after being googled a lot, finally i am going to ask this to you guys.
i'v created scrollviewer, which contains items(listboxItems) and these items fetching from the webservices. but at once only 5 items can fetched. so initially it'll be 5 items, then next 5(appended to the scrollviewer) and then next 5 and so on......
note:-here listBoxitems are used inside the scrollviewer, not the listbox
data fetched from webservice also contains--->
total items
numResults (current number of items fetched)
now suppose my method to fetch data is--->
getData(int nextResult)
{
// some code to fetch the data
}
where nextResult is next item number(ex:- nextResult is 6, if requesting 2nd time)
but i am unable to write the code to detect that the user scrolled the scrollviewer to the end & then a method to be called or fired, whatever say!
i'v been badly confused among scrollviewer's VerticalOffset, ExtentHeight, ViewportHeight, ScrollableHeight etc, about to use them & calculate desired information to achieve above requirements.
so if anyone knows about the same or used ever scrollviwer, than please post answer.
I achieved it by registering new DependencyProperty ListVerticalOffset with appropriate event:
// Constructor
public MainPage()
{
InitializeComponent();
ListVerticalOffsetProperty = DependencyProperty.Register("ListVerticalOffset", typeof(double), typeof(MainPage), new PropertyMetadata(OnListVerticalOffsetChanged));
YourScrollViewer.Loaded += YourScrollViewer_Loaded;
}
void YourScrollViewer_Loaded(object sender, RoutedEventArgs e)
{
var binding = new Binding
{
Source = YourScrollViewer,
Path = new PropertyPath("VerticalOffset"),
Mode = BindingMode.OneWay
};
SetBinding(ListVerticalOffsetProperty, binding);
}
private void OnListVerticalOffsetChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
{
var atBottom = YourScrollViewer.VerticalOffset >= YourScrollViewer.ScrollableHeight;
if (atBottom) MessageBox.Show("End");
}
public readonly DependencyProperty ListVerticalOffsetProperty;
public double ListVerticalOffset
{
get { return (double)GetValue(ListVerticalOffsetProperty); }
set { SetValue(ListVerticalOffsetProperty, value); }
}
May be this solution or it's realization is not optimal, but it's working for me.
Related
I am not quite sure if I am asking the right question. I assume other people have had this issue.
I built my own Blazor Grid component. I am using an bound to a property.
I have a function to load my grid. I changed my bound property to a full getter,setter. In the setter, I call my function to load the grid. This works fast and easy in pretty much all instances. But, I have one grid that when binding it will take a few extra seconds to complete.
The problem: I can't seem to figure out how to get my waiting spinner component to show when loading my grid.
Example Blazor Markup:
#if (dataGrid == null)
{
<hr />
<BitcoSpinner></BitcoSpinner>
}
else
{
<BitcoGrid TheGrid="dataGrid"></BitcoGrid>
}
Here is my property and GridLoading:
private string selectedGroup1 = "";
public string selectedGroup
{
get => selectedGroup1;
set
{
selectedGroup1 = value;
LoadGrid();
}
}
private void LoadGrid()
{
dataGrid = null;
PT_Grid_Admin ptGrid = new PT_Grid_Admin(permitTraxLibrary, gridParams);
dataGrid = ptGrid.ADMIN_FeeList(feeList.Fee_Key, selectedGroup);
}
You should define LoadGrid method asynchronously. Therefore, at the beginning of the program, when the data grid value is set, your spinner will be displayed until the data grid value is not received. Then, after receiving the data grid value, the else part of the condition will be executed and its value will be displayed to the user.
It may not take much time to receive information from the DB in local mode, so the following code can be used to simulate the delay:
System.Threading.Thread.Sleep(5000);
In general, I think that if your code changes like this, you can see the spinner.
private string selectedGroup1 = "";
public string selectedGroup
{
get => selectedGroup1;
set
{
selectedGroup1 = value;
LoadGrid();
}
}
private async Task LoadGrid()
{
dataGrid = null;
System.Threading.Thread.Sleep(5000);
.
.
}
Of course, it is better to load the datagrid in OnInitializedAsync method. For more info you can refer to this link.
I have a BindingList< KeyValuePair < string, string > > that is bound to a ComboBox control. Based on some conditions, the BindingList will be added a new KeyValuePair. Now, the Newly added item shows up at index 0 of the Combobox, instead of at the end.
While debugging, I found that the BindingList has got the right order. (i.e, the new KeyValuePair is appended)
Also, I check the SelectedValue of the ComboBox in it's SelectedIndexChanged handler and it seems to be not of the ListItem that got selected. Instead, it is that of the supposed ListItem, if the ComboBox had got the right order as in its DataSource, - the BindingList..
The code is a small part of a large project.. Plz let me know if the question is not clear. I can put the relevant parts of the code as per our context.
How could something like this happen? What can I do differently?
I have this class something like this.
public class DropdownEntity
{
//removed all except one members and properties
private string frontEndName
public string FrontEndName
{
get {return this.frontEndName; }
set {this.frontEndName= value; }
}
//One Constructor
public DropdownEntity(string _frontEndName)
{
this.FrontEndName = _frontEndName;
//Removed code which initializes several members...
}
//All methods removed..
public override string ToString()
{
return frontEndName;
}
}
In my windows form, I have a tab control with several tabs. In one of the tabs pages, I have a DataGridView. The user is supposed to edit the cells and click on a Next - button. Then, some processing will be done, and the TabControl will be navigated to the next tab page.
The next tab page has the combobox that has the problem I mentioned. This page also has a back button, which will take back.. the user can modify the gridview cells again.. and click on the next button. This is when the order gets messed up.
I am posting here the Click event handler of the Next Button.. Along with the class, with the rest of the code removed.
public partial class AddUpdateWizard : Form
{
//Removed all members..
BindingList<KeyValuePair<string, string>> DropdownsCollection;
Dictionary<string, DropdownEntity> DropdownsDict;
//Defined in a partial definition of the class..
DataGridView SPInsertGridView = new DataGridView();
ComboBox DropdownsCmbBox = new ComboBox();
Button NextBtn2 = new Button();
Button BackBtn3 = new Button();
//Of course these controls are added to one of the panels
public AddUpdateWizard(MainForm mainForm)
{
InitializeComponent();
DropdownsDict = new Dictionary<string, DropdownEntity>();
}
private void NextBtn2_Click(object sender, EventArgs e)
{
string sqlArgName;
string frontEndName;
string fieldType;
for (int i = 0; i < SPInsertGridView.Rows.Count; i++)
{
sqlArgName = "";
frontEndName = "";
fieldType = "";
sqlArgName = SPInsertGridView.Rows[i].Cells["InsertArgName"].Value.ToString().Trim();
if (SPInsertGridView.Rows[i].Cells["InsertArgFrontEndName"].Value != null)
{
frontEndName = SPInsertGridView.Rows[i].Cells["InsertArgFrontEndName"].Value.ToString().Trim();
}
if (SPInsertGridView.Rows[i].Cells["InsertArgFieldType"].Value != null)
{
fieldType = SPInsertGridView.Rows[i].Cells["InsertArgFieldType"].Value.ToString().Trim();
}
//I could have used an enum here, but this is better.. for many reasons.
if (fieldType == "DROPDOWN")
{
if (!DropdownsDict.ContainsKey(sqlArgName))
DropdownsDict.Add(sqlArgName, new DropdownEntity(frontEndName));
else
DropdownsDict[sqlArgName].FrontEndName = frontEndName;
}
else
{
if (fieldType == "NONE")
nonFieldCount++;
if (DropdownsDict.ContainsKey(sqlArgName))
{
DropdownsDict.Remove(sqlArgName);
}
}
}
//DropdownsCollection is a BindingList<KeyValuePair<string, string>>.
//key in the BindingList KeyValuePair will be that of the dictionary.
//The value will be from the ToString() function of the object in the Dictionary.
DropdownsCollection = new BindingList<KeyValuePair<string,string>>(DropdownsDict.Select(kvp => new KeyValuePair<string, string>(kvp.Key, kvp.Value.ToString())).ToList());
DropdownsCmbBox.DataSource = DropdownsCollection;
DropdownsCmbBox.DisplayMember = "Value";
DropdownsCmbBox.ValueMember = "Key";
//Go to the next tab
hiddenVirtualTabs1.SelectedIndex++;
}
private void BackBtn3_Click(object sender, EventArgs e)
{
hiddenVirtualTabs1.SelectedIndex--;
}
//On Selected Index Changed of the mentioned Combobox..
private void DropdownsCmbBox_SelectedIndexChanged(object sender, EventArgs e)
{
if (DropdownsCmbBox.SelectedValue != null)
{
if (DropdownsDict.ContainsKey((DropdownsCmbBox.SelectedValue.ToString())))
{
var dropdownEntity = DropdownsDict[DropdownsCmbBox.SelectedValue.ToString()];
DropdownEntityGB.Text = "Populate Dropdowns - " + dropdownEntity.ToString();
//Rest of the code here..
//I see that the Datasource of this ComboBox has got the items in the right order.
// The Combobox's SelectedValue is not that of the selected item. Very Strange behavior!!
}
}
}
}
The very first time the user clicks the Next Button, it's fine. But if he clicks the Back Button again and changes the Data Grid View cells.. The order will be gone.
I know, it can be frustrating to look at. It's a huge thing to ask for help. Any help would be greatly appreciated!
Please let me know if you need elaboration at any part.
Thanks a lot :)
I think you have two problems here.
First, if you want to retain the order of the items you should use an OrderedDictionary instead of a regular one. A normal collection will not retain the order of the items when you use Remove method. You can see more info about this related to List here.
You could use such dictionary like this:
DropDownDict = new OrderedDictionary();
// Add method will work as expected (as you have it now)
// Below you have to cast it before using Select
DropDownCollection = new BindingList<KeyValuePair<string, string>>(DropDownDict.Cast<DictionaryEntry>().Select(kvp => new KeyValuePair<string, string>(kvp.Key.ToString(), kvp.Value.ToString())).ToList());
The second problem could be that you change the display name (FrontEndName) of already existing items, but the key is preserved. When you add a new item, try to remove the old one that you're not using anymore and add a new item.
The Sorted Property of the Combobox is set to True! I didn't check that until now. I messed up. Terribly sorry for wasting your time Adrian. Thanks a lot for putting up with my mess here.. :)
I asked this question previously and did not get an answer but now I have more detail.
Basically I want to programatically display the column sort icon in a wpf datagrid column.
I have the following code to do this:
private void dtgMain_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
{
dtgMain.Columns[0].SortDirection = ListSortDirection.Ascending;
}
This seems to set the sort order of the column but when the grid is drawn the icon does not show.
When I add a message box into the method it works fine. My question is twofold. Why would the message box cause the method to work? And how can I get it to work without the use of a messagebox?
This is the method working with the messagebox in it:
private void dtgMain_DataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
{
MessageBox.Show("Here");
dtgMain.Columns[0].SortDirection = ListSortDirection.Ascending;
}
edit
Here is the method that is setting the datacontext of the datagrid
public void processLoad(string response)
{
XmlDataProvider provider = new XmlDataProvider();
if (provider != null)
{
System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
doc.LoadXml(response);
provider.Document = doc;
provider.XPath = "/moo/response/data/load/panel";
dtgMain.DataContext = provider;
}
}
Please let me know if you need anymore information.
OK, I suspect what is happening is that the data layout changes caused by the DataContext update are being completed after your call to set the direction arrow, and it is therefore being erased after you set it. Interestingly, in my case it failed to work even when I put the messagebox in, perhaps because that was hanging up the UI thread while it displayed.
Could you try replacing the line that sets the sort direction with a similar call put on the dispatcher queue:
dtgMain.Dispatcher.BeginInvoke(new Action(() =>
{
dtgMain.Columns[0].SortDirection = ListSortDirection.Ascending;
}), DispatcherPriority.ApplicationIdle);
and see if that works?
When I change the datasource of my Listbox all items are cleared, when loading new data into this Listbox it stays clear.
I have another ListBox right new to this one with the same refresh code but that one refreshes perfectly.
private void RefreshContacts()
{
this.ListContacts.DataSource = null;
this.ListContacts.DataSource = this.contacts;
this.BoxCountContacts.Text = this.ListContacts.Items.Count.ToString();
}
Anyone have an idea how to fix the listbox from being cleared and bugged?
Here is the full refresh codes of the two listboxes
private Contact[] contacts, feed; private Boolean isFeed;
internal ArcFeed()
{
this.InitializeComponent();
this.contacts = this.feed = new Contact[0];
}
private void RefreshForm(Boolean isFeed)
{
if (isFeed)
{
this.RefreshFeed();
}
else
{
this.RefreshContacts();
}
}
private void RefreshContacts()
{
this.ListContacts.DataSource = null;
this.ListContacts.DataSource = this.contacts;
this.BoxCountContacts.Text = this.ListContacts.Items.Count.ToString();
}
private void RefreshFeed()
{
this.ListFeed.DataSource = null;
this.ListFeed.DataSource = this.feed;
this.BoxCountFeed.Text = this.ListFeed.Items.Count.ToString();
}
private void OpenFile()
{
if (this.isFeed)
{
this.BoxFileFeed.Text = this.DialogOpen.FileName;
this.feed = ArcBuzz.Load(this.DialogOpen.FileName);
}
else
{
this.BoxFileContacts.Text = this.DialogOpen.FileName;
this.contacts = ArcBuzz.Load(this.DialogOpen.FileName);
}
this.RefreshForm(this.isFeed);
}
All code is debugged and follows it's course properly, I don't see any errors, the correct listbox's datasource are set and changed.
Just to make sure, have you checked that there are actually items in the contacts collection?
Also, if you've got two Listboxes, double check that you are using the right Listbox in each of the refresh code sections.
Sounds stupid, but its silly mistakes like this that get overlooked a lot of the time. With databinding its usually something small like this stopping it working.
Earlier today i was suggested in here to use a DataGridView to print messages that needed a individual mark as read.
I followed the suggestion, and with some reading online i managed to bind it to my message list with the following results after some tweaking.
alt text http://img237.imageshack.us/img237/3015/datagridview.jpg
Currently i have 2 issues, the first one is that i didn't find a way to resize the row height to display the full message, and the second one is that when the list is updated, the DataGridView doesn't display the modifications.
Any way to solve both problems? Or do i need to use something other than DataGridView, and in that case what should i be using?
Also, is there any way to urls contained in the message to become clickable and be opened in the default browser?
EDIT
More info in relation to the binding.
Basically i have a class variable inside the form, and i do the initial binding with a button.
private void button1_Click(object sender, EventArgs e)
{
list.Add(new Class1() { Message = "http://www.google.com/", Read = false });
list.Add(new Class1() { Message = "Message way too long to fit in this small column width", Read = false });
dataGridView1.DataSource = list;
}
I then have another button that adds some more entries just to test it, and i know the list is properly updated, but there are no changes in the dataGridView.
EDIT 2
If i wasn't clear before i need for the width to be fixed, and the cell height that contains the long text to be enlarged and display the text in 2 lines
have you checked the options in the EditColumn using smart tag ?
you can add column of type
DataGridViewLinkColumn, set its Text property to Message
Try removing any value from width
and height properties for a
column. In this way, it will set the
column size (cell) size according to
the data size.
hope this helps
I'll take a stab and see if I can help.
First off the row height. There are two DataGridView Methods called AutoResizeRow and AutoResizeRows which will adjust the height of the row to fit the contents.
Can you show us how you are binding your data to the DataViewGrid and how the data might be modified? That will help with the modifications not updating.
As for the link, unfortunately I can't seem to find an object which handles this sort of thing natively. Most likely you will first have to decide if the text going into the DataGridView is a link (using a Regular Expression, if you were me). Second, display it differently in the DataGridView (underline it, make it blue). Third, put a click event on it and when that cell is clicked handle that by throwing it out to a browser. I will look a little further into it though since this seems like a lot of work (and I will keep my fingers crossed that someone knows better than I do).
Regarding the list not updating; there are two issues;
To notice add/remove, you need list binding events. The easiest way to do this is to ensure you use a BindingList<YourClass> rather than a List<YourClass>.
To notice changes to individual properties (in this context) you'll need to implement INotifyPropertyChanged on your type:
public class YourClass : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
private void OnPropertyChanged(string propertyName)
{
PropertyChangedEventHandler handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
private string message;
public string Message
{
get { return message; }
set { message = value; OnPropertyChanged("Message"); }
}
public bool isRead;
[DisplayName("Read")]
public bool IsRead
{
get { return isRead; }
set { isRead = value; OnPropertyChanged("IsRead"); }
}
}
For an example showing binding that to a list:
[STAThread]
static void Main()
{
Application.EnableVisualStyles();
BindingList<YourClass> list = new BindingList<YourClass>();
DataGridView grid = new DataGridView();
grid.Dock = DockStyle.Fill;
grid.DataSource = list;
Button add = new Button();
add.Text = "Add";
add.Dock = DockStyle.Bottom;
add.Click += delegate
{
YourClass newObj = new YourClass();
newObj.Message = DateTime.Now.ToShortTimeString();
list.Add(newObj);
};
Button edit = new Button();
edit.Text = "Edit";
edit.Dock = DockStyle.Bottom;
edit.Click += delegate
{
if (list.Count > 0)
{
list[0].Message = "Boo!";
list[0].IsRead = !list[0].IsRead;
}
};
Form form = new Form();
form.Controls.Add(grid);
form.Controls.Add(add);
form.Controls.Add(edit);
Application.Run(form);
}