2020-03-11 18:27:38 +01:00

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# View Pager(2) dots indicator
This repository was created to present you implemented dots indicator
either for `ViewPager` or `ViewPager2`.
## How to implement View Pager dots indicator?
Here is description how to implement dots indicator - full example you can find in repository above.
All we need are: [ViewPager][1], [TabLayout][2] and 2 drawables for
selected and default dots.
> Implementation for `ViewPager2` is almost the same:
> Replace `androidx.viewpager.widget.ViewPager` with `androidx.viewpager2.widget.ViewPager2`.
Firstly, we have to add `TabLayout` to our screen layout, and connect it
with `ViewPager`. We can do this in two ways:
#### Nested `TabLayout` in `ViewPager`
```xml
<androidx.viewpager.widget.ViewPager
android:id="@+id/photos_viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent">
<com.google.android.material.tabs.TabLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</androidx.viewpager.widget.ViewPager>
```
> In this case `TabLayout` will be automatically connected with
> `ViewPager`, but `TabLayout` will be next to `ViewPager`, not over it.
#### Separate `TabLayout`
```xml
<androidx.viewpager.widget.ViewPager
android:id="@+id/photos_viewpager"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
<com.google.android.material.tabs.TabLayout
android:id="@+id/tab_layout"
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
```
> In this case, we can put `TabLayout` anywhere, but we have to connect
> `TabLayout` with `ViewPager` programmatically
**for `ViewPager`**
```kotlin
val viewPager = findViewById<ViewPager>(R.id.viewPager)
val tabLayout = findViewById<TabLayout>(R.id.tabLayout)
viewPager.adapter = sectionsPagerAdapter
tabLayout.setupWithViewPager(viewPager)
```
**for `ViewPager2`**
```kotlin
val viewPager2 = findViewById<ViewPager2>(R.id.viewPager2)
val tabLayout = findViewById<TabLayout>(R.id.tabLayout)
viewPager.adapter = sectionsPagerAdapter
TabLayoutMediator(tabLayout, viewPager2) { tab, position ->
//Some implementation...
}.attach()
```
Once we created our layout, we have to prepare our dots. So we create
three files: `selected_dot.xml`, `default_dot.xml` and
`tab_selector.xml`.
#### selected_dot.xml
```xml
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape
android:innerRadius="0dp"
android:shape="ring"
android:thickness="8dp"
android:useLevel="false">
<solid android:color="@color/colorAccent"/>
</shape>
</item>
</layer-list>
```
#### default_dot.xml
```xml
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android">
<item>
<shape
android:innerRadius="0dp"
android:shape="ring"
android:thickness="8dp"
android:useLevel="false">
<solid android:color="@android:color/darker_gray"/>
</shape>
</item>
</layer-list>
```
#### tab_selector.xml
```xml
<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
<item android:drawable="@drawable/selected_dot"
android:state_selected="true"/>
<item android:drawable="@drawable/default_dot"/>
</selector>
```
Now we need to add only 3 lines of code to `TabLayout` in our XML
layout.
```xml
app:tabBackground="@drawable/tab_selector"
app:tabGravity="center"
app:tabIndicatorHeight="0dp"
```
---
*[ViewPager with dots indicator][3] at medium.com*
*Up-votes are welcome ;-)*
[1]:
https://developer.android.com/reference/androidx/viewpager/widget/ViewPager?hl=en
[2]: https://developer.android.com/reference/com/google/android/material/tabs/TabLayout?hl=en
[3]: https://medium.com/@adrian.kuta93/android-viewpager-with-dots-indicator-a34c91e59e3a