feat(creator): 채널 홈 스크롤 상태 계산을 추가한다

app/src/main/java/kr/co/vividnext/sodalive/v2/creator/channel/model/CreatorChannelScrollState.kt

@@ -0,0 +1,19 @@
+package kr.co.vividnext.sodalive.v2.creator.channel.model
+
+object CreatorChannelScrollState {
+
+    fun shouldUseBlackTitleBar(
+        titleBarBottom: Int,
+        tabBarTop: Int,
+        profileImageVisibleHeight: Int,
+        profileImageTotalHeight: Int
+    ): Boolean {
+        val isTabBarCloseToTitleBar = tabBarTop <= titleBarBottom
+        val isProfileImageHalfHidden = profileImageVisibleHeight <= profileImageTotalHeight / 2
+        return isTabBarCloseToTitleBar && isProfileImageHalfHidden
+    }
+
+    fun calculateStickyTop(statusBarHeight: Int, titleBarHeight: Int): Int {
+        return statusBarHeight + titleBarHeight
+    }
+}

app/src/test/java/kr/co/vividnext/sodalive/v2/creator/channel/CreatorChannelScrollStateTest.kt

@@ -0,0 +1,56 @@
+package kr.co.vividnext.sodalive.v2.creator.channel
+
+import kr.co.vividnext.sodalive.v2.creator.channel.model.CreatorChannelScrollState
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertFalse
+import org.junit.Assert.assertTrue
+import org.junit.Test
+
+class CreatorChannelScrollStateTest {
+
+    @Test
+    fun `title bar와 tab bar가 가까워지고 프로필 이미지가 절반 이상 사라지면 black 전환한다`() {
+        val shouldUseBlackTitleBar = CreatorChannelScrollState.shouldUseBlackTitleBar(
+            titleBarBottom = 88,
+            tabBarTop = 88,
+            profileImageVisibleHeight = 200,
+            profileImageTotalHeight = 402
+        )
+
+        assertTrue(shouldUseBlackTitleBar)
+    }
+
+    @Test
+    fun `title bar와 tab bar가 떨어져 있으면 프로필 이미지가 절반 이상 사라져도 black 전환하지 않는다`() {
+        val shouldUseBlackTitleBar = CreatorChannelScrollState.shouldUseBlackTitleBar(
+            titleBarBottom = 88,
+            tabBarTop = 120,
+            profileImageVisibleHeight = 200,
+            profileImageTotalHeight = 402
+        )
+
+        assertFalse(shouldUseBlackTitleBar)
+    }
+
+    @Test
+    fun `프로필 이미지가 절반보다 많이 보이면 title bar와 tab bar가 가까워져도 black 전환하지 않는다`() {
+        val shouldUseBlackTitleBar = CreatorChannelScrollState.shouldUseBlackTitleBar(
+            titleBarBottom = 88,
+            tabBarTop = 88,
+            profileImageVisibleHeight = 202,
+            profileImageTotalHeight = 402
+        )
+
+        assertFalse(shouldUseBlackTitleBar)
+    }
+
+    @Test
+    fun `sticky top은 status bar 높이와 title bar 높이를 합산한다`() {
+        val stickyTop = CreatorChannelScrollState.calculateStickyTop(
+            statusBarHeight = 28,
+            titleBarHeight = 60
+        )
+
+        assertEquals(88, stickyTop)
+    }
+}