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hi everybody!
I have a problem that I can't find a solution.
I made a project (vs2008 xp sp2) wpf browser aplication.
I need to use midi functions of winmm.dll but there is a problem with "System.Security.Permissions.SecurityPermission".
I made a simple project (code below) with a button where by pressing it the debug stops.
.....
using System.Runtime.InteropServices;
namespace WpfBrowserApplication1
{
public partial class Page1 : Page
{
[DllImport("winmm.dll")] public static extern int midiInGetNumDevs();
public Page1()
{
InitializeComponent();
}
private void button1_Click(object sender, RoutedEventArgs e)
{
int aa = midiInGetNumDevs();
}
}
}
What shall I do? Somebody can help me?
My final project is to realize a musical keyboard that should play music according to a partiture upon the web. (sorry for my english)
Many Thanks for your attention.
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Calling into native code probably isn't something that you can do in a WPF browser app since they normally run in a partial trust environment: WPF Partial Trust Security[^].
As far as your goal of a musical keyboard deployed to the web is concerned:
* look into the possibility of using Silverlight (Silverlight Audio and Video Overview[^]
* you could go with a regular WPF application and distribute it using ClickOnce (see what MediaElement can do for you here)
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Hi ,
i'm trying to understand how create role and save them in the database so doing i can add or delete the role for each user when i need ...i explain better my idea.
I created a form authentication(username,password) in Wpf to access to the application now i wish create roles and save on the database(with Linq ToSql) so doing i will assign roles(to deny or access to use buttons,Forms,Delete,Add,Edit etc.etc.) to user's for use the application but i don't know how procede with code to create roles and save it on database.
Do you have any idea to clarify my purpose and procede to work out this feature?
Have a happy day.
Bye
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Sorry ,
maybe my question is not clear i fell confuse about that.... 
If you have some link that can clarify my mind i'm happy for your support.
Have a nice day.
Bye
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In order to make this message go away on WCF method invoke,
"cannot be ISerializable and have DataContractAttribute attribute"
I commented out "Serializable" and ISerializable
<br />
[DataContract()]<br />
[GenericObjectAttribute(ObjectClassifier = "Person")]<br />
public class Person : IPerson
{<br />
...<br />
}
Does this means all DataContract must NOT be ISerilizable?
Thanks!
dev
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If you turn your DataContract into a NetDataContractSerializer, you can mark it as Serializable. However, the DataContract is serialized for you by WCF so you shouldn't need to manage this yourself.
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No problem. 
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Hi all,
I'm very new to WPF and so don't mind me asking very silly questions.
Well I'm creating this application where I have a window which hosts a "login" and a "loginCheck" usercontrol. Both usercontrols are not visible at the same time and have the same background but different foregrounds elements. When the user clicks the sign in button in the Login usercontrol I want the Login usercontrol to make a flip and show the loginCheck usercontrol where the authentication will happen and feedback the user about successful or unsuccessful login status and then if its unsuccessful then again flip to the login side, but if its successful I want it to fade away and get removed from the parent container(as in children.remove(login)).
Now my problem is I have created both login and logincheck usercontrols but how can I make the login to logincheck 3D flip happen after the user presses the "Sign In" button from the login usercontrol and also remove it after successful authentication.
Any help would be deeply appreciated.
Regards,
Soham Dasgupta
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Hi,
My problem is when i am trying to use the header value of existing treeviewitems.
Let me explain the situation.
1)I have a label .I want to give content to that lable.
2) I have treeview control with 1 parent and 3 childs.I am using context menu .
I am using this context menu for the above tree control. i have one menu item in the context menu.
3)So whenever i do mouserightclick on any node of treecontrol(without selecting node--simply mouserightclick on nodes) it will display menuitem of context menu.(selecting node also ok.but currently i am trying without selecting the node)
4)if i click the menuitem it will fire an event , in which i am assigning content to label
5) I want to assign the currentnode header value to label content
I am trying it through code.of course i don't know how it will be done in xaml also.
Still i am thinging whether it is possible or not?
If possible could anyone provide source code to overcome this probelm as soon as possible
Thanks in Advance
Rama Krishna Makkena
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From what I could understand, in the context menu items click event you want to set a controls property ??
If yes, I found this on msdn [^]
Karl Shifflet has given the following suggestion, "Have you tried databinding a specific value to the menuitem? You can stick a value in the Tag property, or you can add a property to the MenuItem in a derived class."
You might need to handle OnContextMenuOpening Example[^]
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Hello everyone,
I have canvas that contains several controls representing network nodes. There are several types of nodes. After selecting one node I need to display property page for it. Each node type has its own customize property page. For example there are nodes that can be accessed via RS232 or TCP/IP or WLAN. Property page should allow to change connection setting and display statistical info about selected connection.
I would like know whats the WPF way of doing such a thing, what would be the 'cleanest' solution?
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A really neat way of dealing with this would be to create your property page in the Adorner layer. You can do some amazing things with this type of effect.
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Hi again!
I need your help again, this time to paint an Oszillograph.
That's what I have so far:
void DrawSpectrum(float[] TraceData, int LeftBwPoint, int RightBwPoint)
{
System.Windows.Point[] PointsCurve = new System.Windows.Point[TraceData.Length];
float maxValue = -5000;
float minValue = 5000;
int curveCount = 0;
for (int i = 0; i < TraceData.Length; i++)
{
if (TraceData[i] > maxValue)
{
maxValue = TraceData[i];
}
if (TraceData[i] < minValue)
{
minValue = TraceData[i];
}
PointsCurve[i].X = i;
PointsCurve[i].Y = (int)TraceData[i];
}
PointCollection pointcoll = new PointCollection();
for (int i = 0; i < TraceData.Length; i = i + TraceData.Length / 20)
{
pointcoll.Add(PointsCurve[i]);
}
DrawPictureSpectrum(pointcoll);
}
Values I get are for example:
{0;-54 25;-53 50;-50 75;-50 100;-49 125;-48 150;-48 175;-48 200;-48 225;-48 250;-48 275;-48 300;-48 325;-48 350;-48 375;-48 400;-49 425;-49 450;-50 475;-52 500;-54}
That's ok, but how can I paint / present this? (minus values!)
I did this once for Windows Forms by creating a Bitmap, painting on it and passing it to a picturebox - unfortunately it seems these techniques won't work in wpf.
Help would be really apreciated, I close to throw out my notebook out of the window 
no serious, please help me with this.
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If you have the option to use the latest .NET 3.5, then check out WriteableBitmap[^] for an efficient way to plot points. This doc has an example inline.
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Thanks for the tip, but I'm not sure if this is really "efficient". Especially the unsafe part is a bit weird for something as full managed as wpf.
What would be a better idea, or better - what would be a typical wpf approach to present data like this (and keep in mind it's being updated a few times every second).
Should I draw directly on a control (and if so how to deal with the negative values)?
If I should draw on a control, how can I do it and how can I get rid of the outdated data without producing memory leaks?
I know I'm asking for much, but I'm really stuck with this.
Nethertheless, thank you very much gurge60 for your help
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Any direct writing to memory like that will be unsafe, but it's
also very efficient.
If you can't use unsafe code then you will sacrifice efficiency.
For example, you could use Marshal.Copy() to copy bits into and out of a
WriteableBitmap's backbuffer, but it will be less efficient.
You could also wrap a WriteableBitmap's backbuffer in a System.Drawing.Bitmap
(GDI+) and use System.Drawing.Graphics methods to draw on the bitmap, which
could even be less efficient.
Mark
Mark Salsbery
Microsoft MVP - Visual C++
![Java | [Coffee]](https://codeproject.global.ssl.fastly.net/script/Forums/Images/coffee.gif)
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Hi,
I am trying to create a WPF application using MVP pattern. The user of the application should be able to create customers and edit customer information. The data is stored in the SQL database at the backend.
Can any one help me by providing information regarding MVP pattern and how we can implement the same with WPF application.
Thanks in advance.
Best regards,
Sarvani
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Rather than use the MVP pattern directly, there's a variation called MVVM. Josh Smith has recently had an article published in MSDN magazine[^] on how to do MVVM in WPF - it's a must read.
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I am using a GridView inside the WPF ListView control. On display of data I perform some validations and change color of some cells in each row accordingly. The problem is that there can be thousands of such rows in the ListView (bound to an observable collection)which leads to high CPU utilization.
Is there a way that i can update only the visible rows in the listview. And as I scroll the listview down the next set of rows start getting updated.. This way the CPU utilization would be kept in check inspite of thousands of rows being updated in the observable collection..
Any help is appreciated.
Thanks.
Pankaj Chamria,
Software Programmer.
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I would use a VirtualizingStackPanel on the listview. This is an attached property, that is used like this:
<ListBox VirtualizingStackPanel.IsVirtualizing = "True" ItemsSource="{Binding MySource}" ItemsTemplate="{Binding MyTemplate}" /<
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Thanks for the reply. I tried your suggestion as shown below for my ListView for which the ItemsSource get assigned to an observable collection from code-behind. However it did not show any performance enhancement.. Can you check and see whether i am missing something.
Also important to note is that the datasource is getting updated continuosly using a live data stream. And i am trying to reflect those changes in the ListView.
<StackPanel Orientation="Vertical" x:Name="pnlMain">
<ListView VirtualizingStackPanel.IsVirtualizing="True" x:Name="gridControl1" VerticalAlignment="Stretch" HorizontalAlignment="Stretch"
Width="Auto" Height="Auto" ScrollViewer.CanContentScroll="False"
IsSynchronizedWithCurrentItem="True" ScrollViewer.HorizontalScrollBarVisibility="Auto"
ScrollViewer.VerticalScrollBarVisibility="Auto"
GridViewColumnHeader.Click="GridViewColumnHeaderClickedHandler"
local:ItemsControlBehavior.AlternateItemContainerStyle="{DynamicResource alternateItemStyle}">
<ListView.View>
<GridView x:Name="view" ColumnHeaderContainerStyle="{DynamicResource MyHeaderStyle}">
</GridView>
</ListView.View>
<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<Setter Property="HorizontalContentAlignment" Value="Stretch" />
</Style>
</ListView.ItemContainerStyle>
</ListView>
</StackPanel>
Thanks!
Pankaj Chamria,
Software Programmer.
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Is it your list that's being heavily hit? My suspicion here is that the ObservableCollection is actually the cause of your problem. Every time you add an item, it fires off the change notification, which results in the list being updated. To minimize the number of times it needs to update, I would consider adding the data in to the collection in reasonably large batches.
I use a custom observable collection[^] to allow me to add large amounts of data.
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My problem is that once the data gets loaded in the observable collection for the first time, the values of properties of the objects in the collection are continuosly getting changed to the tune of 500-600 objects per second and each object has about 18 properties which get updated. The object itself is not getting overwritten/ added/ deleted. Its properties are just being modified. Also i observe that the Collection Change and Property Change events do not get called for such updates. It gets called only when the collection is first being created.
With virtualization i was hoping that although 500 objects may get updated evry sec but the UI changes will be generated only for the visible objects. But that is not the case with my usage of observable collection.
I guess due such large no of updates every second the UI sort of hangs, and CPU utilization goes 80-90%.
Any suggestions what can i try further?
Thanks!
Pankaj Chamria,
Software Programmer.
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