Develop Reference

Differentiate items loading to list vs scroll event Xamarin forms listview

This is my code that can successfully detect scroll up or down:
MyListView.ItemAppearing += async (object sender, ItemVisibilityEventArgs e) =>
{
var currentIdx = CurrentList.IndexOf((MyClass)e.Item);
if (currentIdx > _lastItemAppearedIdx)
ShowChopped();
else
ShowFull();
_lastItemAppearedIdx = CurrentList.IndexOf((MyClass)e.Item);
};
What is working is the following: Items get added to the list, then once i start scrolling it works fine where ShowChoppedand ShowFull are methods with animations that just makes a simple animation to either half the size of an object or make it full. This works fine, but if i however click a new category that changes the content in the list, ItemAppearing gets triggered of course and ShowChoppedand ShowFull are called even though i only want it called during a scrollevent.
How would i be able to differentiate a scroll to a item collection change? I have only tried this on iOS.
Updated code:
public class ListView_iOS : ListViewRenderer
{
private IDisposable _offsetObserver;
private double _prevYOffset;
private IListView _myListView;
protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.ListView> e)
{
base.OnElementChanged(e);
if (e.NewElement is IListView)
_offsetObserver = Control.AddObserver("contentOffset",
Foundation.NSKeyValueObservingOptions.New, HandleAction);
}
private static bool CloseTo(double x, double y)
{
return Math.Abs(x - y) < 0.1;
}
private void HandleAction(Foundation.NSObservedChange obj)
{
var effectiveY = Math.Max(Control.ContentOffset.Y, 0);
if (!CloseTo(effectiveY, _prevYOffset) && Element is IListView)
{
var myList = Element as IListView;
myList.IsScrolling = true;
}
}
}

You can differentiate items loading from list scrolling by
1 adding the code if (EmployeeView.IsScrolling) within ItemAppearing method.
2 adding the code EmployeeView.IsScrolling = false; within any function you write to change the appearing of items without scrolling action, for example, when you add items or change category.
And the EmployeeView.IsScrolling value is set from listview renderer.
So the code is like:
NativeListView.cs
public class NativeListView : ListView
{
public static readonly BindableProperty
IsScrollingProperty =
BindableProperty.Create(nameof(IsScrolling),
typeof(bool), typeof(NativeListView), false);
public bool IsScrolling
{
get { return (bool)GetValue(IsScrollingProperty); }
set { SetValue(IsScrollingProperty, value); }
}
}
NativeAndroidListViewRenderer.cs
[assembly: ExportRenderer(typeof(NativeListView), typeof(NativeAndroidListViewRenderer))]
namespace App2.Droid
{
public class NativeAndroidListViewRenderer : ListViewRenderer
{
public NativeAndroidListViewRenderer(Context context) : base(context)
{
}
protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.ListView> e)
{
base.OnElementChanged(e);
if (e.NewElement is NativeListView)
Control.Scroll += Control_Scroll;
}
private void Control_Scroll(object sender, AbsListView.ScrollEventArgs e)
{
var myList = Element as NativeListView;
myList.IsScrolling = true;
}
}
}
NativeiOSListViewRenderer.cs
private IDisposable _offsetObserver;
private double _prevYOffset;
protected override void OnElementChanged(ElementChangedEventArgs<Xamarin.Forms.ListView> e)
{
base.OnElementChanged(e);
if (e.NewElement is NativeListView)
_offsetObserver = Control.AddObserver("contentOffset",
Foundation.NSKeyValueObservingOptions.New, HandleAction);
}
private void HandleAction(Foundation.NSObservedChange obj)
{
var effectiveY = Math.Max(Control.ContentOffset.Y, 0);
if (!CloseTo(effectiveY, _prevYOffset) && Element is NativeListView)
{
var myList = Element as NativeListView;
myList.IsScrolling = true;
_prevYOffset = effectiveY;
}
}
private static bool CloseTo(double x, double y)
{
return Math.Abs(x - y) < 0.1;
}
protected override void Dispose(bool disposing)
{
base.Dispose(disposing);
if (disposing && _offsetObserver != null)
{
_offsetObserver.Dispose();
_offsetObserver = null;
}
}
MainPage.xaml.cs
namespace App2
{
public partial class MainPage : ContentPage
{
ObservableCollection<String> employeeList = new ObservableCollection<String>();
int count = 0;
public MainPage()
{
InitializeComponent();
AddButtion.Clicked += AddButtion_Clicked;
DelButtion.Clicked += DelButtion_Clicked;
EmployeeView.ItemsSource = employeeList;
EmployeeView.ItemAppearing += async (object sender, ItemVisibilityEventArgs e) =>
{
if (EmployeeView.IsScrolling) {
await DisplayAlert("ItemAppearing", e.Item + " row is appearing", "OK");
Console.WriteLine("ItemAppearing!!!!!!!!!!");
}
};
}
private void AddButtion_Clicked(object sender, EventArgs e)
{
employeeList.Add("Mr. Mono"+ count++);
EmployeeView.IsScrolling = false;
}
private void DelButtion_Clicked(object sender, EventArgs e)
{
if (employeeList.Count > 0) {
employeeList.RemoveAt(0);
}
EmployeeView.IsScrolling = false;
}
}
}

ErrorProvider - Change BackColor Instead of Showing Icon

I'm stuck with some legacy code that I want to upgrade a bit. I want to change the way the ErrorProvider shows the error status on a Control. Default behavior is the Icon, and a ToolTip if you hover on the icon.
I would like to change this behavior to be more similar to what we use in our WPF controls. Which is a red back-color(Salmon pink) and the tool-tip on the control itself.
Any tips, links or some way forward
EDIT.
See my answer below, on what i ended up with.

ErrorProvider component doesn't support this feature and if you need it you can create it yourself.
You can subscribe to BindingComplete event of a BindingManagerBase and then you can use the event arg which is of type BindingCompleteEventArgs that contains some useful properties:
ErrorText to determine if there is an error in data-binding
Binding.Control to determine the control which is bounded to
These are enough for us to implement our solution.
Code
Here is a sample code which shows how can you handle BindingComplete event and use it to change BackColor and tool-tip of a control based on it's valid or invalid state.
Suppose you have a binding source, myBindingSource which is bound to a SampleModel class which is implemented IDataErrorInfo. You can subscribe to BindingComplete event of this.BindingContext[this.myBindingSource]:
private void Form1_Load(object sender, EventArgs e)
{
this.myBindingSource.DataSource = new SampleModel();
var bindingManager = this.BindingContext[this.myBindingSource];
bindingManager.BindingComplete += bindingManager_BindingComplete;
}
Dictionary<Control, Color> Items = new Dictionary<Control, Color>();
private void bindingManager_BindingComplete(object sender, BindingCompleteEventArgs e)
{
var control = e.Binding.Control;
//Store Original BackColor
if (!Items.ContainsKey(control))
Items[control] = control.BackColor;
//Check If there is an error
if (!string.IsNullOrEmpty(e.ErrorText))
{
control.BackColor = Color.Salmon;
this.errorToolTip.SetToolTip(control, e.ErrorText);
}
else
{
e.Binding.Control.BackColor = Items[e.Binding.Control];
this.errorToolTip.SetToolTip(control, null);
}
}

Thank you Reza Aghaei. This is what i came up with based on your comment and some additional searching... Some of this code comes from msdn resource
using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.Design;
using System.Drawing;
using System.Linq;
using System.Security.Permissions;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
namespace ErrorProvider
{
class BackgroundColorErrorProvider: Component, IExtenderProvider, ISupportInitialize
{
public BackgroundColorErrorProvider()
{
currentChanged = new EventHandler(ErrorManager_CurrentChanged);
}
public BackgroundColorErrorProvider(ContainerControl parentControl)
: this()
{
this.parentControl = parentControl;
propChangedEvent = new EventHandler(ParentControl_BindingContextChanged);
parentControl.BindingContextChanged += propChangedEvent;
}
public BackgroundColorErrorProvider(IContainer container)
: this()
{
if (container == null) {
throw new ArgumentNullException("container");
}
container.Add(this);
}
public bool CanExtend(object extendee)
{
return extendee is Control && !(extendee is Form) && !(extendee is ToolBar);
}
private bool inSetErrorManager = false;
private object dataSource;
private string dataMember = null;
private ContainerControl parentControl;
private BindingManagerBase errorManager;
private bool initializing;
private EventHandler currentChanged;
private EventHandler propChangedEvent;
private Dictionary<Control, Color> originalColor = new Dictionary<Control, Color>();
private Color errorBackgroundColor;
public ContainerControl ContainerControl
{
[UIPermission(SecurityAction.LinkDemand, Window = UIPermissionWindow.AllWindows)]
[UIPermission(SecurityAction.InheritanceDemand, Window = UIPermissionWindow.AllWindows)]
get
{
return parentControl;
}
set
{
if (parentControl != value)
{
if (parentControl != null)
parentControl.BindingContextChanged -= propChangedEvent;
parentControl = value;
if (parentControl != null)
parentControl.BindingContextChanged += propChangedEvent;
Set_ErrorManager(this.DataSource, this.DataMember, true);
}
}
}
public string DataMember
{
get { return dataMember; }
set
{
if (value == null) value = "";
Set_ErrorManager(this.DataSource, value, false);
}
}
public object DataSource
{
get { return dataSource; }
set
{
if ( parentControl != null && value != null && String.IsNullOrEmpty(this.dataMember))
{
// Let's check if the datamember exists in the new data source
try
{
errorManager = parentControl.BindingContext[value, this.dataMember];
}
catch (ArgumentException)
{
// The data member doesn't exist in the data source, so set it to null
this.dataMember = "";
}
}
Set_ErrorManager(value, this.DataMember, false);
}
}
public override ISite Site
{
set
{
base.Site = value;
if (value == null)
return;
IDesignerHost host = value.GetService(typeof(IDesignerHost)) as IDesignerHost;
if (host != null)
{
IComponent baseComp = host.RootComponent;
if (baseComp is ContainerControl)
{
this.ContainerControl = (ContainerControl)baseComp;
}
}
}
}
private ToolTip toolTip;
public ToolTip ToolTip
{
get { return toolTip; }
set { toolTip = value; }
}
public Color ErrorBackgroundColor
{
get { return errorBackgroundColor; }
set { errorBackgroundColor = value; }
}
private void Set_ErrorManager(object newDataSource, string newDataMember, bool force)
{
if (inSetErrorManager)
return;
inSetErrorManager = true;
try
{
bool dataSourceChanged = this.DataSource != newDataSource;
bool dataMemberChanged = this.DataMember != newDataMember;
//if nothing changed, then do not do any work
//
if (!dataSourceChanged && !dataMemberChanged && !force)
{
return;
}
// set the dataSource and the dataMember
//
this.dataSource = newDataSource;
this.dataMember = newDataMember;
if (!initializing)
{
UnwireEvents(errorManager);
// get the new errorManager
//
if (parentControl != null && this.dataSource != null && parentControl.BindingContext != null)
{
errorManager = parentControl.BindingContext[this.dataSource, this.dataMember];
}
else
{
errorManager = null;
}
// wire the events
//
WireEvents(errorManager);
// see if there are errors at the current
// item in the list, w/o waiting for the position to change
if (errorManager != null)
UpdateBinding();
}
}
finally
{
inSetErrorManager = false;
}
}
public void UpdateBinding()
{
ErrorManager_CurrentChanged(errorManager, EventArgs.Empty);
}
private void UnwireEvents(BindingManagerBase listManager)
{
if (listManager != null)
{
listManager.CurrentChanged -= currentChanged;
listManager.BindingComplete -= new BindingCompleteEventHandler(this.ErrorManager_BindingComplete);
CurrencyManager currManager = listManager as CurrencyManager;
if (currManager != null)
{
currManager.ItemChanged -= new ItemChangedEventHandler(this.ErrorManager_ItemChanged);
currManager.Bindings.CollectionChanged -= new CollectionChangeEventHandler(this.ErrorManager_BindingsChanged);
}
}
}
private void WireEvents(BindingManagerBase listManager)
{
if (listManager != null)
{
listManager.CurrentChanged += currentChanged;
listManager.BindingComplete += new BindingCompleteEventHandler(this.ErrorManager_BindingComplete);
CurrencyManager currManager = listManager as CurrencyManager;
if (currManager != null)
{
currManager.ItemChanged += new ItemChangedEventHandler(this.ErrorManager_ItemChanged);
currManager.Bindings.CollectionChanged += new CollectionChangeEventHandler(this.ErrorManager_BindingsChanged);
}
}
}
private void ErrorManager_BindingsChanged(object sender, CollectionChangeEventArgs e)
{
ErrorManager_CurrentChanged(errorManager, e);
}
private void ParentControl_BindingContextChanged(object sender, EventArgs e)
{
Set_ErrorManager(this.DataSource, this.DataMember, true);
}
private void ErrorManager_ItemChanged(object sender, ItemChangedEventArgs e)
{
BindingsCollection errBindings = errorManager.Bindings;
int bindingsCount = errBindings.Count;
// If the list became empty then reset the errors
if (e.Index == -1 && errorManager.Count == 0)
{
for (int j = 0; j < bindingsCount; j++)
{
if ((errBindings[j].Control != null))
{
// ...ignore everything but bindings to Controls
SetError(errBindings[j].Control, "");
}
}
}
else
{
ErrorManager_CurrentChanged(sender, e);
}
}
private void SetError(Control control, string p)
{
if (String.IsNullOrEmpty(p))
{
if (originalColor.ContainsKey(control))
control.BackColor = originalColor[control];
toolTip.SetToolTip(control, null);
}
else
{
control.BackColor = ErrorBackgroundColor;
toolTip.SetToolTip(control, p);
}
}
private void ErrorManager_BindingComplete(object sender, BindingCompleteEventArgs e)
{
Binding binding = e.Binding;
if (binding != null && binding.Control != null)
{
SetError(binding.Control, (e.ErrorText == null ? String.Empty : e.ErrorText));
}
}
private void ErrorManager_CurrentChanged(object sender, EventArgs e)
{
if (errorManager.Count == 0)
{
return;
}
object value = errorManager.Current;
if (!(value is IDataErrorInfo))
{
return;
}
BindingsCollection errBindings = errorManager.Bindings;
int bindingsCount = errBindings.Count;
// We can only show one error per control, so we will build up a string...
//
Hashtable controlError = new Hashtable(bindingsCount);
for (int j = 0; j < bindingsCount; j++)
{
// Ignore everything but bindings to Controls
if (errBindings[j].Control == null)
{
continue;
}
string error = ((IDataErrorInfo)value)[errBindings[j].BindingMemberInfo.BindingField];
if (error == null)
{
error = "";
}
string outputError = "";
if (controlError.Contains(errBindings[j].Control))
outputError = (string)controlError[errBindings[j].Control];
// VSWhidbey 106890: Utilize the error string without including the field name.
if (String.IsNullOrEmpty(outputError))
{
outputError = error;
}
else
{
outputError = string.Concat(outputError, "\r\n", error);
}
controlError[errBindings[j].Control] = outputError;
}
IEnumerator enumerator = controlError.GetEnumerator();
while (enumerator.MoveNext())
{
DictionaryEntry entry = (DictionaryEntry)enumerator.Current;
SetError((Control)entry.Key, (string)entry.Value);
}
}
public void BeginInit()
{
initializing = true;
}
public void EndInit()
{
initializing = false;
Set_ErrorManager(this.DataSource, this.DataMember, true);
}
}
}

Set tooltip on range of text in wpf richtextbox

I am trying to set a tooltip on an arbitrary range of text on a richtextbox. Is this possible? If so how would I do it e.g by passing in parameters "from" and "to" as (int) indexes.
Thanks

You could use the following as a starting point:
Add a reference to System.Windows.Interactivity.
Add the following classes to your project:
public class TextRangeToolTip
{
public int StartPosition { get; set; }
public int Length { get; set; }
public object ToolTip { get; set; }
internal bool IsInRange(int position)
{
return this.StartPosition <= position && position < this.StartPosition + this.Length;
}
}
public class TextRangeToolTipCollection : ObservableCollection<TextRangeToolTip> {}
[ContentProperty("Ranges")]
public class ToolTipBehavior : Behavior<RichTextBox>
{
private const int ToolTipHideMouseDelta = 9;
public static readonly DependencyProperty RangesProperty
= DependencyProperty.Register("Ranges", typeof(TextRangeToolTipCollection),
typeof (ToolTipBehavior),
new PropertyMetadata(OnRangesChanged));
private readonly DispatcherTimer timer;
private readonly ToolTip toolTip;
private Point lastMousePosition;
public TextRangeToolTipCollection Ranges
{
get
{
return (TextRangeToolTipCollection)this.GetValue(RangesProperty)
?? (this.Ranges = new TextRangeToolTipCollection());
}
set { this.SetValue(RangesProperty, value); }
}
public ToolTipBehavior()
{
this.Ranges = new TextRangeToolTipCollection();
this.timer = new DispatcherTimer();
this.timer.Tick += this.TimerOnTick;
this.timer.Interval = TimeSpan.FromSeconds(1);
this.toolTip = new ToolTip {Placement = PlacementMode.Relative};
}
protected override void OnAttached()
{
this.AssociatedObject.ToolTip = this.toolTip;
this.toolTip.PlacementTarget = this.AssociatedObject;
ToolTipService.SetIsEnabled(this.AssociatedObject, false);
this.AssociatedObject.MouseMove += this.AssociatedObjectOnMouseMove;
}
protected override void OnDetaching()
{
this.timer.Stop();
this.toolTip.PlacementTarget = null;
this.AssociatedObject.ToolTip = null;
this.AssociatedObject.ClearValue(ToolTipService.IsEnabledProperty);
this.AssociatedObject.MouseMove -= this.AssociatedObjectOnMouseMove;
}
private void AssociatedObjectOnMouseMove(object sender, MouseEventArgs mouseEventArgs)
{
Point currentMousePosition = mouseEventArgs.GetPosition(this.AssociatedObject);
if (this.AssociatedObject.IsMouseCaptured)
{
Vector delta = currentMousePosition
- this.lastMousePosition;
if (delta.X*delta.X + delta.Y*delta.Y <= ToolTipHideMouseDelta)
{
this.toolTip.HorizontalOffset = currentMousePosition.X + 10;
this.toolTip.VerticalOffset = currentMousePosition.Y + 10;
return;
}
this.AssociatedObject.ReleaseMouseCapture();
this.toolTip.IsOpen = false;
}
if (this.AssociatedObject.IsMouseOver)
{
this.lastMousePosition = currentMousePosition;
this.timer.Stop();
this.timer.Start();
}
}
private static void OnRangesChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
((ToolTipBehavior) d).OnRangesChanged((IEnumerable<TextRangeToolTip>) e.OldValue,
(IEnumerable<TextRangeToolTip>) e.NewValue);
}
private void OnRangesChanged(IEnumerable<TextRangeToolTip> oldRanges, IEnumerable<TextRangeToolTip> newRanges)
{
var oldObservable = oldRanges as INotifyCollectionChanged;
if (oldObservable != null)
{
CollectionChangedEventManager.RemoveHandler(oldObservable, this.OnRangesCollectionChanged);
}
var newObservable = newRanges as INotifyCollectionChanged;
if (newObservable != null)
{
CollectionChangedEventManager.AddHandler(newObservable, this.OnRangesCollectionChanged);
}
this.UpdateToolTip();
}
private void OnRangesCollectionChanged(
object sender,
NotifyCollectionChangedEventArgs notifyCollectionChangedEventArgs)
{
this.UpdateToolTip();
}
private bool SetToolTipData()
{
if (this.Ranges == null)
{
return false;
}
TextPointer pointer = this.AssociatedObject.GetPositionFromPoint(this.lastMousePosition, false);
if (pointer == null)
{
return false;
}
int position = this.AssociatedObject.Document.ContentStart.GetOffsetToPosition(pointer);
TextRangeToolTip matchingRange = this.Ranges.FirstOrDefault(r => r.IsInRange(position));
if (matchingRange == null)
{
return false;
}
this.toolTip.Content = matchingRange.ToolTip;
return true;
}
private void TimerOnTick(object sender, EventArgs eventArgs)
{
this.timer.Stop();
if (this.AssociatedObject.IsMouseOver && this.SetToolTipData())
{
this.toolTip.IsOpen = true;
this.AssociatedObject.CaptureMouse();
}
}
private void UpdateToolTip()
{
if (this.AssociatedObject != null && this.AssociatedObject.IsMouseCaptured && !this.SetToolTipData())
{
this.toolTip.IsOpen = false;
this.AssociatedObject.ReleaseMouseCapture();
}
}
}
Use it on your RichTextBox like this:
<RichTextBox>
<i:Interaction.Behaviors>
<myapp:ToolTipBehavior>
<myapp:TextRangeToolTip StartPosition="10" Length="4" ToolTip="some" />
<myapp:TextRangeToolTip StartPosition="15" Length="4" ToolTip="text" />
</myapp:ToolTipBehavior>
</i:Interaction.Behaviors>
<FlowDocument>
<Paragraph>This is some text. This is some other text.</Paragraph>
</FlowDocument>
</RichTextBox>
Alternatively, you can bind a TextRangeToolTipCollection to the Ranges property like this:
<RichTextBox Document="{Binding Document}">
<i:Interaction.Behaviors>
<myapp:ToolTipBehavior Ranges="{Binding RangeToolTips}" />
</i:Interaction.Behaviors>
</RichTextBox>
Getting the positions right is a bit tricky, because WPF counts symbols, not characters. You could extend the TextRangeToolTip class to have properties of type TextPointer or TextRange and construct it using your FlowDocument instance.

how to check multiple row in DevExpress CheckEdit

This is my code
gridView1.Columns.Add(new DevExpress.XtraGrid.Columns.GridColumn()
{
Caption = "Selected",
ColumnEdit = new RepositoryItemCheckEdit() { },
VisibleIndex = 1,
UnboundType = DevExpress.Data.UnboundColumnType.Boolean
});
But I cant check multiple checkEdit at the same time.
Why was that?
And please show me the way out.
Thanks.

Well, there are two answers to that question, one very simple, and one very complex, let's start with the simple:
If you want to have an column that has the "Selected" caption and act as a checkbox to indicate that a particular record was selected, you have two options:
1) If you can alter the class in your data source to add a property that is bool and could be used with DataBinding, then, all is done in a very simple way, jast add the property and bind the data and it will work:
class SimplePerson
{
public string Name { get; set; }
public bool IsSelected { get; set; }
}
BindingList<SimplePerson> source = new BindingList<SimplePerson>();
void InitGrid()
{
source.Add(new SimplePerson() { Name = "John", IsSelected = false });
source.Add(new SimplePerson() { Name = "Gabriel", IsSelected = true });
gridControl.DataSource = source;
}
2) You cannot alter you classes, so you need to this by signing the correct grid events and drawing the column yourself, and also adding the right handlers for all the actions.... is a very complex case, but for your luck i have this done, because i have had this problem in the past, so i will post you my full class!
public class GridCheckMarksSelection
{
public event EventHandler SelectionChanged;
protected GridView _view;
protected ArrayList _selection;
private GridColumn _column;
private RepositoryItemCheckEdit _edit;
public GridView View
{
get { return _view; }
set
{
if (_view == value)
return;
if (_view != null)
Detach();
_view = value;
Attach();
}
}
public GridColumn CheckMarkColumn { get { return _column; } }
public int SelectedCount { get { return _selection.Count; } }
public GridCheckMarksSelection()
{
_selection = new ArrayList();
}
public GridCheckMarksSelection(GridView view)
: this()
{
this.View = view;
}
protected virtual void Attach()
{
if (View == null)
return;
_selection.Clear();
_view = View;
_edit = View.GridControl.RepositoryItems.Add("CheckEdit")
as RepositoryItemCheckEdit;
_edit.EditValueChanged += edit_EditValueChanged;
_column = View.Columns.Insert(0);
_column.OptionsColumn.AllowSort = DefaultBoolean.False;
_column.VisibleIndex = int.MinValue;
_column.FieldName = "CheckMarkSelection";
_column.Caption = "Mark";
_column.OptionsColumn.ShowCaption = false;
_column.UnboundType = UnboundColumnType.Boolean;
_column.ColumnEdit = _edit;
View.CustomDrawColumnHeader += View_CustomDrawColumnHeader;
View.CustomDrawGroupRow += View_CustomDrawGroupRow;
View.CustomUnboundColumnData += view_CustomUnboundColumnData;
View.MouseUp += view_MouseUp;
}
protected virtual void Detach()
{
if (_view == null)
return;
if (_column != null)
_column.Dispose();
if (_edit != null)
{
_view.GridControl.RepositoryItems.Remove(_edit);
_edit.Dispose();
}
_view.CustomDrawColumnHeader -= View_CustomDrawColumnHeader;
_view.CustomDrawGroupRow -= View_CustomDrawGroupRow;
_view.CustomUnboundColumnData -= view_CustomUnboundColumnData;
_view.MouseDown -= view_MouseUp;
_view = null;
}
protected virtual void OnSelectionChanged(EventArgs e)
{
if (SelectionChanged != null)
SelectionChanged(this, e);
}
protected void DrawCheckBox(Graphics g, Rectangle r, bool Checked)
{
var info = _edit.CreateViewInfo() as CheckEditViewInfo;
var painter = _edit.CreatePainter() as CheckEditPainter;
ControlGraphicsInfoArgs args;
info.EditValue = Checked;
info.Bounds = r;
info.CalcViewInfo(g);
args = new ControlGraphicsInfoArgs(info, new GraphicsCache(g), r);
painter.Draw(args);
args.Cache.Dispose();
}
private void view_MouseUp(object sender, MouseEventArgs e)
{
if (e.Clicks == 1 && e.Button == MouseButtons.Left)
{
GridHitInfo info;
var pt = _view.GridControl.PointToClient(Control.MousePosition);
info = _view.CalcHitInfo(pt);
if (info.InRow && _view.IsDataRow(info.RowHandle))
UpdateSelection();
if (info.InColumn && info.Column == _column)
{
if (SelectedCount == _view.DataRowCount)
ClearSelection();
else
SelectAll();
}
if (info.InRow && _view.IsGroupRow(info.RowHandle)
&& info.HitTest != GridHitTest.RowGroupButton)
{
bool selected = IsGroupRowSelected(info.RowHandle);
SelectGroup(info.RowHandle, !selected);
}
}
}
private void View_CustomDrawColumnHeader
(object sender, ColumnHeaderCustomDrawEventArgs e)
{
if (e.Column != _column)
return;
e.Info.InnerElements.Clear();
e.Painter.DrawObject(e.Info);
DrawCheckBox(e.Graphics, e.Bounds, SelectedCount == _view.DataRowCount);
e.Handled = true;
}
private void View_CustomDrawGroupRow
(object sender, RowObjectCustomDrawEventArgs e)
{
var info = e.Info as GridGroupRowInfo;
info.GroupText = " " + info.GroupText.TrimStart();
e.Info.Paint.FillRectangle
(e.Graphics, e.Appearance.GetBackBrush(e.Cache), e.Bounds);
e.Painter.DrawObject(e.Info);
var r = info.ButtonBounds;
r.Offset(r.Width * 2, 0);
DrawCheckBox(e.Graphics, r, IsGroupRowSelected(e.RowHandle));
e.Handled = true;
}
private void view_CustomUnboundColumnData
(object sender, CustomColumnDataEventArgs e)
{
if (e.Column != CheckMarkColumn)
return;
if (e.IsGetData)
e.Value = IsRowSelected(View.GetRowHandle(e.ListSourceRowIndex));
else
SelectRow(View.GetRowHandle(e.ListSourceRowIndex), (bool)e.Value);
}
private void edit_EditValueChanged(object sender, EventArgs e)
{
_view.PostEditor();
}
private void SelectRow(int rowHandle, bool select, bool invalidate)
{
if (IsRowSelected(rowHandle) == select)
return;
object row = _view.GetRow(rowHandle);
if (select)
_selection.Add(row);
else
_selection.Remove(row);
if (invalidate)
Invalidate();
OnSelectionChanged(EventArgs.Empty);
}
public object GetSelectedRow(int index)
{
return _selection[index];
}
public int GetSelectedIndex(object row)
{
return _selection.IndexOf(row);
}
public void ClearSelection()
{
_selection.Clear();
View.ClearSelection();
Invalidate();
OnSelectionChanged(EventArgs.Empty);
}
private void Invalidate()
{
_view.CloseEditor();
_view.BeginUpdate();
_view.EndUpdate();
}
public void SelectAll()
{
_selection.Clear();
var dataSource = _view.DataSource as ICollection;
if (dataSource != null && dataSource.Count == _view.DataRowCount)
_selection.AddRange(dataSource); // fast
else
for (int i = 0; i < _view.DataRowCount; i++) // slow
_selection.Add(_view.GetRow(i));
Invalidate();
OnSelectionChanged(EventArgs.Empty);
}
public void SelectGroup(int rowHandle, bool select)
{
if (IsGroupRowSelected(rowHandle) && select) return;
for (int i = 0; i < _view.GetChildRowCount(rowHandle); i++)
{
int childRowHandle = _view.GetChildRowHandle(rowHandle, i);
if (_view.IsGroupRow(childRowHandle))
SelectGroup(childRowHandle, select);
else
SelectRow(childRowHandle, select, false);
}
Invalidate();
}
public void SelectRow(int rowHandle, bool select)
{
SelectRow(rowHandle, select, true);
}
public bool IsGroupRowSelected(int rowHandle)
{
for (int i = 0; i < _view.GetChildRowCount(rowHandle); i++)
{
int row = _view.GetChildRowHandle(rowHandle, i);
if (_view.IsGroupRow(row))
if (!IsGroupRowSelected(row))
return false;
else
if (!IsRowSelected(row))
return false;
}
return true;
}
public bool IsRowSelected(int rowHandle)
{
if (_view.IsGroupRow(rowHandle))
return IsGroupRowSelected(rowHandle);
object row = _view.GetRow(rowHandle);
return GetSelectedIndex(row) != -1;
}
public void UpdateSelection()
{
_selection.Clear();
Array.ForEach(View.GetSelectedRows(), item => SelectRow(item, true));
}
}
And now you need to know how to use this:
void InitGrid()
{
gridControl.DataSource = source;
// Do this after the database for the grid is set!
selectionHelper = new GridCheckMarksSelection(gridView1);
// Define where you want the column (0 = first)
selectionHelper.CheckMarkColumn.VisibleIndex = 0;
// You can even subscrive to the event that indicates that
// there was change in the selection.
selectionHelper.SelectionChanged += selectionHelper_SelectionChanged;
}
void selectionHelper_SelectionChanged(object sender, EventArgs e)
{
// Do something when the user selects or unselects something
}
But how do you retrieve all the selected items? There is a example assuming that the type bond is 'Person'
/// <summary>
/// Return all selected persons from the Grid
/// </summary>
public IList<Person> GetItems()
{
var ret = new List<Person>();
Array.ForEach
(
gridView1.GetSelectedRows(),
cell => ret.Add(gridView1.GetRow(cell) as Person)
);
return ret;
}

Asp.net Custom Server Control: When and how to retrieve value of hidden field to feed property?

I'm trying to develop a Custom ASP.Net Server Control, which can be manipulated at the client. To save the changes after a Postback there is a hidden field. On the OnLoad event I retrieve the value to write the Property, but it seems too late, because the controls are already built. I know I could manipulate the controls on the PreRender event, but to me it seems there is a better way to handle this. Anyone an idea?
public class Control : CompositeControl {
private bool mProperty;
private HiddenField hiddenField;
public virtual bool Property {
get {
return mProperty;
}
set {
mProperty = value;
}
}
protected override void CreateChildControls() {
Controls.Clear();
CreateControlHierarchy();
ClearChildViewState();
}
protected virtual void CreateControlHierarchy() {
CreateHiddenField();
CreateContent();
}
protected virtual void CreateHiddenField() {
hiddenField = new HiddenField();
hiddenField.ID = "hiddenField";
hiddenField.Value = Property.ToString().ToLower();
Controls.Add(hiddenField);
}
protected virtual void CreateContent() {
contentPanel = new Panel();
contentPanel.ID = "content";
contentPanel.Vsiible = Property;
Controls.Add(contentPanel);
}
protected override void OnLoad(EventArgs e) {
base.OnLoad(e);
if(Page.IsPostback) {
Property = Convert.ToBoolean(Page.Request.Form[hiddenField.UniqueId]);
}
}
}
Edit Possible Solution:
I got rid of the OnLoad event and edited the property like so:
public virtual bool Property {
get {
if (Page.IsPostBack) {
EnsureChildControls();
return Convert.ToBoolean(Page.Request.Form[hiddenField.UniqueID]);
}
return mProperty;
}
set {
mProperty = value;
}
}
Is that a good approach?

One suggestion is to set the post back value both on Property and on control, because the property is used only when the control is created.
protected override void OnLoad(EventArgs e) {
base.OnLoad(e);
if(Page.IsPostback) {
if(hiddenField != null)
hiddenField.Value = Page.Request.Form[hiddenField.UniqueId].ToString();
Property = Convert.ToBoolean(Page.Request.Form[hiddenField.UniqueId].ToString());
}
}

I achieved what I wanted to do, by implementing a ValueChanged EventHandler for the hidden field and edit the setter of the property to take care of all dependencies.
public class Control : CompositeControl {
private bool mProperty;
private HiddenField hiddenField;
public virtual bool Property {
get {
return mProperty;
}
set {
mProperty = value;
if (contentPanel != null) contentPanel.Visible = value;
if (hiddenField != null && hiddenField.Value != value.ToString().ToLower()) hiddenField.Value = value.ToString().ToLower();
}
}
protected override void CreateChildControls() {
Controls.Clear();
CreateControlHierarchy();
ClearChildViewState();
}
protected virtual void CreateControlHierarchy() {
CreateHiddenField();
CreateContent();
}
protected virtual void CreateHiddenField() {
hiddenField = new HiddenField();
hiddenField.ID = "hiddenField";
hiddenField.Value = Property.ToString().ToLower();
hiddenField.ValueChanged += hiddenField_ValueChanged;
Controls.Add(hiddenField);
}
protected virtual void CreateContent() {
contentPanel = new Panel();
contentPanel.ID = "content";
contentPanel.Vsiible = Property;
Controls.Add(contentPanel);
}
void hiddenField_ValueChanged(object sender, EventArgs e) {
Property = Convert.ToBoolean(hiddenField.Value);
}
protected override void OnInit(EventArgs e) {
EnsureChildControls();
base.OnInit(e);
}
}