JAVASCRIPT亮度功能 - 降低

Question

我在这里创办了这一段代码堆栈：

function increase_brightness(hex, percent){ 
    var r = parseInt(hex.substr(1, 2), 16), 
     g = parseInt(hex.substr(3, 2), 16), 
     b = parseInt(hex.substr(5, 2), 16); 

    return '#' + 
     ((0|(1<<8) + r + (256 - r) * percent/100).toString(16)).substr(1) + 
     ((0|(1<<8) + g + (256 - g) * percent/100).toString(16)).substr(1) + 
     ((0|(1<<8) + b + (256 - b) * percent/100).toString(16)).substr(1); 
} 

没有人知道如何使完全相同逆？

功能decreas_brightness(){}我的意思是

Answer 1

你的代码是从JavaScript Calculate brighter colour。根据评论，下面的改变应该会使亮度下降：

function decrease_brightness(hex, percent){ 
    var r = parseInt(hex.substr(1, 2), 16), 
     g = parseInt(hex.substr(3, 2), 16), 
     b = parseInt(hex.substr(5, 2), 16); 

    return '#' + 
     ((0|(1<<8) + r * (100 - percent)/100).toString(16)).substr(1) + 
     ((0|(1<<8) + g * (100 - percent)/100).toString(16)).substr(1) + 
     ((0|(1<<8) + b * (100 - percent)/100).toString(16)).substr(1); 
}