Update bank mandate CTA UX.

app/src/main/java/org/thoughtcrime/securesms/compose/StatusBarColorAnimator.kt

@@ -0,0 +1,62 @@
+package org.thoughtcrime.securesms.compose
+
+import android.animation.ValueAnimator
+import android.app.Activity
+import androidx.core.content.ContextCompat
+import com.google.android.material.animation.ArgbEvaluatorCompat
+import org.thoughtcrime.securesms.R
+import org.thoughtcrime.securesms.util.WindowUtil
+
+/**
+ * Controls status-bar color based off ability to scroll up
+ */
+class StatusBarColorAnimator(
+  private val activity: Activity
+) {
+  private var animator: ValueAnimator? = null
+  private var previousCanScrollUp: Boolean = false
+
+  private val normalColor = ContextCompat.getColor(activity, R.color.signal_colorBackground)
+  private val scrollColor = ContextCompat.getColor(activity, R.color.signal_colorSurface2)
+
+  fun setCanScrollUp(canScrollUp: Boolean) {
+    if (previousCanScrollUp == canScrollUp) {
+      return
+    }
+
+    previousCanScrollUp = canScrollUp
+    applyState(canScrollUp)
+  }
+
+  fun setColorImmediate() {
+    val end = when {
+      previousCanScrollUp -> scrollColor
+      else -> normalColor
+    }
+
+    animator?.cancel()
+    WindowUtil.setStatusBarColor(
+      activity.window,
+      end
+    )
+  }
+
+  private fun applyState(canScrollUp: Boolean) {
+    val (start, end) = when {
+      canScrollUp -> normalColor to scrollColor
+      else -> scrollColor to normalColor
+    }
+
+    animator?.cancel()
+    animator = ValueAnimator.ofFloat(0f, 1f).apply {
+      duration = 200
+      addUpdateListener {
+        WindowUtil.setStatusBarColor(
+          activity.window,
+          ArgbEvaluatorCompat.getInstance().evaluate(it.animatedFraction, start, end)
+        )
+      }
+      start()
+    }
+  }
+}