Comments on: Silverlight 2.0 In Examples: Part ? Drag and Drop Inside Out

By: Eduardo

Eduardo — Thu, 03 Sep 2009 14:02:02 +0000

Great man,
Thanks!

You are de first who used the events on the Grid “LayoutRoot”. I see many peoples who used the events on the objects and not maked the test on the function
” foreach (UIElement element in elements)
{

if (element is Ellipse)”

I was looking for this. I will make an example based on your’s post in my blog(Portuguese).

By: dykin's me2DAY

dykin's me2DAY — Mon, 11 May 2009 14:53:11 +0000

리거니의 생각…

Silverlight 2.0 In Examples: Part ? Drag and Drop Inside Out « Nick Polyak’s Software Blog(고급)…

By: npolyak

npolyak — Tue, 31 Mar 2009 06:26:25 +0000

Hi MavashiKid,
thanks for your remarks. I am a little out of date on my blog matters because I am working on a big Silverlight project.
Can you send an ftp or http url to download your code that does not work. I can try to figure out what is wrong.
Concerning the code update – I’ll try to post it within a week or two.

By: MawashiKid

MawashiKid — Sun, 29 Mar 2009 23:23:37 +0000

Hi,

I’ve tested your code, very interesting indeed…
I had to make some minor modifications in the code though.
As Rob Gibson said, the function HitTest is no longer supported by the Silverlight 2 RTM version (and the Silverlight 3 Beta also…)
so we have to use VisualTreeHelper class instead.

Example: In the SimpleDragAndDrop application the following line:

void LayoutRoot_MouseLeftButton(object sender, MouseButtonEventArgs e)
{
List element = (List)this.HitTest(e.GetPosition(null)); ….

will generate an error with Silverlight 2 RTM version
and should therefore be replace with:

void LayoutRoot_MouseLeftButton(object sender, MouseButtonEventArgs e)
{
IEnumerable elements = VisualTreeHelper.FindElementsInHostCoordinates(e.GetPosition(null), this);

in order to run properly.

I’ve also made the same type of modifications in the ListDragAndDrop application so that
the code no longer generates any errors during compilation. However when I run
the ListDragAndDrop application, the elements in the listbox “Box1″ just won’t respond to any behaviour… Strange…

I’m sure that any update of your code would be very much appreciated.
Thank you and keep on your ggod work.

By: npolyak

npolyak — Fri, 06 Mar 2009 04:05:08 +0000

Actually, re-reading your comment more carefully, apparently you are using the VSM to expand and shrink each item. VisualStateManager can be controlled programmatically.
Basically you can get the VisualStateGroups from the visual state manager and then states from the groups and then you can get a needed storyboard from the state. Then, you can probably run the story board whenever you need by using Begin method.
Examples of getting the visual states programmatically can be found at http://silverlight.net/forums/p/17802/60387.aspx.
Again I’ll be able to say more if I have the code.

By: npolyak

npolyak — Fri, 06 Mar 2009 03:43:01 +0000

Hey Jim,
apparently for some reason MouseLeave event does not fire. You can probably add the shrinking functionality to DoDrop function.
If you send me your code, I’ll be happy to try to figure it out.

By: Jim

Jim — Thu, 05 Mar 2009 21:58:45 +0000

Very nice job. Well commented and the article was very clear. Thanks, it taught me a lot. I’m new to Silverlight and did run into something I just can’t figure out. I’m using the GenericDragDropLib for copying items from one list box to others. I have a control template for my list items that basically makes the items magnify when the mouse moves over them (CommonStates MouseOver). When an item gets dragged the source (original) item does not shrink down when the mouse leaves with the dragging copy. It’s like the item does not change states when the mouse is no longer over the item. I have to run the mouse over it again after the drop and it restores.

Any ideas?

By: npolyak

npolyak — Mon, 05 Jan 2009 02:46:23 +0000

Sorry, i have not had time to update my blog recently.
Thanks for figuring it out!

By: Brian

Brian — Sun, 04 Jan 2009 21:03:46 +0000

I got the same error when attempting to initiate a drag operation. It’s because the the template was not being applied so your DragDropPopup was never being initialized (since OnApplyTemplate was never called) and that’s what leads to the null reference exception on the DragDropPopup.IsOpen line.

The solution is to move the generic.xaml file that’s contained in the GenericDragDropLib project into a new sub-folder called Themes as required by the final version of SL.

By: jocknuke

jocknuke — Mon, 29 Dec 2008 04:09:58 +0000

Failed at DragDropPopup.IsOpen while trying to click on the object. Object is null.