How to change centre point of shape's linear gradient?
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I have a shape defined as follows:

    <?xml version="1.0" encoding="utf-8"?>
    <shape
      xmlns:android="http://schemas.android.com/apk/res/android"
      android:shape="rectangle" >
      <gradient
        android:angle="90"
        android:endColor="@color/white"
        android:startColor="@color/grey"
        android:type="linear" />
    </shape>

The gradient transitions from grey to white evenly from bottom to top, reaching the colour that is between grey and white in the middle. I would like to change the mid-point of the gradient to be closer to the bottom, so that the shape is more white than grey, if that makes sense?! Anyone know how to do this, or whether this is not possible? I have tried setting the `android:centerY` attribute to `0.1` and `0.9` but I see no visible difference.