Custom TextSize of BottomNavigationView support android

Question

I am trying to change the textSize of BottomNavigationView from android support library 25.0.0

Answer 1

To do this, I just decided to override the navigation item layout :

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android">
    <ImageView
        android:id="@+id/icon"
        android:layout_width="24dp"
        android:layout_height="24dp"
        android:layout_gravity="center_horizontal"
        android:layout_marginTop="@dimen/design_bottom_navigation_margin"
        android:layout_marginBottom="@dimen/design_bottom_navigation_margin"
        android:duplicateParentState="true" />
    <android.support.design.internal.BaselineLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom|center_horizontal"
        android:clipToPadding="false"
        android:paddingBottom="10dp"
        android:duplicateParentState="true">
        <TextView
            android:id="@+id/smallLabel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:textSize="@dimen/design_bottom_navigation_text_size"
            android:singleLine="true"
            android:duplicateParentState="true" />
        <TextView
            android:id="@+id/largeLabel"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:visibility="invisible"
            android:textSize="@dimen/design_bottom_navigation_active_text_size"
            android:singleLine="true"
            android:duplicateParentState="true" />
    </android.support.design.internal.BaselineLayout>
</merge>

Just make sure you name it design_bottom_navigation_item

Answer 2

You can change BottomNavigationView text appearance by defining your own styles for Component Attributes itemTextAppearanceActive and itemTextAppearanceInactive. By default they have textAppearanceCaption check section Theme Attribute Mapping in the docs Bottom Navigation.

<android.support.design.widget.BottomNavigationView
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:itemTextAppearanceActive="@style/BottomNavigationView.Active"
    app:itemTextAppearanceInactive="@style/BottomNavigationView"
    app:menu="@menu/bottom_navigation_main" />

styles.xml

<style name="BottomNavigationView" parent="@style/TextAppearance.AppCompat.Caption">
    <item name="android:textSize">10sp</item>
</style>

<style name="BottomNavigationView.Active" parent="@style/TextAppearance.AppCompat.Caption">
    <item name="android:textSize">11sp</item>
</style>

• Next, Change Text Color selected and icon:
  Just Create bottom_nav_icon_color_selector & bottom_nav_text_color_selector on drawable to edit default value.

• For change icon color - bottom_nav_icon_color_selector.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:color="@color/colorPrimary" android:state_checked="true" /> <!-- colorIcon Active -->
    <item android:color="@color/colorPrimary" android:state_enabled="true" android:state_pressed="true" /> <!-- colorIcon Active -->
    <item android:color="@color/colorIconInActive" /> <!-- colorIcon InActive -->
</selector>

• For change text color - bottom_nav_text_color_selector.xml

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:color="@color/colorPrimary" android:state_checked="true" /> <!-- colorText Active -->
    <item android:color="@color/colorPrimary" android:state_enabled="true" android:state_pressed="true" /> <!-- colorText Active -->
    <item android:color="@color/colorTextInActive" /> <!-- colorText InActive -->
</selector>

• Note : @color/colorIconInActive is a color disable/inactive, you can set this color in your res-values-colors
• Finish, try to see, your navigation bottom. color icon and text will be change.

Answer 3

Add the TabTextStyle code inside the UpdateBarTextColor (this void exist in BottomBarPageRenderer)

 void UpdateBarTextColor()
    {
        if (_disposed || _bottomBar == null)
        {
            return;
        }
        //This is linked to styles.xml to set size of text
        _bottomBar.SetTextAppearance(Resource.Style.TabTextStyle);
        //Set color of text and icon in BottomNavBar
        _bottomBar.SetActiveTabColor(Element.BarTextColor.ToAndroid(Color.FromHex("#0094F0")));
        // The problem SetActiveTabColor does only work in fiexed mode // haven't found yet how to set text color for tab items on_bottomBar, doesn't seem to have a direct way
    }

And then add this inside the styles.xml:

<style name="TabTextStyle" parent="@android:style/TextAppearance.Medium"> 
    <item name="android:textSize">8dp</item> 
</style> 

Answer 4

I used the snippet below to change the NavigationView style using the Material design.

<style name="MyBottomNavigationView" parent="Widget.MaterialComponents.BottomNavigationView">
    <item name="itemIconTint">@color/bottom_navigation_item_selector</item>
    <item name="itemTextColor">@color/bottom_navigation_item_selector</item>
    <item name="itemTextAppearanceActive">@style/MyBottomNavigationView.TextAppearance</item>
    <item name="itemTextAppearanceInactive">@style/MyBottomNavigationView.TextAppearance</item>
</style>

<style name="MyBottomNavigationView.TextAppearance" parent="TextAppearance.MaterialComponents.Caption">
    <item name="android:textSize">11sp</item>
    <item name="fontFamily">@font/exo2_medium</item>
</style>

Then set the style to the BottomNavigationView element

<com.google.android.material.bottomnavigation.BottomNavigationView
    ...
    style="@style/MyBottomNavigationView" />

Answer 5

Another solution is to use Spannable to adjust the size color, font or other a text attributes ....

private static class MenuSpannable extends MetricAffectingSpan{
        int color = Color.RED;
        int size = 40;

        public MenuSpannable() {
            setSelected(false);
        }

        @Override
        public void updateMeasureState(TextPaint p) {
            p.setColor(color);
            p.setTextSize(size);
            /* p.setText --- whatever --- */
        }

        @Override
        public void updateDrawState(TextPaint tp) {
            tp.setColor(color);
            tp.setTextSize(size);
            /* tp.setText --- whatever --- */
        }
        private void setSelected(boolean selected){
            if(selected){
                color = Color.RED;
                size = 40;
            }else{
                color = Color.BLUE;
                size = 20;
            }
        }
}

And then set the span for any menu item...

@Override
protected void onCreate(Bundle savedInstanceState) {
        BottomNavigationView mBottomNavigationView = (BottomNavigationView)findViewById(R.id.bottom_menu);
        final Menu menu = mBottomNavigationView.getMenu();
        final Font font = Font.getFromContext(this);
        for(int i = 0; i < menu.size(); i++) {
            SpannableString spannableString = new SpannableString(menu.getItem(i).getTitle());
            spannableString.setSpan(new MenuSpannable(),0,spannableString.length(),0);
            menu.getItem(i).setTitle(spannableString);
        }
}

In case you want the text to change with the selection state

mBottomNavigationView.setOnNavigationItemSelectedListener(new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
             Menu menu = mBottomNavigationView.getMenu();
             for(int i = 0; i < menu.size(); i++) {
                MenuSpannable menuSpannable = new MenuSpannable();
                menuSpannable.setSelected(item.getItemId() == menu.getItem(i).getItemId());
                SpannableString sString = new SpannableString(menu.getItem(i).getTitle());
                sString.setSpan(menuSpannable,0,sString.length(),0);
                menu.getItem(i).setTitle(sString);
                }
            return false;
            }
        });

Answer 6

Unfortunately overriding dimen did not work for me at com.android.support:design:28.0.0

Finally I was able to change the text size by using <font size="8"></font> tag for each title string resource used in menu.xml.

For example I have a menu declared here menu_bottom_navigation.xml, which has item like:

<item
  ...
  android:title="@string/main_navi_item_home"
  .../>

In string.xml, set the target resource like:

<string name="main_navi_item_home"><font size="8">Home</font></string>