slider 概览
像 <input type="range"> 一样，<mat-slider> 允许通过鼠标、触控或键盘来从范围中选择一个值。
<mat-slider> allows for the selection of a value from a range via mouse, touch, or keyboard,
similar to <input type="range">.
注意：该组件的滑动行为要求本页面中加载过 HammerJS 库。
Note: the sliding behavior for this component requires that HammerJS is loaded on the page.
默认情况下，滑杆（slider）的最小值是 0，最大值是 100，滑块（thumb）移动时的增量是 1。
这些值可以通过设置 min、max 和 step 属性进行修改。除非另行指定，否则其初始值就等于最小值。
By default the minimum value of the slider is 0, the maximum value is 100, and the thumb moves
in increments of 1. These values can be changed by setting the min, max, and step attributes
respectively. The initial value is set to the minimum value unless otherwise specified.
<mat-slider min="1" max="5" step="0.5" value="1.5"></mat-slider>
默认情况下，滑杆是水平放置的，其最小值在左侧，最大值在右侧。可以给滑杆添加 vertical 属性，来让它变成垂直的，其最小值在底部，而最大值在顶部。
By default sliders are horizontal with the minimum value on the left and the maximum value on the
right. The vertical attribute can be added to a slider to make it vertical with the minimum value
on bottom and the maximum value on top.
<mat-slider vertical></mat-slider>还可以指定 invert 属性，来翻转坐标轴（滑块会沿着它移动）。
翻转后的水平滑杆，其最小值在右侧，而最大值在左侧；翻转后的垂直滑杆，其最小值在上部，而最大值在底部。
An invert attribute is also available which can be specified to flip the axis that the thumb moves
along. An inverted horizontal slider will have the minimum value on the right and the maximum value
on the left, while an inverted vertical slider will have the minimum value on top and the maximum
value on bottom.
<mat-slider invert></mat-slider>
默认情况下，滑杆所选的精确值不会显示给用户。不过，可以通过 thumbLabel 属性来把这个值显示在滑块上。
By default, the exact selected value of a slider is not visible to the user. However, this value can
be added to the thumb by adding the thumbLabel attribute.
Material Design 规范建议只为那些用来显示离散值（比如 1~5 的打分值）的滑杆使用 thumbLabel 属性（同时设置 tickInterval="1"）。
The Material Design spec recommends using the
thumbLabel attribute (along with tickInterval="1") only for sliders that are used to display a
discrete value (such as a 1-5 rating).
<mat-slider thumbLabel tickInterval="1"></mat-slider>
默认情况下，滑块标签上的值会始终和模型的值相同，不过它可能太大，而没办法放进标签中。
如果你要控制要显示的值，你可以使用输入属性 displayWith 来实现。
By default, the value in the slider's thumb label will be the same as the model value, however this
may end up being too large to fit into the label. If you want to control the value that is being
displayed, you can do so using the displayWith input.
默认情况下，滑杆不会在滑块的导轨（track）上显示刻度标记，不过可以使用 tickInterval 属性来启用它。tickInterval 的值应该是一个表示刻度之间步长的数字。比如 tickInterval 为 3 而 step 为 4 时，将会每隔 3 步画出一个标记，每 12 个值重复一轮。
By default, sliders do not show tick marks along the thumb track. This can be enabled using the
tickInterval attribute. The value of tickInterval should be a number representing the number
of steps between ticks. For example a tickInterval of 3 with a step of 4 will draw
tick marks at every 3 steps, which is the same as every 12 values.
<mat-slider step="4" tickInterval="3"></mat-slider>tickInterval 还可以设置为 auto 来自动选择步数，来让刻度之间至少相距 30px。
The tickInterval can also be set to auto which will automatically choose the number of steps
such that there is at least 30px of space between ticks.
<mat-slider tickInterval="auto"></mat-slider>滑杆始终会在导轨的起点和终点显示一个刻度。如果剩下的控件不够添加了，那么最后一个间距可能被缩短或拉长，以便让刻度显示在导轨的末尾。
The slider will always show a tick at the beginning and end of the track. If the remaining space doesn't add up perfectly the last interval will be shortened or lengthened so that the tick can be shown at the end of the track.
Material Design 规范 建议只为那些用来显示离散值（比如 1~5 的打分值）的滑杆设置 tickInterval 属性（同时把 thumbLabel 属性设置为 1）。
The Material Design spec recommends using the
tickInterval attribute (set to 1 along with the thumbLabel attribute) only for sliders that
are used to display a discrete value (such as a 1-5 rating).
滑杆具有下列键盘绑定：
The slider has the following keyboard bindings:
按键 Key |
操作 Action |
|---|---|
右方向键 Right arrow |
滑杆的值增加一步（在 RTL 下则减小）。 Increment the slider value by one step (decrements in RTL). |
上方向键 Up arrow |
滑杆的值增加一步。 Increment the slider value by one step. |
左方向键 Left arrow |
滑杆的值减小一步（在 RTL 下则增加）。 Decrement the slider value by one step (increments in RTL). |
下方向键 Down arrow |
滑杆的值减小一步。 Decrement the slider value by one step. |
上翻页 Page up |
滑杆的值增加 10 步。 Increment the slider value by 10 steps. |
下翻页 Page down |
滑杆的值减小 10 步。 Decrement the slider value by 10 steps. |
| End | 设置为可能的最大值。 Set the value to the maximum possible. |
| Home | 设置为可能的最小值。 Set the value to the minimum possible. |
没有文本或标签的滑杆应该通过 aria-label 或 aria-labelledby 给出一个有意义的标签。
Sliders without text or labels should be given a meaningful label via aria-label or
aria-labelledby.