IconElement implementation

[IvanDmitriev1]

Implements a IconElement control almost like in winui 3.
Replaces SymbolIcon with IconElement.

Pull request type

• Update
• Bugfix
• Feature
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no api changes)
• Build related changes
• Documentation content changes

Other information

[IvanDmitriev1]

@pomianowski I hope you haven't forgotten about this interesting pull-request.

[pomianowski]

Hey @IvanDmitriev1 thank you again for your huge contribution and effort. You did a great job modifying the icons by the way changing strong dependencies on specific classes. Apart from a few minor things, the code looks fine to me.

However, looking at your recent changes, I think it's probably better to put all the control-related classes in one Controls directory. It may be a lot stuff in one place, but I think it will be easier for the end user to use, similar to what is done in WPF.

As for presenting icons, I think ContentPresenter is a better than ContentControl for that.

<ContentPresenter
    x:Name="ControlIconLeft"
    Grid.Column="0"
    Margin="{StaticResource TextBoxLeftIconMargin}"
    VerticalAlignment="Top"
    Content="{TemplateBinding Icon}"
    Focusable="False"
    TextElement.FontSize="16"
    TextElement.Foreground="{TemplateBinding Foreground}"
    Visibility="Visible" />

Eventually, ContentControl uses ContentPresenter to present content, so we can consider ContentPresenter as more ligthweight
https://github.com/dotnet/wpf/blob/main/src/Microsoft.DotNet.Wpf/src/Themes/XAML/ContentControl.xaml#LL17C21-L17C40

[IvanDmitriev1]

As for presenting icons, I think ContentPresenter is a better than ContentControl for that.

<ContentPresenter
    x:Name="ControlIconLeft"
    Grid.Column="0"
    Margin="{StaticResource TextBoxLeftIconMargin}"
    VerticalAlignment="Top"
    Content="{TemplateBinding Icon}"
    Focusable="False"
    TextElement.FontSize="16"
    TextElement.Foreground="{TemplateBinding Foreground}"
    Visibility="Visible" />

Eventually, ContentControl uses ContentPresenter to present content, so we can consider ContentPresenter as more ligthweight https://github.com/dotnet/wpf/blob/main/src/Microsoft.DotNet.Wpf/src/Themes/XAML/ContentControl.xaml#LL17C21-L17C40

ContentControl is used for proper foreground inheritance. And also with ContentPresenter it didn't work, but right now it seems to work. Well, I need to check everything again.