修复可能出现的pdf查看错误。

app/proguard-rules.pro

@@ -20,7 +20,13 @@
 # hide the original source file name.
 #-renamesourcefileattribute SourceFile
 
--keep class com.shockwave.**
+# PDFium完整保留
+-keep class com.shockwave.** { *; }
+-keep class com.github.barteksc.pdfviewer.** { *; }
+-keepclassmembers class * {
+    native <methods>;
+}
+
 -keep class com.luck.picture.lib.** { *; }
 -keep class com.luck.lib.camerax.** { *; }
 -dontwarn com.yalantis.ucrop**