如何更改 mdc-select 下拉箭头的颜色？

Question

我正在尝试更改 mdc-select 中下拉箭头的默认紫色：

似乎没有一个 sass mixin 可以做到这一点。

它是怎么做的？

这是我迄今为止尝试过的：

HTML

<div class="mdc-select mdc-select--outlined">
    <input type="hidden" name="enhanced-select">
    <i class="mdc-select__dropdown-icon"></i>
    <div class="mdc-select__selected-text" class="mdc-select__selected-text" role="button" aria-haspopup="listbox" aria-labelledby="demo-label"></div>
    <div class="mdc-select__menu mdc-menu mdc-menu-surface">
        <ul class="mdc-list">
            <li class="mdc-list-item" data-value="41" role="option">41</li>
            <li class="mdc-list-item" data-value="42" role="option">42</li>
            <li class="mdc-list-item" data-value="43" role="option">43</li>
        </ul>
    </div>
    <div class="mdc-notched-outline">
        <div class="mdc-notched-outline__leading"></div>
        <div class="mdc-notched-outline__notch">
            <label class="mdc-floating-label">Answer to Life</label>
        </div>
        <div class="mdc-notched-outline__trailing"></div>
    </div>
</div>  

SCSS

@import "@material/list/mdc-list";
@import "@material/menu-surface/mdc-menu-surface";
@import "@material/menu/mdc-menu";
@import "@material/select/mdc-select";

.mdc-select {
    @include mdc-select-ink-color(red);
    // @include mdc-select-container-fill-color(red);
    @include mdc-select-label-color(red);
    @include mdc-select-focused-label-color(red);
    @include mdc-select-bottom-line-color(red);
    @include mdc-select-focused-bottom-line-color(red);
    @include mdc-select-hover-bottom-line-color(red);
    @include mdc-select-outline-color(red);
    @include mdc-select-focused-outline-color(red);
    @include mdc-select-hover-outline-color(red);
    @include mdc-select-icon-color(red);
}

TS

import { MDCSelect } from '@material/select';
const select = new MDCSelect(document.querySelector('.mdc-select'));

Answer 1

最简单最简单的方法是隐藏 SVG 并通过 CSS 创建自己的下拉箭头（无需更改 HTML）。然后，您可以根据需要轻松更改颜色：

.mdc-select__dropdown-icon{
  background: none;
  width: 0;
  height: 0;
  bottom: 24px;
  right: 10px;  
  border-left: 5px solid transparent;
  border-right: 5px solid transparent;
  border-top: 5px solid #333333;
}
.mdc-select--activated .mdc-select__dropdown-icon,
.mdc-select--focused .mdc-select__dropdown-icon {
  border-top: 5px solid #FF0000;
}

Answer 2

我设法通过使用 MDC 内部 Sass 混合来为其设置主题：mdc-select-dd-arrow-svg-bg_。一个例子是：

.mdc-select .mdc-select__dropdown-icon {
    @include mdc-select-dd-arrow-svg-bg_(COLOR, 1);
}

其中COLOR 是MDC 主题属性（例如'secondary'）或HTML 颜色（例如#ff0000）。它不能是 var，因为正如 @KuldipKoradia 所指出的，SVG 是在编译时生成的。

Answer 3

这不是图标或字体，此箭头是.mdc-select--focused .mdc-select__dropdown-icon 类的背景图像。您可以使用filter css 属性更改图像颜色。

filter: hue-rotate(60deg);

将此 css 应用到您的自定义 css 类 .mdc-select--focused .mdc-select__dropdown-icon 它将起作用。

谢谢。