image source="New.png" /><br />
</button><br />
<button tooltip="Save"><br />
<image source="Save.png" /><br />
</button><br />
<button tooltip="Delete"><br />
<image source="Delete.png" /><br />
</button> <br />
< /ToolBar ><br />
< /MyDataGridToolBarControl >
The only decison that suits me less or mor for now is to make custom control inherited from Datarid (as DataGrid is more significant in this pair) and redefine Template including both datagrid and toolbar. This gives me all power of datagrid but, if I want get Toolbar part, I need to do it through code, seeking it in viual and logical trees i.e. getting access o it programmatcally, which is not pretty decision.
Please help a newbie to solve this task ) Thanks in advance...
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You're obviously very new to this. Any property you add to your control, can be set from XAML.
Christian Graus
Driven to the arms of OSX by Vista.
"I am new to programming world. I have been learning c# for about past four weeks. I am quite acquainted with the fundamentals of c#. Now I have to work on a project which converts given flat files to XML using the XML serialization method" - SK64 ( but the forums have stuff like this posted every day )
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Thats it, I'd like not to transmit every property and event of each component control to the level of composite control. I'd like (if it is posible) to inherit all of them! But multiple inheritance in c# is not allowed, so I can't go this way! So, because of it I am here and your answer is inappropriate. If you are lazy to answer, it would be better not answer at all. Thanks
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Hi.
I'm working VS2008 SP1 and SilverLight 2.
My SL's Application has worked until 2 hours ago very well ,but Browsers just couldn't show it anymore.
BTW I change my project name manually 
What's wrong with it ?
How can I fix it ?
Would appreciate for any guides.
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If you changed the name of something, make sure the name is changed anywhere
in the code that's effected.
For example, if the name of the xap is now different, you may need to change
the reference to the xap in your hosting web page.
Mark
Mark Salsbery
Microsoft MVP - Visual C++
![Java | [Coffee]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/coffee.gif)
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I've done it, but it didn't work.
I forced to make a new Project.
Thanks anyway.
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Hello.
Is it possible to assign a command parameter to a canvas? Instead of using buttons we wish to use canvases for certain parts of the UI, but it needs to send a command parameter like a button. Can we do this?
Regards, E.
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You mean command bindings ? See here Link[^]
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Hello, exactly right 
One issue though is lack of backspace or enter key support. Can we trigger these commands via a canvas press?
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I might not be understanding your question correct. But wouldn't KeyBinding work ?
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Dear All,
I am a newbie to .Net Framework 3.5.
I am interested in creating a web application using WPF.
I have created a WPF Browse application.
I don't know how to have it in my Virtual directory.
Can any one help me in this regard?
Thanks a lot in advance
Best Regards,
M. J. Jaya Chitra
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You want to look in to silverlight, that's how you do WPF for the web.
Christian Graus
Driven to the arms of OSX by Vista.
"I am new to programming world. I have been learning c# for about past four weeks. I am quite acquainted with the fundamentals of c#. Now I have to work on a project which converts given flat files to XML using the XML serialization method" - SK64 ( but the forums have stuff like this posted every day )
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Has anybody used these and got them to work?
I just get: The attachable property 'VisualStateGroups' was not found in type 'VisualStateManager'.
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I did and came to the conclusion that I will get round to using themes when they are ready for non trivial apps.
Thanks.
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