android - What should be the color of the Ripple, colorPrimary or colorAccent? (Material Design)

Question

I have reading Material Design Guidelines but I don't know what should be the color of the Ripple if it isn't black (with alpha).

For example, I have an app with colorPrimary = blue, and colorAccent = red. Actually I am using the colorAccent (with alpha), I should use colorPrimary (with alpha) if I want a color different of black to the ripple?

I checked all app of Google but they never use ripples with color.

An image like I have now:

Answer 1

Use 26% alpha for colored ripples.

Android L doesn't support theme attributes in color state lists and the <ripple> element doesn't have an alpha channel, but for bounded ripples you can do something like:

<ripple xmlns:android="http://schemas.android.com/apk/res/android"
        android:color="?android:attr/colorAccent">
    <item android:id="@android:id/mask">
        <color android:color="#42ffffff" />
    </item>
</ripple>

This won't work for an unbounded ripple. Alternatively, since you know your own accent color, you can either define a 26% alpha version or use a color state list. Either of these will work fine for an unbounded ripple.

<ripple xmlns:android="http://schemas.android.com/apk/res/android"
        android:color="@color/accent_26" />

res/values/colors.xml:

<resources>
    ...
    <color name="accent">#ff33b5e5</color>
    <color name="accent_alpha26">#4233b5e5</color>
</resources>

res/color/accent_alpha26.xml:

<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:color="@color/accent"
          android:alpha="0.26" />
</selector>