I am new to this all (this is my first post), so please bear with me. Any improvements is more then welcome.
I am writing an appointment scheduler using .Net 4.0, visual studio 2010. The XAML consists of a DataGrid with rows that are 15minutes apart and four columns, the left most column used for time. The backing data consists of AppointmentRows, an ObservableCollection. Each row itself consisting of an ObservalbeCollection of Appointmnets. I am using DragAndDrop as my input method.
DragAndDrop seems to work correctly to the cell-level. Items can be dropped on the datagrid, removed from the datagrid and rearranged within the datagrid. When an appointment is dropped on the datagrid, the first DataTrigger sets the custom attached propety of HasAppointment to true and the second Trigger responds to this attached property by setting the DataGridCell background color to one of four colors depending on whether the cell is now empty, contains an appointment of somebody who is new, who is old, or who requires special management.
Problem#1:
After loading the DataGrid, the Trigger responsible for coloring the background of a cell does not fire if that cell has been previously used—even though the DataTrigger responsible for setting the HasAppointment attached property does. That is, during loading and any time an UNUSED cell has an appointment dropped on it, all the triggers work correctly. However, once the triggers have fired on the cell—as when first being loaded or when a new appointment was dropped on it—the trigger responsible for background coloring never fires despite the first trigger correctly setting the HasAppointment attached property correctly and the cell returns to its first background coloring of the first appointment it contained. To be clear:
- DataGrid is loaded. Cell has its default color of green background and is empty.
- User drops a new appointment on the cell. All triggers fire and cell is colored yellow.
- User then drags the contents of that cell to another place on the grid. Cell where the appointment WAS correctly reports as being empty, HasAppointment is false, and the color returns to the default green background.
- User now drops another appointment on that cell. The DataTrigger responsible for setting the HasAppointment attached property fires correctly and sets the cell HasAppointment to true.
- The Trigger for coloring does not fire and the cell returns to the yellow background of the first appointment it contained.
Problem#2:
After dropping an appointment on a cell, the DataTrigger resonsible for setting the HasAppointment associacted property runs twice before allowing the Trigger responsible for coloring to run. It runs correctly, but why twice?
Problem#3:
Each cell may or may not have an appointment. Each cell that has an appoinment maybe one of three collors. So what is the best way of returning multiple different values from a converter to a DataTrigger without repeating the code for each value? At this momemt I am using a Trigger, which works well WHEN IT WORKS.
Problem#4:
Can a DataTrigger operate on an attached property, and if it can, how is the binding set?
Thank you for any help to these matters.
Here is the XAML:
<Window x:Class="Chaos.Scheduler.Scheduler"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:Chaos.Scheduler"
xmlns:my1="clr-namespace:UpDownCtrls;assembly=UpDownCtrls"
Title="Scheduler" Height="556" Width="1024"
DataContext="{Binding RelativeSource={RelativeSource Self}}"
WindowStartupLocation="CenterScreen">
<!--Resources is a dictionary. so it allows assigning an x:Key value to Styles.-->
<Window.Resources>
<!--Declare converters for custom binding logic-->
<local:RescheduleConverter x:Key="rescheduleConverter" />
<local:ColorConverter x:Key="colorConverter" />
<local:AppointmentConverter x:Key="appointmentConverter" />
<local:WatchApppointmentNamesConverter x:Key="watchAppointmentNamesConverter" />
<!--Show buttons as Red when an edit has occured-->
<Style x:Key="SaveButtonStyle" TargetType="{x:Type Button}">
<Style.Triggers>
<DataTrigger Binding="{Binding HasEdits}" Value="True" >
<Setter Property="Background" Value="Red" />
</DataTrigger>
</Style.Triggers>
</Style>
<!--The XAML will create a "Style" object/instance of type "DataGridCell". Without an x:Key value, this "style" object
will be used as the parent style for all the DataGridCells. -->
<Style TargetType="{x:Type DataGridCell}" x:Key="AppointmentStyle" >
<EventSetter Event="PreviewMouseLeftButtonDown" Handler="DataGridCell_PreviewMouseLeftButtonDown" />
<EventSetter Event="MouseMove" Handler="DataGridCell_MouseMove" />
<EventSetter Event="DragEnter" Handler="DataGridCell_DragEnter" />
<EventSetter Event="Drop" Handler="DataGridCell_Drop" />
<!--Must use Right/LeftButtonUp and not Right/LeftButtonDown as these events are Direct, not tunneling or bubbled.-->
<!--This makes no sense and is probably a bug, but it works-->
<EventSetter Event="PreviewMouseRightButtonUp" Handler="DataGridCell_PreviewMouseRightButtonUp" />
<!--There is no way to replace only part of the visual tree of a control. To change the visual tree of a control you must set the
Template property of the control to its new and COMPLETE ControlTemplate. -->
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type DataGridCell}">
<!--Define the DataGridCell content. Bind the Grid control background color to the DataGridCell Style template.
The Background color will be inherited by the textblock (that is within the <Grid> by default).-->
<Grid Background="{TemplateBinding Background}">
<ContentPresenter AllowDrop="True" />
</Grid>
</ControlTemplate>
</Setter.Value>
</Setter>
<!--Set default background color for the entire row-->
<Setter Property="Background" Value="Green"/>
<Style.Triggers>
<Trigger Property="local:Scheduler.HasAppointment" Value="true">
<Setter Property="Background">
<Setter.Value>
<MultiBinding Converter="{StaticResource colorConverter}" >
<MultiBinding.Bindings>
<!--Sends the "DataGirdCell" object to the converter-->
<Binding RelativeSource="{RelativeSource Self}"></Binding>
<!--Sends the current "DataGridRow" to the converter. The DataGridRow is the DataContext for the cell -->
<Binding RelativeSource="{RelativeSource FindAncestor, AncestorType={x:Type DataGridRow}, AncestorLevel=1}" Path="." />
</MultiBinding.Bindings>
</MultiBinding>
</Setter.Value>
</Setter>
</Trigger>
<!--If the Converter returns True, then the Background will be red for the row-->
<DataTrigger Value="True">
<DataTrigger.Binding>
<!--The DataTrigger is operating on the entire row-->
<MultiBinding Converter="{StaticResource watchAppointmentNamesConverter}" ConverterParameter="0">
<!--send the DataGridCell in effect when the displayname properites change-->
<Binding RelativeSource="{RelativeSource Self}"></Binding>
<!--binding will watch the displaynames for each column. The AppointmentRow is the DataContext for all cells-->
<Binding Path="[0].displayname"></Binding>
<Binding Path="[1].displayname"></Binding>
<Binding Path="[2].displayname"></Binding>
</MultiBinding>
</DataTrigger.Binding>
<!--Any setter here will be applied to the entire row, not just the cell. There MUST HAVE be setter for the Converter to be executed-->
<Setter Property="Background" Value="Red"/>
</DataTrigger>
</Style.Triggers>
</Style>
</Window.Resources>
<Grid Name="MainGrid">
<!--Set AllowDrop="False" to show the scrollbars as not droppable targets-->
<DataGrid AutoGenerateColumns="False" CellStyle="{StaticResource AppointmentStyle}" ItemsSource="{Binding MySchedule.AppointmentRows}"
HorizontalAlignment="Stretch" Margin="302,47,0,37"
Name="dataGridScheduler" VerticalAlignment="Stretch" Width="688"
AllowDrop="False" SelectionUnit="Cell" SelectionMode="Single"
CanUserReorderColumns="False" CanUserAddRows="False" IsReadOnly="True" >
<!--Must have AllowDrop = True to allow dropping on the cells-->
<DataGrid.RowStyle>
<Style TargetType="{x:Type DataGridRow}">
<Setter Property="AllowDrop" Value="True" />
</Style>
</DataGrid.RowStyle>
<DataGrid.Columns>
<!--{Binding /, Path=[0].displayname} is binding to the current item of the collection, the appointment row,
with index of 0, the appointment, and shows the property of appointment displayname. The displayname must use the INotifyPropertyChanged interface-->
<DataGridTextColumn Binding="{Binding time}" Header="Time" Width="58" IsReadOnly="True" />
<DataGridTextColumn Binding="{Binding /, Path=[0].displayname}" Header="Name" Width="240*" />
<DataGridTextColumn Binding="{Binding /, Path=[1].displayname}" Header="Name" Width="240*" />
<DataGridTextColumn Binding="{Binding /, Path=[2].displayname}" Header="Name" Width="240*" />
</DataGrid.Columns>
</DataGrid>
…..........
</Window>
Here is the code-behind:
#region Attached Property HasAppointment
// Attached properties are added to the control, not the data being displayed, and used by the XAML directly.
// Example useage in XAML: <Trigger Property="local:Scheduler.HasAppointment" Value="True">
// The attached property template is obtained by typing <propa> tab tab into the code-behind.
public static Boolean GetHasAppointment(DependencyObject obj)
{
return (Boolean)obj.GetValue(HasAppointmentProperty);
}
public static void SetHasAppointment(DependencyObject obj, Boolean value)
{
obj.SetValue(HasAppointmentProperty, value);
}
// Using a DependencyProperty as the backing store for HasAppointment. This enables animation, styling, binding, etc...
public static readonly DependencyProperty HasAppointmentProperty =
DependencyProperty.RegisterAttached("HasAppointment", typeof(Boolean), typeof(Scheduler), new UIPropertyMetadata(false));
#endregion
/* Converters apply custom logic to the XAML Bindings */
/// <summary>
/// Tests the DataGridCell for a displayname. Returns false for no displayname, true for a display name.
/// </summary>
[ValueConversion(typeof(String), typeof(Boolean))]
public class AppointmentConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
String displayname = value as String;
if (string.IsNullOrEmpty(displayname))
return false;
return true;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
/// <summary>
/// Label the reschedule shape with "Reschedule Appointment" or the patient name.
/// </summary>
[ValueConversion(typeof(Appointment), typeof(String))]
public class RescheduleConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
Appointment apt = value as Appointment;
if (apt.displayname == null) return "Reschedule Appointment";
else return apt.displayname;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
/* Color a grid cell based on appointment type and patient history */
public class ColorConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (values[1] is DataGridRow)
{
// The "cell" tells nothing about its contents, only its location in the grid, its column name and column position.
// The datacontext comes from the datagrid row.
DataGridCell cell = (DataGridCell)values[0];
if (cell.Column.DisplayIndex > 0)
{
Boolean hasappointment = Scheduler.GetHasAppointment(cell);
// the object "row" is of type AppointmentRow.
DataGridRow row = (DataGridRow)values[1];
// gets the physical row number of this row in the grid.
int rowIndex = row.GetIndex();
// SortMemberPath returns: "time", "[0].displayname", " "[1].displayname", "[2].displayname"
string columnName = cell.Column.SortMemberPath;
Appointment appointment = ((AppointmentRow)row.Item)[cell.Column.DisplayIndex - 1] as Appointment;
if (null != appointment.displayname)
{
if ((appointment.type & AppointmentType.Excision) == AppointmentType.Excision)
{
// return new SolidColorBrush(Colors.Red);
return Brushes.Red;
}
else if (null == appointment.lastvisit)
{
// return new SolidColorBrush(Colors.Yellow);
return Brushes.Yellow;
}
}
}
}
// return System.Windows.SystemColors.AppWorkspaceColor;
return new SolidColorBrush(Colors.White);
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
/// <summary>
/// Set the HasAppointment flag for all cells in the AppointmentRow.
/// For some reason, this routine will process the entire row twice on a drop. I suspect setting the HasAppointment flag forces the
/// second processeing as the "cell" object itself maybe changed.
/// [0] = DataGridCell
/// [1] = AppointmentRow[0].displayname
/// [2] = AppointmentRow[1].displayname
/// [3] = AppointmentRow[2].displayname
/// </summary>
public class WatchApppointmentNamesConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
DataGridCell cell = values[0] as DataGridCell;
if (!String.IsNullOrWhiteSpace((string)values[1]))
{
if (cell.Column.DisplayIndex == 1)
Scheduler.SetHasAppointment(cell, true);
}
else
{
if (cell.Column.DisplayIndex == 1)
Scheduler.SetHasAppointment(cell, false);
}
if (!String.IsNullOrWhiteSpace((string)values[2]))
{
if (cell.Column.DisplayIndex == 2)
Scheduler.SetHasAppointment(cell, true);
}
else
{
if (cell.Column.DisplayIndex == 2)
Scheduler.SetHasAppointment(cell, false);
}
if (!String.IsNullOrWhiteSpace((string)values[3]))
{
if (cell.Column.DisplayIndex == 3)
Scheduler.SetHasAppointment(cell, true);
}
else
{
if (cell.Column.DisplayIndex == 3)
Scheduler.SetHasAppointment(cell, false);
}
// need to return false or will force background to red.
return false;
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}
https://stackoverflow.com/questions/19161061
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