api 21 support

Author: rishujam

app/build.gradle

@@ -9,7 +9,7 @@ android {
 
     defaultConfig {
         applicationId "com.docs.pdfviewer"
-        minSdk 26
+        minSdk 21
         targetSdk 33
         versionCode 1
         versionName "1.0"

docwatcher/build.gradle

@@ -9,7 +9,7 @@ android {
     compileSdk 33
 
     defaultConfig {
-        minSdk 26
+        minSdk 21
         targetSdk 33
 
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"

docwatcher/src/main/java/com/docs/docwatcher/DocView.kt

@@ -3,6 +3,7 @@ package com.docs.docwatcher
 import android.content.Context
 import android.graphics.Bitmap
 import android.graphics.pdf.PdfRenderer
+import android.os.Build
 import android.os.ParcelFileDescriptor
 import android.util.AttributeSet
 import android.view.LayoutInflater
@@ -90,16 +91,30 @@ class DocView @JvmOverloads constructor(
         val cardText = "1 / ${list.size}"
         pageText.text = cardText
         pageCard.showPagesViewForSomeSeconds(coroutineScope, context)
-        rv.setOnScrollChangeListener { _, _, _, _, _ ->
-            val visiblePosition = (rv.layoutManager as LinearLayoutManager).findFirstCompletelyVisibleItemPosition()
-            if(visiblePosition != -1) {
-                val currPage = visiblePosition + 1
-                if(!noOfPages.isNullOrEmpty()) {
-                    pageCard.show()
-                    val text = "$currPage / $noOfPages"
-                    pageText.text = text
-                    pageCard.showPagesViewForSomeSeconds(coroutineScope, context)
+        if(Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
+            rv.addOnScrollListener(object : RecyclerView.OnScrollListener() {
+
+                override fun onScrolled(recyclerView: RecyclerView, dx: Int, dy: Int) {
+                    super.onScrolled(recyclerView, dx, dy)
+                    handleOnScroll()
                 }
+            })
+        } else {
+            rv.setOnScrollChangeListener { _, _, _, _, _ ->
+                handleOnScroll()
+            }
+        }
+    }
+
+    private fun handleOnScroll() {
+        val visiblePosition = (rv.layoutManager as LinearLayoutManager).findFirstCompletelyVisibleItemPosition()
+        if(visiblePosition != -1) {
+            val currPage = visiblePosition + 1
+            if(!noOfPages.isNullOrEmpty()) {
+                pageCard.show()
+                val text = "$currPage / $noOfPages"
+                pageText.text = text
+                pageCard.showPagesViewForSomeSeconds(coroutineScope, context)
             }
         }
     }

docwatcher/src/main/java/com/docs/docwatcher/data/PdfDownloader.kt

@@ -4,9 +4,9 @@ import android.app.DownloadManager
 import android.content.Context
 import android.database.ContentObserver
 import android.net.Uri
+import android.os.Build
 import android.os.Handler
 import android.os.Looper
-import android.util.Log
 import androidx.core.net.toUri
 import com.docs.docwatcher.DocView
 
@@ -19,7 +19,11 @@ internal class PdfDownloader(
     private val listener: DocView.DownloadListener
 ) {
 
-    private val downloadManager = context.getSystemService(DownloadManager::class.java)
+    private val downloadManager = if (Build.VERSION.SDK_INT <= Build.VERSION_CODES.M) {
+        context.getSystemService(Context.DOWNLOAD_SERVICE) as DownloadManager
+    } else {
+        context.getSystemService(DownloadManager::class.java)
+    }
 
     fun download(url: String) {
         val request = DownloadManager.Request(url.toUri())

docwatcher/src/main/java/com/docs/docwatcher/util/PdfExtFun.kt

@@ -43,8 +43,4 @@ internal fun View.show() {
 
 internal fun View.gone() {
     this.visibility = View.GONE
-}
-
-internal fun View.invisible() {
-    this.visibility = View.INVISIBLE
 }