ui: Switch to MODE_SCROLLABLE when tab width is about to overflow

package im.angry.openeuicc.ui.widget

import android.content.Context

import android.util.AttributeSet

import android.view.ViewGroup

import com.google.android.material.R

import com.google.android.material.tabs.TabLayout

/**

 * A TabLayout that automatically switches to MODE_SCROLLABLE when

 * child tabs overflow the full width of the layout.

 */

class DynamicModeTabLayout @JvmOverloads constructor(

    context: Context,

    attrs: AttributeSet? = null,

    defStyleAttr: Int = R.attr.tabStyle

) : TabLayout(context, attrs, defStyleAttr) {

    init {

        addOnLayoutChangeListener { _, _, _, _, _, _, _, _, _ ->

            updateModeIfNecessary()

        }

    }

    private fun updateModeIfNecessary() {

        if (width <= 0 || tabCount == 0) return

        val tabStrip = getChildAt(0) as? ViewGroup ?: return

        val totalTabWidth = (0 until tabStrip.childCount).sumOf { index ->

            val tabView = tabStrip.getChildAt(index)

            val layoutParams = tabView.layoutParams as? MarginLayoutParams

            tabView.measure(

                MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED),

                MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED)

            )

            tabView.measuredWidth + (layoutParams?.leftMargin ?: 0) + (layoutParams?.rightMargin ?: 0)

        }

        val availableWidth = width - paddingLeft - paddingRight

        val shouldScroll = totalTabWidth > availableWidth

        val targetMode = if (shouldScroll) MODE_SCROLLABLE else MODE_FIXED

        val targetGravity = if (shouldScroll) GRAVITY_START else GRAVITY_FILL

        if (tabMode != targetMode) {

            tabMode = targetMode

        }

        if (tabGravity != targetGravity) {

            tabGravity = targetGravity

        }

    }

}

    <include layout="@layout/toolbar_activity" />

    <com.google.android.material.tabs.TabLayout

    <im.angry.openeuicc.ui.widget.DynamicModeTabLayout

        android:id="@+id/main_tabs"

        android:layout_width="match_parent"

        android:layout_height="wrap_content"