im quite new in vb programming..
i have this code snippet in my Form.xaml
<MenuItem Name="testItem" Background="Gray" Width="37" >
<MenuItem.Icon>
<Image Source="Image\test.png" Width="35" Height="35"/>
</MenuItem.Icon>
</MenuItem>
and in my Form.xaml.vb how do I access testItem's Background? I did something like
testItem.Background = Colors.Blue
but it doesnt work..
The Background property of the Menu expects a Brush, not a Color. You could use a SolidColorBrush like this:
testItem.Background = New SolidColorBrush(Colors.Red)
Related
The template is defined as:
<ContentPage.Resources>
<DataTemplate x:Key="MenuOptionTemplate">
<controls:MenuButtonControl />
</DataTemplate>
</ContentPage.Resources>
<ScrollView Orientation="Vertical">
<FlexLayout
AlignContent="Start"
AlignItems="Start"
BindableLayout.ItemTemplate="{StaticResource MenuOptionTemplate}"
BindableLayout.ItemsSource="{Binding MenuOptions}"
JustifyContent="SpaceEvenly"
VerticalOptions="Start"
Wrap="Wrap" />
</ScrollView>
The MenuButtonControl is define as:
...
<ImageButton
Source="{AppThemeBinding Light={Binding LightImageSource},
Dark={Binding DarkImageSource}}"/>
...
MenuOptions is is dynamically generated based on the user's role, but basically each menu option is create like so:
new MenuOption {
Title = "My Title",
LightImageSource = "sample_light",
DarkImageSource = "sample_dark"
}
{Binding LightImageSource} does not work.
So what is the correct way to implement this?
Because AppThemeBinding.Light is a markup extension (inherit from IMarkupExtension) property and not a BindableProperty you cannot use DynamicResource or Binding with it.
Thus you cannot use AppThemeBinding in this case. But you can use bindings (without AppThemeBinding), converters.. (see answers on the linked question), you just need to add the logic to conditionally set the appropriate image source based on the active theme using:
Application.Current.RequestedTheme;
Binding image source dynamically on xamarin forms
AppThemeBinding source
RequestedTheme
Edit
To react on theme changes use the event rather than testing the property RequestedThemeChanged:
How to detect Xamarin Forms System Theme Change
ImageButtons on a ListView is giving me a headache. Take a look at the gif here.
As you can see, the ImageButtons (3 vertical dots on the right of every ListView row) which were hidden gets super small as the ListView is scrolled up and down.
This is the corresponding XAML:
<ImageButton
Source="more_options"
HorizontalOptions="End"
WidthRequest="21"
BackgroundColor="Transparent"
Clicked="OnMoreOptionsTapped"
CommandParameter="{Binding .}"
Grid.Column="2"
Grid.Row="0"/>
Full XAML is here. ImageButton is at line 56.
I'm doing something wrong? How can I fix this?
Also, I know I could use just an Image with a TapGestureRecognizer but that's being a big issue for me, because I need access to the Image element to get it's coordinates and spawn the menu on the right location. Doing that with an ImageButton is a piece of cake, but it's not so easy with a TapGestureRecognizer. I did something like this:
XAML
<Image
Source="more_options"
Aspect="AspectFit"
HorizontalOptions="End"
WidthRequest="21"
BackgroundColor="Transparent"
Grid.Column="2"
Grid.Row="0">
<Image.GestureRecognizers>
<TapGestureRecognizer
Tapped="OnMoreOptionsTapped"
CommandParameter="{Binding .}"/>
</Image.GestureRecognizers>
</Image>
Code-behind:
private void OnMoreOptionsTapped(object sender, TappedEventArgs args)
{
var tapGesture = sender as TapGestureRecognizer;
var button = tapGesture.Parent as Image;
...
}
Basically, with an ImageButton element, the object sender is an ImageButton element, but with an Image, the object sender is a TapGestureRecognizer and I can't find a way to get the Image parent while I have only the TapGestureRecognizer child. Also, tapGesture.Parent is null and tapGesture.Parent.Parent is null too. I've tried both.
So:
ImageButtons on ListView are bugging out hard. Anyone have a fix?
Anyone could tell me how to get the Image parent having only the child TapGestureRecognizer?
I believe answering any of those two questions would solve my problem hehe.
Also, this is one of my first experiences asking questions here, I beg your pardon if I did something wrong.
Thanks all :)
The reason behind your issue is a bug that is currently in the xamarin listview which can be found here :
https://github.com/xamarin/Xamarin.Forms/issues/5200
Solution is to downgrade to v3.4 for now until we get an intimate from XF side
Goodluck revert if you have queries
I use WinRt MapControl on Windows Phone 8.1. But when I trying add MapIcon or MapPolyline map elements I get only text like this:
XAML code looks like this:
<maps:MapControl x:Name="MapOnScreenControl"
MapServiceToken="12345">
<maps:MapPolyline Path="{Binding Route, Converter={StaticResource RouteToGeopathConverter}}"/>
</maps:MapControl>
What I am doing is wrong? Thanks.
Unfortunately map elements cannot be added to the map via XAML. You will need to add them within code.
MapOnScreenControl.MapElements.Add(new MapPolyline());
A trick I like to do is use the viewmodel to add elements to the map by either setting a Map property or a MapElements property of my viewmodel.
private void MapPage_DataContextChanged(FrameworkElement sender, DataContextChangedEventArgs args)
{
var vm = DataContext as MapViewModel;
vm.MapElements = MyMap.MapElements;
}
Then within the viewmodel you can add items to the elements.
You can also add a collection of items using the MapItemsControl.
<maps:MapControl x:Name="Map" MapServiceToken="abcdef-abcdefghijklmno">
<maps:MapItemsControl ItemsSource="{Binding Locations}">
<maps:MapItemsControl.ItemTemplate>
<DataTemplate>
<Image Source="Assets/Mappin.png" Height="25"
maps:MapControl.NormalizedAnchorPoint="1,0.5"
maps:MapControl.Location="{Binding Geopoint}" />
</DataTemplate>
</maps:MapItemsControl.ItemTemplate>
</maps:MapItemsControl>
</maps:MapControl>
Beginner here. I want to create a button in XAML which has text based on a variable in VB. I have the variable set in VB with
Dim ButtonName1 = "Test"
What will I need to do to make the button content display ButtonName1?
It is really quite easy. Your Button has a Name Property that you can use to reference it in your code behind, note in this example it is Button1 you just need to assign your string to the Button's Content Property
Xaml
<Button Content="Button" Height="23" HorizontalAlignment="Left" Margin="10,10,0,0" Name="Button1" VerticalAlignment="Top" Width="75" />
xaml.vb
Dim ButtonName1 = "Test"
Button1.Content = ButtonName1
I have the following xaml code:
<dxb:BarButtonItem Name="btnPrev" Cursor="Hand" ItemClick="btnPrev_ItemClick">
<dxb:BarButtonItem.ContentTemplate>
<DataTemplate>
<Image x:Name="imgSkipLeft" Source="/ProjectTool;component/images/arrowleft.png" Height="16" Width="16">
<ToolTipService.ToolTip>
<TextBlock x:Name="txtBlockTip_Left"/>
</ToolTipService.ToolTip>
</Image>
</DataTemplate>
</dxb:BarButtonItem.ContentTemplate>
</dxb:BarButtonItem>
How can I find txtBlockTip_Left and modify the text
Rather that trying to find the TextBlock on the DataTemplate to change the text it would be better to set the text through a binding and then change the property that the Text property is bound to. The following resource has an example on how to use data binding within a DataTemplate: http://www.silverlight.net/learn/data-networking/binding/data-binding-to-controls-%28silverlight-quickstart%29
Using the VisualTreeHelperExtensions class and put a grid inside the data template and give it a name, in the example below the name is grdTemplate.
var bttn= btnPrev.ItemContainerGenerator.ContainerFromItem(btnPrev);
var dataTemplate = bttn.GetDescendantsOfType<Grid>().FirstOrDefault(g => g.Name == ("grdTemplate"));
var textBlocks= VisualTreeHelperExtensions.GetDescendantsOfType<TextBlock>(dataTemplate);
TextBlock txtBlockTip_left = textBlocks.ElementAt(0);