seekbar thumb 透明效果出现父布局背景颜色的解决方法

在seekbar中添加  android:splitTrack="false" 即可
<SeekBar  
           android:id="@+id/seekbar"  
           android:layout_width="match_parent"  
           android:layout_height="wrap_content"  
           android:max="@integer/max_step"  
           android:maxHeight="@dimen/seekbar_height"  
           android:minHeight="@dimen/seekbar_height"  
           android:padding="0dp"  
          <span style="color:#ff0000;"> android:splitTrack="false"</span>  
           android:progress="0"  
           android:progressDrawable="@drawable/bg_seekbar"  
           android:thumb="@drawable/bg_seekbar_thumbs"  
           android:thumbOffset="0dp" />