Android Share Intent for a Bitmap - is it possible

问题:

I try to export a bitmap from my app using share intent without saving a file for a temporal location. All the examples I found are two-step 1) save to SD Card and create Uri for that file 2) start the intent with this Uri

Is it possible to make it without requiring WRITE_EXTERNAL_STORAGE permission, saving the file [and removing it afterwards]? How to address devices without ExternalStorage?

回答1:

I had this same problem. I didn't want to have to ask for the read and write external storage permissions. Also, sometimes there are problems when phones don't have SD cards or the cards get unmounted.

The following method uses a ContentProvider called FileProvider. Technically, you are still saving the bitmap (in internal storage) prior to sharing, but you don't need to request any permissions. Also, every time you share the bitmap the image file gets overwritten. And since it is in the internal cache, it will be deleted when the user uninstalls the app. So in my opinion, it is just as good as not saving the image. This method is also more secure than saving it to external storage.

The documentation is pretty good (see the Further Reading below), but some parts are a little tricky. Here is a summary that worked for me.

Set up the FileProvider in the Manifest

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

Replace com.example.myapp with your app package name.

Create res/xml/filepaths.xml

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

This tells the FileProvider where to get the files to share (using the cache directory in this case).

Save the image to internal storage

// save bitmap to cache directory
try {

    File cachePath = new File(context.getCacheDir(), "images");
    cachePath.mkdirs(); // don't forget to make the directory
    FileOutputStream stream = new FileOutputStream(cachePath + "/image.png"); // overwrites this image every time
    bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
    stream.close();

} catch (IOException e) {
    e.printStackTrace();
}

Share the image

File imagePath = new File(context.getCacheDir(), "images");
File newFile = new File(imagePath, "image.png");
Uri contentUri = FileProvider.getUriForFile(context, "com.example.myapp.fileprovider", newFile);

if (contentUri != null) {
    Intent shareIntent = new Intent();
    shareIntent.setAction(Intent.ACTION_SEND);
    shareIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION); // temp permission for receiving app to read this file
    shareIntent.setDataAndType(contentUri, getContentResolver().getType(contentUri));
    shareIntent.putExtra(Intent.EXTRA_STREAM, contentUri);
    startActivity(Intent.createChooser(shareIntent, "Choose an app"));
}

Further reading

• FileProvider
• Storage Options - Internal Storage
• Sharing Files
• Saving Files

回答2:

I try to export a bitmap from my app using share intent without saving a file for a temporal location.

In theory, this is possible. In practice, it is probably not possible.

In theory, all you need to share is a Uri that will resolve to the bitmap. The simplest approach is if that is a file that is directly accessible by the other application, such as on external storage.

To not write it to flash at all, you would need to implement your own ContentProvider, figure out how to implement openFile() to return your in-memory bitmap, and then pass a Uri representing that bitmap in the ACTION_SEND Intent. Since openFile() needs to return a ParcelFileDescriptor, I don't know how you would do that without an on-disk representation, but I have not spent much time searching.

Is it possible to make it without requiring WRITE_EXTERNAL_STORAGE permission, saving the file [and removing it afterwards]?

If you simply do not want it on external storage, you can go the ContentProvider route, using a file on internal storage. This sample project demonstrates a ContentProvider that serves up a PDF file via ACTION_VIEW to a PDF viewer on a device; the same approach could be used for ACTION_SEND.

回答3:

This for sharing CardView as an Image then saving it in the cache subdirectory of the app's internal storage area. hope it will be helpful.

        @Override
        public void onClick(View view) {

            CardView.setDrawingCacheEnabled(true);
            CardView.buildDrawingCache();
            Bitmap bitmap = CardView.getDrawingCache();

            try{
                File file = new File(getContext().getCacheDir()+"/Image.png");
                bitmap.compress(Bitmap.CompressFormat.PNG,100,new FileOutputStream(file));
                Uri uri = FileProvider.getUriForFile(getContext(),"com.mydomain.app", file);

                Intent shareIntent = new Intent();
                shareIntent.setAction(Intent.ACTION_SEND);
                shareIntent.putExtra(Intent.EXTRA_STREAM, uri);
                shareIntent.setType("image/jpeg");
                getContext().startActivity(Intent.createChooser(shareIntent, "Share"));

            }catch (FileNotFoundException e) {e.printStackTrace();}

        }
    });

回答4:

Here is working method to make a screenshot of own app and share it as image via any messanger or email client.

To fix the bitmap not updating problem I improved Suragch's answer, using Gurupad Mamadapur's comment and added own modifications.

---

Here is code in Kotlin language:

private lateinit var myRootView:View // root view of activity
@SuppressLint("SimpleDateFormat")
private fun shareScreenshot() {
    // We need date and time to be added to image name to make it unique every time, otherwise bitmap will not update
    val sdf = SimpleDateFormat("yyyyMMdd_HHmmss")
    val currentDateandTime = sdf.format(Date())
    val imageName = "/image_$currentDateandTime.jpg"       

    // CREATE
    myRootView = window.decorView.rootView
    myRootView.isDrawingCacheEnabled = true
    myRootView.buildDrawingCache(true) // maybe You dont need this
    val bitmap = Bitmap.createBitmap(myRootView.drawingCache)
    myRootView.isDrawingCacheEnabled = false

    // SAVE
    try {
        File(this.cacheDir, "images").deleteRecursively() // delete old images
        val cachePath = File(this.cacheDir, "images")
        cachePath.mkdirs() // don't forget to make the directory
        val stream = FileOutputStream("$cachePath$imageName")
        bitmap.compress(Bitmap.CompressFormat.JPEG, 90, stream) // can be png and any quality level
        stream.close()
    } catch (ex: Exception) {
        Toast.makeText(this, ex.javaClass.canonicalName, Toast.LENGTH_LONG).show() // You can replace this with Log.e(...)
    }

    // SHARE
    val imagePath = File(this.cacheDir, "images")
    val newFile = File(imagePath, imageName)
    val contentUri = FileProvider.getUriForFile(this, "com.example.myapp.fileprovider", newFile)
    if (contentUri != null) {
        val shareIntent = Intent()
        shareIntent.action = Intent.ACTION_SEND
        shareIntent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION) // temp permission for receiving app to read this file
        shareIntent.type = "image/jpeg" // just assign type. we don't need to set data, otherwise intent will not work properly
        shareIntent.putExtra(Intent.EXTRA_STREAM, contentUri)
        startActivity(Intent.createChooser(shareIntent, "Choose app"))
    } 
}

回答5:

If anyone still looking for easy and short solution without any storage permission (Supports nougat 7.0 as well). Here it is.

Add this in Manifest

<provider
     android:name="android.support.v4.content.FileProvider"
     android:authorities="${applicationId}.provider"
     android:exported="false"
     android:grantUriPermissions="true">
     <meta-data
          android:name="android.support.FILE_PROVIDER_PATHS"
          android:resource="@xml/provider_paths" />
 </provider>

Now create provider_paths.xml

<paths>
    <external-path name="external_files" path="."/>
</paths>

Finally Add this method to your activity/fragment (rootView is the view you want share)

 private void ShareIt(View rootView){
        if (rootView != null && context != null && !context.isFinishing()) {
            rootView.setDrawingCacheEnabled(true);
            Bitmap bitmap = Bitmap.createBitmap(rootView.getDrawingCache());
            if (bitmap != null ) {
                 //Save the image inside the APPLICTION folder
                File mediaStorageDir = new File(AppContext.getInstance().getExternalCacheDir() + "Image.png");

                try {
                    FileOutputStream outputStream = new FileOutputStream(String.valueOf(mediaStorageDir));
                    bitmap.compress(Bitmap.CompressFormat.PNG, 100, outputStream);
                    outputStream.close();

                } catch (FileNotFoundException e) {
                    e.printStackTrace();
                } catch (IOException e) {
                    e.printStackTrace();
                }

                if (ObjectUtils.isNotNull(mediaStorageDir)) {

                    Uri imageUri = FileProvider.getUriForFile(getActivity(), getActivity().getApplicationContext().getPackageName() + ".provider", mediaStorageDir);

                    if (ObjectUtils.isNotNull(imageUri)) {
                        Intent waIntent = new Intent(Intent.ACTION_SEND);
                        waIntent.setType("image/*");
                        waIntent.putExtra(Intent.EXTRA_STREAM, imageUri);
                        startActivity(Intent.createChooser(waIntent, "Share with"));
                    }
                }
            }
        }
    }