Develop Reference

Removing default Scroll bar from UWP app using XAML

In my UWP app, I have a datagrid which already has a separate scroll bar but I am also getting the app default scroll bar which is I tried to hide and disable in following way:
ScrollViewer.VerticalScrollBarVisibility="Hidden"
ScrollViewer.VerticalScrollMode="Disabled"
but still on hovering I am getting a default scroll bar. Please refer to the attached image.
Could anyone help me in removing the default scroll bar?
App Image

Please refer the source code, it was not implemented with ScrollViewer, we can't get the scrollviewer instance. for this scenario, you could detect vertical scrollbar with visual tree helper and hidden it, for more please refer the following code.
var scrollbar = MyFindDataGridChildOfType<ScrollBar>(MyDataGrid);
Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
{
scrollbar.Visibility = Visibility.Collapsed;
});
public static T MyFindDataGridChildOfType<T>(DependencyObject root) where T : class
{
var MyQueue = new Queue<DependencyObject>();
MyQueue.Enqueue(root);
while (MyQueue.Count > 0)
{
DependencyObject current = MyQueue.Dequeue();
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(current); i++)
{
var child = VisualTreeHelper.GetChild(current, i);
var typedChild = child as T;
if (typedChild != null)
{
return typedChild;
}
MyQueue.Enqueue(child);
}
}
return null;
}

Allow a ListBox to overlap a TableLayoutPanel (C# .NET)

I have a form that contains a TableLayoutPanel with various controls and labels in it. One of them is a custom control that inherits from ComboBox that has extra auto-complete behavior (auto-completes on any text rather than just left to right). I didn't write the code for this control, so I'm not super familiar with how it works, but essentially upon clicking on the Combobox, it adds a ListBox below the ComboBox, within the same Panel of the TableLayoutPanel, that covers the normal drop down.
Unfortunately, the TableLayoutPanel prevents the ListBox from being fully visible when added, and only one item is shown. The goal is to get it to look like a normal ComboBox which would drop down to cover any controls below it.
Is there any way to allow a control that is in a TableLayoutPanel to overlap the TableLayoutPanel to get this to work as I want? I want to avoid any controls moving around due to the TableLayoutPanel growing to accommodate the ListBox.
Relevant code from the control:
void InitListControl()
{
if (listBoxChild == null)
{
// Find parent - or keep going up until you find the parent form
ComboParentForm = this.Parent;
if (ComboParentForm != null)
{
// Setup a messaage filter so we can listen to the keyboard
if (!MsgFilterActive)
{
Application.AddMessageFilter(this);
MsgFilterActive = true;
}
listBoxChild = listBoxChild = new ListBox();
listBoxChild.Visible = false;
listBoxChild.Click += listBox1_Click;
ComboParentForm.Controls.Add(listBoxChild);
ComboParentForm.Controls.SetChildIndex(listBoxChild, 0); // Put it at the front
}
}
}
void ComboListMatcher_TextChanged(object sender, EventArgs e)
{
if (IgnoreTextChange > 0)
{
IgnoreTextChange = 0;
return;
}
InitListControl();
if (listBoxChild == null)
return;
string SearchText = this.Text;
listBoxChild.Items.Clear();
// Don't show the list when nothing has been typed
if (!string.IsNullOrEmpty(SearchText))
{
foreach (string Item in this.Items)
{
if (Item != null && Item.ToLower().Contains(SearchText.ToLower()))
{
listBoxChild.Items.Add(Item);
listBoxChild.SelectedIndex = 0;
}
}
}
if (listBoxChild.Items.Count > 0)
{
Point PutItHere = new Point(this.Left, this.Bottom);
Control TheControlToMove = this;
PutItHere = this.Parent.PointToScreen(PutItHere);
TheControlToMove = listBoxChild;
PutItHere = ComboParentForm.PointToClient(PutItHere);
TheControlToMove.Anchor = ((System.Windows.Forms.AnchorStyles)
((System.Windows.Forms.AnchorStyles.Left | System.Windows.Forms.AnchorStyles.Right)));
TheControlToMove.BringToFront();
TheControlToMove.Show();
TheControlToMove.Left = PutItHere.X;
TheControlToMove.Top = PutItHere.Y;
TheControlToMove.Width = this.Width;
int TotalItemHeight = listBoxChild.ItemHeight * (listBoxChild.Items.Count + 1);
TheControlToMove.Height = Math.Min(ComboParentForm.ClientSize.Height - TheControlToMove.Top, TotalItemHeight);
}
else
HideTheList();
}
Images:
Desired behavior
Current behavior

Going on the suggestion from TaW, I came up with a tentative solution. This form isn't re-sizable but does auto-size so that it looks ok if the user changes their DPI in Windows.
To resolve this, I moved the control out of the TableLayoutPanel to an arbitrary position in the Parent of the TableLayoutPanel. On form loading, I summed the coordinates of the TableLayoutPanel and an empty panel in the cell that I wanted the control to be located on top of. This worked for my needs but it feels like a kludge.
The better solution is probably to use Control.PointToScreen and Control.PointToClient methods, however I wasn't able to get these methods to give me the correct coordinates.

How does one get a ListView (GridView) cell's contents when clicked with a mouse

I am trying to get the text value of a "cell" inside of a GridView that is set as the view of a ListView. I do not want to get the SelectedItem of the ListView as that just returns my entire View Model (but not which property the cell refers to).
I am able to get the text value by responding to direct mouse events (up down or whatever) and if the value is a textblock, obviously I can use the text. This works great and as of right now this is my only solution, although its currently limited.
I would like to take it a step further and be able to click anywhere with in the cell area, navigate around to find the appropriate textblock and then use that value. I have tried a half million ways to do this but what seems logical doesn't seem to quite work out like it should.
Setup:
I have a dynamic GridView that creates its own columns and bindings based on data models that I pass to it. I am using a programmatic cell template (shown below) to have individual control over the cells, particularly so I can add a "border" to it making it actually separate out each cell. I have named the objects so I can access them easier when I'm navigating around the VisualTree.
Here is the Template Code. (Note that the content presenter originally was a textblock itself, but this was changed for later flexibility)
private DataTemplate GetCellTemplate(string bindingName)
{
StringBuilder builder = new StringBuilder();
builder.Append("<DataTemplate ");
builder.Append("xmlns='http://schemas.microsoft.com/winfx/");
builder.Append("2006/xaml/presentation' ");
builder.Append("xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml' ");
builder.Append("xmlns:local = 'clr-namespace:XXXXXXXX");
builder.Append(";assembly=XXXXXXXXX'>");
builder.Append("<Border Name=\"border\" BorderThickness=\"1,0,0,0\" BorderBrush=\"Gray\" Margin=\"-6,-3,-6,-3\">");
builder.Append("<Grid Margin=\"6,3,6,3\">");
builder.Append("<ContentPresenter Name=\"content\" HorizontalAlignment=\"Stretch\" Content=\"{Binding ");
builder.Append(string.Format("{0}", bindingName));
builder.Append("}\"/>");
builder.Append("</Grid>");
builder.Append("</Border>");
builder.Append("</DataTemplate>");
DataTemplate cellTemplate= (DataTemplate)XamlReader.Parse(builder.ToString());
return cellTemplate;
}
What I have Tried:
The logical approach for me was to react to a Mouse event. From the object that had the mouse event I would do either
A. Look at its children to find a textblock, or
B. Get its parent then look for child with a textblock.
My assumption is that if I click in white space I'm clicking in a container that has my textblock. So far the two things that come up are a Border and a Rectangle (if I don't click the text itself). A. Returns absolutely nothing except for the recangle and the border. When I do B i can find textblocks but they are every single text block in the entire row.
So what I try to do from that is get all textblocks, then go backwards till I find which one has a IsMouseOver property as true. It turns out none of these objects EVER have a IsMouseOver except the content presenter for the entire row. So this seems to indicate to me is that the whitespace in the cells does not actually contain the textblock.
What I find is that when I click on the Border and start looking at children, I eventually get to a container that has a rectangle (the rectangle I click) and a grid row view presenter. The presenter shows all of the objects inside the row (hence why i would get all textblocks when i do this recursive scan).
Here is some of the code used to do this to get an idea of what i'm doing. I have written about 10 different versions of this same recursive code generally attempting to find who has the Mouse over it and is related to a textbox.
private void OnPreviewMouseUp(object sender, MouseButtonEventArgs e)
{
object original = e.OriginalSource;
if (original is TextBlock)
{
this.valueTextBlock.Text = ((TextBlock)original).Text;
}
else if (original is FrameworkElement)
{
var result = GetAllNestedChildren<Border>(VisualTreeHelper.GetParent((DependencyObject)original)).Where(x => x.Name == "border").Where(x => HasAChildWithMouse(x)).ToList();
}
else
{
this.valueTextBlock.Text = string.Empty;
}
}
private bool HasAChildWithMouse(UIElement element)
{
if (element.IsMouseOver || element.IsMouseDirectlyOver)
return true;
var childCount = VisualTreeHelper.GetChildrenCount(element);
for (int i = 0; i < childCount; ++i)
{
var child = VisualTreeHelper.GetChild(element, i);
if (child is UIElement)
if (HasAChildWithMouse((UIElement)child))
return true;
}
return false;
}
private IEnumerable<T> GetAllNestedChildren<T>(DependencyObject obj) where T : UIElement
{
if (obj is T)
yield return obj as T;
var childCount = VisualTreeHelper.GetChildrenCount(obj);
for (int i = 0; i < childCount; ++i)
{
var child = VisualTreeHelper.GetChild(obj, i);
foreach (var nested in GetAllNestedChildren<T>(child))
yield return nested;
}
}
private T GetObjectByTypeParentHasMouse<T>(DependencyObject obj) where T : UIElement
{
if (obj is T)
{
if ((VisualTreeHelper.GetParent(obj) as UIElement).IsMouseOver )
{
return obj as T;
}
}
var childCount = VisualTreeHelper.GetChildrenCount(obj);
for (int i = 0; i < childCount; ++i)
{
var child = VisualTreeHelper.GetChild(obj, i);
var correctType = GetObjectByTypeParentHasMouse<T>(child);
if (correctType != null)
return correctType;
}
return null;
}
private T GetContainedType<T>(DependencyObject obj, bool checkForMouseOver) where T : UIElement
{
if (obj is T && ((T)obj).IsMouseOver)
return obj as T;
var childCount = VisualTreeHelper.GetChildrenCount(obj);
for (int i = 0; i < childCount; ++i)
{
var child = VisualTreeHelper.GetChild(obj, i);
var correctType = GetContainedType<T>(child, checkForMouseOver);
if (correctType != null)
return correctType;
}
return null;
}
The other approach I took was to start with the TextBlock itself, find its containing parent and find out how i can navigate to the answer. I find the templateparent is the ContentPresenter (named ="content") I find the grid, and then the border. The parent of the border is a content presenter whos content is the data view model for the entire row. The parent of this contentpresenter is the grid column's presenter. This is the same one that i was navigating up to in the other one.
It would appear that the first approach objects while are contain the cell do not actually contain the textblock or the entire cell templated items. It would appear to me there is no way to go from the Border or Rectangle that is clicked, back to the actual text field.
"Long story short" is there ANY way to make this connection?
(Btw I am not willing to give up this ListView/GridView because its payoffs far outweigh this negative and I'd gladly give up on this idea to keep the rest).

I think you sjould be able to either
1) Add some kind of (toggle)button to the root of your data template, and either bind to Command and handle it on your viewmodel or bind to IsChecked/IsPressed and handle changes via data triggers or w/e on the view side.
2) Add EventTrigger to your datatemplate at some point, and handle PreviewNouseUp/Down events there via simple animations.

Setting DataGrid row height property programmatically

I have one question regarding standard WPF DataGrid in .NET 4.0.
When I try to set DataGrid grid row height programmaticaly using simple code:
private void dataGrid1_LoadingRow(object sender, DataGridRowEventArgs e)
{
e.Row.Height = 120;
}
everything goes fine till I try to resize grid row on the user interface /standard way on the side using mouse like in excel/ - then it appears grid row can't be resized. It just keep being 120. Its content by the way all goes messed up...
Like Sinead O'Connor would say: tell me baby - where did I go wrong?

You are not meant to set the Height of the row itself as it is resized via the header and such. There is a property, DataGrid.RowHeight, which allows you to do this properly.
If you need to set the height selectively you can create a style and bind the height of the DataGridCellsPresenter to some property on your items:
<DataGrid.Resources>
<Style TargetType="DataGridCellsPresenter">
<Setter Property="Height" Value="{Binding RowHeight}" />
</Style>
</DataGrid.Resources>
Or you can get the presenter from the visual tree (i do not recommend this) and assign a height there:
// In LoadingRow the presenter will not be there yet.
e.Row.Loaded += (s, _) =>
{
var cellsPresenter = e.Row.FindChildOfType<DataGridCellsPresenter>();
cellsPresenter.Height = 120;
};
Where FindChildOfType is an extension method which could be defined like this:
public static T FindChildOfType<T>(this DependencyObject dpo) where T : DependencyObject
{
int cCount = VisualTreeHelper.GetChildrenCount(dpo);
for (int i = 0; i < cCount; i++)
{
var child = VisualTreeHelper.GetChild(dpo, i);
if (child.GetType() == typeof(T))
{
return child as T;
}
else
{
var subChild = child.FindChildOfType<T>();
if (subChild != null) return subChild;
}
}
return null;
}

This works for me.
private void SetRowHeight(double height)
{
Style style = new Style();
style.Setters.Add(new Setter(property: FrameworkElement.HeightProperty, value: height));
this.RowStyle = style;
}

WPF TreeView Scrolled to Bottom automatically?

WPF default TreeView is scrolled to bottom of the node automatically where as we need to show the top view of the tree view. How to do that?
Also I could not get the scroll viewer by walking down the Visual Tree.

Preselect top node and call TreeViewItem.BringIntoView method on selection changed event. Call TreeView.ItemContainerGenerator.ContainerFromItem(e.NewValue) to get hold of the TreeViewItem.

This code is very rough.
The key to getting the TreeViewItem.BringIntoView() to get an item to the top, is to first scroll the TreeView to the bottom rather than the top.
To do this, we need to access the ScrollViewer inside the TreeView's control template first. Lots of messing around IMO, that should have been provided in the framework from the outset.
Your item control in this case, should be your TreeViewItem that you are trying to get to the top.
The uxTree control is the TreeView.
item.IsSelected = true;
ScrollViewer scroller = (ScrollViewer)this.FindVisualChildElement(this.uxTree, typeof(ScrollViewer));
scroller.ScrollToBottom();
item.BringIntoView();
private FrameworkElement FindVisualChildElement(DependencyObject element, Type childType)
{
int count = VisualTreeHelper.GetChildrenCount(element);
for (int i = 0; i < count; i++)
{
var dependencyObject = VisualTreeHelper.GetChild(element, i);
var fe = (FrameworkElement)dependencyObject;
if (fe.GetType() == childType)
{
return fe;
}
FrameworkElement ret = null;
if (fe.GetType().Equals(typeof(ScrollViewer)))
{
ret = FindVisualChildElement((fe as ScrollViewer).Content as FrameworkElement, childType);
}
else
{
ret = FindVisualChildElement(fe, childType);
}
if (ret != null)
{
return ret;
}
}
return null;
}