I have started a a new project (to refactor some code), and just can't work out why I keep getting "Can't find page /Index" error. The code works fine until I use an add method (on any collection type). So I don't think there is a problem with the navigation, but an issue with my IndexViewModel class.
public partial class Index : Page
{
private IndexViewModel _vm;
public Index()
{
InitializeComponent();
_vm = new IndexViewModel();
...
public class IndexViewModel //: ViewModelBase
{
public SortableCollectionView Rows {get;set;}
public IndexViewModel()
{
// generate some dummy data
Random rand = new Random();
for (int i = 0; i < 200; i++)
{
Row row = new Row();
row["stuff"] = s_names[rand.Next(s_names.Length)];
**Rows.Add(row);**
}
}
Looks like you never new up your Rows variable.
Rows = new SortableCollectionView();
To get to the actual error you can use this trick copied from my answer on another question:
To see what the issue is you need to make one change to your MainPage.xaml.cs:
// If an error occurs during navigation, show an error window
private void ContentFrame_NavigationFailed(object sender, NavigationFailedEventArgs e)
{
Exception ex = e.Exception;
while (ex.InnerException != null)
{
ex = ex.InnerException;
}
e.Handled = true;
ChildWindow errorWin = new ErrorWindow(ex);
errorWin.Show();
}
Once you've made that change when you start the application you should see the exception instead of the page where the exception occurred.
You need
Rows = new SortableCollectionView();
somewhere in your code.
Related
I have a Setting.cs file containing the info
[Serializable]
public class Setting
{
public Setting() {}
public String defaultAlertTone = Path.GetDirectoryName(Application.ExecutablePath) + "\\Sounds\\applause-2.wav";
}
and my settingsForm retrieving the info through this code
Setting settingObject;
public SoundPlayer player;
public settingsForm(backgroundForm backgroundFormObject)
{
InitializeComponent();
this.backgroundFormObject = backgroundFormObject;
settingObject = backgroundFormObject.getSetting();
}
private void InitializeSound()
{
// Create an instance of the SoundPlayer class.
player = new SoundPlayer();
player.SoundLocation = settingObject.defaultAlertTone;
// Listen for the LoadCompleted event.
player.LoadCompleted += new AsyncCompletedEventHandler(player_LoadCompleted);
// Listen for the SoundLocationChanged event.
player.SoundLocationChanged += new EventHandler(player_LocationChanged);
}
Why is it that every time I run the app, there would be a null reference exception on the
player.SoundLocation = settingObject.defaultAlertTone;
the backgroundFormObject.getSetting(); is just a method to retrieve the setting object. the code for it are as follows
Setting settingObj = new Setting();
public Setting getSetting()
{
return settingObj;
}
The reasons could be
InitializeSound() is somehow running before settingsForm (not likely, but this would make the settingObject not initialized and refer to null).
If this is the complete code for Setting class, i don't see how calling new Setting() anywhere would make a difference. So use Setting settingObject = new Setting(); when you first define this property in the settingsForm class.
It is not the settingObject which is null.
I have a issue in our application where the memory is not released when the user controls
are unloaded. This will increase the memory starting from 40MB and ends up with 200MB and more.
To simulate this,
I created a wpf project which has the main window and a user control
loaded 1000 objects into a wpf datagrid which is placed in a user control
A scroll viewer is put in the main window
The user control is loaded inside this scroll viewer Once the show button is clicked
The user control is removed from the Content of the Scroll viwer once the Close button is clicked
Once i checked with the task manager, before the 1000 objects are loaded to the grid, the memory consumption is 14MB. Once its loaded by clicking on the show button it increases to 70MB. But when i click on Close button to remove the user control from the window, the memory reduces to 67MB only. Shouldn't it reduce to 14BMB or something close to that??
When i checked this with the ANTS memory profiler, it shows that the 1000 objects remain in memory even after the User control is removed from the Window. Shouldn't the garbage collector release these objects when the user control is removed from the window (once the Scroll viewer Content Property is set to null)?
Following is the Code i used for this. I didn't use any styles, data templates or any third party controls, only used the WPF DataGrid control to load the data.
The User Control Code Behind
public partial class UserControl1 : UserControl,IDisposable
{
List<TestClass> list = null;
public UserControl1()
{
InitializeComponent();
}
public void Dispose()
{
BindingOperations.ClearBinding(dgList, DataGrid.ItemsSourceProperty);
list.Clear();
GC.Collect();
}
private void UserControl_Loaded(object sender, RoutedEventArgs e)
{
list = new List<TestClass>();
for (int i = 0; i < 1000; i++)
{
TestClass obj = new TestClass();
obj.Name = "test name";
obj.Age = 34;
list.Add(obj);
}
dgList.ItemsSource = list;
}
}
public class TestClass
{
public string Name { get; set; }
public int Age { get; set; }
}
Main Window Code behind
public partial class MainWindow : Window
{
UserControl1 control = null;
public MainWindow()
{
InitializeComponent();
}
private void btnClose_Click(object sender, RoutedEventArgs e)
{
control.Dispose();
scwContent.Content = null;
control = null;
}
private void btnShow_Click(object sender, RoutedEventArgs e)
{
control = new UserControl1();
scwContent.Content = control;
}
}
Thanks.
The Garbage collector only collects when memory is needed, not when references are set to null.
(Only exception: calling GC.Collect())
Why are you trying to call GC? That is not required
Change
for (int i = 0; i < 1000; i++)
{
TestClass obj = new TestClass();
...
To
TestClass obj;
for (int i = 0; i < 1000; i++)
{
obj = new TestClass();
...
You can set the list object to null ..
Read this for understanding setting objects to null
Setting an object to null vs Dispose()
So I'm trying out a concept tool of mine where I need to be able to read and write data from a database real easy. I've set up the form as I like and spread around different text boxes and dropdownboxes to read the data from the database. And I've got it all to work and all, but there's a small bug I don't fully understand why's there. Some textboxes don't update the text from the database. But it seems as it only occurs if the data in the database is nothing. So the value from the last row is still hanging in the textbox and thus, clicking "Update" actually updates the value from the field from the last row, into the new row. Messing everything up.
Now, what I'm the most interested in is the shear flow of the code. What's the best way of laying out the code to do all this? So far I've got this:
This is the code when clicking on a cell in the datagridview:
Private Sub DataGridView_CellClick(ByVal sender As System.Object, ByVal e As System.Windows.Forms.DataGridViewCellEventArgs) Handles DataGridView.CellClick
On Error Resume Next
selectedName = Me.DataGridView.CurrentRow.Cells(0).Value
selectedGenre = Me.DataGridView.CurrentRow.Cells(1).Value
selectedRhytm = Me.DataGridView.CurrentRow.Cells(2).Value
selectedLength = Me.DataGridView.CurrentRow.Cells(3).Value
selectedFinished = Me.DataGridView.CurrentRow.Cells(4).Value
selectedSoundFile = Me.DataGridView.CurrentRow.Cells(5).Value
txtBoxName.Text = selectedName
txtBoxGenre.Text = selectedGenre
txtBoxRhytm.Text = selectedRhytm
txtBoxLength.Text = selectedLength
txtBoxFinished.Text = selectedFinished
txtBoxSoundFile.Text = selectedSoundFile
End Sub
The "selected"-variables are all declared in a GlobalCode.vb I've got where I create all of them for use later. They are defined like this:
Friend Module GlobalVariables
Friend selectedName As String = Nothing
Friend selectedGenre As String = Nothing
Friend selectedRhytm As String = Nothing
Friend selectedLength As String = Nothing
Friend selectedFinished As String = Nothing
Friend selectedSoundFile As String = Nothing
End Module
I haven't really done anything like this before. I'm more of a designer rather than programmer, but I really need to try out a concept so I'm not sure this is the way of doing this at all. I've found that it works, most of the times. But I reckon skilled programmers have a way of designing the layout of the code so it's efficient, clean and easy to read.
So how does this look?
(I can't see anything database related in the question, btw)
Perhaps the best way of laying out this code is... not to. Don't write code for things that the standard data-binding frameworks can handle. For example (sorry it is C#, but it should translate - all of the "good" bits here are provided by the .NET framework, not the language); some UI code - note no code to copy values:
static class Program {
[STAThread]
static void Main() {
Application.EnableVisualStyles();
// some sample data
BindingList<Track> tracks = new BindingList<Track>();
tracks.Add(new Track { Name = "foo", Genre = "Rock", Rhythm = "insane", Length = 180 });
tracks.Add(new Track { Name = "bar", Genre = "Classic", Rhythm = "sedate", Length = 240 });
// show the data on a form
using (Form form = new Form {
Controls = {
new DataGridView { DataSource = tracks, Dock = DockStyle.Fill },
new TextBox { DataBindings = {{"Text", tracks, "Name"}}, Dock = DockStyle.Bottom},
new TextBox { DataBindings = {{"Text", tracks, "Genre"}}, Dock = DockStyle.Bottom},
new TextBox { DataBindings = {{"Text", tracks, "Rhythm"}}, Dock = DockStyle.Bottom},
new TextBox { DataBindings = {{"Text", tracks, "Length"}}, Dock = DockStyle.Bottom},
}
}) {
Application.Run(form);
}
}
}
With supporting data entity:
class Track : INotifyPropertyChanged {
private string name, genre, rhythm;
private int length;
public event PropertyChangedEventHandler PropertyChanged;
private void SetField<T>(ref T field, T value, string propertyName) {
if (!EqualityComparer<T>.Default.Equals(field, value)) {
field = value;
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
}
}
public string Name { get { return name; } set { SetField(ref name, value, "Name"); } }
public string Genre { get { return genre; } set { SetField(ref genre, value, "Genre"); } }
public string Rhythm { get { return rhythm; } set { SetField(ref rhythm, value, "Rhythm"); } }
public int Length { get { return length; } set { SetField(ref length, value, "Length"); } }
}
Try commenting out On Error Resume Next for a bit and seeing what happens. I've managed to confuse myself more times than I can count with that statement.
EDIT
I just realized this is VB.Net. You shouldn't ever be using On Error Resume Next in this case. Use Try Catch structures.
I'm trying to drag data from the Winforms portion of my application on a WPF controls that's contained inside an "ElementHost". And it crashes when I try doing so.
Trying the same thing but from Winforms to Winforms works fine. (See example code below)
I need help on making this work... have any clues what I'm doing wrong?
Thanks!
Example:
In the sample code below, I'm just trying to drag a custom MyContainerClass object created when initating the drag on the label control on a 1) System.Windows.Forms.TextBox (Winforms) and 2) System.Windows.TextBox (WPF, added to an ElementHost).
Case 1) works fine but case 2) is crashing when trying to retrieve the drop data using GetData(). GetDataPresent("WindowsFormsApplication1.MyContainerClass") returns "true" so In theory, I should be able to retrive my drop data of that type like in Winforms.
Here is the stack trace of the crash:
"Error HRESULT E_FAIL has been returned from a call to a COM component" with the following stack trace:
at System.Runtime.InteropServices.Marshal.ThrowExceptionForHRInternal(Int32 errorCode, IntPtr errorInfo)
at System.Windows.Forms.DataObject.GetDataIntoOleStructs(FORMATETC& formatetc, STGMEDIUM& medium)
at System.Windows.Forms.DataObject.System.Runtime.InteropServices.ComTypes.IDataObject.GetDataHere(FORMATETC& formatetc, STGMEDIUM& medium)
at System.Windows.Forms.DataObject.System.Runtime.InteropServices.ComTypes.IDataObject.GetData(FORMATETC& formatetc, STGMEDIUM& medium)
at System.Windows.DataObject.OleConverter.GetDataInner(FORMATETC& formatetc, STGMEDIUM& medium)
at System.Windows.DataObject.OleConverter.GetDataFromOleHGLOBAL(String format, DVASPECT aspect, Int32 index)
at System.Windows.DataObject.OleConverter.GetDataFromBoundOleDataObject(String format, DVASPECT aspect, Int32 index)
at System.Windows.DataObject.OleConverter.GetData(String format, Boolean autoConvert, DVASPECT aspect, Int32 index)
at System.Windows.DataObject.OleConverter.GetData(String format, Boolean autoConvert)
at System.Windows.DataObject.GetData(String format, Boolean autoConvert)
at System.Windows.DataObject.GetData(String format)
at WindowsFormsApplication1.Form1.textBox_PreviewDragEnter(Object sender, DragEventArgs e) in WindowsFormsApplication1\WindowsFormsApplication1\Form1.cs:line 48
Here is some code:
// -- Add an ElementHost to your form --
// -- Add a label to your form --
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
System.Windows.Controls.TextBox textBox = new System.Windows.Controls.TextBox();
textBox.Text = "WPF TextBox";
textBox.AllowDrop = true;
elementHost2.Child = textBox;
textBox.PreviewDragEnter += new System.Windows.DragEventHandler(textBox_PreviewDragEnter);
System.Windows.Forms.TextBox wfTextBox = new System.Windows.Forms.TextBox();
wfTextBox.Text = "Winforms TextBox";
wfTextBox.AllowDrop = true;
wfTextBox.DragEnter += new DragEventHandler(wfTextBox_DragEnter);
Controls.Add(wfTextBox);
}
void wfTextBox_DragEnter(object sender, DragEventArgs e)
{
bool dataPresent = e.Data.GetDataPresent("WindowsFormsApplication1.MyContainerClass");
// NO CRASH here!
object data = e.Data.GetData("WindowsFormsApplication1.MyContainerClass");
}
void textBox_PreviewDragEnter(object sender, System.Windows.DragEventArgs e)
{
bool dataPresent = e.Data.GetDataPresent("WindowsFormsApplication1.MyContainerClass");
// Crash appens here!!
// {"Error HRESULT E_FAIL has been returned from a call to a COM component."}
object data = e.Data.GetData("WindowsFormsApplication1.MyContainerClass");
}
private void label1_MouseDown(object sender, MouseEventArgs e)
{
label1.DoDragDrop(new MyContainerClass(label1.Text), DragDropEffects.Copy);
}
}
public class MyContainerClass
{
public object Data { get; set; }
public MyContainerClass(object data)
{
Data = data;
}
}
#Pedery & jmayor: Thanks for the suggestions guys! (see my findings below)
After quite a few experimentation, trials and errors, and a bit of "Reflector'ing", I managed to figure out exactly why I was receiving the cryptic error message "Error HRESULT E_FAIL has been returned from a call to a COM component".
It was due to the fact that when dragging data WPF <-> Winforms in a same app, that data has to be Serializable!
I've checked how difficult it would be to transform all of our classes to "Serializable" and I would have a been a real pain for a couple of reasons... one, we would need to practically make all of classes serializable and two, some of these classes have references to Controls! And Controls aren't serializable. So a major refactoring would have been needed.
So... since we wanted to pass any object of any class to drag from/to WPF inside the same application, I decided to create a wrapper class, with the Serializable attribute and implementing ISerializable. I would have 1 contructor with 1 parameter of type "object" which would be the actual drag data. That wrapper, when serializing/de-serializing, would serialize not the object itself... but rather the IntPtr to the object (which we can do since we only want that functionnality inside our 1 instance only application.) See code sample below:
[Serializable]
public class DataContainer : ISerializable
{
public object Data { get; set; }
public DataContainer(object data)
{
Data = data;
}
// Deserialization constructor
protected DataContainer(SerializationInfo info, StreamingContext context)
{
IntPtr address = (IntPtr)info.GetValue("dataAddress", typeof(IntPtr));
GCHandle handle = GCHandle.FromIntPtr(address);
Data = handle.Target;
handle.Free();
}
#region ISerializable Members
public void GetObjectData(SerializationInfo info, StreamingContext context)
{
GCHandle handle = GCHandle.Alloc(Data);
IntPtr address = GCHandle.ToIntPtr(handle);
info.AddValue("dataAddress", address);
}
#endregion
}
To keep the IDataObject functionnality, I created the following DataObject wrapper:
public class DataObject : IDataObject
{
System.Collections.Hashtable _Data = new System.Collections.Hashtable();
public DataObject() { }
public DataObject(object data)
{
SetData(data);
}
public DataObject(string format, object data)
{
SetData(format, data);
}
#region IDataObject Members
public object GetData(Type format)
{
return _Data[format.FullName];
}
public bool GetDataPresent(Type format)
{
return _Data.ContainsKey(format.FullName);
}
public string[] GetFormats()
{
string[] strArray = new string[_Data.Keys.Count];
_Data.Keys.CopyTo(strArray, 0);
return strArray;
}
public string[] GetFormats(bool autoConvert)
{
return GetFormats();
}
private void SetData(object data, string format)
{
object obj = new DataContainer(data);
if (string.IsNullOrEmpty(format))
{
// Create a dummy DataObject object to retrieve all possible formats.
// Ex.: For a System.String type, GetFormats returns 3 formats:
// "System.String", "UnicodeText" and "Text"
System.Windows.Forms.DataObject dataObject = new System.Windows.Forms.DataObject(data);
foreach (string fmt in dataObject.GetFormats())
{
_Data[fmt] = obj;
}
}
else
{
_Data[format] = obj;
}
}
public void SetData(object data)
{
SetData(data, null);
}
#endregion
}
And we are using the above classes like this:
myControl.DoDragDrop(new MyNamespace.DataObject(myNonSerializableObject));
// in the drop event for example
e.Data.GetData(typeof(myNonSerializableClass));
I know I know... it's not very pretty... but it's doing what we wanted. We also created a dragdrop helper class which masks the DataObject creation and has templated GetData functions to retrieve the data without any cast... a bit like:
myNonSerializableClass newObj = DragDropHelper.GetData<myNonSerializableClass>(e.Data);
So thanks again for the replies! You guys gave me good ideas where to look at for possible solutions!
-Oli
I had a "similar" issue some time ago so I can at least tell you what I found out.
It seems .Net is resorting to OLE remoting when drag/drop operations are performed in but the simplest of cases. For some reason GetDataPresent will in these cases be successful and GetData will fail. This is furthermore mystified by the fact that there are several versions of the IDataObject in the .Net framework.
Windows Forms defaults to System.Windows.Forms.IDataObject. However, in your case you could try to give System.Runtime.InteropServices.ComTypes.IDataObject a shot instead. You can also check out my discussion here.
Hope this helps.
Seems wonderfull at first sight. I tried it but got some errors on implementations.
I began to correct some errors when I decided to look for something a little bit more simplier, that do not have pointers (humm I don't like that, particularly with carbage collection, but I have no idea if it could have real impact) and that do not use Interop.
I come up with that. It works for me and I hope it will work for anybody else. It is only intended to be used for local drag drop (inside the same app).
How to use to drag:
DragDrop.DoDragDrop(listBoxOfAvailableScopes, new DragDropLocal(GetSelectedSimulResultScopes()),
DragDropEffects.Copy);
How to use to drop (get):
DragDropLocal dragDropLocal = (DragDropLocal)e.Data.GetData(typeof(DragDropLocal));
SimulResultScopes simulResultScopes = (SimulResultScopes)dragDropLocal.GetObject();
Code:
namespace Util
{
[Serializable]
public class DragDropLocal
{
private static readonly Dictionary<Guid, object> _dictOfDragDropLocalKeyToDragDropSource = new Dictionary<Guid, object>();
private Guid _guid = Guid.NewGuid();
public DragDropLocal(object objToDrag)
{
_dictOfDragDropLocalKeyToDragDropSource.Add(_guid, objToDrag);
}
public object GetObject()
{
object obj;
_dictOfDragDropLocalKeyToDragDropSource.TryGetValue(_guid, out obj);
return obj;
}
~DragDropLocal()
{
_dictOfDragDropLocalKeyToDragDropSource.Remove(_guid);
}
}
}
Maybe the events are in the opposite way. The PreviewDragEnter should be related with the WPFTextBox. Also watch out the DragEventArgs class. There is one in System.Windows.Form ( Windows Form version) and the one under System.Windows( for WPF version).
I am using the code below to save and restore the window position and size upon restart.
I am observing an upward drift of 28 pixels everytime I execute this code!
Am I reading the wrong values, or am I restoring them incorrectly? Where is the number 28 (size of the chrome?) coming from (and how would I account for it programmatically, rather than a fixed number in code)?
Here is my code:
public partial class MainStudioWindowControl : RibbonWindow
{
public MainStudioWindowControl()
{
App.MainWindowOwner = this;
this.Loaded += new System.Windows.RoutedEventHandler(MainStudioWindowControl_Loaded);
}
void MainStudioWindowControl_Loaded(object sender, System.Windows.RoutedEventArgs e)
{
System.Windows.Window mainWindow = System.Windows.Application.Current.MainWindow;
mainWindow.WindowStartupLocation = System.Windows.WindowStartupLocation.Manual;
if (Studio.Properties.Settings.Default.Width > 0)
{
mainWindow.Left = Studio.Properties.Settings.Default.Left;
mainWindow.Top = Studio.Properties.Settings.Default.Top;
mainWindow.Width = Studio.Properties.Settings.Default.Width;
mainWindow.Height = Studio.Properties.Settings.Default.Height;
}
Debug.WriteLine(string.Format("Loading: Top = {0}", this.Top));
}
protected override void OnClosing(System.ComponentModel.CancelEventArgs e)
{
base.OnClosing(e);
System.Windows.Window mainWindow = System.Windows.Application.Current.MainWindow;
Studio.Properties.Settings.Default.Left = mainWindow.Left;
Studio.Properties.Settings.Default.Top = mainWindow.Top;
Studio.Properties.Settings.Default.Width = mainWindow.Width;
Studio.Properties.Settings.Default.Height = mainWindow.Height;
Studio.Properties.Settings.Default.Save();
Debug.WriteLine(string.Format("Saving: Settings.Top = {0}", Studio.Properties.Settings.Default.Top));
}
}
Try this:
1) Derive your class from the normal Window, not the RibbonWindow - if that fixes it, it's a RibbonWindow issue.
2) Use hard-coded values to set the measurments in the Loaded handler - if that fixes it, the problem's got something to do with the settings.
With these two changes, it worked fine for me. The window appeared where it should every time.