None, The content preserves its original size.
<Image Source="/WpfApp169;component/cl.jpg" Stretch="None"/>
Fill,The content is resized to fill the destination dimensions. The aspect ratio is not preserved.
<Image Source="/WpfApp169;component/cl.jpg" Stretch="Fill"/>
Uniform,The content is resized to fit in the destination dimensions while it preserves its native aspect ratio
<Image Source="/WpfApp169;component/cl.jpg" Stretch="Uniform"/>
UniformToFill, The content is resized to fill the destination dimensions while it preserves its native aspect ratio. If the aspect ratio of the destination rectangle differs from the source, the source content is clipped to fit in the destination dimensions.
<Image Source="/WpfApp169;component/cl.jpg" Stretch="UniformToFill"/>
标签：None,ratio,dimensions,UnformToFill,Stretch,destination,Uniform,content,aspect From： https://www.cnblogs.com/Fred1987/p/18249668