I'm using a listbox to display a list of numeric values where the selected value get applied to an object and is saved. I had the idea to set the height on on the listbox to be just enough to display a single row. Of course this causes the vertical scollbar to appear, and without a scroll body, which is exactly what I was looking for.
When I click the up/down arrow on the list box scrollbar, it scrolls the next item into view correctly. However, the item is not selected. I immediately had problems with the actual selected value being saved and not the value that is in view. This is because it requires a click on the number after the scrollbar button to actually select the value, which is not very intuitive.
So, after some intel-sense hunting, I began search for possible ways to increment the selected value with clicks on the listbox scrollbar buttons, but I can't find anything that actually uses them.
I have found posts that describe actions when clicking on the scroll bar body, and still others that use designer added buttons to perform the index change on the listbox. However, the scroll bar body is not visible do to the short height of the list box and it seems silly to add more buttons when I already have those two available and doing most of the work.
I have also found a post that described something similar, but using a listview. But, I would hate to have to swap the control out at this point for one feature I really think should be available somewhere on the control I'm currently using.
So, I guess what I'm looking for is a way to address the click event handler of the vertical scrollbar buttons on a listbox control.
Any help would be greatly appreciated.
(Thanks all, for the 1000 other things I didn't have to post to solve here!)
I had heard about that Phil, and your right. I'm doing a replacement for the numeric up-down.
I just figured that there was probably a viable alternative, since that specific control was not originally part of the framework. I had also gotten much of it working and really like the results, and the way it picked up the theme.
Since the core of this application will become a start point for future applications, I wanted to include this functionality and was prepared to do a little work for it.
What I ended up doing was a little complicated that it was worth, but made easy with a useful helper function. I needed to search the 'Visual Tree' for my target type. From there I was able to access enough functionality to finish up.
First:
Using a helper function I found here (Thanks Bruno) I was able to add this to my Loaded event:
private Double currentVerticalOffset;
private void Page_Loaded_1(object sender, RoutedEventArgs e)
{
ScrollViewer sv = Helpers.ViewHelpers.ListBoxHelper.FindVisualChild<ScrollViewer>(listbox);
sv.ScrollChanged += HandleRankScrollChange;
currentVerticalOffset = sv.VerticalOffset;
}
Then, I handle the scroll changed event:
private void HandleRankScrollChange(object sender, ScrollChangedEventArgs e)
{
ScrollViewer sv = Helpers.ViewHelpers.ListBoxHelper.FindVisualChild<ScrollViewer>(listbox);
if (sv.VerticalOffset > currentVerticalOffset)
{
Helpers.ViewHelpers.ListBoxHelper.SelectNextItem(listbox);
}
if (sv.VerticalOffset < currentVerticalOffset)
{
Helpers.ViewHelpers.ListBoxHelper.SelectPreviousItem(listbox);
}
currentVerticalOffset = sv.VerticalOffset;
}
The helpers I call here are pretty simple, but again, this will become a foundation kit, so having the methods will probably come in handy again.
public static void SelectNextItem(ListBox lb)
{
if (lb.SelectedIndex < lb.Items.Count)
{
lb.SelectedIndex++;
}
}
public static void SelectPreviousItem(ListBox lb)
{
if (lb.SelectedIndex > 0)
{
lb.SelectedIndex--;
}
}
Bruno's helper function
public static childItem FindVisualChild<childItem>(DependencyObject obj) where childItem : DependencyObject
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(obj); i++)
{
DependencyObject child = VisualTreeHelper.GetChild(obj, i);
if (child != null && child is childItem)
{
return (childItem)child;
}
else
{
childItem childOfChild = FindVisualChild<childItem>(child);
if (childOfChild != null)
{
return childOfChild;
}
}
}
return null;
}
Thanks again.
Related
In WPF, I use tabcontrol have tabitems to create new Dynamic content. I have button Reset to clear all textboxes in All TabItems. My code is working with tab focus. But, When I click the other tab and click again old tab, The content show again. Please help me so that I can clear all textboxes in all tabItems
My Code here:
private void ClearControls(DependencyObject root)
{
System.Windows.Controls.TabControl controls = new System.Windows.Controls.TabControl();
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(root); i++)
{
var control = VisualTreeHelper.GetChild(root, i);
if (control is System.Windows.Controls.TextBox)
{
(control as System.Windows.Controls.TextBox).Text = String.Empty;
}
else if (VisualTreeHelper.GetChildrenCount(control) > 0)
{
ClearControls(control);
}
}
}
private void BtnResetTurnbyTurn_Click(object sender, RoutedEventArgs e)
{
ClearControls(this);
}
Don't waste your time with tree visualizer
Design your ui in a separately usercontrol and give a name then from
Then head to your main window and give the area that is supposed to display the ui a name or just declare a grid and give it a name
Now head to your tabs and double click the one that is suppoused to show the ui you want and from the code just write the following
Just to clarify the names
I have my separately designd ui in a file called pages and it's name is myui and my usercontrol tag is name child
My viewing area is filled with a grid named
Mainview
I have double clicked the required tab and it drove me to the cs file inside the click event
My code is
` pages.myui mu =new pages.myui();
Mainview.Children.Clear();
Mainview.Cildren.Add(mu.child);`
It might be the most basic way to accomplish the mission but believe me it is a life saver
Comment for any question
I hope i have helped you
Yusuf naeem
I have a grid which contains 2 rows and 2 columns. Each cell hosting a windows forms host control. I want to capture the selected cell when the user clicks on any of the cell. I have searched and found that there is no 'Click' event but I can make use of 'MouseDown' event with similar results. But now I am stuck because you would think there must be an easier way like 'GetCurentRow' and 'GetCurrentColumn' to capture the selected cell but there isn't.
What I want further to do is to get the child element in that particular cell of the grid.
I tried the following code but no matter which cell I click, I always get 0 for the row and column:
void InnerGridToContainWindowsFormsHost_MouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
var element = (UIElement)e.Source;
int c = Grid.GetColumn(element);
int r = Grid.GetRow(element);
}
Is there any way to get the selected/clicked cell details or the children inside the cell?
I think that you may be going down the wrong route here... if you just want to know what control was clicked on, try using the VisualTreeHelper.HitTest method. You can find information on the VisualTreeHelper.HitTest Method page on MSDN. Basically, you would do something like:
private void OnMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
// Get the position of the mouse pointer relative to the grid
Point clickPoint = e.GetPosition(grid);
HitTestResult result = VisualTreeHelper.HitTest(grid, clickPoint);
if (result != null)
{
// Do something here
}
}
You may also need some kind of basic recursive function to drill down through the Visual objects until you get to the one you want.
I'm having difficulty with something which seems like it should be very simple. I'm coming from Windows Forms and starting up with WPF. I think I have a simple syntax issue but I can't seem to find a specific example for this radio button issue.
I have a radio button on my GUI for a query to run either via a map selection or a list. When load is clicked, it should perform one operation if map is selected, a different operation for list. Code looks similar to this:
private void Load_Click(object sender, RoutedEventArgs e)
{
if (rdBtnList.Checked == true)
{
//do this
}
// if rdBtnList not checked (ie if rdBtnMap is checked)
// do this
}
Any help would be greatly appreciated. Thanks.
Change:
if (rdBtnList.Checked == true)
to
if (rdBtnList.IsChecked == true)
Note:
I'm coming from Windows Forms and starting up with WPF
You must forget everything you ever learned in winforms, and embrace MVVM. You should create a ViewModel and bind your rdBtnList.IsChecked property to some boolean value in the ViewModel, then perform your logic in there. The views' code behind is not the right place for application logic.
The property in WPF is called IsChecked hence you just need to update the if statement
if (rdBtnList.IsChecked == true) {
...
}
The IsChecked property is bool? (nullable value) in WPF so you may choose to be more explicit here by doing the following
if (rdBtnList.IsChecked.HasValue && rdBtnList.IsChecked.Value) {
...
}
Are you missing a return statement? As is, the posted code will always execute the if not checked path:
private void Load_Click(object sender, RoutedEventArgs e)
{
if (rdBtnList.IsChecked == true)
{
//do this
return; // return, or the if not checked path below will always win.
}
// if rdBtnList not checked (ie if rdBtnMap is checked)
// do this
}
In WPF, you'll need to use the IsChecked property. See the RadioButton Class for more details.
The following code is taken direct from Microsoft at http://msdn.microsoft.com/en-us/library/system.windows.forms.treeview.aftercheck%28VS.80%29.aspx.
// Updates all child tree nodes recursively.
private void CheckAllChildNodes(TreeNode treeNode, bool nodeChecked)
{
foreach (TreeNode node in treeNode.Nodes)
{
node.Checked = nodeChecked;
if (node.Nodes.Count > 0)
{
// If the current node has child nodes, call the CheckAllChildsNodes method recursively.
this.CheckAllChildNodes(node, nodeChecked);
}
}
}
// NOTE This code can be added to the BeforeCheck event handler instead of the AfterCheck event.
// After a tree node's Checked property is changed, all its child nodes are updated to the same value.
private void node_AfterCheck(object sender, TreeViewEventArgs e)
{
// The code only executes if the user caused the checked state to change.
if (e.Action != TreeViewAction.Unknown)
{
if (e.Node.Nodes.Count > 0)
{
/* Calls the CheckAllChildNodes method, passing in the current
Checked value of the TreeNode whose checked state changed. */
this.CheckAllChildNodes(e.Node, e.Node.Checked);
}
}
}
You put it in a form containing a treeview and call node_AfterCheck on (surprise, surprise), the treeview AfterCheck event. It then recursively checks or unchecks the child nodes on the treeview.
However if you actually try it, and click several times on the same treeview check box fast enough, the child nodes end up with their check out-of-sync with the parent. You probably need a couple of levels of children with perhaps 100 children in-total for the UI update to be slow enough to notice this happening.
I've tried a couple of things (such as disabling the treeview control at the beginning of node_AfterCheck and re-enabling at the end), but the out-of-sync problem still happens.
Any ideas?
The .NET TreeView class heavily customizes mouse handling for the native Windows control in order to synthesize the Before/After events. Unfortunately, they didn't get it quite right. When you start clicking fast, you'll generate double-click messages. The native control responds to a double-click by toggling the checked state for the item, without telling the .NET wrapper about it. You won't get a Before/AfterCheck event.
It's a bug but they won't fix it. The workaround is not difficult, you'll need to prevent the native control from seeing the double-click event. Add a new class to your project and paste the code shown below. Compile. Drop the new control from the top of the toolbox, replacing the existing one.
using System;
using System.Windows.Forms;
class MyTreeView : TreeView {
protected override void WndProc(ref Message m) {
// Filter WM_LBUTTONDBLCLK
if (m.Msg != 0x203) base.WndProc(ref m);
}
}
Using the solution above, I think it is need to paint more detailed steps, how to apply it for those who want to apply it to an already created TreeView. For example, for me, a beginner, this caused difficulties, but here is the solution:
Creating a class "NoClickTree.cs" in your project.
Include this code in new class:
public class NoClickTree : TreeView
{
protected override void WndProc(ref Message m)
{
// Suppress WM_LBUTTONDBLCLK
if (m.Msg == 0x203) { m.Result = IntPtr.Zero; }
else base.WndProc(ref m);
}
}
Go to Form1.Designer.cs or "yourWindowWithTreeView".Designer.cs
Find original initialization at the end of the file, something like private System.Windows.Forms.TreeView treeView;
Replace them on private NoClickTree treeView;
In function private void InitializeComponent() find original initialization, something like this.treeView = new System.Windows.Forms.TreeView();
Replace them on this.treeView = new NoClickTree();
Done!
This steps helped me for solve this problem.
I'm using a DataGrid in my silverlight application to display some data that's refreshed on a timer. My problem is that when this happens the vertical scrollbar in the grid resets to the top, whereas I want it to stay in the same position. Does anyone know how I can make this happen?
I've tried overriding the ItemsSource property on the grid to store the vertical scroll position and then reset it, but this only affects the scrollbar and doesn't force the correct rows to be displayed. Is there a way to force this behaviour?
Here is a similar question about Setting the scroll bar position on a ListBox
After rebinding Silverlight Listbox control how do you get it listbox to scroll to back to the top?
Since the DataGrid also supports a ScrollIntoView method, you should be able to use a similar technique such as
theDataGrid.ItemsSource = data;
theDataGrid.UpdateLayout();
theDataGrid.ScrollIntoView(theDataGrid.SelectedItem, theDataGrid.Columns[0]);
I couldn't find a decent answer last time I looked. I wanted to keep the current element selected in the grid but that wouldn't work on an ICollectionView refresh (I use MVVM and get automatic updates from the server).
ScrollIntoView() was not an option for me because the currently selected item may NOT be in view. Having the CurrentChanged event firing out of control was also quite a bother.
In the end, I used the Infragistics grid and it does just that out of the box. Problem solved for me.
You may have a look at the DevExpress free grid. I think it had the same nice behaviour (I tested it but I can't remember the outcome).
You could try setting the SelectedItem thro the UI thread, so that the UI can refresh itself,
like so
private void Button_Click(object sender, RoutedEventArgs e)
{
Person p = new Person() { Name="sss",Age=11}; //datagird's itemsSource is Collection<person>
people.Add(p);
dg.SelectedItem = p; //dg is my datagrid name
Dispatcher.BeginInvoke(() => { dg.SelectedItem = p; });
}
Im assuming that new rows are loaded thro the ViewModel, so thats why it makes sense to place the BeginInvoke there. Since the ViewModel operations run on a different thread, and just setting the SelectedItem on its own might not work, this has worked for someone else
I've also had issues with this. I solved it by remembering the item I want to scroll to, then re-binding the DataGrid. I handle the LayoutUpdated event in order to implement the desired functionality:
void MyDataGrid_LayoutUpdated(object sender, EventArgs e)
{
// Reference the data item in the list you want to scroll to.
object dataItem = yourDataItem;
// Make sure the item is not null and didn't already scroll to the item.
if (dataItem != null && this.dataItemScrolledTo != dataItem)
{
// Remember the item scrolled to.
this.dataItemScrolledTo = dataItem;
// Scroll datagrid to the desired item.
MyDataGrid.ScrollIntoView(dataItem, MyDataGrid.Columns[0]);
}
}
I've modified CodeMaster's solution so that you don't need a class level variable. Put this code in the method that updates the ItemsSource. It will dynamically create the eventhandler, attach it, then detach it.
EventHandler MyDataGrid_LayoutUpdated = null;
MyDataGrid_LayoutUpdated = (s, e) =>
{
MyDataGrid.ScrollIntoView(dataItem, MyDataGrid.Columns[0]);
MyDataGrid.LayoutUpdated -= MyDataGrid_LayoutUpdated;
};
MyDataGrid.LayoutUpdated += MyDataGrid_LayoutUpdated;