支持视差Header效果

Author: AlanCheen

app/src/main/java/me/yifeiyuan/flapdev/testcases/HeaderFooterTestcase.kt

@@ -2,14 +2,17 @@ package me.yifeiyuan.flapdev.testcases
 
 import android.graphics.Color
 import android.graphics.drawable.ColorDrawable
+import android.os.Build
 import android.util.Log
 import android.view.LayoutInflater
 import android.view.View
-import androidx.recyclerview.widget.GridLayoutManager
+import android.view.animation.TranslateAnimation
 import androidx.recyclerview.widget.ItemTouchHelper
+import androidx.recyclerview.widget.RecyclerView
 import kotlinx.android.synthetic.main.debug_menu.*
 import me.yifeiyuan.flap.ext.HeaderFooterAdapter
 import me.yifeiyuan.flap.ext.SwipeDragHelper
+import me.yifeiyuan.flap.widget.enableParallaxHeader
 import me.yifeiyuan.flapdev.R
 import me.yifeiyuan.flapdev.mockMultiTypeModels
 
@@ -27,7 +30,7 @@ class HeaderFooterTestcase : BaseTestcaseFragment() {
 
         val headerFooterAdapter = HeaderFooterAdapter(adapter)
 
-        val headerView = LayoutInflater.from(activity).inflate(R.layout.header_layout, null, false)
+        val headerView = LayoutInflater.from(activity).inflate(R.layout.header_layout_image, null, false)
         headerFooterAdapter.setupHeaderView(headerView)
 
         headerView.setOnClickListener {
@@ -99,6 +102,7 @@ class HeaderFooterTestcase : BaseTestcaseFragment() {
 //            }
 //        }
 
+        recyclerView.enableParallaxHeader()
     }
 
     override fun createRefreshData(size: Int): MutableList<Any> {

app/src/main/res/drawable-xxhdpi/flap_xcz.jpg

@@ -2,7 +2,9 @@
 <FrameLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
-    android:layout_height="wrap_content">
+    android:layout_height="wrap_content"
+    android:background="#BA68C8"
+    >
 
     <ImageView
         android:id="@+id/logo"

app/src/main/res/layout/component_simple_image.xml

@@ -2,7 +2,7 @@
 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    android:background="#0ff0ff"
+    android:background="#0288D1"
     android:orientation="horizontal"
     android:paddingVertical="12dp"
     >

app/src/main/res/layout/flap_item_simple_text.xml

@@ -23,6 +23,7 @@
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
             android:orientation="vertical"
+            android:background="#ffffff"
             app:layoutManager="me.yifeiyuan.flap.widget.FlapLinearLayoutManager" />
     </androidx.swiperefreshlayout.widget.SwipeRefreshLayout>
 

app/src/main/res/layout/fragment_base_case.xml

@@ -0,0 +1,16 @@
+<?xml version="1.0" encoding="utf-8"?>
+<FrameLayout
+    xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:background="#E6DB7C">
+
+    <ImageView
+        android:src="@drawable/flap_xcz"
+        android:layout_width="match_parent"
+        android:layout_height="240dp"
+        android:text="Header"
+        android:gravity="center"
+        android:scaleType="centerCrop"
+        android:textColor="#FFFFFF"
+        />
+</FrameLayout>

app/src/main/res/layout/header_layout_image.xml

@@ -0,0 +1,25 @@
+package me.yifeiyuan.flap.widget
+
+import androidx.recyclerview.widget.RecyclerView
+
+/**
+ * Created by 程序亦非猿 on 2022/10/18.
+ */
+
+/**
+ * 开启视差 Header 效果
+ * @since 3.1.9
+ */
+fun RecyclerView.enableParallaxHeader(factor: Float = 0.5f) {
+    addOnScrollListener(ParallaxHeaderHandler(factor))
+}
+
+internal class ParallaxHeaderHandler(private val factor: Float = 0.5f) : RecyclerView.OnScrollListener() {
+    override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
+        super.onScrolled(recyclerView, dx, dy)
+        val child = recyclerView.getChildAt(0)
+        if (child != null && recyclerView.getChildAdapterPosition(child) == 0) {
+            child.translationY = -child.top * factor
+        }
+    }
+}