RatingControl is the RatingControl of WinUI for WPF: a row of stars the user clicks to give a rating, with an optional caption after it.

<mah:RatingControl Caption="42 ratings" Value="3" />

Value

Value is a double and -1 means not rated, which is also the default. MaxRating gives the number of stars, 5 by default. A click sets the star under the pointer, and a click on the star of the current value clears the rating again, unless IsClearEnabled is off. Dragging off the left side of the row clears it as well. ValueChanged is raised when the user changes the rating, not when code sets Value.

The keyboard follows WinUI: Left and Right change the rating by one star (mirrored right to left), Up and Down do the same without the mirroring, Home clears it, or goes to the lowest rating while IsClearEnabled is off, and End gives the full rating. From no rating, the first step goes to InitialSetValue, 1 by default. IsReadOnly shows the value and takes no input.

Fractions and half stars

Since Value is a double, code or a binding can set any fraction, and the star it ends in is drawn in part. The pointer and the keyboard give whole stars, as in WinUI.

IsHalfStepEnabled goes a step further than WinUI: the left half of a star gives a half, the right half the whole star, and the keys count in halves. The smallest rating is then 0.5. It is off by default.

<mah:RatingControl IsHalfStepEnabled="True" Value="3.5" />

Placeholder

PlaceholderValue is shown while there is no rating, for example the average of all ratings, in the text colour instead of the accent. Unlike Value it may be any fraction, also below 1.

<mah:RatingControl Caption="3.5 on average, from 128 reviews"
                   IsClearEnabled="False"
                   PlaceholderValue="3.5" />

Glyphs and images

ItemInfo decides what the items look like. A RatingItemFontInfo takes glyphs of a font, by default the filled and the outlined star of the symbol font, and a RatingItemImageInfo takes an ImageSource per state. Both have a property for the set, the unset, the placeholder, the pointer over a set rating, the pointer over the placeholder and the disabled state; one left empty falls back to the next, in the end to Glyph or Image.

<mah:RatingControl MaxRating="7" Value="5">
    <mah:RatingControl.ItemInfo>
        <mah:RatingItemFontInfo Glyph="&#xEB52;" UnsetGlyph="&#xEB51;" />
    </mah:RatingControl.ItemInfo>
</mah:RatingControl>

The three looks

The colours come from the theme: MahApps.Brushes.RatingControl.Unselected, .Selected, .Placeholder, .PointerOverUnselected, .PointerOverPlaceholder, .PointerOverSelected, .DisabledSelected and .Caption for Metro, and the same eight with .Win10. and .WinUI. in front of the state for the other two. Override these keys to change the colours; a copy of the template can't set them, since the properties that carry them into the template are internal.

Differences to WinUI

There is no gamepad engagement and no sound. IsHalfStepEnabled is new. The pointer over the stars is measured the same way for the preview and for the click, where WinUI measures the two from slightly different points.

Related

Win10 and WinUI for the sets.