Fix Android async issue (#64)

Author: MatthieuLemoine

android/src/main/java/android/print/PdfConverter.java

@@ -14,6 +14,12 @@
 import android.webkit.WebViewClient;
 
 import java.io.File;
+import android.util.Base64;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+
+import com.facebook.react.bridge.Promise;
+import com.facebook.react.bridge.WritableMap;
 
 /**
  * Converts HTML to PDF.
@@ -32,6 +38,9 @@ public class PdfConverter implements Runnable {
     private PrintAttributes mPdfPrintAttrs;
     private boolean mIsCurrentlyConverting;
     private WebView mWebView;
+    private boolean mShouldEncode;
+    private WritableMap mResultMap;
+    private Promise mPromise;
 
     private PdfConverter() {
     }
@@ -58,7 +67,19 @@ public void onPageFinished(WebView view, String url) {
                     documentAdapter.onWrite(new PageRange[]{PageRange.ALL_PAGES}, getOutputFileDescriptor(), null, new PrintDocumentAdapter.WriteResultCallback() {
                         @Override
                         public void onWriteFinished(PageRange[] pages) {
-                            destroy();
+                            try {
+                                String base64 = "";
+                                if (mShouldEncode) {
+                                    base64 = encodeFromFile(mPdfFile);
+                                }
+                                mResultMap.putString("filePath", mPdfFile.getAbsolutePath());
+                                mResultMap.putString("base64", base64);
+                                mPromise.resolve(mResultMap);
+                            } catch (IOException e) {
+                                mPromise.reject(e.getMessage());
+                            } finally {
+                                destroy();
+                            }
                         }
                     });
                 }
@@ -75,7 +96,7 @@ public void setPdfPrintAttrs(PrintAttributes printAttrs) {
         this.mPdfPrintAttrs = printAttrs;
     }
 
-    public void convert(Context context, String htmlString, File file) {
+    public void convert(Context context, String htmlString, File file, boolean shouldEncode, WritableMap resultMap, Promise promise) {
         if (context == null)
             throw new IllegalArgumentException("context can't be null");
         if (htmlString == null)
@@ -90,6 +111,9 @@ public void convert(Context context, String htmlString, File file) {
         mHtmlString = htmlString;
         mPdfFile = file;
         mIsCurrentlyConverting = true;
+        mShouldEncode = shouldEncode;
+        mResultMap = resultMap;
+        mPromise = promise;
         runOnUiThread(this);
     }
 
@@ -126,5 +150,15 @@ private void destroy() {
         mPdfPrintAttrs = null;
         mIsCurrentlyConverting = false;
         mWebView = null;
+        mShouldEncode = false;
+        mResultMap = null;
+        mPromise = null;
+    }
+
+    private String encodeFromFile(File file) throws IOException{
+      RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r");
+      byte[] fileBytes = new byte[(int)randomAccessFile.length()];
+      randomAccessFile.readFully(fileBytes);
+      return Base64.encodeToString(fileBytes, Base64.DEFAULT);
     }
 }

android/src/main/java/com/christopherdro/htmltopdf/RNHTMLtoPDFModule.java

@@ -11,11 +11,6 @@
 import java.io.File;
 import java.util.UUID;
 
-import android.util.Base64;
-import java.io.IOException;
-import java.io.RandomAccessFile;
-
-
 import android.os.Environment;
 import android.print.PdfConverter;
 
@@ -59,31 +54,29 @@ public void convert(final ReadableMap options, final Promise promise) {
         destinationFile = getTempFile(fileName);
       }
 
-      String filePath = convertToPDF(htmlString, destinationFile);
-      String base64 = "";
-
-      if (options.hasKey("base64") && options.getBoolean("base64") == true) {
-        base64 = encodeFromFile(destinationFile);
-      }
-
-
-      WritableMap resultMap = Arguments.createMap();
-      resultMap.putString("filePath", filePath);
-      resultMap.putString("base64", base64);
-
-      promise.resolve(resultMap);
+      convertToPDF(
+        htmlString,
+        destinationFile,
+        options.hasKey("base64") && options.getBoolean("base64") == true,
+        Arguments.createMap(),
+        promise
+      );
     } catch (Exception e) {
       promise.reject(e.getMessage());
     }
   }
 
-  private String convertToPDF(String htmlString, File file) throws Exception {
+  private void convertToPDF(String htmlString, File file, boolean shouldEncode, WritableMap resultMap, Promise promise) throws Exception {
     try {
       PdfConverter.getInstance()
-              .convert(mReactContext, htmlString, file);
-      String absolutePath = file.getAbsolutePath();
-
-      return absolutePath;
+              .convert(
+                mReactContext,
+                htmlString,
+                file,
+                shouldEncode,
+                resultMap,
+                promise
+              );
     } catch (Exception e) {
       throw new Exception(e);
     }
@@ -100,11 +93,4 @@ private File getTempFile(String fileName) throws Exception {
       throw new Exception(e);
     }
   }
-
-  private String encodeFromFile(File file) throws IOException{
-    RandomAccessFile randomAccessFile = new RandomAccessFile(file, "r");
-    byte[] fileBytes = new byte[(int)randomAccessFile.length()];
-    randomAccessFile.readFully(fileBytes);
-    return Base64.encodeToString(fileBytes, Base64.DEFAULT);
-  }
 }