Sliders – Material Component For Android

Sliders used to view and select a value or range from the given slider bar.They’re mainly used for adjusting settings such as volume and brightness, etc.

Sliders can use icons on both ends of the bar to represent a numeric or relative scale. The range of values or the nature of the values, such as volume change, can be communicated with icons.

Sliders add into Material design in library version 1.2.0. So, you need to add 1.2.0 or higher version on material design.

Before starting checkout my other post on material design:

ShapeableImageView – Material components for android

Progress Indicators – Material Components For Android

Android Chips — Material Component For Android

Android Snackbar Example

Sliders design

Types of sliders

There are two types of sliders.

  • Continuous Slider
  • Discrete Slider

Also, We have a another slider called range slider.

Lets see about these sliders in detail.

Continuous Slider

Continuous sliders allow us to select any value between the given start and end value.

For example, valueFrom = “0.0” and valueTo=”100.0″ in this case, you can select any values between from and to values like 55.5, 62.0, etc.

continuous slider

defining the slider In the layout,

<com.google.android.material.slider.Slider
        android:id="@+id/continuousSlider"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:valueFrom="0.0"
        android:valueTo="100.0"
        android:value="20.0"/>

in the layout,

valueFrom : starting value of the slider.

valueTo : ending value of the slider.

value: setting the initial value of the slider.

Similarly, we can add a RangeSlider in a layout:

<com.google.android.material.slider.RangeSlider
        android:id="@+id/rangeSlider"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:valueFrom="0.0"
        android:valueTo="100.0"
        android:stepSize="10.0"
        app:values="@array/initial_range_slider_values" />

The RangeSlider has app:values attribute to set the range for the slider. we need to provide the range in arrays.

values/arrays.xml:

<resources>
    <array name="initial_range_slider_values">
        <item>20.0</item>
        <item>80.0</item>
    </array>
</resources>
Continuous range slider

Values changes Listeners

We can observe the changes of the slider in two different ways.

addOnSliderTouchListener

by using addOnSliderTouchListener, we can observe the sliders start and stop touch position values.

continuousSlider.addOnSliderTouchListener(object : Slider.OnSliderTouchListener {
            override fun onStartTrackingTouch(slider: Slider) {
                // Responds to when slider's touch event is being started
                Log.d("onStartTrackingTouch", slider.value.toString())
            }

            override fun onStopTrackingTouch(slider: Slider) {
                // Responds to when slider's touch event is being stopped
                Log.d("onStopTrackingTouch", slider.value.toString())
            }
        })

similarly, we can add touch listener for the range slider.

rangeSlider.addOnSliderTouchListener(object : RangeSlider.OnSliderTouchListener{
            override fun onStartTrackingTouch(slider: RangeSlider) {
                val values = rangeSlider.values
                Log.d("onStartTrackingTouch From", values[0].toString())
                Log.d("onStartTrackingTouch T0", values[1].toString())
            }

            override fun onStopTrackingTouch(slider: RangeSlider) {
                val values = rangeSlider.values
                Log.d("onStopTrackingTouch From", values[0].toString())
                Log.d("onStopTrackingTouch T0", values[1].toString())
            }
        })

addOnChangeListener

Sliders OnChangeListener notified eveerytime the slider value changes.

continuousSlider.addOnChangeListener(object: Slider.OnChangeListener{
            override fun onValueChange(slider: Slider, value: Float, fromUser: Boolean) {
                Log.d("addOnChangeListener", slider.value.toString())
            }
        })

Also, OnChangeListener for the RangeSlider.

rangeSlider.addOnChangeListener(object : RangeSlider.OnChangeListener{

            override fun onValueChange(slider: RangeSlider, value: Float, fromUser: Boolean) {
                val values = rangeSlider.values
                Log.d("From", values[0].toString())
                Log.d("T0", values[1].toString())
            }
        })

Discrete Slider

Discrete slider allows user to select an exact value in the given input range.

If you want to slider to be discrete, then you need to add an attribute called android:stepSize=”5.0″. This will setup the step between valueFrom and valueTo values based on the stepSize value.

For example, valueFrom = 10.0, valueTo = 50.0 and stepSize = 10.0, then you can able to select values 10.0, 20.0, 30.0, 40.0, 50.0 only.

Discrete slider

defining discrete slider in the layout:

<com.google.android.material.slider.Slider
        android:id="@+id/discreteSlider"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:valueFrom="0.0"
        android:valueTo="100.0"
        android:stepSize="10.0"
        android:value="30.0"
        />

Also, we can add discrete in the RangeSlider.

Discrete range slider

We can observe the discrete slider values change the same as a continuous slider. Please check the value changes Listeners above.

Setup the Slider Label

The label will be shown at the top of the slider thumb after you touch the thumb. Basically, the Slider layout holding the currently selected value of the slider.

We can change the behavior and label format using the below methods.

app:labelBehavior

You can change how it’s drawn via the app:labelBehavior attribute or setLabelBehavior method.

app:labelBehavior having three different modes.

floating (default) — draw the label above the slider view.

Floating Slider

withinBounds — draw the label within the slider view. So the label height will be include in the slider height.

withinBounds slider

gone — the label wont display.

LabelFormatter

By using a LabelFormatter you can change the display format of the selected values based on your requirement like 10KG, 12MB, like that.

That can be achieved through the setLabelFormatter method. That can be achieved through the setLabelFormatter method.

continuousSlider.setLabelFormatter { value: Float ->
    return@setLabelFormatter "$${value.roundToInt()}"
}

In above code, I have rounded the selected values and converted into dollars.

LabelFormatter

key properties of sliders

A Slider has a four UI elements.

  1. Track
  2. Thumb
  3. Value Label
  4. Tick Mark (only for discrete slider)
Slider UI elements

Track Attributes

https://gist.github.com/velmurugan35/4648b893c14b82a16ddbf25ae812aa19

Thumb Attributes

https://gist.github.com/velmurugan35/de280c105da33c456bb9678146315258

Values Label Attributes

https://gist.github.com/velmurugan35/d3af48bfc84e50217d0cc55b1d0db159

Tick Mark Attributes

https://gist.github.com/velmurugan35/1a9d693b74e4e7fdb9c4aed1ae9c8218

Implementing slider theming

Sliders support Material Theming and can be customized in terms of color and typography.

Slider theming

Add all the theme related changes in res/values/styles.xml

Setting slider primary colors

<style name="Widget.App.Slider" parent="Widget.MaterialComponents.Slider">
        <item name="materialThemeOverlay">@style/ThemeOverlay.App.Slider</item>
        <item name="labelStyle">@style/Widget.App.Tooltip</item>
    </style>

    <style name="ThemeOverlay.App.Slider" parent="">
        <item name="colorPrimary">@color/green_200</item>
        <item name="colorOnPrimary">@color/green_900</item>
        <item name="colorOnSurface">@color/green_200</item>
    </style>

Theming slider Tooltip

<style name="Widget.App.Tooltip" parent="Widget.MaterialComponents.Tooltip">
        <item name="android:textAppearance">@style/TextAppearance.App.Tooltip</item>
        <item name="backgroundTint">@color/green_200</item>
    </style>

    <style name="TextAppearance.App.Tooltip" parent="TextAppearance.MaterialComponents.Tooltip">
        <item name="android:textColor">@android:color/black</item>
    </style>

Finally, add all the changes into AppTheme to reflect the changes in all the sliders.

<style name="AppTheme" parent="Theme.MaterialComponents.Light.DarkActionBar">
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
        <item name="sliderStyle">@style/Widget.App.Slider</item>
    </style>

That’s it.

You can download my Slider example in Github.

Thanks for the reading.

Please share if you like it.

Also, checkout my other post related to material design.

Android Chips : Material Component For Android

Android Snackbar Example

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