Sharing Bitmap via Android Intent

Question

In my android app, I have a bitmap (say b) and a button. Now when I click on the button, I want to share the bitmap. I am making use of the below code inside my onClick() to achieve this :-

Intent intent = new Intent(Intent.ACTION_SEND); intent.setType("image/png"); intent.putExtra(Intent.EXTRA_STREAM, b); startActivity(Intent.createChooser(intent , "Share")); 

I was expecting a list of all application which are able to handle this intent but I get nothing. There is no list of apps nor is there any error in android studio. My application just get hanged for sometime and then quits.

I have checked the bitmap and it is fine (its not null).

Where am I a going wrong ?

Answer 1

I found 2 variants of the solution. Both involve saving Bitmap to storage, but the image will not appear in the gallery.

First variant:

Saving to external storage

• but to private folder of the app.
• for API <= 18 it requires permission, for newer it does not.

1. Setting permissions

Add into AndroidManifest.xml before tag

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" android:maxSdkVersion="18"/> 

2. Saving method:

 /**  * Saves the image as PNG to the app's private external storage folder.  * @param image Bitmap to save.  * @return Uri of the saved file or null  */ private Uri saveImageExternal(Bitmap image) {     //TODO - Should be processed in another thread     Uri uri = null;     try {         File file = new File(getExternalFilesDir(Environment.DIRECTORY_PICTURES), "to-share.png");         FileOutputStream stream = new FileOutputStream(file);         image.compress(Bitmap.CompressFormat.PNG, 90, stream);         stream.close();         uri = Uri.fromFile(file);     } catch (IOException e) {         Log.d(TAG, "IOException while trying to write file for sharing: " + e.getMessage());     }     return uri; } 

3. Checking storage accesibility

External storage might not be accessible, so you should check it before trying to save: https://developer.android.com/training/data-storage/files

/**  * Checks if the external storage is writable.  * @return true if storage is writable, false otherwise  */ public boolean isExternalStorageWritable() {     String state = Environment.getExternalStorageState();     if (Environment.MEDIA_MOUNTED.equals(state)) {         return true;     }     return false; } 

Second variant

Saving to cacheDir using FileProvider. It does not require any permissions.

1. Setup FileProvider in AndroidManifest.xml

<manifest>     ...     <application>         ...         <provider             android:name="android.support.v4.content.FileProvider"             android:authorities="com.mydomain.fileprovider"             android:exported="false"             android:grantUriPermissions="true">                 <meta-data                     android:name="android.support.FILE_PROVIDER_PATHS"                     android:resource="@xml/file_paths" />         </provider>         ...     </application> </manifest> 

2. Add path to the res/xml/file_paths.xml

<?xml version="1.0" encoding="utf-8"?> <resources>     <paths xmlns:android="http://schemas.android.com/apk/res/android">          <cache-path name="shared_images" path="images/"/>     </paths> </resources> 

3. Saving method:

 /**  * Saves the image as PNG to the app's cache directory.  * @param image Bitmap to save.  * @return Uri of the saved file or null  */ private Uri saveImage(Bitmap image) {     //TODO - Should be processed in another thread     File imagesFolder = new File(getCacheDir(), "images");     Uri uri = null;     try {         imagesFolder.mkdirs();         File file = new File(imagesFolder, "shared_image.png");          FileOutputStream stream = new FileOutputStream(file);         image.compress(Bitmap.CompressFormat.PNG, 90, stream);         stream.flush();         stream.close();         uri = FileProvider.getUriForFile(this, "com.mydomain.fileprovider", file);      } catch (IOException e) {         Log.d(TAG, "IOException while trying to write file for sharing: " + e.getMessage());     }     return uri; } 

More info about file provider - https://developer.android.com/reference/android/support/v4/content/FileProvider

Compressing and saving can be time-consuming, therefore this should be done in a different thread

Actual sharing

/**  * Shares the PNG image from Uri.  * @param uri Uri of image to share.  */ private void shareImageUri(Uri uri){     Intent intent = new Intent(android.content.Intent.ACTION_SEND);     intent.putExtra(Intent.EXTRA_STREAM, uri);     intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);     intent.setType("image/png");     startActivity(intent); }