In my app, i need to get current wallpaper of the device:
Wallpaper = WallpaperManager.getInstance(getApplicationContext()).peekDrawable();
no, the problem is that this action will cause the UI to lag a bit while it's getting the background, furthermore, i need to set it as my app's background, i've tried this:
//Drawable Wallpaper defined already...
new Thread(new Runnable() {
public void run() {
Wallpaper = WallpaperManager.getInstance(getApplicationContext()).peekDrawable();
}
}).start();
if (Wallpaper == null)
{
//Resources res = getResources();
//Drawable drawable1 = res.getDrawable(R.drawable.bg1);
//getWindow().setBackgroundDrawable(drawable1);
}
else
{
Wallpaper.setAlpha(50);
getWindow().setBackgroundDrawable(Wallpaper);
}
//........
but it's not working, any ideas?
if possible, please give the code, i'm still kinda new to android..
also, is there a better way to do this?
Try the following and see if it helps. I've commented the code for you to expand on (if needed).
private class SetWallpaperTask extends AsyncTask<Void, Void, Void> {
Drawable wallpaperDrawable;
#Override
protected void onPreExecute() {
// Runs on the UI thread
// Do any pre-executing tasks here, for example display a progress bar
Log.d(TAG, "About to set wallpaper...");
}
#Override
protected Void doInBackground(Void... params) {
// Runs on the background thread
WallpaperManager wallpaperManager = WallpaperManager.getInstance
(getApplicationContext());
wallpaperDrawable = wallpaperManager.getDrawable();
}
#Override
protected void onPostExecute(Void res) {
// Runs on the UI thread
// Here you can perform any post-execute tasks, for example remove the
// progress bar (if you set one).
if (wallpaperDrawable != null) {
wallpaperDrawable.setAlpha(50);
getWindow().setBackgroundDrawable(wallpaperDrawable);
Log.d(TAG, "New wallpaper set");
} else {
Log.d(TAG, "Wallpaper was null");
}
}
}
And to execute this (background) task:
SetWallpaperTask t = new SetWallpaperTask();
t.execute();
If you're still stuck, I recommend you go through the SetWallpaperActivity.java example and try to replicate that.
Related
I'm currently working on my first Android application.
The application accesses a database to get some informations that I want to print on the screen. To send requests and get answers on the network, I need to use a new thread (I'll name it "N thread"), different from the UI Thread. This part is ok.
Now, I want to modify the variable eventList to get the values stored in a collection, in the N thread.
public class MainActivity extends AppCompatActivity {
public List<Event> eventList = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
/* I fill the list in an other thread */
new Thread(new Runnable() {
public void run(){
eventList = new WebService().getEvents(); //returns a list
}
// if I check here, eventList contains elements
}).start();
/* I check the result */
TextView respView = (TextView) findViewById(R.id.responseView);
if(eventList != null)
{
respView.setText("Ok");
} else {
respView.setText("Not ok");
}
...
}
The problem is : eventList is not modified. How can modify this variable and print it from the UI thread ?
Thank you for your help.
You can use runOnUiThread function or Handler to update UI from other thread. I suggest you reading the below tutorial first: AndroidBackgroundProcessing
Try this
new AsyncTask<Void, Void, Void>() {
#Override
protected Void doInBackground(Void... params)
{
eventList = new WebService().getEvents();
runOnUiThread(new Runnable() {
#Override
public void run() {
TextView respView = (TextView) findViewById(R.id.responseView);
if(eventList != null)
{
respView.setText("Ok");
} else {
respView.setText("Not ok");
}
}
});
}
}.execute();
private class EventsDownloader extends AsyncTask<Void, Void, Void> {
protected Long doInBackground(Void... params) {
eventList = new WebService().getEvents()
}
protected void onPostExecute(Void result) {
TextView respView = (TextView) findViewById(R.id.responseView);
if(eventList != null)
{
respView.setText("Ok");
} else {
respView.setText("Not ok");
}
}
}
This AsyncTask does what you want, the doInBackground runs on a thread and the 'onPostExecute' runs on the UI thread, and it's only called after the doInBackground finishes. This class is "managed" by the OS. To run it you just need to instantiate it and call 'execute'. I recommend doing something like this
The thing with your code is that the thread runs at the same time as the rest of your code (the calls to the setText), this means when it runs the setText the Thread is still getting the events.
I have a listView with ImageViews.
I try to compress the bitmaps with the following code:
public void getImage(final String urlStr, final ImageView toSet) {
// set the tag immediately, to prevent delayed image downloads from
// setting this image.
toSet.setTag(urlStr);
getImage(urlStr, new ImageRepository.ImageRepositoryListener() {
#Override
public void onImageRetrieved(final Drawable drawable) {
if (drawable == null)
return;
toSet.post(new Runnable() {
#Override
public void run() {
// make sure the tag is still the one we set at the
// beginning of this function
if (toSet.getTag() == urlStr) {
toSet.setImageDrawable(drawable);
drawable.setCallback(null);
}
}
});
}
});
}
public class DownloadImageAsyncTask2 extends
AsyncTask<String, Void, Bitmap> {
private final ImageView imageView;
private String imageUrl;
public DownloadImageAsyncTask2(ImageView imageView) {
this.imageView = imageView;
}
#Override
protected void onPreExecute() {
Log.i("DownloadImageAsyncTask", "Starting image download task...");
}
#Override
protected Bitmap doInBackground(String... params) {
imageUrl = params[0];
try {
imageRepository.getImage(imageUrl, imageView);
return BitmapFactory.decodeStream((InputStream) new URL(
imageUrl).getContent());
} catch (IOException e) {
Log.e("DownloadImageAsyncTask", "Error reading bitmap" + e);
downloadingImageUrls.remove(imageUrl);
}
return null;
}
#Override
protected void onPostExecute(Bitmap bitmap) {
imageCache.put(imageUrl, bitmap);
downloadingImageUrls.remove(imageUrl);
if (bitmap != null
&& ((String) imageView.getTag()).equals(imageUrl)) {
imageView.setImageBitmap(bitmap);
}
}
}
How can I make the image loading time be faster?
(I have tried to downsize the images on the server side, but I want to think what can I improve in the client side).
I use async download task to download the images and a cache layer to persist them.
Here is the code:
Your image loading is slow because:
After downloading and saving images in the cache , the AsyncTask is used to load but it doesn't give the result immediately.
Firstly, it is controlled by the global Thread's pool with the number maximum of thread in concurrence. Sometimes , it begins after finishing the other AsyncTask .
Secondly, the method "onPostExecute" is executed in Main Thread but after finishing all the other messages of Main Thread.
So:
Use AsyncTask only to download and save images in the cache.
Try to check if the expected image exists in the cache before using AsyncTask. If it exists then you display it directly in Main thread. Make sure that the size of expected image fits well in your image view .
In your case , add the code like this:
public void getImage(final String urlStr, final ImageView toSet) {
//get the expected image associated with this url and the size of this image view in the cache
Bitmap bitmap = getExpectedBitmap(urlStr,expectedSize);
if(bitmap != null) {
//if it exists , set it in the image view and finish.
toSet.setImageBitmap(bitmap);
return;
}
// set the tag immediately, to prevent delayed image downloads from
// setting this image.
toSet.setTag(urlStr);
getImage(urlStr, new ImageRepository.ImageRepositoryListener() {
#Override
public void onImageRetrieved(final Drawable drawable) {
if (drawable == null)
return;
toSet.post(new Runnable() {
#Override
public void run() {
// make sure the tag is still the one we set at the
// beginning of this function
if (toSet.getTag() == urlStr) {
toSet.setImageDrawable(drawable);
drawable.setCallback(null);
}
}
});
}
});
}
I am quite new to Android/Java, and my first app is using MetaIO SDK.
I am trying to implement "Loading" progress bar, while app (MetaIO SDK) is loading.
Overlay background is shown
Loading dialog is appeared and "loading image" starts spinning
Overlay background disappears and loading image stops spinning <- the problem
After 2-3 seconds it unfreezes and ARELViewActivity is executed.
The code:
public void onScanButtonClick(View v)
{
new ScanLoadingDialog().execute(0);
}
private class ScanLoadingDialog extends AsyncTask<Integer, Integer, Boolean>
{
//Before running code in separate thread
#Override
protected void onPreExecute()
{
progressDialog = new ProgressDialog(MainActivity.this);
progressDialog.setMessage("Loading");
progressDialog.setCancelable(false);
progressDialog.setIndeterminate(false);
progressDialog.show();
}
#Override
protected Boolean doInBackground(Integer... params)
{
try
{
synchronized (this) {
AssetsManager.extractAllAssets(getApplicationContext(), true);
startActivity( new Intent(getApplicationContext(), ARELViewActivity.class));
}
}
catch (IOException e)
{
MetaioDebug.log(Log.ERROR, "Error extracting assets: "+e.getMessage());
MetaioDebug.printStackTrace(Log.ERROR, e);
return false;
}
return true;
}
#Override
protected void onPostExecute(Boolean result)
{
progressDialog.dismiss();
finish();
}
}
Am I doing something wrong?
P.S. Full source code can be found here: link text
P.S.S. Related to this question, but I am using technique suggested there, and it still doesn't want to work
I had a similar problem and i solved it by running the UI handling code on the UI thread like so
runOnUiThread(new Runnable() {
#Override
public void run() {
if (imgvExampleOverlay != null)
imgvExampleOverlay.setVisibility(View.VISIBLE);
}
});
imgvExampleOverlay is an image like the one the user has to capture.
Hope this helps
I am very frustrated as I've been trying to implement a super simple loading wheel while waiting on a network call. I have searched and read dozens of SO questions and I just feel like I must be missing something, unless nobody really does what I'm trying to do. I have tried going down the AsyncTask route, but that's not what I want.
Let me also say that right now my app works perfectly, it's just that the transition from screen to screen appears to hang as it waits on the network. I just want a loading wheel so that in the 1-2 seconds the user knows the app is working and didn't freeze.
Here's what my current network call looks like:
private static String sendDataToServer(String arg1, String arg2)
{
Thread dbThread = new Thread()
{
public void run()
{
// do the call that takes a long time
}
};
dbThread.start();
try {
// I do this so that my program doesn't continue until
// the network call is done and I have received the information
// I need to render my next screen
dbThread.join();
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
Now, why can't I just add the ProgressDialog like this? If I do this, the progressDialog never appears.
private static String sendDataToServer(String arg1, String arg2)
{
final ProgressDialog progress = new ProgressDialog(BaseActivity.getInstance());
progress.setIndeterminate(true);
progress.setMessage("Loading...");
progress.show();
Thread dbThread = new Thread()
{
public void run()
{
// do the call that takes a long time
}
};
dbThread.start();
try {
dbThread.join();
progress.dismiss();
}
catch (InterruptedException e) {
e.printStackTrace();
}
}
I think I'm stuck because the network call needs to be on a separate thread from the UI thread, yet I don't want to continue in my application because I need the results of that call to continue. But if I do thread.join() I hold up everything. I thought I needed AsyncTask but that went downhill quickly. Here's my question on that if you're curious.
Android's AsyncTask: multiple params, returning values, waiting
How the heck to I just show a loading dialog while this call happens without proceeding through the rest of my application?
EDIT
Here's my AsyncTask attempt.
private class PostToFile extends AsyncTask<PostToFile, Void, Void>{
private String functionName;
private ArrayList<NameValuePair> postKeyValuePairs;
private String result = "";
public PostToFile(String function, ArrayList<NameValuePair> keyValuePairs){
functionName= function;
postKeyValuePairs = keyValuePairs;
}
#Override
protected void onPreExecute() {
progressDialog = ProgressDialog.show(BaseActivity.getInstance(), "Loading", "Please wait...", true, false);
}
#Override
protected Void doInBackground(PostToFile... params) {
ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
nameValuePairs.add(new BasicNameValuePair(FUNCTION_KEYWORD, functionName));
for (int i = 0; i < postKeyValuePairs.size(); i++) {
nameValuePairs.add(postKeyValuePairs.get(i));
}
try{
// ***do the POST magic.***
result = response.toString();
}
catch (Exception e){
// clean up my mess
}
return null;
}
private String getResult(){
return result; // can I use this somehow???
}
#Override
protected void onPostExecute(Void result) {
progressDialog.dismiss();
}
}
And when I use it:
new PostToPHP(FUNCTION_NAME, postPairings){
#Override
protected void onPostExecute(String result) {
super.onPostExecute(result);
try
{
if (result != null && !result.startsWith("null"))
{
JSONArray jArray = new JSONArray(result);
parseData(jArray);
}
}
catch (JSONException e)
{
Log.e(Constants.LOG_TAG, e.toString());
}
};
}.execute()
The problem is, I have a couple of these calls back to back, and they're each dependent on each other. So the first one starts, and the second one starts immediately after the first one starts, but before the first one is finished. So I get erroneous behavior. How can I start the second call only after the first is completely done?
Maybe this will work, I haven't tested, but you can try:
public class MyTask extends AsyncTask<String, Void, String> {
private int flag;
public MyTask(int flag) {
this.flag = flag;
}
#Override
protected String doInBackground(String... params) {
switch (flag) {
case 1:
return doNetworking1();
break;
case 2:
return doNetworking2();
break;
case 3:
return doNetworking3();
break;
default:
return doNetworking1();
}
}
#Override
protected void onPreExecute() {
//show progress dialog
}
#Override
protected void onPostExecute(String s) {
//hide progress dialog
switch (flag) {
case 1: //do something with result
new MyTask(2).execute();
break;
case 2: //do other stuff
new MyTask(3).execute();
break;
case 3: //do event more stuff
break;
default:
//do something
}
}
}
and usage:
new MyTask(1).execute();
In cases of network connections I would use IntentService instead of AsyncTask.
For example create IntentServices for network connection:
public class NetworkCallIntentService extends IntentService {
public static final String BROADCAST_ACTION = "com.yourpackage:NETWORK_CALL_BROADCAST";
public static final String RESULT = "com.yourpackage:NETWORK_CALL_RESULT";
public NetworkCallIntentService() {
super(NetworkCallIntentService.class.getSimpleName());
}
#Override
protected void onHandleIntent(Intent intent) {
// get data from intent if needed
// do the call that takes long time
// send broadcast when done
Intent intent = new Intent(BROADCAST_ACTION);
intent.putExtra(RESULT, "some_result");//and more results
LocalBroadcastManager.getInstance(this).sendBroadcast(intent);
}
}
Next, start that service from activity, show progress dialog and move code responsible for showing next screen to BroadcastReceiver#onReceive() method:
public class SomeActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//start service
Intent serviceIntent = new Intent(this, NetworkCallIntentService.class);
//put extras into intent if needed
//serviceIntent.putExtra("some_key", "some_string_value");
startService(serviceIntent);
//here just show progress bar/progress dialog
}
#Override
protected void onResume() {
super.onResume();
LocalBroadcastManager.getInstance(getApplicationContext()).registerReceiver(mNetworkCallReceiver,
new IntentFilter(NetworkCallIntentService.BROADCAST_ACTION));
}
#Override
protected void onPause() {
super.onPause();
LocalBroadcastManager.getInstance(getApplicationContext()).unregisterReceiver(mNetworkCallReceiver);
}
private BroadcastReceiver mNetworkCallReceiver = new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
//hide progress bar/progress dialog
//here get results from intent extras
String result = intent.getStringExtra(NetworkCallIntentService.RESULT);
//process results and continue program(go to next screen, show error message etc.)
}
}
}
Declare service in manifest file:
<service
android:name="com.yourpackage.DownloadSvtValuesIntentService"
android:exported="false" >
</service>
I have a handler used to display images in a specified interval loop, on reaching the last image, it goes back to the first image which is the correct. However, i'm having problems with it as it's causing some devices to crash and makes the CPU usage go up significantly, i'm just wondering what is wrong with the code?
I instantiate it like the following at the top of the fragment:
final public static Handler handler = new Handler();
boolean isRunning = false;
Then in the onPostExecute part of an AsyncTask, I have this code:
#Override
protected void onPostExecute(Void v) {
if(!isRunning) {
Runnable runnable = new Runnable() {
#Override
public void run() {
anImageView.setVisibility(View.VISIBLE);
isRunning = true;
counter++;
//imageDownloader.download(data.get(i).getImageURL(), anmageView);
if(TabsViewPagerFragmentActivity.theImages !=null && TabsViewPagerFragmentActivity.theImages.size() > 0){
Bitmap anImage = TabsViewPagerFragmentActivity.theImages.get(i);
anImageView.setImageBitmap(anImage);
}
i++;
if(i>TabsViewPagerFragmentActivity.theImages.size()-1)
{
i=0;
}
handler.postDelayed(this, 1500);
}
};
handler.postDelayed(runnable, 0);
}
}
The above AsyncTask is called within the onCreate() method.
Secondly, I have a refresh button which re-downloads these images in order to get the latest ones as they change periodically. Therefore I have an onClick() event attached to the refresh button. This also works fine but here is the code which is called:
#Override
protected void onPostExecute(Void v) {
for(int i=0;i<data.size()-1;i++) {
Bitmap anImage = getBitmapFromURL(data.get(i).getImageURL());
theImagesRefreshed.add(anImage);
}
if(!isRunning) {
Runnable runnable = new Runnable() {
#Override
public void run() {
anImageView.setVisibility(View.VISIBLE);
isRunning = true;
counter++;
//imageDownloader.download(data.get(i).getImageURL(), anImageView);
if(theImagesRefreshed !=null && theImagesRefreshed.size() > 0){
Bitmap anImage = theImagesRefreshed.get(i);
anImageView.setImageBitmap(anImage);
}
i++;
if(i>theImagesRefreshed.size()-1)
{
i=0;
}
handler.postDelayed(this, 1500);
}
};
handler.postDelayed(runnable, 0);
}
}
I think that the handler is not setup right and is causing the performance issues. Can anyone see anything wrong with this code?
Thanks in advance!
You need to call Looper.prepare() while using handlers in threads .So write Looper.prepare() after you are creating instance of Runnable