Updated to 1.0.0-beta09 version

README.md

@@ -35,7 +35,7 @@ repositories {
 
 ```groovy
 dependencies {
-    implementation 'com.github.germainkevinbusiness:CollapsingTopBarCompose:1.0.0-beta08'
+    implementation 'com.github.germainkevinbusiness:CollapsingTopBarCompose:1.0.0-beta09'
 }
 ```
 

app/build.gradle

@@ -11,7 +11,7 @@ android {
         minSdk 21
         targetSdk 32
         versionCode 1
-        versionName "1.0.0-beta08"
+        versionName "1.0.0-beta09"
 
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
         vectorDrawables {

app/src/main/java/com/germainkevin/collapsingtopbarcompose/MainActivity.kt

@@ -103,6 +103,13 @@ class MainActivity : ComponentActivity() {
     }
 }
 
+/**
+ * @param scrollBehavior Defines how a [CollapsingTopBar] should behave during a
+ * [Modifier.nestedScroll][androidx.compose.ui.input.nestedscroll.nestedScroll] event.
+ * @param contactNames Just the list of contact names so we can count how much names there are to
+ * display that number inside our subtitle [Text]
+ * @param openLeftDrawer Triggers the Left Drawer to be displayed
+ * */
 @Composable
 fun OurCollapsingTopBar(
     scrollBehavior: CollapsingTopBarScrollBehavior,

collapsingtopbar/build.gradle

@@ -24,7 +24,7 @@ afterEvaluate {
                 // You can then customize attributes of the publication as shown below.
                 groupId = 'com.germainkevin.collapsingtopbarcompose'
                 artifactId = 'collapsingtopbarcompose'
-                version = '1.0.0-beta08'
+                version = '1.0.0-beta09'
             }
         }
     }

collapsingtopbar/src/main/java/com/germainkevin/collapsingtopbar/CollapsingTopBar.kt

@@ -1,13 +1,10 @@
 package com.germainkevin.collapsingtopbar
 
 import androidx.compose.animation.*
-import androidx.compose.animation.core.animateFloatAsState
 import androidx.compose.foundation.layout.*
 import androidx.compose.material.*
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.CompositionLocalProvider
-import androidx.compose.runtime.State
-import androidx.compose.runtime.getValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.alpha
@@ -48,20 +45,6 @@ fun CollapsingTopBar(
     scrollBehavior: CollapsingTopBarScrollBehavior,
     elevation: Dp = CollapsingTopBarDefaults.DefaultCollapsingTopBarElevation,
 ) = with(scrollBehavior) {
-
-    val columnWithTitleSubtitleAlpha by getTitleAndSubtitleColumnAlpha(
-        currentTopBarHeight = currentTopBarHeight,
-        collapsedTopBarHeight = collapsedTopBarHeight,
-        expandedTopBarMaxHeight = expandedTopBarMaxHeight,
-        margin = 20.dp
-    )
-
-    val collapsedTitleAlpha by getCollapsedTitleAlpha(
-        currentTopBarHeight = currentTopBarHeight,
-        visibleValue = collapsedTopBarHeight,
-        invisibleValue = collapsedTopBarHeight + 6.dp
-    )
-
     CollapsingTopBarLayout(
         modifier = modifier,
         title = title,
@@ -71,8 +54,8 @@ fun CollapsingTopBar(
         centeredTitleAndSubtitle = centeredTitleAndSubtitle,
         contentPadding = contentPadding,
         colors = colors,
-        columnWithTitleSubtitleAlpha = columnWithTitleSubtitleAlpha,
-        collapsedTitleAlpha = collapsedTitleAlpha,
+        expandedColumnAlphaValue = expandedColumnAlphaValue.invoke().value,
+        collapsedTitleAlpha = collapsedTitleAlpha.invoke().value,
         currentTopBarHeight = currentTopBarHeight,
         elevation = elevation
     )
@@ -103,7 +86,7 @@ private fun CollapsingTopBarLayout(
     centeredTitleAndSubtitle: Boolean,
     contentPadding: PaddingValues,
     colors: CollapsingTopBarColors,
-    columnWithTitleSubtitleAlpha: Float,
+    expandedColumnAlphaValue: Float,
     collapsedTitleAlpha: Float,
     currentTopBarHeight: Dp,
     elevation: Dp,
@@ -134,7 +117,7 @@ private fun CollapsingTopBarLayout(
                             end = appBarHorizontalPadding
                         )
                     )
-                    .alpha(columnWithTitleSubtitleAlpha),
+                    .alpha(expandedColumnAlphaValue),
                 horizontalAlignment =
                 if (centeredTitleAndSubtitle) Alignment.CenterHorizontally else Alignment.Start,
                 verticalArrangement = Arrangement.Center,
@@ -223,77 +206,4 @@ private val actionsRow: @Composable (@Composable RowScope.() -> Unit) -> Unit =
         verticalAlignment = Alignment.Bottom,
         content = it
     )
-}
-
-/**
- * In order to know when the "title subtitle column" should have a 1f alpha visibility or 0f alpha
- * visibility or a alpha value between 0f and 1f, we need to base that alpha value on the
- * [currentTopBarHeight] of the [CollapsingTopBar].
- *
- * So in this sense when the [currentTopBarHeight] of the [CollapsingTopBar]
- * is [collapsedTopBarHeight] + [margin] then  the "title subtitle column" should be invisible
- * or alpha = 0f, and when the [CollapsingTopBar]'s [currentTopBarHeight] is
- * [expandedTopBarMaxHeight] then the "title subtitle column" should be visible or alpha = 1f.
- *
- * But we also want the "title subtitle column"'s alpha value to be between 0f and 1f when the
- * [CollapsingTopBar]'s [currentTopBarHeight] is between
- * [collapsedTopBarHeight] + [margin] and [expandedTopBarMaxHeight]
- *
- * We'll reference [collapsedTopBarHeight] as 56 (Dp) and [expandedTopBarMaxHeight] as 200 (Dp), and
- * the [margin] as 20 (Dp)
- *
- * 56 + 20  --------> 0f (alpha value meaning  when the title subtitle column is fully invisible)
- *
- * 200      --------> 1f (alpha value meaning when the title subtitle column is fully visible)
- *
- * The distance between [expandedTopBarMaxHeight] - ([collapsedTopBarHeight] + [margin])
- * << A distance which we will label as 124 (Dp) because (200 - (56+20) = 124) >>,
- * is going to be the 100% distance from making the "title subtitle column" fully visible (100%) or
- * alpha =1f and fully invisible (0%) or alpha = 0f, or in between (0%..100%) 0.0f to 1.0f.
- *
- * So what we do is:
- * 124                                ----------> 100%
- *
- * currentTopBarHeight's actual value -------------> alphaValue
- *
- * Whatever value alphaValue is, is considered the level of visibility the "title subtitle column"
- * should have
- *
- * @param currentTopBarHeight The current height of the [CollapsingTopBar] in [Dp]
- * @param collapsedTopBarHeight The height of the [CollapsingTopBar] when it is collapsed
- * @param expandedTopBarMaxHeight The height of the [CollapsingTopBar] when it is expanded
- * @param margin Making sure that the 'title subtitle column" become visible once the
- * [currentTopBarHeight] reaches past [collapsedTopBarHeight] + [margin]
- */
-@Composable
-private fun getTitleAndSubtitleColumnAlpha(
-    currentTopBarHeight: Dp,
-    collapsedTopBarHeight: Dp,
-    expandedTopBarMaxHeight: Dp,
-    margin: Dp
-): State<Float> {
-    return animateFloatAsState(
-        (currentTopBarHeight - (collapsedTopBarHeight + margin)) /
-                (expandedTopBarMaxHeight - (collapsedTopBarHeight + margin))
-    )
-}
-
-/**
- * Sets the alpha value of the collapsed title section
- * @param currentTopBarHeight The current height of the [CollapsingTopBar] in [Dp]
- * @param visibleValue A value in [Dp] that if [currentTopBarHeight] reaches it, the
- * Collapsed Title should become visible
- * @param invisibleValue A value in [Dp] that if [currentTopBarHeight] reaches it, the
- * Collapsed Title section should become invisible
- * */
-@Composable
-private fun getCollapsedTitleAlpha(
-    currentTopBarHeight: Dp,
-    visibleValue: Dp,
-    invisibleValue: Dp
-): State<Float> {
-    return animateFloatAsState(
-        if (currentTopBarHeight == visibleValue) 1f
-        else (visibleValue - currentTopBarHeight) / (invisibleValue - visibleValue)
-    )
 }

collapsingtopbar/src/main/java/com/germainkevin/collapsingtopbar/CollapsingTopBarScrollBehavior.kt

@@ -76,6 +76,17 @@ interface CollapsingTopBarScrollBehavior {
      * keep track of the scroll events.
      */
     val nestedScrollConnection: NestedScrollConnection
+
+    /**
+     * The visibility alpha value of the Column which holds as children the Title and Subtitle
+     * */
+    val expandedColumnAlphaValue: @Composable () -> State<Float>
+
+    /**
+     * The visibility alpha value of the Title displayed and visible when the [CollapsingTopBar] is
+     * collapsed
+     * */
+    val collapsedTitleAlpha: @Composable () -> State<Float>
 }
 
 class DefaultBehaviorOnScroll(
@@ -88,7 +99,8 @@ class DefaultBehaviorOnScroll(
 
     init {
         require(expandedTopBarMaxHeight > collapsedTopBarHeight) {
-            "expandedTopBarMaxHeight must be greater than collapsedTopBarHeight"
+            "expandedTopBarMaxHeight ($expandedTopBarMaxHeight) must be greater " +
+                    "than collapsedTopBarHeight ($collapsedTopBarHeight)"
         }
     }
 
@@ -133,4 +145,75 @@ class DefaultBehaviorOnScroll(
             return Offset.Zero
         }
     }
+
+    override val expandedColumnAlphaValue: @Composable () -> State<Float> = {
+        getExpandedColumnAlpha()
+    }
+
+    override val collapsedTitleAlpha: @Composable () -> State<Float> = {
+        getCollapsedTitleAlpha()
+    }
+
+    /**
+     * In order to know when the "title subtitle column" should have a 1f alpha visibility or 0f alpha
+     * visibility or a alpha value between 0f and 1f, we need to base that alpha value on the
+     * [currentTopBarHeight] of the [CollapsingTopBar].
+     *
+     * So in this sense when the [currentTopBarHeight] of the [CollapsingTopBar]
+     * is [collapsedTopBarHeight] + [margin] then  the "title subtitle column" should be invisible
+     * or alpha = 0f, and when the [CollapsingTopBar]'s [currentTopBarHeight] is
+     * [expandedTopBarMaxHeight] then the "title subtitle column" should be visible or alpha = 1f.
+     *
+     * But we also want the "title subtitle column"'s alpha value to be between 0f and 1f when the
+     * [CollapsingTopBar]'s [currentTopBarHeight] is between
+     * [collapsedTopBarHeight] + [margin] and [expandedTopBarMaxHeight]
+     *
+     * We'll reference [collapsedTopBarHeight] as 56 (Dp) and [expandedTopBarMaxHeight] as 200 (Dp), and
+     * the [margin] as 20 (Dp)
+     *
+     * 56 + 20  --------> 0f (alpha value meaning  when the title subtitle column is fully invisible)
+     *
+     * 200      --------> 1f (alpha value meaning when the title subtitle column is fully visible)
+     *
+     * The distance between [expandedTopBarMaxHeight] - ([collapsedTopBarHeight] + [margin])
+     * << A distance which we will label as 124 (Dp) because (200 - (56+20) = 124) >>,
+     * is going to be the 100% distance from making the "title subtitle column" fully visible (100%) or
+     * alpha =1f and fully invisible (0%) or alpha = 0f, or in between (0%..100%) 0.0f to 1.0f.
+     *
+     * So what we do is:
+     * 124                                ----------> 100%
+     *
+     * currentTopBarHeight's actual value -------------> alphaValue
+     *
+     * Whatever value alphaValue is, is considered the level of visibility the "title subtitle column"
+     * should have
+     *
+     * @param margin Making sure that the 'title subtitle column" become visible once the
+     * [currentTopBarHeight] reaches past [collapsedTopBarHeight] + [margin]
+     */
+    @Composable
+    fun getExpandedColumnAlpha(margin: Dp = 20.dp): State<Float> {
+        return animateFloatAsState(
+            (currentTopBarHeight - (collapsedTopBarHeight + margin)) /
+                    (expandedTopBarMaxHeight - (collapsedTopBarHeight + margin))
+        )
+    }
+
+    /**
+     * Sets the alpha value of the collapsed title section
+     * @param visibleValue A value in [Dp] that if [currentTopBarHeight] reaches it, the
+     * Collapsed Title should become visible
+     * @param invisibleValue A value in [Dp] that if [currentTopBarHeight] reaches it, the
+     * Collapsed Title section should become invisible
+     * */
+    @Composable
+    fun getCollapsedTitleAlpha(
+        visibleValue: Dp = collapsedTopBarHeight,
+        invisibleValue: Dp = collapsedTopBarHeight + 6.dp
+    ): State<Float> {
+        return animateFloatAsState(
+            if (currentTopBarHeight == visibleValue) 1f
+            else (visibleValue - currentTopBarHeight) / (invisibleValue - visibleValue)
+        )
+    }
 }