Files
Brandy Carney 94159291b2 feat(components): improve button states and add new css properties (#19440)
Before users had to know the exact opacity that the MD/iOS spec called for in order to change the hover or focused background color. This allows them to change the background without having to know the opacity. 

- changes apply to Action Sheet (Buttons), Back Button, Button, FAB Button, Item, Menu Button, Segment Button, Tab Button
- greatly reduces the requirement by users to set the background hover, focused states for dark modes and custom themes, also eliminates the need to know what the hover opacity is for each based on the spec
- updates the MD dark theme per their spec
- adds a component guide for internal use changing Ionic components

references #18279 fixes #20213 fixes #19965

BREAKING CHANGE:

*Activated Class*

The `activated` class that is automatically added to buttons on press has been renamed to `ion-activated`. This will be more consistent with our `ion-focused` class we add and also will reduce conflicts with user's CSS.

*CSS Variables*

The `--background-hover`, `--background-focused` and `--background-activated` CSS variables on components that render native buttons will now have an opacity automatically set. If you are setting any of these like the following:

```
--background-hover: rgba(44, 44, 44, 0.08);
```

You will likely not see a hover state anymore. It should be updated to only set the desired color:

```
--background-hover: rgba(44, 44, 44);
```

If the opacity desired is something other than what the spec asks for, use:

```
--background-hover: rgba(44, 44, 44);
--background-hover-opacity: 1;
```
2020-01-23 16:57:47 -05:00
..

ion-tab-button

A tab button is a UI component that is placed inside of a tab bar. The tab button can specify the layout of the icon and label and connect to a tab view.

See the tabs documentation for more details on configuring tabs.

Usage

Angular

<ion-tabs>

  <ion-tab-bar slot="bottom">
    <ion-tab-button tab="schedule">
      <ion-icon name="calendar"></ion-icon>
      <ion-label>Schedule</ion-label>
    </ion-tab-button>

    <ion-tab-button tab="speakers">
      <ion-icon name="person-circle"></ion-icon>
      <ion-label>Speakers</ion-label>
    </ion-tab-button>

    <ion-tab-button tab="map">
      <ion-icon name="map"></ion-icon>
      <ion-label>Map</ion-label>
    </ion-tab-button>

    <ion-tab-button tab="about">
      <ion-icon name="information-circle"></ion-icon>
      <ion-label>About</ion-label>
    </ion-tab-button>
  </ion-tab-bar>

</ion-tabs>

Javascript

<ion-tabs>

  <ion-tab-bar slot="bottom">
    <ion-tab-button tab="schedule" href="/app/tabs/(schedule:schedule)">
      <ion-icon name="calendar"></ion-icon>
      <ion-label>Schedule</ion-label>
    </ion-tab-button>

    <ion-tab-button tab="speakers" href="/app/tabs/(speakers:speakers)">
      <ion-icon name="person-circle"></ion-icon>
      <ion-label>Speakers</ion-label>
    </ion-tab-button>

    <ion-tab-button tab="map" href="/app/tabs/(map:map)">
      <ion-icon name="map"></ion-icon>
      <ion-label>Map</ion-label>
    </ion-tab-button>

    <ion-tab-button tab="about" href="/app/tabs/(about:about)">
      <ion-icon name="information-circle"></ion-icon>
      <ion-label>About</ion-label>
    </ion-tab-button>
  </ion-tab-bar>

  <ion-tab tab="schedule">
    <ion-router-outlet name="schedule"></ion-router-outlet>
  </ion-tab>

  <ion-tab tab="speakers">
    <ion-router-outlet name="speakers"></ion-router-outlet>
  </ion-tab>

  <ion-tab tab="map">
    <ion-router-outlet name="map"></ion-router-outlet>
  </ion-tab>

  <ion-tab tab="about">
    <ion-router-outlet name="about"></ion-router-outlet>
  </ion-tab>

</ion-tabs>

React

import React from 'react';
import { IonTabs, IonTabBar, IonTabButton, IonIcon, IonLabel, IonContent } from '@ionic/react';

export const TabButtonExample: React.FC = () => (
  <IonContent>
    <IonTabs>
      <IonTabBar slot="bottom">
        <IonTabButton tab="schedule">
          <IonIcon name="calendar" />
          <IonLabel>Schedule</IonLabel>
        </IonTabButton>

        <IonTabButton tab="speakers">
          <IonIcon name="person-circle" />
          <IonLabel>Speakers</IonLabel>
        </IonTabButton>

        <IonTabButton tab="map">
          <IonIcon name="map" />
          <IonLabel>Map</IonLabel>
        </IonTabButton>

        <IonTabButton tab="about">
          <IonIcon name="information-circle" />
          <IonLabel>About</IonLabel>
        </IonTabButton>
      </IonTabBar>
    </IonTabs>
  </IonContent>
);

Vue

<template>
  <ion-tabs>

    <ion-tab-bar slot="bottom">
      <ion-tab-button tab="schedule">
        <ion-icon name="calendar"></ion-icon>
        <ion-label>Schedule</ion-label>
      </ion-tab-button>

      <ion-tab-button tab="speakers">
        <ion-icon name="person-circle"></ion-icon>
        <ion-label>Speakers</ion-label>
      </ion-tab-button>

      <ion-tab-button tab="map">
        <ion-icon name="map"></ion-icon>
        <ion-label>Map</ion-label>
      </ion-tab-button>

      <ion-tab-button tab="about">
        <ion-icon name="information-circle"></ion-icon>
        <ion-label>About</ion-label>
      </ion-tab-button>
    </ion-tab-bar>

  </ion-tabs>
</template>

Properties

Property Attribute Description Type Default
disabled disabled If true, the user cannot interact with the tab button. boolean false
download download This attribute instructs browsers to download a URL instead of navigating to it, so the user will be prompted to save it as a local file. If the attribute has a value, it is used as the pre-filled file name in the Save prompt (the user can still change the file name if they want). string | undefined undefined
href href Contains a URL or a URL fragment that the hyperlink points to. If this property is set, an anchor tag will be rendered. string | undefined undefined
layout layout Set the layout of the text and icon in the tab bar. It defaults to 'icon-top'. "icon-bottom" | "icon-end" | "icon-hide" | "icon-start" | "icon-top" | "label-hide" | undefined undefined
mode mode The mode determines which platform styles to use. "ios" | "md" undefined
rel rel Specifies the relationship of the target object to the link object. The value is a space-separated list of link types. string | undefined undefined
selected selected The selected tab component boolean false
tab tab A tab id must be provided for each ion-tab. It's used internally to reference the selected tab or by the router to switch between them. string | undefined undefined
target target Specifies where to display the linked URL. Only applies when an href is provided. Special keywords: "_blank", "_self", "_parent", "_top". string | undefined undefined

CSS Custom Properties

Name Description
--background Background of the tab button
--background-focused Background of the tab button when focused with the tab key
--background-focused-opacity Opacity of the tab button background when focused with the tab key
--color Color of the tab button
--color-focused Color of the tab button when focused with the tab key
--color-selected Color of the selected tab button
--padding-bottom Bottom padding of the tab button
--padding-end Right padding if direction is left-to-right, and left padding if direction is right-to-left of the tab button
--padding-start Left padding if direction is left-to-right, and right padding if direction is right-to-left of the tab button
--padding-top Top padding of the tab button
--ripple-color Color of the button ripple effect

Dependencies

Depends on

Graph

graph TD;
  ion-tab-button --> ion-ripple-effect
  style ion-tab-button fill:#f9f,stroke:#333,stroke-width:4px

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