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在进行多媒体或游戏程序开发时,会需要对重叠的颜色处理其透明度以产生更好的效果。下面为大家介绍如何用Java语言实现透明值混算的方法。
各点像素的RGB值是按一定比例混合而成的,这个比例由Alpha值决定,具体算式见下:
Alpha = 0 ~ 100 R = ( R1 * (100 - Alpha) + R2 * Alpha ) / 100 G = ( G1 * (100 - Alpha) + G2 * Alpha ) / 100 B = ( B1 * (100 - Alpha) + B2 * Alpha ) / 100
示例: RGB1 ( 232, 54, 13 ) RGB2 ( 94, 186, 233 )
Alpha = 30 R = ( 232 * 70 + 94 * 30 ) / 100 = 190.6 -> 190 G = ( 54 * 70 + 186 * 30 ) / 100 = 93.6 -> 93 B = ( 13 * 70 + 233 * 30 ) / 100 = 79 Alpha = 50 R = ( 232 * 50 + 94 * 50 ) / 100 = 163 G = ( 54 * 50 + 186 * 50 ) / 100 = 120 B = ( 13 * 50 + 233 * 50 ) / 100 = 123 这样在Java中可以对以上计算方法封装成函数或类,以方便代码复用,对应的Java代码如下:
protected Color calculateAlphaValue(Color c1, Color c2, int alpha)
{
if (alpha < MIN_ALPHA)
alpha = MIN_ALPHA;
else if (alpha > MAX_ALPHA)
alpha = MAX_ALPHA;
int R = (c1.getRed() * (MAX_ALPHA - alpha) + c2.getRed() * alpha) / MAX_ALPHA;
int G = (c1.getGreen() * (MAX_ALPHA - alpha) + c2.getGreen() * alpha) / MAX_ALPHA;
int B = (c1.getBlue() * (MAX_ALPHA - alpha) + c2.getBlue() * alpha) / MAX_ALPHA;
return new Color(R, G, B);
} |

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