Save HTML5 Canvas Image to Gallery – Phonegap Android plugin

Update

Readers of this post have raised issues with the plugin. I have to personally check for the issues but while using the plugin if you find any issues, you might want to debug it in ADT. I will come up with a working plugin soon. Thanks.

Sometime back I worked on a Phonegap Android plugin that helps to save an HTML5 Canvas Image to the device’s gallery. Well, the title of this post may be misleading but note that when you save an image, you actually have to save it on the SD Card or the device’s memory. The Gallery is just an app that shows the collection of images from various locations on the SD Card. So, there’s nothing like saving an image directly to the Gallery.
I had this working with Phonegap 2.2.0 (the version that I used). Newer versions of Phonegap/Cordova are available and things might have changed a bit, specially in the way custom plugins are written. Hence, if you are using newer versions of Phonegap you should have a look at the official documentation before proceeding.
Alright, here is what I did. I tried to save an image using the FileWriter – Phonegap API, but as it turned out, it can save only text data on the device’s memory. So, only way to do it was write a Phonegap plugin, pass the Canvas details from JavaScript interface to the Java side and let the Java class save the Canvas image on the SD Card.
Note that I am not a Java developer, and there may be better ways of writing this plugin.

How to install the plugin?
You need to get hold of two files :
1) The Java class – SavePhotoPlugin.java
2) The JavaScript interface – SavePhotoPlugin.js

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How to install Phonegap Facebook plugin for iOS

This post has come out of my recent struggle to integrate the Facebook Connect plugin by Dave Johnson and make it work with my Phonegap iOS app. I had a hard time figuring things out as I was new to Phonegap iOS development. I was already doing Android apps with Phonegap, but iOS has given me some tough time. Nevertheless, around 2 days of gloomy and sad face was finally rewarded with a big smile. So, better I document it somewhere so that I do not struggle again and that’s where the inspiration for this post lies. And I must say, the official documentation is pathetic for newbies.
Alright, let’s get started. I will go step by step into the process with all details and screenshots so that it is very easy for you. In this post however, I will not be talking on how to create a Phonegap iOS app, or how to create Phonegap iOS plugins. For that you still need to look at the official documentation. I will only discuss on how we can install the Facebook plugin with a Phonegap iOS app and get started using it.
Before moving further I would like to inform you that I am using Phonegap 2.2.0 for my demo. There are new versions available – 2.5.0 being the latest at the time of writing. So you might want to check the official pages if you are using the latest version of Phonegap. But the steps mentioned below should work with the new versions of Phonegap as well. OK, time to start now.

Note: Phonegap and Cordova are the same (well, at least for me..). I prefer calling Phonegap.

1) Do I need a Mac? Simple answer – Yes, you need a Mac. I have heard and read thousand times about  people asking if iOS apps can be developed in a Windows machine. Simply, I just did not research, instead I have a Mac and I started on it. But the answer is you need a Mac definitely, since you will use XCode and the iOS SDK for development.

2) Create a Phonegap iOS App – I am using Phonegap 2.2.0. I am not going to show how to create a Phonegap iOS app. For that look at this pdf documentation here. If you cannot open it, check out this link which is the pdf source. This should get you started. However I have some screenshots below which should also help you out.
a) I have created a basic Phonegap app – FacebookPluginTest inside Cordova22FacebookTest folder under Documents. See the screenshot below. I have used the Terminal to create the app. You can find details about the command in the document above. So make sure you go through it once.
Create a basic Phonegap app with Terminal Read More »

Adding Calendar Events – Phonegap Android plugin

Alright, I worked on this sometime back and I will share this with you. I was looking to programmatically  add events to the native Android calendar from a Phonegap android app. There is not an official plugin that is available as of now. So I wrote a custom workaround for this. Again, I am not a Java developer and there might be better ways of writing the plugin code. But just wanted to share the code, and any feedback would just be appreciated.

Alright, let’s get started. So, there are two files that I developed. One is the CalendarEventPlugin.java file which has the plugin’s JAVA code. The other one is the CalendarEventPlugin.js file which is the javascript interface of the plugin. At this point, if you are not sure of what goes into writing a custom Phonegap plugin for Android, then you might want to have a look at this. I am using Phonegap 2.2.0 for my purpose. There has been newer version of Phoengap that is available now, 2.4.0 being the latest at the time of writing. So you can use the latest version as well, but do check the documentation once, there might be some changes.

Check the two files out. I have inline comments that will help you to understand. Rest, is very simple to grasp. Now let’s check how to use and implement this plugin into your Phonegap Android project.

1) Firstly you have to add these two files to your Phonegap Android project. Add the CalendarEventPlugin.js file inside assets/www/ folder and provide a reference to it in your index.html file, like this

<script type="text/javascript" charset="utf-8" src="CalendarEventPlugin.js"></script>

2) Then create a directory inside your project’s src folder that matches the package name of CalendarEventPlugin.java class. For our case make a directory – /org/apache/cordova/plugin inside src and then paste CalendarEventPlugin.java file inside it. If you change the package name, make sure to change the directory structure as well. The package name can be found at the top of CalendarEventPlugin.java file.

3) Next thing to do is to register the plugin in the config file – open res/xml/config.xml and then add the plugin details given below to the <plugins></plugins> section of the XML file. The name attribute is the Java class name and the value is the path of the class. This should match the package name.

<plugin name="CalendarEventPlugin" value="org.apache.cordova.plugin.CalendarEventPlugin"/>

4) And then call the plugin inside your javascript (your script.js file or so) code like this. (You can call this inside a button click handler or so),
   window.addcalendareventplugin(function(val){
        alert(val);   //once success message come and you have tested it, you can remove this alert.
    });

Once everything runs fine, you will see that when you click a button or so in your demo app and it calls the callback function in step 4, the native Calendar Add event is popped up with values already set in it (which you can change in the java file of the plugin). From there on its just the normal way of adding events to Calendar.
Hope this helps!!

Note

  • I have tried this on an Android 4.0 device (Galaxy S3) and it works. I have not really tried this on lower Android versions.

Saving Image to Android device’s Gallery – Phonegap Android

Update
Save HTML5 Canvas Image to Gallery – Phonegap Android plugin
I have a Phonegap Android plugin that helps to save HTML5 Canvas Image to the Gallery. See it here.

Now, back to the actual post,

Quick snippet of code that will help a Phonegap Android app to save an image to the Android device’s SD Card and make it available to the Gallery app to show. The title of this post may be misleading but note that when you save an image, you actually have to save it on the SD Card or the device’s memory. The Gallery is just an app that shows the collection of images from various locations on the SD Card. So, there’s nothing like saving an image directly to the Gallery.

Moreover I tried to save an image using the FileWriter – Phonegap API, but as it turned out, it can save only text data on the device’s memory. So, only way to do it was write a Phonegap plugin, pass the image data from JavaScript interface to the Java side and let the Java class save the image on the SD Card. Well I am not going to talk on the entire plugin, but I will share the Java code,

The methods below should be included inside your plugin’s Java class. The idea is simple, whatever be your image/ image data (eg. Base64 data), you take that image data and save it on the SD Card using the FileOutputStream. You get the file path by querying the external storage public directory which is the first line inside the savePhoto() method below. Now, after the image is saved you broadcast it through the System’s Media Scanner so that it becomes available to the Android Gallery app and to other apps. Hope this is clear, time for action now.

private String savePhoto(Bitmap bmp)
{
  //File imageFileFolder = new File(Environment.getExternalStorageDirectory(),"MyFolder"); //when you need to save the image inside your own folder in the SD Card
  File path = Environment.getExternalStoragePublicDirectory(
     Environment.DIRECTORY_PICTURES
  ); //this is the default location inside SD Card - Pictures folder
  //imageFileFolder.mkdir(); //when you create your own folder, you use this line.
  FileOutputStream out = null;
  Calendar c = Calendar.getInstance();
  String date = fromInt(c.get(Calendar.MONTH))
  + fromInt(c.get(Calendar.DAY_OF_MONTH))
  + fromInt(c.get(Calendar.YEAR))
  + fromInt(c.get(Calendar.HOUR_OF_DAY))
  + fromInt(c.get(Calendar.MINUTE))
  + fromInt(c.get(Calendar.SECOND));
  File imageFileName = new File(path, date.toString() + ".jpg"); //imageFileFolder
  try
  {
    out = new FileOutputStream(imageFileName);
    bmp.compress(Bitmap.CompressFormat.JPEG, 100, out);
    out.flush();
    out.close();
    scanPhoto(imageFileName.toString());
    out = null;
  } catch (Exception e)
  {
    e.printStackTrace();
  }
  return imageFileName.toString();
}
private String fromInt(int val)
{
  return String.valueOf(val);
}

/* invoke the system's media scanner to add your photo to the Media Provider's database,
* making it available in the Android Gallery application and to other apps. */
private void scanPhoto(String imageFileName)
{
  Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE);
  File f = new File(imageFileName);
  Uri contentUri = Uri.fromFile(f);
  mediaScanIntent.setData(contentUri);
  //this.cordova.getContext().sendBroadcast(mediaScanIntent); //this is deprecated
  this.cordova.getActivity().sendBroadcast(mediaScanIntent); 
}

Note that I am not a Java developer, and you may need to modify this code as per your needs. But it should work. First save your image (create a Phonegap Android app and test it) and after that you can see it being displayed in the gallery app. I did collect this code by browsing the net and made it work 100%. Otherwise it was difficult for me, since I did not find any concrete answer on this. Leave a suggestion if there is a better solution.

HTML5 Canvas – toDataURL() support for Android devices – working Phonegap 2.2.0 Plugin

Update
Save HTML5 Canvas Image to Gallery – Phonegap Android plugin
I have a Phonegap Android plugin that helps to save HTML5 Canvas Image to the Gallery. See it here.

Back to the actual post,

I have been working on a Phonegap based Android app which involves the HTML5 Canvas. So this is what I had been trying for some time – get a png/jpeg image of the Canvas (its a Canvas paint app, something like this and I want to get an image of the drawing..) and then upload the image to Facebook on a user’s album. Let me tell you, it has been a heck of a task and around 15-20 days of restlessness.

The problem stood tall when I discovered that for Android 2.3 (in general Android < 4.0) devices the native HTML5 Canvas- toDataURL() function does not work, which would otherwise give a base64 encoded string  as image data which then can be used as a source for a HTML <img /> tag. It was working for 4.0 devices as I tested it on a Samsung Galaxy S3 and a Samsung Tab. Hence I Goggled a bit and found out various people had this issue before. So it seemed that older Android web-kits (a Phonegap app runs on the Android webview which is actually the webkit browser inside a native wrapper) does not support that native method of converting a Canvas to an image through toDataURL() generated base64 encoded strings. Guess what I had todo? I had to go for a custom Phonegap plugin as there was no other way. This is how I thought of implementing it – pass the canvas object from javascript side to the Phonegap plugin’s Java class and somehow get the base64 encoded string of the Canvas and return it back to javascript as the callback parameter. This is what the native toDataURL() method actually does – convert the Canvas to a base64 encoded image data string.

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