Implement version of toDataURL with width and height options

https://github.com/react-native-community/react-native-svg/issues/855

android/src/main/java/com/horcrux/svg/SvgView.java

@@ -306,6 +306,20 @@ public class SvgView extends ReactViewGroup implements ReactCompoundView, ReactC
         return Base64.encodeToString(bitmapBytes, Base64.DEFAULT);
     }
 
+    String toDataURL(int width, int height) {
+        Bitmap bitmap = Bitmap.createBitmap(
+                width,
+                height,
+                Bitmap.Config.ARGB_8888);
+
+        drawChildren(new Canvas(bitmap));
+        ByteArrayOutputStream stream = new ByteArrayOutputStream();
+        bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
+        bitmap.recycle();
+        byte[] bitmapBytes = stream.toByteArray();
+        return Base64.encodeToString(bitmapBytes, Base64.DEFAULT);
+    }
+
     void enableTouchEvents() {
         if (!mResponsible) {
             mResponsible = true;

android/src/main/java/com/horcrux/svg/SvgViewModule.java

@@ -13,6 +13,7 @@ import com.facebook.react.bridge.Callback;
 import com.facebook.react.bridge.ReactApplicationContext;
 import com.facebook.react.bridge.ReactContextBaseJavaModule;
 import com.facebook.react.bridge.ReactMethod;
+import com.facebook.react.bridge.ReadableMap;
 
 class SvgViewModule extends ReactContextBaseJavaModule {
     SvgViewModule(ReactApplicationContext reactContext) {
@@ -33,4 +34,19 @@ class SvgViewModule extends ReactContextBaseJavaModule {
             successCallback.invoke(svg.toDataURL());
         }
     }
+
+
+    @ReactMethod
+    public void toDataURL(int tag, ReadableMap options, Callback successCallback) {
+        SvgView svg = SvgViewManager.getSvgViewByTag(tag);
+
+        if (svg != null) {
+            successCallback.invoke(
+                svg.toDataURL(
+                    options.getInt("width"),
+                    options.getInt("height")
+                )
+            );
+        }
+    }
 }