Android color 平滑过渡计算

最新推荐文章于 2021-05-26 21:29:50 发布

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本文介绍了一种根据fraction值计算颜色渐变的方法。通过提取起始颜色和结束颜色的各个通道值，计算它们之间的差值，并利用fraction参数来确定当前颜色各通道的具体数值。

/**
 * 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);
}