add Android timezone offset support

android/src/main/java/com/reactcommunity/rndatetimepicker/RNDate.java

@@ -1,13 +1,19 @@
 package com.reactcommunity.rndatetimepicker;
 
 import java.util.Calendar;
+import java.util.TimeZone;
 import android.os.Bundle;
 
 public class RNDate {
   private Calendar now;
 
   public RNDate(Bundle args) {
     now = Calendar.getInstance();
+    if (args != null && args.containsKey("timeZoneOffsetInMinutes")) {
+      now.setTimeZone(TimeZone.getTimeZone("GMT"));
+      Integer timeZoneOffsetInMinutes = args.getInt("timeZoneOffsetInMinutes");
+      now.add(Calendar.MILLISECOND, timeZoneOffsetInMinutes * 60000);
+    }
 
     if (args != null && args.containsKey(RNConstants.ARG_VALUE)) {
       set(args.getLong(RNConstants.ARG_VALUE));

android/src/main/java/com/reactcommunity/rndatetimepicker/RNTimePickerDialogModule.java

@@ -148,6 +148,9 @@ private Bundle createFragmentArguments(ReadableMap options) {
     if (options.hasKey(RNConstants.ARG_INTERVAL) && !options.isNull(RNConstants.ARG_INTERVAL)) {
       args.putInt(RNConstants.ARG_INTERVAL, options.getInt(RNConstants.ARG_INTERVAL));
     }
+    if (options.hasKey("timeZoneOffsetInMinutes") && !options.isNull("timeZoneOffsetInMinutes")) {
+      args.putInt("timeZoneOffsetInMinutes", options.getInt("timeZoneOffsetInMinutes"));
+    }
     return args;
   }
 }

src/datetimepicker.android.js

@@ -38,6 +38,7 @@ function getPicker({
   maximumDate,
   neutralButtonLabel,
   minuteInterval,
+  timeZoneOffsetInMinutes,
 }) {
   switch (mode) {
     case MODE_TIME:
@@ -47,6 +48,7 @@ function getPicker({
         minuteInterval,
         is24Hour,
         neutralButtonLabel,
+        timeZoneOffsetInMinutes,
       });
     case MODE_DATE:
     default:
@@ -72,6 +74,7 @@ export default function RNDateTimePicker(props: AndroidNativeProps) {
     maximumDate,
     neutralButtonLabel,
     minuteInterval,
+    timeZoneOffsetInMinutes,
   } = props;
   const valueTimestamp = value.getTime();
 
@@ -92,11 +95,12 @@ export default function RNDateTimePicker(props: AndroidNativeProps) {
         maximumDate,
         neutralButtonLabel,
         minuteInterval,
+        timeZoneOffsetInMinutes,
       });
 
       picker.then(
         function resolve({action, day, month, year, minute, hour}) {
-          const date = new Date(valueTimestamp);
+          let date = new Date(valueTimestamp);
           const event: AndroidEvent = {
             type: 'set',
             nativeEvent: {},
@@ -109,7 +113,14 @@ export default function RNDateTimePicker(props: AndroidNativeProps) {
               break;
 
             case TIME_SET_ACTION:
-              event.nativeEvent.timestamp = date.setHours(hour, minute);
+              date.setHours(hour, minute);
+              if (timeZoneOffsetInMinutes !== undefined) {
+                const offset =
+                  date.getTimezoneOffset() * 60000 +
+                  timeZoneOffsetInMinutes * 60000;
+                date = new Date(date.getTime() - offset);
+              }
+              event.nativeEvent.timestamp = date;
               onChange(event, date);
               break;
 

src/types.js

@@ -136,6 +136,7 @@ export type AndroidNativeProps = $ReadOnly<{|
    */
   display: Display,
 
+  timeZoneOffsetInMinutes?: ?number,
   /**
    * The interval at which minutes can be selected.
    */