fix(android): reduce unnecessary rerenders

android/build.gradle

@@ -16,7 +16,6 @@ buildscript {
 
 apply plugin: 'com.android.library'
 apply plugin: 'kotlin-android'
-apply plugin: 'kotlin-android-extensions'
 
 def getExtOrDefault(name) {
   return rootProject.ext.has(name) ? rootProject.ext.get(name) : project.properties['PdfViewer_' + name]

android/gradle.properties

@@ -1,4 +1,4 @@
-PdfViewer_kotlinVersion=1.3.50
+PdfViewer_kotlinVersion=1.4.30
 PdfViewer_compileSdkVersion=28
 PdfViewer_buildToolsVersion=28.0.3
 PdfViewer_targetSdkVersion=28

android/src/main/java/com/alpha0010/pdf/PdfView.kt

@@ -27,6 +27,7 @@ enum class ResizeMode(val jsName: String) {
 @SuppressLint("ViewConstructor")
 class PdfView(context: Context, private val pdfMutex: Lock) : View(context) {
   private var mBitmap: Bitmap
+  private var mDirty = false
   private var mPage = 0
   private var mResizeMode = ResizeMode.CONTAIN
   private var mSource = ""
@@ -38,7 +39,7 @@ class PdfView(context: Context, private val pdfMutex: Lock) : View(context) {
 
   fun setPage(page: Int) {
     mPage = page
-    renderPdf()
+    mDirty = true
   }
 
   fun setResizeMode(mode: String) {
@@ -52,12 +53,12 @@ class PdfView(context: Context, private val pdfMutex: Lock) : View(context) {
     }
 
     mResizeMode = resizeMode
-    renderPdf()
+    mDirty = true
   }
 
   fun setSource(source: String) {
     mSource = source
-    renderPdf()
+    mDirty = true
   }
 
   private fun computeDestRect(srcWidth: Int, srcHeight: Int): RectF {
@@ -70,11 +71,12 @@ class PdfView(context: Context, private val pdfMutex: Lock) : View(context) {
     }
   }
 
-  private fun renderPdf() {
-    if (height < 1 || width < 1 || mSource.isEmpty()) {
+  fun renderPdf() {
+    if (height < 1 || width < 1 || mSource.isEmpty() || !mDirty) {
       // View layout not yet complete, or nothing to render.
       return
     }
+    mDirty = false
 
     CoroutineScope(Dispatchers.Main).launch(Dispatchers.IO) {
       val file = File(mSource)
@@ -187,6 +189,7 @@ class PdfView(context: Context, private val pdfMutex: Lock) : View(context) {
 
   override fun onSizeChanged(w: Int, h: Int, oldw: Int, oldh: Int) {
     mViewRect.set(0, 0, w, h)
+    mDirty = true
     renderPdf()
   }
 }

android/src/main/java/com/alpha0010/pdf/PdfViewManager.kt

@@ -10,21 +10,15 @@ import java.util.concurrent.locks.Lock
 class PdfViewManager(private val pdfMutex: Lock) : BaseViewManager<PdfView, PdfViewShadowNode>() {
   private val mMeasureCache = LruCache<String, Size>(128)
 
-  override fun getName(): String {
-    return "RNPdfView"
-  }
+  override fun getName() = "RNPdfView"
 
   override fun createViewInstance(reactContext: ThemedReactContext): PdfView {
     return PdfView(reactContext, pdfMutex)
   }
 
-  override fun createShadowNodeInstance(): PdfViewShadowNode {
-    return PdfViewShadowNode(mMeasureCache, pdfMutex)
-  }
+  override fun createShadowNodeInstance() = PdfViewShadowNode(mMeasureCache, pdfMutex)
 
-  override fun getShadowNodeClass(): Class<out PdfViewShadowNode> {
-    return PdfViewShadowNode::class.java
-  }
+  override fun getShadowNodeClass() = PdfViewShadowNode::class.java
 
   override fun getExportedCustomBubblingEventTypeConstants(): MutableMap<String, Any> {
     return mutableMapOf(
@@ -39,13 +33,16 @@ class PdfViewManager(private val pdfMutex: Lock) : BaseViewManager<PdfView, PdfV
 
   override fun updateExtraData(root: PdfView, extraData: Any?) {}
 
+  override fun onAfterUpdateTransaction(view: PdfView) {
+    super.onAfterUpdateTransaction(view)
+    view.renderPdf()
+  }
+
   /**
    * Page (0-indexed) of document to display.
    */
   @ReactProp(name = "page", defaultInt = 0)
-  fun setPage(view: PdfView, page: Int) {
-    view.setPage(page)
-  }
+  fun setPage(view: PdfView, page: Int) = view.setPage(page)
 
   /**
    * How pdf page should be scaled to fit in view dimensions.
@@ -66,7 +63,5 @@ class PdfViewManager(private val pdfMutex: Lock) : BaseViewManager<PdfView, PdfV
    * Document to display.
    */
   @ReactProp(name = "source")
-  fun setSource(view: PdfView, source: String?) {
-    view.setSource(source ?: "")
-  }
+  fun setSource(view: PdfView, source: String?) = view.setSource(source ?: "")
 }