Fancy Android Ruler

androidkotlincustom-viewlibraryui-componentsrtl-support
Kotlin GitHub

Building a Ruler That Actually Works

When I was developing a fitness app that needed height input, I wanted something more intuitive than a number picker. A ruler felt natural - slide to your height, see the number update in real-time.

The problem? Existing solutions were either too basic, didn’t support RTL (right-to-left) layouts, or lacked the customization I needed.

So I built FancyAndroidRuler.

RTL Ruler Demo
RTL Ruler Demo

RTL Support Done Right

As someone who works with Arabic-language apps, RTL support isn’t optional - it’s essential. This ruler works seamlessly in both directions:

LTR Ruler Demo
LTR Ruler Demo

The ruler automatically adapts its scroll direction and marker positions based on your layout direction.

Features

Measurement Systems

Switch between imperial (inches with quarters) and metric systems:

app:rulerSystem="imperial"
<!-- or -->
app:rulerSystem="metric"

Full Color Customization

Every element can be styled:

<dev.abd3lraouf.custom.ruler.FancyRuler
    app:rulerPointerColor="#FF0000FF"
    app:rulerNormalUnitBarColor="#FF0000FF"
    app:rulerMiddleUnitBarColor="#00BCD4"
    app:rulerQuarterUnitBarColor="#E91E63"
    app:rulerThreeQuartersUnitBarColor="#FFEB3B"
    app:rulerMainUnitBarColor="#4CAF50"
    app:rulerBackgroundColor="#000" />

Theme Options

RTL Themes
RTL Themes

LTR Themes
LTR Themes

Installation

Available on Maven Central:

repositories {
    mavenCentral()
}


dependencies {
    implementation 'dev.abd3lraouf.ruler:android:<VERSION>'
}

Usage

XML Layout

<TextView
    android:id="@+id/value_text"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:textSize="32sp" />


<dev.abd3lraouf.custom.ruler.FancyRuler
    android:id="@+id/ruler"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    app:rulerMinValue="15"
    app:rulerMaxValue="108"
    app:rulerDefaultPosition="67.5"
    app:rulerSystem="imperial" />

Kotlin

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)


        ruler.setOnScrollChangedListener({ scrollX ->
            value_text.text = ruler.getReading(scrollX).toString()
        }, debounceMs = 250)
    }
}

Technical Details

The ruler is built using a HorizontalScrollView with custom drawing on a Canvas. This provides:

Resources