Balachandar Kolathur Mani balachandarlinks

How to create custom button styles using Android's AppCompat-v7:21

Introduction

AppCompat is an Android support library to provide backwards-compatible functionality for Material design patterns. It currently comes bundled with a set of styles in the Theme.AppCompat and Widget.AppCompat namespaces. However, there is a critical component missing which I would have thought essential to provide the a default from which we could inherit our styles: Widget.AppCompat.Button. Sure, there's Widget.AppCompat.Light.ActionButton, but that doesn't actually inherit from Widget.ActionButton, which does not inherit from Widget.Button, so we might get some unexpected behavior using that as our base button style, mainly because Widget.ActionButton strictly belongs in the ActionBar.

So, if we want to have a decently normal default button style related to AppCompat, we need to make it ourselves. Let's start by digging into the Android SDK to see how it's doing default styles.

Digging In

Simple RecyclerView Divider

Simple Horizontal Divider Item Decoration for RecyclerView

    mRecyclerView.addItemDecoration(new SimpleDividerItemDecoration(
            getApplicationContext()
    	));

NOTE: Add item decoration prior to setting the adapter



	import android.content.Context;
	import android.graphics.Canvas;
	import android.graphics.Paint;
	import android.support.annotation.NonNull;
	import android.support.annotation.Nullable;
	import android.text.Editable;
	import android.text.Spannable;
	import android.text.TextWatcher;

	From theme

	<style name="SearchToolbar" parent="Theme.AppCompat.Light.NoActionBar">
	//toolbar back arrow color
	<item name="android:textColorSecondary">@android:color/white</item>
	//toolbar title color
	<item name="android:textColorPrimary">@android:color/white</item>
	</style>

	Also we can do it from java code:

	/*
	* Copyright 2015 "Henry Tao <hi@henrytao.me>"
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software

	#!/bin/bash

	# This is a very naive script, it doesn't do grouping and returns all branches
	# I only really care about branches that have not seen commits in two months
	#
	# I am hoping to find some time to write a tool that can output these reports for me
	# In the meantime, I am using this

	echo "Merged branches"
	for branch in `git branch -r --merged \| grep -v HEAD`;do echo -e `git log --no-merges -n 1 --format="%ci, %cr, %an, %ae, " $branch \| head -n 1` \\t$branch; done \| sort -r

	import android.support.v7.widget.LinearLayoutManager;
	import android.support.v7.widget.RecyclerView;

	public abstract class EndlessRecyclerOnScrollListener extends RecyclerView.OnScrollListener {
	public static String TAG = EndlessRecyclerOnScrollListener.class.getSimpleName();

	private int previousTotal = 0; // The total number of items in the dataset after the last load
	private boolean loading = true; // True if we are still waiting for the last set of data to load.
	private int visibleThreshold = 5; // The minimum amount of items to have below your current scroll position before loading more.
	int firstVisibleItem, visibleItemCount, totalItemCount;

	AppCompat-v7:21 provides a very useful way of dealing with pressed/focused/activated states maintaining backwards compatibility downto API-7, but there's a small issue (big for some) with the default selectableItemBackground: It uses some PNGs and/or default values for API<21.

	The main reason is that android drawable resource definitions (prior API 21) CANNOT use theme attributes at all, so there's no way of making something like:
	<shape android:shape="rectangle">
	<solid android:color="?attr/colorControlHighlight" />
	</shape>

	For this, I've put this simple mockup on how to give your app better drawables that the appcompat defaults.

	import android.content.Context;
	import android.support.v7.widget.RecyclerView;
	import android.util.AttributeSet;
	import android.view.View;
	import org.jetbrains.annotations.NotNull;
	import org.jetbrains.annotations.Nullable;

	public class EmptyRecyclerView extends RecyclerView {
	@Nullable View emptyView;

	package com.aracem.utils.animations.pagetransformation;

	import org.jetbrains.annotations.NotNull;

	import android.support.v4.view.ViewPager;
	import android.view.View;

	import java.util.ArrayList;
	import java.util.List;