SeekBarWidget.java 文件源码

/**
 * Updates a scale level of the thumb's drawable.
 *
 * @param scale The scale value from the range {@code [0.0, 1.0]}.
 */
@SuppressWarnings("Range")
void setThumbScale(float scale) {
    if (view.mThumb instanceof ScaleDrawable) {
        final int scaleLevel = Math.round(scale * MAX_LEVEL);
        view.mThumb.setLevel(Build.VERSION.SDK_INT > Build.VERSION_CODES.JELLY_BEAN ?
                scaleLevel :
                // Correct scale level for pre JELLY_BEAN Android versions.
                // scaleLevel(10000) = scale(1.0) [expected scale(1.0)]
                // scaleLevel(5000)  = scale(0.0) [expected scale(0.5)]
                // scaleLevel(0)     = scale(1.0) [expected scale(0.0)]
                scaleLevel + (int) ((10000 - scaleLevel) / 10000f * 5000)
        );
    }
}