item.xml

<item android:top="300dp"
      android:bottom="-100dp"
      android:left="0dp"
      android:right="-300dp">
      <rotate
          android:fromDegrees="-10"
          android:pivotX="0%"
          android:pivotY="100%">
          <shape
              android:shape="rectangle">
              <solid
                  android:color="?android:colorBackground"/>
          </shape>
      </rotate>
  </item>