If i have 9 TextBlock declared on the XAML file like this:
<TextBlock Name="cellText_00" Tag="0"/>
<TextBlock Name="cellText_01" Tag="1"/>
<TextBlock Name="cellText_02" Tag="2"/>
<TextBlock Name="cellText_20" Tag="3"/>
...
<TextBlock Name="cellText_22" Tag="8"/>
There is a way to interact with it from the .cs getting exactly the desired tag element?
For instance is it possible to give all the same name and get it in this way:
TextBlock tb = get(cellText,0);
where the first field is the name and the second one is the tag?
No, you can't use the same name for many controls.
However there is a workaround: using the FindName method:
http://msdn.microsoft.com/en-us/library/system.windows.frameworkelement.findname(v=vs.95).aspx
There Why can't I access a TextBox by Name with FindName()?
you can find an example and a solution related to namespaces issues.
FindName uses a string to retrieve the control. So you can do something like this: FindName("cellText_" + identifier); and take the element you need.
#Sandrouos, I don't think he's using the same name.
This blogpost explains it perfectly:
http://blog.jerrynixon.com/2012/09/how-to-access-named-control-inside-xaml.html
Related
I want one datetime field's background colour to depend on its value. Like if a certain date is passed, the background changes to red.
Is there a way to make this in XAML?
I know there is no possibility of an "if" condition/instruction, but maybe you guys found some way to implement a similar function.
<Canvas Canvas.Left="893" Canvas.Top="208" Height="25" Width="99" Background="red" Panel.ZIndex="-1"/>
<assembly:FieldControl Canvas.Left="890" Canvas.Top="206" FieldControlType="DateControl" FormField="{x:Null}" Height="25" LabelColumnWidth="0" Refnr="123456789" ShowCaption="False" StateImageAlignment="Hidden" Width="106" FontSize="10" Foreground="DimGray"/>
this is my code so far. The Canvas-Part makes the Background go red.
I also tried to put the background property in the "FieldControl" but there it's useless.
EDIT:
After getting the information, that Data Binding could help me with this problem, i tested it like this:
<TextBox Canvas.Left="890" Canvas.Top="226" Name="Date" Width="99" Height="25" VerticalAlignment="Top" Text="{Binding ElementName=Date, Path = SelectedItem.Content, Mode = TwoWay, UpdateSourceTrigger = PropertyChanged}" Background="{Binding ElementName=Date, Path=SelectedItem.Content}">
But this is not the direction, i need. Do you have maybe any suggestion, how I can use Data binding to solve my problem?
Yes, it is possible. The concept you need to learn is XAML Data Binding.
You can implement the IValueConverter for this.
https://learn.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/data-binding/converters
You can check the value on binding and return the background color.
how to give different text color for each item of listview in xamarin forms
I am trying to create a ListView cell data template with a label that shows either a "detailed" description or a "short" description based on whether another variable ViewLevel is "Detailed" or "Short".
I am using an IValueConverter and trying to bind the ConverterParameter, but that does not work as I don't think the ConverterParameter is bindable.
Is there a best practice for doing this?
The label I currently have is:
<Label Binding Options, Converter={viewModels:DetailLabelConverter}, ConverterParameter='Detail'}" />
It works, but obviously has the hardcoded Detail view. I've also tried:
<Label Text="{Binding Options, Converter={viewModels:DetailLabelConverter}, ConverterParameter={Binding Source={x:Reference BasePage}, Path=BindingContext.ViewLevel}}"/>
Which works, insomuch as it calls the DetailLabelConverter. Unfortunately the parameter is not loaded with the value of ViewLevel but a Xamarin.Forms.Binding object.
It seems like this should be a fairly common pattern but I can't find a reasonable solution.
I want to make a TextBlock visible only when a collection is empty. I have a ListView that is data-bound to the collection already and that's simple. I just want to display something else when the ListView is otherwise empty.
I wrote an IValueConverter that would take the collection, or count, or whatever I need, and return a Visibility appropriately. The XAML looks like this:
<TextBlock Visibility="{Binding Count, ElementName=ContactsList, Converter={StaticResource visibilityWhenEmpty}}"
Text="No contacts yet. Add one using the AppBar below." />
The trouble is that binding just the collection itself only calls my value converter once, when it's empty, and not again when the contents of the collection changes (kinda makes sense). And when, as shown above, I try binding against the collection's Count property, it doesn't call my value converter at all.
Any ideas?
I have faced the same issue. I applied a tricky solution. It might work for you as well. Taks a temporary combo box and bind the collection with that.
<ComboBox x:Name="TempComboBox"
ItemsSource="{Binding DataContext.ContactsList,
RelativeSource={RelativeSource Mode=FindAncestor,AncestorType=UserControl}}" >
<ComboBox.Template>
<ControlTemplate>
<!--Add file button..-->
<TextBlock Content="Your text..."
>
<TextBlock.Visibility>
<Binding Path="Items.Count"
RelativeSource="{RelativeSource Mode=FindAncestor,AncestorType=ComboBox}"
Converter="{StaticResource visibilityWhenEmpty}">
</Binding>
</TextBlock.Visibility>
</TextBlock>
</ControlTemplate>
</ComboBox.Template>
</ComboBox>
You could use notifyPropertyChanged for Count, or implement using BindableBase.
I would like to create a page a little like the Grouped Items Page inside the Contoso Cookbook application (if you have seen it). Basically, it's a GridView bound to a CollectionViewSource.
<CollectionViewSource
x:Name="groupedItemsViewSource"
Source="{Binding Groups}"
IsSourceGrouped="true"
ItemsPath="TopItems"
d:Source="{Binding AllGroups, Source={d:DesignInstance Type=data:SampleDataSource, IsDesignTimeCreatable=True}}"/>
The GridView appears to bind the Groups to the highest level of the CVS data source with the Source attribute and then binds each individual section with the ItemsPath attribute.
However, my page differs in that my groups are static, they are: Times, Categories, List. The first will have a listview, the second a grid of tiles and the third will be another listview.
Also, each group section itself has a different layout. It's not just repeating groups and repeating item-layouts. I was expecting to be able to define "static" groups and a layout for each group directly in the XAML and maybe even add test data to those elements, but it seems like GridView requires data binding, even if just to a dummy data source at design time.
So how would you do this? So essentially, it needs exactly the same horizontal scroll and wrapping as the GridView, but the groups have totally different layouts and each group should ideally be definable directly in the XAML?
I'm thinking of creating a normal grid enclosed in a scroll viewer... what do you think? What would you do?
In a GridView, groups can be assigned a GroupStyle like this:
<GridView.GroupStyle>
<GroupStyle HeaderTemplate="{StaticResource MyGroupHeaderTemplate}"
Panel="{StaticResource MyGroupItemsPanelTemplate}"
HidesIfEmpty="True" />
</GridView.GroupStyle>
Now, in your case each group will need its own GroupStyle.
So instead of using a ListView within each group in a GridView, you could:
Define 2 different group styles with header templates and the panel (ItemsPanelTemplate (MSDN)) that you want to use
Define a class that has your custom logic to select which group style to use for a group.(GroupStyleSelector)
Set the GroupStyleSelector property on the GridView in XAML
Define static groups in your view model to contain the data you want: (Times, Categories, List)
This can be accomplished with a DataTemplateSelector. You would have multiple groups, but within each group the items are styled differently. See this SO post for more help articles.
I have format strings in my resource files. I am trying to access these from the Text attribute of TextBlock using FormatString
Text="{Binding Path=Project.Name, StringFormat={Binding Path=WkStrings.DisplayProjectName, Source={StaticResource ResourceWrapper}}}"
I am getting the following error:
Provide value on 'System.Windows.Data.Binding' threw an exception
Error points to Text=.
Is it possible to access resources from a "nested binding"?
Binding.StringFormat is not a dependency property and therefore you cannot set a binding to this property. If you want to assign a value to that property, your value has to be a static resource, like this:
<TextBlock Text="{Binding ProjectName, StringFormat={StaticResource ProjectNameFormat}}"/>
You should declare your resource like this:
<UserControl.Resources>
<System:String x:Key="ProjectNameFormat">Project: {0}</System:String>
</UserControl.Resources>
The end result looks like this:
Your syntax is wrong for using StringFormat and you may want something other than StringFormat. StringFormat is used to manipulate the output of what is assigned to the Path of the Binding. In your example you're binding to the Project.Name property.
StringFormat should be used to achieve the similar effect as using String.Format in code. See this reference for formatting: http://msdn.microsoft.com/en-us/library/26etazsy(v=VS.95).aspx
Other answers around this topic:
Does Silverlight support StringFormat in binding?
http://blog.davemdavis.net/2009/12/03/silverlight-4-data-binding-string-format/
Here's some example code of using StringFormat:
<TextBlock Text="{Binding Path=Cost, StringFormat=\{0:c\}}" />