Develop Reference

Querying Android ContentResolver for gallery files and determining image vs video

I'm trying to make a simple Android app for my own phone that looks at my Gallery, and for each image/video file:
creates a Bitmap thumbnail of the file
records the file's absolute path on the phone
Essentially, I'll have the following data model:
public class MediaFileModel {
private Bitmap thumbnail;
private String absPath;
// ctor, getters and setters omitted for brevity
}
And I need something that looks at all the files in my Gallery and yields a List<MediaFileModel>. My best attempt is here:
public List<MediaFileModel> getAllGalleryMedia() {
String[] projection = { MediaStore.MediaColumns.DATA };
List<MediaFileModel> galleryMedia = new ArrayList<>();
Cursor cursor = getActivity().getContentResolver().query(
MediaStore.Images.Media.EXTERNAL_CONTENT_URI,
projection,
null,
null,
null);
// I believe here I'm iterating over all the gallery files (???)
while(cursor.moveToNext()) {
MediaFileModel next = new MediaFileModel();
// is this how I get the abs path of the current file?!?
String absPath = cursor.getString(cursor.getColumnIndex(MediaStore.MediaColumns.DATA));
Bitmap thumbnail = null;
if (true /* ??? cursor is pointing to a media file that is an image/photo ??? */) {
thumbnail = ThumbnailUtils.extractThumbnail(BitmapFactory.decodeFile(absPath), 64, 64);
} else {
// else we have a video (I assume???)
thumbnail = ThumbnailUtils.createVideoThumbnail(absPath, MediaStore.Images.Thumbnails.MINI_KIND);
}
next.setThumbnail(thumbnail);
next.setAbsPath(absPath);
galleryMedia.add(next);
}
return galleryMedia;
}
However I'm not sure if my media query is setup correctly and I'm definitely not sure how to determine whether the file is an image/photo of a video, which I (believe I) need so that I can use the correct method for obtaining the thumbnail Bitmap.
Can anyone help nudge me over the finish line here?

Here is a code I was using for something similar, I hope this will help:
//The code has been removed
Note: Sorry I've removed the code because I am not sure if it has some portion copied from other open-sourced codes, I am using it in my apps but I can't remember if it is quoted from other source, so I've removed it, also it could be auto-completed using github copilot

Android: open video picker and filter videos seen by length

This is my code for opening up the picker for Videos and Images - however I need to not show Videos that are longer than 5 minutes in length. Is this possible?
public void startChoosePhotoFromLibrary() {
if (checkOrRequestExternalStoreagePermission()) {
if (Build.VERSION.SDK_INT < 19) {
Intent photoPickerIntent = new Intent(Intent.ACTION_PICK);
photoPickerIntent.setType("image/* video/*");
startActivityForResult(photoPickerIntent, PICK_PHOTO_ACTIVITY_REQUEST_CODE);
} else {
Intent photoPickerIntent = new Intent(Intent.ACTION_GET_CONTENT);
photoPickerIntent.setType("*/*");
photoPickerIntent.putExtra(Intent.EXTRA_MIME_TYPES, new String[]{"image/*", "video/*"});
startActivityForResult(photoPickerIntent, PICK_PHOTO_ACTIVITY_REQUEST_CODE);
}
}
}

This is my code for opening up the picker for Videos and Images
ACTION_PICK does not use MIME types. ACTION_PICK picks from a collection of content, where that collection is identified by the Uri that you supply in the Intent.
Also, MIME types do not have spaces in them.
Is this possible?
Not via those Intent actions, or via any content-selection mechanism that is part of the Android SDK.
You are welcome to query the MediaStore for videos, and there may be a way to filter such videos by length. But then you would need to present your own UI for allowing the user to choose something from the query results (e.g., ListView, RecyclerView).

Why is DocumentFile so slow, and what should I use instead?

I want to create something like "PDF Viewer app". Application will search for all *.pdf files in location chosen by user. User can choose this folder by this function:
Intent intent = new Intent(Intent.ACTION_OPEN_DOCUMENT_TREE);
startActivityForResult(intent, REQUEST_CODE);
Then I get DocumentFile (folder):
#Override
public void onActivityResult(int requestCode, int resultCode, Intent data) {
if (resultCode == getActivity().RESULT_OK && requestCode == REQUEST_CODE) {
Uri uriTree = data.getData();
DocumentFile documentFile = DocumentFile.fromTreeUri(getActivity(), uriTree);
//rest of code here
}
}
Why I chose this method of selecting folder? Because I want to make possible to choose Secondary Storage (you know, in Android >= 5.0, you can't access Secondary Storage with Java.io.file).
Ok, so I get folder with all *.pdf as DocumentFile. Then I call:
for(DocumentFile file: documentFile.listFiles()){
String fileNameToDisplay = file.getName();
}
And this is VERY SLOW. It takes almost 30 seconds when there are ~600 files in chosen folder. To prove it, I chose directory from External Storage (not secondary storage), and then I tried two solutions: DocumentFile and File.
File version looks like it:
File f = new File(Environment.getExternalStorageDirectory()+"/pdffiles");
for(File file: f.listFiles()){
String fileNameToDisplay = file.getName();
}
}
Second version works about 500x faster. There is almost no time in displaying all files on List View.
Why is DocumentFile so slow?

If you read the source code of TreeDocumentFile, you will find that each call to listFiles() and getName() invokes ContentResolver#query() under the hood. Like CommonsWare said, this would perform hundreds of queries, which is very inefficient.
Here is the source code of listFiles():
#Override
public DocumentFile[] listFiles() {
final ContentResolver resolver = mContext.getContentResolver();
final Uri childrenUri = DocumentsContract.buildChildDocumentsUriUsingTree(mUri,
DocumentsContract.getDocumentId(mUri));
final ArrayList<Uri> results = new ArrayList<>();
Cursor c = null;
try {
c = resolver.query(childrenUri, new String[] {
DocumentsContract.Document.COLUMN_DOCUMENT_ID }, null, null, null);
while (c.moveToNext()) {
final String documentId = c.getString(0);
final Uri documentUri = DocumentsContract.buildDocumentUriUsingTree(mUri,
documentId);
results.add(documentUri);
}
} catch (Exception e) {
Log.w(TAG, "Failed query: " + e);
} finally {
closeQuietly(c);
}
final Uri[] result = results.toArray(new Uri[results.size()]);
final DocumentFile[] resultFiles = new DocumentFile[result.length];
for (int i = 0; i < result.length; i++) {
resultFiles[i] = new TreeDocumentFile(this, mContext, result[i]);
}
return resultFiles;
}
In this function call, listFiles() made a query that only selects the document ID column. However, in your case you also want the file name for each file. Therefore, you can add the column COLUMN_DISPLAY_NAME to the query. This would retrieve the filename and document ID (which later you will convert it into Uri) in a single query and is much more efficient. There are also many other columns available such as file type, file size, and last modified time, which you may want to retrieve them as well.
c = resolver.query(mUri, new String[] {
DocumentsContract.Document.COLUMN_DOCUMENT_ID,
DocumentsContract.Document.COLUMN_DISPLAY_NAME
}, null, null, null);
Within the while loop, retrieve the filename by
final String filename = c.getString(1);
The above modified code is able to instantly retrieve the Uri and filename of a directory with 1000+ files.
In summary, my recommendation is to avoid using DocumentFile if you are working with more than just a few files. Instead use ContentResolver#query() to retrieve the Uri and other information by selecting multiple columns in the query. For file operations, use the static methods in the DocumentsContract class by passing the appropriate Uri's.
By the way, it seems that the sortOrder parameter of ContentResolver#query() gets completely ignored in the above code snippet when tested on Android 11 and Android 9. I would manually sort the results instead of relying on the query order.

Why is DocumentFile so slow?
For ~600 files you are performing ~600 requests of a ContentProvider to get the display name, which means ~600 IPC transactions.
Instead, use MediaStore to query for all indexed media with the application/pdf MIME type.

In case someone comes up here still looking for a solution,
I built a wrapper over this with some pretty good performance.
You can check the wrapper & performance info. here:
https://github.com/ItzNotABug/DocumentFileCompat

To use DocumentsContract to obtain children documents, see https://developer.android.com/reference/android/provider/DocumentsContract.html#buildChildDocumentsUriUsingTree(android.net.Uri, java.lang.String).
The Uri returned from ACTION_OPEN_DOCUMENT_TREE is a tree document URI. Use the above method to build the Uri to query all children documents.
The root document ID can be obtained using https://developer.android.com/reference/android/provider/DocumentsContract.html#getTreeDocumentId(android.net.Uri) with the Uri returned from ACTION_OPEN_TREE_DOCUMENT.

To obtain a speed little less than the one from File use DocumentsContract instead of DocumentFile to list the content of trees obtained with Intent.ACTION_OPEN_DOCUMENT_TREE.

How to get variables from AndroidJavaObject into a C# class using Unity3D

I can't find how to get ListArray variables from an AndroidJavaObject in C#.
I'm trying to make a for function using a Count for the number of items in the ListArray that is stored as an AndroidJavaObject. But I need to know how to get the Count from the AndroidJavaObject and how to use it properly.
This is what I'm using to get the variables, also notice that "packages" is not an AndroidJavaObject[].
AndroidJavaClass jc = new AndroidJavaClass("com.unity3d.player.UnityPlayer");
AndroidJavaObject currentActivity = jc.GetStatic<AndroidJavaObject>("currentActivity");
int flag = new AndroidJavaClass("android.content.pm.PackageManager").GetStatic<int>("GET_META_DATA");
AndroidJavaObject pm = currentActivity.Call<AndroidJavaObject>("getPackageManager");
AndroidJavaObject packages = pm.Call<AndroidJavaObject>("getInstalledApplications", flag);
it's very rudimentary at this point, but it works thanks to some help from this How to get installed apps list with Unity3D?
The progress thus far stalls at getting the icon, everything else works perfect, I need a way to get either a string that links to the icon somehow, or the Texture2D of the icon. Another alternative would be a to use a AndroidJavaObject that contains a drawable as if it's a Texture2D. I have no idea how to accomplish any of this though.Another Idea I had was to convert it to another variable, like byte[] that can be transferred and converted back, but I have yet to find a method of that which works under the circumstance.
int count = packages.Call<int>("size");
AndroidJavaObject[] links = new AndroidJavaObject[count];
string[] names = new string[count];
Texture2D[] icons = new Texture2D[count];
int ii =0;
for(int i=0; ii<count;){
//get the object
AndroidJavaObject currentObject = packages.Call<AndroidJavaObject>("get", ii );
try{
//try to add the variables to the next entry
links[i] = pm.Call<AndroidJavaObject>("getLaunchIntentForPackage", currentObject.Get<AndroidJavaObject>("processName"));
names[i] = pm.Call<string>("getApplicationLabel", currentObject);
icons[i] = pm.Call<Texture2D>("getApplicationIcon", currentObject);
Debug.Log ("(" + ii + ") " + i +" "+ names[i]);
//go to the next app and entry
i++;
ii++;
}
catch
{
//if it fails, just go to the next app and try to add to that same entry.
Debug.Log("skipped "+ ii);
ii++;
}
}
I really hate to ask two questions in a row here, and I apologize for having to do so, but this is a difficult and seemingly awkward circumstance, that has little to no documentation (that I can find).

First of all the docs on the interop between Unity3D and Android are scarce at best.
The most important thing is that the only interface Unity exposes to work with java object is AndroidJavaObject and that interface has only a couple of methods defined. You can only use those ones and only those.
This means that you don't get a Count object when working with an java array and you'll still be working with AndroidJavaObject.
int count = packages.Call<int>("size"); //getting the size of the array
for( int i = 0; i < count; i++ )
{
//getting the object at location i
AndroidJavaObject currentObject = packages.Call("get", i );
//use currentObject using the same methods as before: Call, CallStatic, Get, GetStatic
}
I know this is verbose, and writing code like this is hard to test, you need to make and apk and deploy it to a device to check that it runs.
Probably a faster way of doing this is to make your own java class that does all this on the java side and expose one method that gets called from the Unity side. This way at least you get the benefit of static typing when making a jar that you'll add in the Plugins/Android folder.

I'm trying to do the same thing here, but my launcher must only show the CardBoard apps. What i've decided is to make a library in java and import it to Unity as a plugin:
This is my Java class:
public class Launcher extends UnityPlayerActivity {
private List<ApplicationInfo> cbApps;
#Override
protected void onStart() {
super.onStart();
PackageManager pm= getPackageManager();
List<ApplicationInfo> lista = pm.getInstalledApplications(PackageManager.GET_META_DATA);
cbApps= new LinkedList<ApplicationInfo>();
for(ApplicationInfo ai : lista){
Intent intentToResolve = new Intent(Intent.ACTION_MAIN);
intentToResolve.addCategory("com.google.intent.category.CARDBOARD");
intentToResolve.setPackage(ai.packageName);
if(pm.resolveActivity(intentToResolve, 0)!=null) {
cbApps.add(ai);
}
}
}
public int getListSize(){
return cbApps.size();
}
And here my C# method:
void Start () {
AndroidJavaClass unity = new AndroidJavaClass ("com.unity3d.player.UnityPlayer");
AndroidJavaObject currentActivity = unity.GetStatic<AndroidJavaObject> ("currentActivity");
texto.text=""+currentActivity.Call<int> ("getListSize");
}
This way I can create in Java every method that I need to acces the list. The problem I'm still having is trying to get the Texture2D of the icons. I've tried returning the Drawable from Java and accesing with a Call just as you did, but it doesn't work at all. I've been 2 days working with that, I'll let you know if I find a solution.
EDIT:
Finally I could get the images:
First in Java I created this method:
public byte[] getIcon(int i) {
BitmapDrawable icon= (BitmapDrawable)context.getPackageManager().getApplicationIcon(cbApps.get(i));
Bitmap bmp = icon.getBitmap();
ByteArrayOutputStream stream = new ByteArrayOutputStream();
bmp.compress(Bitmap.CompressFormat.PNG, 100, stream);
byte[] byteArray = stream.toByteArray();
return byteArray;
}
That way I can access the Byte array representing the Drawable from Unity and show it as the main texture of a Plane:
void Start () {
using (AndroidJavaClass unity = new AndroidJavaClass ("com.unity3d.player.UnityPlayer")) {
context = unity.GetStatic<AndroidJavaObject> ("currentActivity");
}
using (AndroidJavaClass pluginClass=new AndroidJavaClass("com.droiders.launcher.Launcher")) {
launcher= pluginClass.CallStatic<AndroidJavaObject>("getInstance", context);
byte[] bytes= launcher.Call<byte[]>("getIcon",0);
Texture2D tex= new Texture2D(2,2);
tex.LoadImage(bytes);
plane.GetComponent<Renderer>().material.mainTexture=tex;
}
}
Hope it helps you. It's been hard but this beast has been tamed :P
Also thanks you all for your ideas.

Reading user photos in android

Trying to read the list of photos taken by the user and display them in the imageview. For the sake of simplicity, trying to just display one for now. Have this piece of code so far:
Cursor cc = this.getContentResolver().query(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, null, null, null,null);
which gets me some data in the cursor, cc.getCount() appears to be making sense (goes up by one when I take a picture, etc.). However, I cannot display the contents in the imageView at all, nothing ever shows up.
Iv'e tried this (s_id is the id of the pic from the cursor above, first returned column):
Uri u;
u = Uri.withAppendedPath(MediaStore.Images.Thumbnails.EXTERNAL_CONTENT_URI, "" + s_id);
im.setImageURI(u);
Also tried this:
Bitmap b = BitmapFactory.decodeFile(u.getPath());
im.setImageBitmap(b);
No worky. Help?
ps. no errors show up anywhere.

Here's another way you can let the user pick an image and display it in an imageview.
This code will allow the user to look through files to pick an image from the gallery:
Intent picture = new Intent(Intent.ACTION_GET_CONTENT);
picture.setType("image/*");
startActivityForResult(picture, YOUR_CODE);
Then in the onActivityResult method you can use the data to set the imageview:
public void onActivityResult(int requestCode, int resultCode, Intent data){
//This is where you can use the data from the previous intent to set the image view
Uri uri = data.getData();
im.setImageURI(uri); //where im is your imageview
}
Check out this link for a more detailed answer.