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CSS styling in GTKSharp

I'm converting a C/GTK+ GUI application to C# using GTKSharp in VS2017. I've installed this package https://www.nuget.org/packages/GtkSharp/3.1.3 via NuGet.
Here's how I load up the CSS (the application uses a Glade file to define the interface):
static void Main(string[] args)
{
new Program(args);
}
public Program(string[] args)
{
Application.Init();
builder = new Builder();
Gtk.CssProvider provider = new CssProvider();
builder.AddFromFile("interface.glade");
provider.LoadFromPath("style.css");
builder.Autoconnect(this);
Gtk.Window window = (Gtk.Window)builder.GetObject("start");
Gtk.StyleContext.AddProviderForScreen(Gdk.Screen.Default, provider, 800); // couldn't find the equivalent to GTK_STYLE_PROVIDER_PRIORITY_USER so I set the priority to a random number
window.Show();
Application.Run();
}
The selector names seem to be different from GTK+. For example,
window {
...
}
works in C/GTK+ but not in C#, whereas
GtkWindow {
...
}
works in C# but not in C/GTK+. Then there are a few widgets I can't seem to style at all. For example,
button {
...
}
works in GTK+ but
GtkButton {
...
}
does not work in C#. I couldn't find any documentation regarding how GTK# handles CSS styling so I thought it'd be the same as GTK+. Any pointers?

The GTKSharp seems more like an expected GTK3 behavior.
Here is the reference manual from developer.gnome.org
Espcially useful should be the Table 1. Selector syntax section.
In short the elements are named after the GTK class name: GtkButton, GtkLabel and so on.
For a class list of default GTK3 wigets check out the docs talbe of content..
The GTK button is a container wiget that doesn't render background so without seeing the actual CSS properties you try to apply using that selector I can't tell you why it doesn't work but so you might need to style it content separately. Eg.
GtkButton GtkLabel {
color: lime;
}
The selector itself GtkButton should be correct.

It was a version issue.
Version 3.22 of GTK# detects the GtkButton selector correctly. I was using GTK 3.14's native libraries. There is one unlisted NuGet package that provides win32 libraries for the 3.22 version. Strangely enough, that version detects the old "button", "window"... instead of the "GtkButton", "GtkWindow"... tags.

Embedded image does not show in Xamarin Android App

I follow the guide on the official Xamarin website telling how to embed the image into the cross-platform app. I build the app only for Android platform.
Unfortunately, the image is not shown during debug on my Sony D5803 Z3 Compact or in Android 7.1 emulator. I use VS 2017 RC on Windows 10. All the previous HelloWorld apps e.g. with downloading the picture via URI worked well on my phone.
I would be grateful for any help or advice how to troubleshoot the problem.
The image picture.jpg has set the build property embedded resource (in Polish Akcja kompilacji: osadzony zasób)
I can see the images in the debug folder as shown in the screenshot
This is the XAML page I use to show the image:
ImageEmbeddedPAge.xaml
<?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:markupExtensions="clr-namespace:HelloWorld.MarkupExtensions;assembly=HelloWorld.Droid"
x:Class="HelloWorld.ImageEmbeddedPAge">
<StackLayout HorizontalOptions="Center"
VerticalOptions="Center">
<Image x:Name="image"
Source="{markupExtensions:ImageResource Source=HelloWorld.Images.picture.jpg}"/>
</StackLayout>
</ContentPage>
ImageResourceExtension.cs in folder MarkupExtensions
namespace HelloWorld.MarkupExtensions
{
[ContentProperty("Source")]
public class ImageResourceExtension : IMarkupExtension
{
public string Source { get; set; }
public object ProvideValue(IServiceProvider serviceProvider)
{
if (Source == null)
{
return null;
}
// Do your translation lookup here, using whatever method you require
var imageSource = ImageSource.FromResource(Source);
return imageSource;
}
}
}
App.xaml.cs
namespace HelloWorld
{
public partial class App : Application
{
public App ()
{
InitializeComponent();
MainPage = new ImageEmbeddedPAge();
}
}
}

Totally agree with #Cheesebaron, since you created a Xamarin.Forms shared projecrt, we need to place resolution images in specially-named directories in Android project, these specially-named directories are all placed under the Resources-> Drawable folder in the Android project.
If you want to use an embedded image, we need to use a Portable Lib for each platfrom, or just create a Xamarin.Forms portable project. If you want to create a PCL by yourself, than please be careful with the targets of this PCL, normally it should be like following image so can it be used for different platforms:
And finally to embed an image in a project, by default the image will have Build Action: None, please set it to Build Action: EmbeddedResource.
The reason why we cannot place images in a shared project is that:
The shared project reference shows up under the References node in the Solution Explorer, but the code and assets in the shared project are treated as if they were files linked into the main project.
The images then are treated as files not resources.

WPF and Workflow foundation don't work together

I have really strange problem. I've created WPF project in 2012 or 2013 VS it doesn't matter. I use .NET 4.5.
I add a new Activity (Workflow class) to that project. Its name is CustomActivity.
Then I add a new class that has got an attached property, example below:
public class AttachedObject : DependencyObject
{
public static readonly DependencyProperty NameProperty = DependencyProperty.RegisterAttached(
"Name",
typeof(string),
typeof(AttachedObject),
new FrameworkPropertyMetadata(
string.Empty,frameworkPropertyMetadataOptions.AffectsRender));
public static void SetName(ContentControl element, string value)
{
element.SetValue(NameProperty, value);
}
public static string GetName(ContentControl element)
{
return (string)element.GetValue(NameProperty);
}
}
The last step is to change MainWindow class that way:
public MainWindow()
{
InitializeComponent();
var activity = new CustomActivity();
}
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:wpfApplication1="clr-namespace:WpfApplication1;assembly=WpfApplication1"
Title="MainWindow" Height="350" Width="525">
<Grid>
<ContentControl wpfApplication1:AttachedObject.Name="MainArea"/>
</Grid>
</Window>
The problem is it doesn't compile because of below error:
Error 1 The type or namespace name 'CustomActivity' could not be found (are you missing a using directive or an assembly reference?) WpfApplication1\MainWindow.xaml.cs 13 32 WpfApplication1
CustomActivity has a default namespace. In obj folder there is CustomActivity.g.cs generated, so I have no idea what's going on.
It's 100% reproducible. When I remove using of CustomActivity or using of AttachedObject from xaml then the problem disappear.

Try replacing this:
xmlns:wpfApplication1="clr-namespace:WpfApplication1;assembly=WpfApplication1"
with this
xmlns:wpfApplication1="clr-namespace:WpfApplication1"
The error you're seeing is due to a "known" issue in WPF applications that xaml namespaces that reference clr namespace from current assembly your in don't require the full assembly qualified name. If you were to declare a xaml namespace that references a clr namespace from another assembly, than you would have to specify the full name (with the ;[assemblyname] syntax).
Workflow Foundation has nothing to do with it.
EDIT:
Didn't realize it was a xaml activity.
But still, you can make it work, maybe, with a few hacks, but I wouldn't recommend it.
The reason you get that error is due to the different code generation and build action VS uses when creating xaml artifacts for WPF (Page):
System.Windows.Application.LoadComponent(this, resourceLocater);
and when creating xaml activities (XamlAppDef):
typeof(CustomActivity).Assembly.GetManifestResourceStream(resourceName);
If you turn your CustomActivity xaml build action to Page, the whole thing will compile - but i'm guessing something else might be broken someplace else...or not, who knows. My guess is that these two kinds of xaml were not meant to live together in a VS WPF application project template. But you can still define activities in a WF activity library, that way your activities will also be more easily reusable for other projects, WPF, console or even services.

I have the same issue under Visual Studio 2017.
The problem in my case is that Visual Studio is not compiling the Workflow activities before the code that use them.
To fix it, what I did is to move all workflows to other project dll, so visual Studio is forced to compile the workflows before the classes that make use of them.

Image Source in WPF

I'm trying to set an image source in XAML but keep getting "Could not find part of a path..." (plus the directory I want to call). I think I'm messing up what location I'm supposed to be calling. The hierarchy looks something like:
-Solution
-Project
-Data
-Images
-Image_I_want_to_use.png (placeholder name)
-Themes
-Demo
-Default
-fileImWorkingIn.xaml
-other files
-other folders
-Another Project
-Third Project
How would I configure my image source in XAML so the file I'm working in can utilize the image(s)?
I tried
<Image Source="/Project;component/Images/image_to_use.png">
(where each name is simply a placeholder) but had no luck. Any pointers? Apologies if this is trivial.
Thanks!

In .NET 4, this Image.Source value would work:
<Image Source="/AssemblyName;component/FolderName/image_to_use.png">
However, Microsoft made some horrible changes in .NET 4.5 that broke many different things and so in .NET 4.5, you'd need to use the full pack path like this:
<Image Source="pack://application:,,,/AssemblyName;component/Images/image_to_use.png">

What fixed it:
<Image Source ="pack://application:,,,/Images/image_name.png"></Image>
I also changed the Build Action to content.
Thanks for your help everyone!

XAML designed fails to load as cannot create a custom object

I have a XAML form for use in my application, and I have subclassed the Frame class to create my own, and edited the interface to specify my own class for the content (as I need to access properties on the content for data binding).
The problem comes then in the designer that the compiler says it cannot create an instance of my control - I've tried to do some designer checks on the offending property bit but that didnt work either.
How can I get the control to display? Works fine at runtime...
XAML:
<Grid Grid.Row="1" Grid.Column="1" Grid.ColumnSpan="2">
<views:PageFrame Name="Content_MainPage" Frame.NavigationUIVisibility="Hidden"/>
</Grid>
CS:
public new BaseView Content
{
get
{
if (DesignerProperties.GetIsInDesignMode(this))
{
return new BaseView();
}
else
{
return (BaseView)base.Content;
}
}
set
{
if (DesignerProperties.GetIsInDesignMode(this))
{
base.Content = new BaseView();
FrameTitle = "design mode";
}
else
{
base.Content = value;
FrameTitle = value.Title;
}
}
}

I came across a similar problem when creating my own Panel class.
Is your PageFrame class defined in the same assembly that your XAML lives in?
I found the only way I could get this to work was to move my "PageFrame" class into a new assembly. From memory I think I even had to build that assembly ahead of time, so that the assembly could be referenced via a file reference (as opposed to a project reference).
I hated this solution, so I hope you find a cleaner one :)
Have you got VS2008 SP1 installed? I had hoped MS would fix this bug. I haven't tried removing my workaround to check...

Its in the same assembly - and yes I have VS2008 SP1 installed too. Not that removing the above property lets it work fine from a vs point of view, but obviously not from my point of view!
I will give this a go - thanks Antony.