WPF What is the correct way of using SVG files as icons in WPF

Your technique will depend on what XAML object your SVG to XAML converter produces. Does it produce a Drawing? An Image? A Grid? A Canvas? A Path? A Geometry? In each case your technique will be different.

In the examples below I will assume you are using your icon on a button, which is the most common scenario, but note that the same techniques will work for any ContentControl.

Using a Drawing as an icon

To use a Drawing, paint an approriately-sized rectangle with a DrawingBrush:

<Button>
  <Rectangle Width="100" Height="100">
    <Rectangle.Fill>
      <DrawingBrush>
        <DrawingBrush.Drawing>

          <Drawing ... /> <!-- Converted from SVG -->

        </DrawingBrush.Drawing>
      </DrawingBrush>
    </Rectangle.Fill>
  </Rectangle>
</Button>

Using an Image as an icon

An image can be used directly:

<Button>
  <Image ... />  <!-- Converted from SVG -->
</Button>

Using a Grid as an icon

A grid can be used directly:

<Button>
  <Grid ... />  <!-- Converted from SVG -->
</Button>

Or you can include it in a Viewbox if you need to control the size:

<Button>
  <Viewbox ...>
    <Grid ... />  <!-- Converted from SVG -->
  </Viewbox>
</Button>

Using a Canvas as an icon

This is like using an image or grid, but since a canvas has no fixed size you need to specify the height and width (unless these are already set by the SVG converter):

<Button>
  <Canvas Height="100" Width="100">  <!-- Converted from SVG, with additions -->
  </Canvas>
</Button>

Using a Path as an icon

You can use a Path, but you must set the stroke or fill explicitly:

<Button>
  <Path Stroke="Red" Data="..." /> <!-- Converted from SVG, with additions -->
</Button>

or

<Button>
  <Path Fill="Blue" Data="..." /> <!-- Converted from SVG, with additions -->
</Button>

Using a Geometry as an icon

You can use a Path to draw your geometry. If it should be stroked, set the Stroke:

<Button>
  <Path Stroke="Red" Width="100" Height="100">
    <Path.Data>
      <Geometry ... /> <!-- Converted from SVG -->
    </Path.Data>
  </Path>
</Button>

or if it should be filled, set the Fill:

<Button>
  <Path Fill="Blue" Width="100" Height="100">
    <Path.Data>
      <Geometry ... /> <!-- Converted from SVG -->
    </Path.Data>
  </Path>
</Button>

How to data bind

If you’re doing the SVG -> XAML conversion in code and want the resulting XAML to appear using data binding, use one of the following:

Binding a Drawing:

<Button>
  <Rectangle Width="100" Height="100">
    <Rectangle.Fill>
      <DrawingBrush Drawing="{Binding Drawing, Source={StaticResource ...}}" />
    </Rectangle.Fill>
  </Rectangle>
</Button>

Binding an Image:

<Button Content="{Binding Image}" />

Binding a Grid:

<Button Content="{Binding Grid}" />

Binding a Grid in a Viewbox:

<Button>
  <Viewbox ...>
    <ContentPresenter Content="{Binding Grid}" />
  </Viewbox>
</Button>

Binding a Canvas:

<Button>
  <ContentPresenter Height="100" Width="100" Content="{Binding Canvas}" />
</Button>

Binding a Path:

<Button Content="{Binding Path}" />  <!-- Fill or stroke must be set in code unless set by the SVG converter -->

Binding a Geometry:

<Button>
  <Path Width="100" Height="100" Data="{Binding Geometry}" />
</Button>