Develop Reference

Android: Display ImageView from 2 different sources

I'm looking to populate an imageview depending on which source contains the data. The holder.imgImage could have either a bitmap source or a drawable path but I only want one to be displayed depending on which image is present. I have tried if (image !=null) but doesnt seeem to work.
#Override
public void onBindViewHolder(#NonNull ViewHolder holder, int position) {
holder.myTextView1.setText(categoryList.get(position).getRecipe_name());
holder.myTextView2.setText(categoryList.get(position).getCategory_name());
String image2 = categoryList.get(position).getImage2();
Bitmap myBitmap = BitmapFactory.decodeFile(image2);
holder.imgImage.setImageBitmap(myBitmap);
holder.imgImage.setImageResource(categoryList.get(position).getImage());
}

maybe check if created Bitmap isn't null?
Bitmap myBitmap = BitmapFactory.decodeFile(image2);
if (myBitmap != null)
holder.imgImage.setImageBitmap(myBitmap);
else
holder.imgImage.setImageResource(categoryList.get(position).getImage());
maybe there is a case when getImage2() returns null or empty string?
String image2 = categoryList.get(position).getImage2();
Bitmap myBitmap = (image2 != null && image2.length()) > 0 ?
BitmapFactory.decodeFile(image2) : null;

ImageView.setImageBitmap not displaying image in RecyclerView

I am displaying an image in a RecyclerView whose source is is a bitmap taken from an MMS message. The problem is that the image is not displaying. Absolutely nothing is displayed. Here is my onBindView:
#Override
public void onBindViewHolder(ViewHolder holder, int position) {
// - get element from your dataset at this position
// - replace the contents of the view with that element
final String name = mDataset.get(position).getContact() ;
final MMSMessage message = mDataset.get(position);
holder.txtHeader.setText(name);
DateTime dateTime = new DateTime(message.getDate());
holder.txtDate.setText(dateTime.toString(Globals.generalSQLFormatterDT));
holder.txtText.setText(message.getBody());
holder.txtText.setVisibility(View.VISIBLE);
Bitmap bitmap = message.getBitmap();
if (bitmap != null) {
//bitmap is not null and I can see an image using Android Studio
bitmap =Bitmap.createScaledBitmap(bitmap, 120, 120, false);
holder.imgMMS.setImageBitmap(bitmap);
} else {
holder.imgMMS.setVisibility(View.GONE);
}
}
The xml for the ImageView:
<ImageView
android:layout_below="#+id/thirdLine"
android:id="#+id/imageMMS"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginRight="6dip"
android:contentDescription="TODO"
/>
I looked here and tried to scale down the image to an arbitrary small size. I don't think it's an out of memory error - I tried putting in the launcher icon as a test. What am I doing wrong?

if (bitmap != null) {
//bitmap is not null and I can see an image using Android Studio
bitmap =Bitmap.createScaledBitmap(bitmap, 120, 120, false);
holder.imgMMS.setImageBitmap(bitmap);
holder.imgMMS.setVisibility(View.GONE);
} else {
holder.imgMMS.setVisibility(View.GONE);
}
You are setting visibility to GONE. My guess is that the RecyclerView is recycling the views, and when it does the view is GONE since you are not setting it to Visible. Try adding holder.imgMMS.setVisibility(View.VISIBLE); for when bitmap is not null, like so:
if (bitmap != null) {
//bitmap is not null and I can see an image using Android Studio
bitmap =Bitmap.createScaledBitmap(bitmap, 120, 120, false);
holder.imgMMS.setImageBitmap(bitmap);
holder.imgMMS.setVisibility(View.VISIBLE);
} else {
holder.imgMMS.setVisibility(View.GONE);
}

Loading a Bitmap thumbnail into a RecyclerView with AsyncTask bug

I am creating an app that has a file directory that contains pictures, videos, pdfs, etc. I am currently working on displaying thumbnails for pictures. I am using the RecyclerView and ViewHolder to display list items that each represent a photo item. I then use an AsyncTask to download the Bitmaps one at a time and store them in a Hashmap. Everything works fine except when I scroll down in a large list of photos very quickly. The placeholder image for random items at the bottom of the list are replaced with thumbnails that have already been loaded at the top of the list. When the background thread reaches the image at the bottom, then the correct image replaces the wrong image. After all the thumbnails are loaded then everything works as intended.
Here is the code for the AsyncTask. I think the problem has to do with the position integer I am passing into the constructor. The position variable represents the position in the Adapter. Maybe there is a way to make sure the image is loading the placeholder image I have in onPreExecute()?
/**
* AsyncTask to download the thumbnails in the RecyclerView list.
*/
private class CreateThumbnail extends AsyncTask<Void, Void, android.graphics.Bitmap> {
// ******
// FIELDS
// ******
private ImageView mPreviewInstance;
private File mFile;
private RelativeLayout.LayoutParams lp;
private FileHolder mFileHolder;
private int mPosition;
private UUID mId;
private FolderFile mFolderFile;
// ***********
// Constructor
// ***********
/**
* #param holder - ViewHolder passed for the list item.
* #param position - position in the Adapter.
* #param id - id for list item stored in database.
*/
private CreateThumbnail(FileHolder holder, int position, UUID id) {
mPosition = position;
mFileHolder = holder;
mPreviewInstance = mFileHolder.mImagePreview;
mId = id;
mFolderFile = FolderFileLab.get(getContext()).getFolderFile(mId);
}
// ****************
// OVERRIDE METHODS
// ****************
#Override
protected void onPreExecute() {
}
#Override
protected Bitmap doInBackground(Void... params) {
FolderFileLab lab = FolderFileLab.get(getContext());
if (!lab.getCurrentMap().containsKey(mId)) {
mFile = lab.getPhotoFile(mFolderFile);
// Create Bitmap (Biggest use of memory and reason this background thread exists)
Bitmap bitmap = PictureUtils.getScaledBitmap(
mFile.getPath(), getActivity());
// Scales Bitmap down for thumbnail.
Bitmap scaledBitmap;
if (bitmap.getWidth() >= bitmap.getHeight()) {
scaledBitmap = Bitmap.createBitmap(bitmap, bitmap.getWidth() / 2
- bitmap.getHeight() / 2,
0, bitmap.getHeight(), bitmap.getHeight());
} else {
scaledBitmap = Bitmap.createBitmap(bitmap, 0, bitmap.getHeight() / 2
- bitmap.getWidth() / 2,
bitmap.getWidth(), bitmap.getWidth());
}
// Cache bitmap
HashMap<UUID, Bitmap> map = lab.getCurrentMap();
map.put(mId, scaledBitmap);
lab.updateMap(map);
return scaledBitmap;
} else {
// If Hashmap already contains the id get the Bitmap.
return lab.getCurrentMap().get(mId);
}
}
#Override
protected void onPostExecute(Bitmap bitmap) {
// Checks to see if the bitmap is still displayed in the list. If not nothing happens.
// If it is then it displays the image.
if (mPreviewInstance.getVisibility() == View.VISIBLE && mFileHolder.getPosition()
== mPosition && bitmap != null) {
// Formatting for thumbnail
lp = new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout
.LayoutParams.WRAP_CONTENT);
lp.setMargins(7, 7, 7, 0);
// Displaying thumbnail on UI thread.
mPreviewInstance.setLayoutParams(lp);
mPreviewInstance.setBackground(null);
mPreviewInstance.setImageBitmap(bitmap);
}
}
}
Here is some of the relevant Adapter code where the AsyncTask is started.
#Override
public void onBindViewHolder(FileHolder holder, int position) {
FolderFile file = mFiles.get(position);
holder.bindFile(file);
if (file.isPhoto()) {
createThumbnail = new CreateThumbnail(holder, position,file.getId());
createThumbnail.execute();
}
}

Figured it out!
I added code to change the photo to the placeholder image after every bind. This is what I changed in my adapter.
#Override
public void onBindViewHolder(FileHolder holder, int position) {
FolderFile file = mFiles.get(position);
holder.bindFile(file);
if (file.isPhoto()) {
Drawable placeholder = getResources().getDrawable(R.mipmap.picture_blu);
holder.mImagePreview.setBackground(placeholder);
holder.mImagePreview.setImageBitmap(null);
createThumbnail = new CreateThumbnail(holder, position, file.getId());
createThumbnail.execute();
}
}

Your views are recycled, so by the time the async task finishes, the imageView has been reused and has a new image assigned to it.
What you can do is assign to the imageView a tag that is the file name of the file you are trying to load into it. You keep track of that same file name in the async task. Then in your AsyncTask, in onPostExecute, you check if the tag the imageView has is the same file name that you just loaded. If it is, you go ahead and set the bitmap to the imageView. If it is not, then the view has been recycled and you simply drop the Bitmap you just created; another async task will be loading the right bitmap.

Synchronous image loading on a background thread with Picasso - without .get()

I have a custom viewgroup (that contains Picasso-loaded images) that can be reused in two places:
Displayed to the user in the application (on the UI thread)
Drawn to a canvas and saved as a .jpeg (on the background thread)
My code for drawing to the canvas looks like this:
int measureSpec = View.MeasureSpec.makeMeasureSpec(width, View.MeasureSpec.EXACTLY);
view.measure(measureSpec, measureSpec);
Bitmap bitmap =
Bitmap.createBitmap(view.getMeasuredWidth(), view.getMeasuredHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
view.layout(0, 0, view.getMeasuredWidth(), view.getMeasuredHeight());
view.draw(canvas);
The problem is that there is no time for the image to load before I draw the view to the canvas. I'm trying to avoid coupling as much as possible here so I'd prefer not to add a Picasso callback because the class that's doing the drawing doesn't know anything about the view that it's drawing.
I'm currently working around the issue by changing the image loading code to .get() rather than .load() and then using imageView.setImageBitmap(). Unfortunately, this adds a ton of complexity to the view and I really don't like it.
What I'd like to do is pass an option to Picasso's RequestCreator that the request should be executed synchronously on the current thread (and throw an exception if it's the main thread). I wonder if this is too much of an edge case for support to be built directly into Picasso? Or is it already in the API and I'm oblivious to it?

Here is my solution:
/**
* Loads the request into an imageview.
* If called from a background thread, the request will be performed synchronously.
* #param requestCreator A request creator
* #param imageView The target imageview
* #param callback a Picasso callback
*/
public static void into(RequestCreator requestCreator, ImageView imageView, Callback callback) {
boolean mainThread = Looper.myLooper() == Looper.getMainLooper();
if (mainThread) {
requestCreator.into(imageView, callback);
} else {
try {
Bitmap bitmap = requestCreator.get();
imageView.setImageBitmap(bitmap);
if (callback != null) {
callback.onSuccess();
}
} catch (IOException e) {
if (callback != null) {
callback.onError();
}
}
}
}

Perfect answer by Jacob Tabak
Here is small addition that handles the case if you load image into Target. I haven't found a way to get the origin of image to pass appropriate LoadedFrom argument.
public static void into(RequestCreator requestCreator, Drawable placeHolder, Drawable errorDrawable, Target target) {
boolean mainThread = Looper.myLooper() == Looper.getMainLooper();
if (mainThread) {
requestCreator.into(target);
} else {
try {
target.onBitmapFailed(placeHolder);
Bitmap bitmap = requestCreator.get();
target.onBitmapLoaded(bitmap, Picasso.LoadedFrom.MEMORY);
} catch (IOException e) {
target.onBitmapFailed(errorDrawable);
}
}
}

Let Volley's NetworkImageView show local image files

I am using NetworkImageView to show some covers downloaded from a remote URL and I successfully manage to cache and show them, but I want to let users set their own cover images if they want.
I tried to use setImageUrl method with Uri.fromFile(mCoverFile).toString() as arguments, but it doesn't work. Since it is a mix of remote and local images I can't switch to regular ImageViews, so I was wondering if there's any way to enable loading of local images.
I am of course aware of the ImageView's setImageBitmap method, but NetworkImageView automatically resizes the created Bitmap and also prevents View recycling in GridViews and ListViews.
UPDATE: njzk2's answer did the trick. To autoresize the Bitmap according to your View size, then just copy the ImageRequest.doParse method from Volley's source.

NetworkImageView uses ImageLoader, which in turn uses an ImageCache.
You can provide a custom ImageCache with your images, provided you use the same mechanism for keys:
return new StringBuilder(url.length() + 12).append("#W").append(maxWidth)
.append("#H").append(maxHeight).append(url).toString();
url is not tested before the actual request would be done, so no issue here.
Typically, your 'cache' could look like :
public class MyCache implements ImageLoader.ImageCache {
#Override
public Bitmap getBitmap(String key) {
if (key.contains("file://")) {
return BitmapFactory.decodeFile(key.substring(key.indexOf("file://") + 7));
} else {
// Here you can add an actual cache
return null;
}
}
#Override
public void putBitmap(String key, Bitmap bitmap) {
// Here you can add an actual cache
}
}
You use it like :
imageView.setImageUrl(Uri.fromFile(mCoverFile).toString(), new MyCache());
(This has not been actually tested and there may be some adjustments to do)

Thank you for your answer. I wrote some code based on your help.
usage: just use LocalImageCache.class as Cache. No more code to change.
private ImageLoader mLocalImageLoader;
mLocalImageLoader = new ImageLoader(mRequestQueue,
new LocalImageCache(mCtx));
NetworkImageView test = (NetworkImageView) findViewById(R.id.iv_test);
test.setImageUrl("/storage/emulated/0/DCIM/Philm/2017_03_24_01_.png", MySingleton.getInstance(this.getApplicationContext()).getLocalImageLoader());
public class LocalImageCache extends LruCache<String, Bitmap> implements ImageLoader.ImageCache {
public LocalImageCache(int maxSize) {
super(maxSize);
}
public LocalImageCache(Context ctx) {
this(getCacheSize(ctx));
}
#Override
public Bitmap getBitmap(String key) {
key = key.substring(key.indexOf("/"));
Bitmap result = get(key);
Log.d("TAG", key);
if (result == null) {
Bitmap temp = BitmapFactory.decodeFile(key);
put(key, temp);
return temp;
} else {
return result;
}
}
#Override
public void putBitmap(String key, Bitmap bitmap) {
// Here you can add an actual cache
// Never touch here
}
// 默认屏幕5倍的图片缓存
// Returns a cache size equal to approximately three screens worth of images.
public static int getCacheSize(Context ctx) {
final DisplayMetrics displayMetrics = ctx.getResources().
getDisplayMetrics();
final int screenWidth = displayMetrics.widthPixels;
final int screenHeight = displayMetrics.heightPixels;
// 4 bytes per pixel
final int screenBytes = screenWidth * screenHeight * 4;
return screenBytes * 5;
}
#Override
protected int sizeOf(String key, Bitmap value) {
return value.getRowBytes() * value.getHeight();
}
}

NetworkImageView extends ImageView. You should be able to use the same methods as a regular ImageView
image.setImageResource(R.drawable.my_image);
or
imageView.setImageBitmap(BitmapFactory.decodeFile(imagePath));