I've a method that when called returns a LinearGradientBrush with random color for the GradientStop and I use on them mylabel.RegisterName for later use in a storyboard animation.
To prevent the error on first call where no registered name are present I do this:
try
{
myLabel.UnregisterName("GS1");
myLabel.UnregisterName("GS2");
myLabel.UnregisterName("GS3");
myLabel.UnregisterName("GS4");
}
catch
{
}
I have not found a way to overwrite registered name. There's a better way to do this?
What about UnregisterName?
(That's what I get for attempting to answer when I can only read part of the question...)
Digging around a bit more, may have found another (WAY simpler) alternative:
var isGs1Defined = NameScope.GetNameScope(myLabel).FindName("GS1") == null;
or packaged up nicely:
public static bool IsNameRegistered(DependencyObject depObject, string name)
{
var namescope = NameScope.GetNameScope(depObject);
if(namescope == null)
return false;
return namescope.FindName(name) != null;
}
Related
I am making a 3D Game with WPF in VB, and I am using a ScrennSpaceLines3D Object I found
http://3dtools.codeplex.com/releases/view/2058
but when I try to remove a line I added to the viewport by using
mainViewport.Children.RemoveAt(i)
it gives a NullExceptionError. I have read that this is because it does not totally come off the rendering queue. There have been fixes for c#, but I have yet to find one that works with VB. Is there a way to make this work or possibly draw a line in 3D space some other way? I find it quite ridiculous that VB doesn't even have a way to easily draw 3D lines...
Remove ScreenSpaceLines3D :
foreach (ScreenSpaceLines3D line3D in lines3DList)
{
lines3D.Points.Clear(); // Very importante
_viewport3D.Children.Remove(lines3D);
}
I'm a bit late to the party but i'm having the same issues.
The access violation occurs because each instance registers an event handler to the Rendering event of the composition target
public ScreenSpaceLines3D()
{
...
CompositionTarget.Rendering += OnRender; // <-- this line
}
but forgets to remove it when the instance is removed from the scene.
So to fix this you need to touch the source code:
public ScreenSpaceLines3D()
{
...
// event registration removed
}
private bool AttachedToCompositionTargetRendering { get; set; }
protected override void OnVisualParentChanged(DependencyObject oldParent)
{
base.OnVisualParentChanged(oldParent);
var parent = VisualTreeHelper.GetParent(this);
if (parent == null)
{
if (AttachedToCompositionTargetRendering)
{
CompositionTarget.Rendering -= OnRender;
AttachedToCompositionTargetRendering = false;
}
}
else
{
if (!AttachedToCompositionTargetRendering)
{
CompositionTarget.Rendering += OnRender;
AttachedToCompositionTargetRendering = true;
}
}
}
Using datagridview bound to BindingSource control bound to a LINQ to SQL class, I wonder how to position the bindingSource to a specific record, that is, when I type a Product name in a textbox, the bindingsource should move to that specific product. Here is my code:
In my form FrmFind:
NorthwindDataContext dc;
private void FrmFind_Load(object sender, EventArgs e)
{
dc = new NorthwindDataContext();
var qry = (from p in dc.Products
select p).ToList();
FindAbleBindingList<Product> list = new FindAbleBindingList<Product>(qry);
productBindingSource.DataSource = list.OrderBy(o => o.ProductName);
}
private void textBox1_TextChanged(object sender, EventArgs e)
{
TextBox tb = sender as TextBox;
int index = productBindingSource.Find("ProductName", tb.Text);
if (index >= 0)
{
productBindingSource.Position = index;
}
}
In the program class:
public class FindAbleBindingList<T> : BindingList<T>
{
public FindAbleBindingList()
: base()
{
}
public FindAbleBindingList(List<T> list)
: base(list)
{
}
protected override int FindCore(PropertyDescriptor property, object key)
{
for (int i = 0; i < Count; i++)
{
T item = this[i];
//if (property.GetValue(item).Equals(key))
if (property.GetValue(item).ToString().StartsWith(key.ToString()))
{
return i;
}
}
return -1; // Not found
}
}
How can I implement the find method to make it work?
You can combine the BindingSource.Find() method with the Position property.
For example, if you have something like this in your TextBox changed event handler:
private void textBox1_TextChanged(object sender, EventArgs e)
{
TextBox tb = sender as TextBox;
int index = bs.Find("Product", tb.Text);
if (index >= 0)
{
bs.Position = index;
}
}
This of course will depend on a lot of things like the particular implementation of the Find method the data source for the binding source has.
In a question you asked a little while ago I gave you an implementation for Find which worked with full matches. Below is a slightly different implementation that will look at the start of the property being inspected:
protected override int FindCore(PropertyDescriptor property, object key)
{
// Simple iteration:
for (int i = 0; i < Count; i++)
{
T item = this[i];
if (property.GetValue(item).ToString().StartsWith(key.ToString()))
{
return i;
}
}
return -1; // Not found
}
Do note that the above method is case sensitive - you can change StartsWith to be case insensitive if you need.
One key thing to note about the way .Net works is that the actual type of an object is not sufficient all the time - the declared type is what consuming code knows about.
This is the reason why you get a NotSupported exception when calling the Find method, even though your BindingList implementation has a Find method - the code that receives this binding list doesn't know about the Find.
The reason for that is in these lines of code:
dc = new NorthwindDataContext();
var qry = (from p in dc.Products
select p).ToList();
FindAbleBindingList<Product> list = new FindAbleBindingList<Product>(qry);
productBindingSource.DataSource = list.OrderBy(o => o.ProductName);
When you set the data source for the binding source you include the extension method OrderBy - Checking this shows that it returns IOrderedEnumerable, an interface described here on MSDN. Note that this interface has no Find method, so even though the underlying FindableBindingList<T> supports Find the binding source doesn't know about it.
There are several solutions (the best is in my opinion to extend your FindableBindingList to also support sorting and sort the list) but the quickest for your current code is to sort earlier like so:
dc = new NorthwindDataContext();
var qry = (from p in dc.Products
select p).OrderBy(p => p.ProductName).ToList();
FindAbleBindingList<Product> list = new FindAbleBindingList<Product>(qry);
productBindingSource.DataSource = list;
In WinForms there are no entirely out of the box solutions for the things you are trying to do - they all need a little bit of custom code that you need to put together to match just your own requirements.
I took a different approach. I figured, programmatically, every record must be checked until a match is found, so I just iterated using the MoveNext method until I found a match. Unsure if the starting position would be the First record or not, so I used the MoveFirst method to ensure that is was.
There is one assumption, and that is that what you are searching for is unique in that column. In my case, I was looking to match an Identity integer.
int seekID;
this.EntityTableBindingSource.MoveFirst();
if (seekID > 0)
{
foreach (EntityTable sd in EntityTableBindingSource)
{
if (sd.ID != seekID)
{
this.t_EntityTableBindingSource.MoveNext();
}
else
{
break;
}
}
}
I didn't really care for either answer provided. Here is what I came up with for my problem:
// Create a list of items in the BindingSource and use labda to find your row:
var QuickAccessCode = customerListBindingSource.List.OfType<CustomerList>()
.ToList().Find(f => f.QuickAccessCode == txtQAC.Text);
// Then use indexOf to find the object in your bindingSource:
var pos = customerListBindingSource.IndexOf(QuickAccessCode);
if (pos < 0)
{
MessageBox.Show("Could not find " + txtQAC.Text);
}
else
{
mainFrm.customerListBindingSource.Position = pos;
}
I found a nice Find Name code snippet that I'm using in a WPF solution:
public static T FindVisualChildByName<T>(DependencyObject parent, string name) where T : DependencyObject
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(parent); i++)
{
var child = VisualTreeHelper.GetChild(parent, i);
string controlName = child.GetValue(Control.NameProperty) as string;
if (controlName == name)
{
return child as T;
}
else
{
T result = FindVisualChildByName<T>(child, name);
if (result != null)
return result;
}
}
return null;
}
But this only works if I am on the UI thread.
I have another thread that is playing an audio file with an end sync. I want to use the code above to set a dep property on the ui thread, but I keep getting a cross-thread error.
Even trying a simple:
SoundFXPad selectedSoundFXPad = (SoundFXPad)m_parent.FindName("panelC" + numbervar);
Gives me the same error
All the other thread-safe WPF Dispatcher-Invoke codes I have seen assume you already know the name of the control. Is there a way to use the either code above in a thread-safe way to affect a UI control from another thread where the name needs to be "found"?
Thank You!
There's generally one UI thread per application (generally; you can create multiple, but it's not common). So you don't need the control name to find the dispatcher - try this:
Application.Current.Dispatcher.Invoke(new Action(
delegate {
// Put code that needs to run on the UI thread here
}));
I have a canvas and it has child DrawingVisuals in its VisualCollection. I want to hit test against some type of child but not for others. To do that I wrote HitTestFilterCallback function:
public HitTestFilterBehavior MyHitTestFilter(DependencyObject o)
{
Debug.WriteLine(o.GetType());
if (o is BackgroundLine)
{
return HitTestFilterBehavior.ContinueSkipSelf;
}
else
{
return HitTestFilterBehavior.Continue;
}
}
So I check whether the child of canvas is a BackgroundLine, which is derived from DrawingVisual, and if it is I skip it. However, the type I am getting from Debug.WriteLine(o.GetType()) is only System.Windows.Media.DrawingVisual. Is there a way I can find the most specific object type?
Rest of the code is below. I want to test against GraphicsBase objects only.
GraphicsBase hit = null;
public HitTestResultBehavior MyHitTestResult(HitTestResult result)
{
hit = (GraphicsBase)result.VisualHit;
return HitTestResultBehavior.Stop;
}
VisualTreeHelper.HitTest(drawingCanvas, new HitTestFilterCallback(MyHitTestFilter),
new HitTestResultCallback(MyHitTestResult), new PointHitTestParameters(point));
if (hit != null)
Debug.WriteLine("hit");
else
Debug.WriteLine("nothing");
I found the problem. The DrawingVisual object I am seeing was the rectangle I added for background color. I forgot about that and thought I was getting BackgroundLine object's type as DrawingVisual. I can get the specific BackgroundLine type as rooks said. Thanks.
I've just answered a question over here where I said that there is no functional difference between
{Binding TargetProperty}
and
{Binding Path=TargetProperty}
and, as far as I'm aware what I have written is fundamentally correct. However the idea that one will use the constructor and the other sets the property got me thinking that there could be a difference, so I whipped open reflector and had a look.
The constructor has the following code in it:
public Binding(string path)
{
this._source = UnsetSource;
if (path != null)
{
if (Dispatcher.CurrentDispatcher == null)
{
throw new InvalidOperationException();
}
this._ppath = new PropertyPath(path, new object[0]);
this._attachedPropertiesInPath = -1;
}
}
The path property is this:
public PropertyPath Path
{
get
{
return this._ppath;
}
set
{
base.CheckSealed();
this._ppath = value;
this._attachedPropertiesInPath = -1;
base.ClearFlag(BindingBase.BindingFlags.PathGeneratedInternally);
}
}
So when you set the path through the property the PathGeneratedInternally flag is cleared. Now, this flag isn't exposed anywhere publicly directly, but it does seem to be used in a few places:
internal void UsePath(PropertyPath path)
{
this._ppath = path;
base.SetFlag(BindingBase.BindingFlags.PathGeneratedInternally);
}
[EditorBrowsable(EditorBrowsableState.Never)]
public bool ShouldSerializePath()
{
return ((this._ppath != null) && !base.TestFlag(BindingBase.BindingFlags.PathGeneratedInternally));
}
I'm sure it's all fairly inconsequential, but does anyone out there know what this flag means and why it maybe different depending on how you declare the binding?
The key is to see where the UsePath method is referenced from. By default the flag won't be set, so clearing it is basically a no-op. There is no reason to clear it in the constructor, because you know it hasn't been set in that case (because the object is still being constructed).
The UsePath method is only called in one location and that's the ClrBindingWorker constructor. If you look in there you will see they automatically create a "blank" or "empty" path and pass that to UsePath.
I suspect they do this so the Path is "valid" when used internally, even if it just refers to the binding source (which is the default behavior when no path is given). If you later set the Path property on the Binding, the flag that indicates the Path was automatically generated must be cleared.