Android uses recyclerview to implement horizontal scroll control

preface

I believe everyone knows that there are many ways to implement Android scroll control, and it is relatively simple to use recyclerview. We have made a simple age scroll control. Let's take a look at the usage of recyclerview, mainly including the following points:

(1) Align the center of the control

(2) Calculate the rolling distance

(3) Highlight the center view

(4) Real time display of central data

(5) Automatic alignment when stopped

(6) When scrolling, set the button status switch

effect

1. Framework

It mainly focuses on the logic of recyclerview

Set a horizontal layout

Add an adapter and set the start and end positions

2. Adapter

Adapter customizes some functions, such as pointing to the center, data linkage display, highlighting item, etc

The width of each cell is one odd part of the screen width. When the screen is filled, the starting point points to the center

If the number of items is singular, the indicator of the center must point to the center of the central item

Update the item style according to the selected status

Set the highlight, highlight the center position, restore both sides, and notify the adapter to redraw the viewholder

Get the width. If the number of items displayed in a row is set to an odd number, the center points to an item

Note that recyclerview cannot move half a cell. If the number of each row is singular, it must point to the center

3. Scroll logic

When scrolling, the page display is updated in real time; When stopped, update the highlighted and stored data; At the end of scrolling, activate the button

Judge the distance unit of scrolling, offset total distance / single item width

Computehorizontalscrolloffset() gets the total offset of the recyclerview

In the middle position, add the number of items in half a line

Judge whether the scrolling stops

Automatic alignment when scrolling stops

Call the item that needs to be highlighted

Note that when scrolling stops, it is better to update the highlight, otherwise the redrawing speed is slow, which will affect the scrolling effect

Sliding effect

summary

Well, that's all the content of this article. We can customize all kinds of scroll bars according to these! I hope this article can help you.