fix: Fix a potential NPE Crash due to Mismatched Thread Lifecycle

- the thread creation and recycling was not being handled symmetrically
- this fix is based off of these two PR: DImuthuUpe#824 and mhiew#2
ref: DImuthuUpe/AndroidPdfViewer@41f912e

Author: facundofernandez

android-pdf-viewer/build.gradle

@@ -3,7 +3,7 @@ plugins {
     id 'maven-publish'
 }
 
-group "com.github.lion1988dev"
+group "com.github.GoIntegro"
 
 android {
     namespace "com.github.barteksc.pdfviewer"
@@ -42,15 +42,15 @@ android {
 
 dependencies {
     implementation 'androidx.appcompat:appcompat:1.6.1'
-    api 'com.github.lion1988dev:PdfiumAndroid:1.9.4'
+    api 'com.github.GoIntegro:PdfiumAndroid:1.9.5'
 }
 
 publishing {
     publications {
         release(MavenPublication) {
-            groupId = 'com.github.lion1988dev'
+            groupId = 'com.github.GoIntegro'
             artifactId = 'AndroidPdfViewer'
-            version = "3.2.4"
+            version = "3.2.5"
 
             afterEvaluate {
                 from components.release

android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/PDFView.java

@@ -245,8 +245,6 @@ ScrollHandle getScrollHandle() {
     public PDFView(Context context, AttributeSet set) {
         super(context, set);
 
-        renderingHandlerThread = new HandlerThread("PDF renderer");
-
         if (isInEditMode()) {
             return;
         }
@@ -462,6 +460,14 @@ public void computeScroll() {
         animationManager.computeFling();
     }
 
+    @Override
+    protected void onAttachedToWindow() {
+        super.onAttachedToWindow();
+        if (renderingHandlerThread == null) {
+            renderingHandlerThread = new HandlerThread("PDF renderer");
+        }
+    }
+
     @Override
     protected void onDetachedFromWindow() {
         recycle();
@@ -753,6 +759,10 @@ void loadComplete(PdfFile pdfFile) {
 
         this.pdfFile = pdfFile;
 
+        if (renderingHandlerThread == null) {
+            renderingHandlerThread = new HandlerThread("PDF renderer");
+        }
+
         if (!renderingHandlerThread.isAlive()) {
             renderingHandlerThread.start();
         }