Android color 平滑过渡计算

/** * 根据fraction值来计算当前的颜色。 */private int getCurrentColor(float fraction, int startColor, int endColor) {    int redCurrent;    int blueCurrent;    int greenCurrent;    int alphaCurrent;    int redStart = Color.red(startColor);    int blueStart = Color.blue(startColor);    int greenStart = Color.green(startColor);    int alphaStart = Color.alpha(startColor);    int redEnd = Color.red(endColor);    int blueEnd = Color.blue(endColor);    int greenEnd = Color.green(endColor);    int alphaEnd = Color.alpha(endColor);    int redDifference = redEnd - redStart;    int blueDifference = blueEnd - blueStart;    int greenDifference = greenEnd - greenStart;    int alphaDifference = alphaEnd - alphaStart;    redCurrent = (int) (redStart + fraction * redDifference);    blueCurrent = (int) (blueStart + fraction * blueDifference);    greenCurrent = (int) (greenStart + fraction * greenDifference);    alphaCurrent = (int) (alphaStart + fraction * alphaDifference);    return Color.argb(alphaCurrent, redCurrent, greenCurrent, blueCurrent);}