Getting the dimensions of an ImageView successful Android improvement tin beryllium amazingly tough. Galore fresh builders presume nonstop entree to tallness and width properties volition activity instantly last declaring the ImageView. Nevertheless, this frequently leads to incorrect values, normally returning zero. Knowing the Android format lifecycle is cardinal to retrieving close dimensions. This station dives into respective dependable strategies for acquiring the accurate width and tallness of an ImageView, explaining the underlying causes and offering applicable examples for assorted situations. We’ll screen strategies for antithetic levels of the structure procedure, guaranteeing you tin acquire the dimensions you demand once you demand them.

Knowing the Android Structure Lifecycle

Earlier diving into the options, it’s important to realize however Android attracts views. The format procedure happens successful phases: measure, structure, and gully. Trying to entree dimensions earlier the structure form completes volition output inaccurate outcomes. This is wherefore merely calling getWidth() oregon getHeight() instantly last declaring the ImageView normally returns zero. The position hasn’t been measured and positioned connected the surface but.

Deliberation of it similar baking a bar. You tin’t measurement the bar’s tallness earlier it’s completed baking and cooling. Likewise, you demand to delay for the Android format procedure to absolute earlier precisely figuring out the ImageView dimensions.

This asynchronous quality requires america to employment circumstantial strategies that guarantee we entree the dimensions astatine the correct minute.

Utilizing onPreDrawListener

1 dependable technique is utilizing ViewTreeObserver.OnPreDrawListener. This listener will get triggered conscionable earlier the position is drawn connected the surface, guaranteeing that the structure procedure is absolute and the dimensions are close. This attack is versatile and plant fine successful about situations.

Present’s however to instrumentality it:

1. Connect an OnPreDrawListener to the ImageView’s ViewTreeObserver.
2. Wrong the onPreDraw() technique, get the width and tallness utilizing getWidth() and getHeight().
3. Retrieve to distance the listener last acquiring the dimensions to debar pointless calls.

imageView.getViewTreeObserver().addOnPreDrawListener(fresh ViewTreeObserver.OnPreDrawListener() { @Override national boolean onPreDraw() { imageView.getViewTreeObserver().removeOnPreDrawListener(this); int width = imageView.getWidth(); int tallness = imageView.getHeight(); // Usage width and tallness present instrument actual; } }); 

Leveraging onGlobalLayoutListener

The onGlobalLayoutListener, different action accessible done the ViewTreeObserver, gives akin performance. This listener is known as every time a alteration happens successful the format of the full position hierarchy containing the ImageView. This tin beryllium utile if you demand to react to dynamic structure changes.

Piece onGlobalLayoutListener tin beryllium effectual, it’s crucial to beryllium conscious of its broader range. It triggers much often than onPreDrawListener, possibly starring to show points if not utilized cautiously. Like onPreDrawListener if you lone demand the first dimensions.

Station-Format Calculations with station()

The station() methodology affords a less complicated alternate for retrieving dimensions last the format is absolute. It permits you to station a Runnable to the communication queue, which will get executed last the position is laid retired. This technique is peculiarly utile once running inside the act oregon fragment lifecycle.

imageView.station(fresh Runnable() { @Override national void tally() { int width = imageView.getWidth(); int tallness = imageView.getHeight(); // Usage width and tallness present } }); 

Dealing with Pictures Loaded from URLs

Once loading pictures from URLs utilizing libraries similar Glide oregon Picasso, the ImageView dimensions mightiness not beryllium disposable instantly due to the fact that the representation loading is asynchronous. Successful these instances, usage a listener offered by the representation loading room to find once the representation is loaded and past acquire the ImageView’s dimensions.

Glide.with(discourse) .burden("your_image_url") .into(fresh SimpleTarget<Drawable>() { @Override national void onResourceReady(@NonNull Drawable assets, @Nullable Modulation<? ace Drawable> modulation) { imageView.setImageDrawable(assets); int width = imageView.getWidth(); int tallness = imageView.getHeight(); // Usage width and tallness present } }); 

FAQ

Q: Wherefore does getWidth() instrument zero initially?

A: The structure procedure hasn’t accomplished but, truthful the dimensions are not calculated.

Knowing the Android structure lifecycle is indispensable for acquiring close ImageView dimensions. By using methods similar onPreDrawListener, onGlobalLayoutListener, oregon station(), you tin guarantee you’re accessing these values astatine the accurate clip. Retrieve to see the circumstantial discourse of your implementation and take the methodology that champion fits your wants. Utilizing these approaches volition aid you debar communal pitfalls and physique much sturdy and responsive Android functions. For much precocious structure methods, cheque retired Android’s documentation connected declaring layouts.

Larn MuchQuestion & Answer :

╔══════════════════════════════════════════════╗ ^ ║ ImageView ╔══════════════╗ ║ | ║ ║ ║ ║ | ║ ║ Existent representation ║ ║ | ║ ║ ║ ║ |60px tallness of ImageView ║ ║ ║ ║ | ║ ║ ║ ║ | ║ ╚══════════════╝ ║ | ╚══════════════════════════════════════════════╝ <------------------------------------------------> 90px width of ImageView 

I person an representation position with any default tallness and width, pictures are saved successful db and I privation to standard Representation in accordance to Imageview tallness width. Arsenic I don’t privation it springiness default values due to the fact that once always I alteration it’s tallness and width I besides person to alteration it successful codification.

I americium attempting to acquire the tallness and width of ImageView however zero is returned to maine successful some circumstances.

int tallness = ((ImageView) v.findViewById(R.id.img_ItemView)).getHeight(); 

this returns maine zero equal it has default tallness and width

My reply connected this motion mightiness aid you:

int finalHeight, finalWidth; last ImageView iv = (ImageView)findViewById(R.id.scaled_image); last TextView television = (TextView)findViewById(R.id.size_label); ViewTreeObserver vto = iv.getViewTreeObserver(); vto.addOnPreDrawListener(fresh ViewTreeObserver.OnPreDrawListener() { national boolean onPreDraw() { iv.getViewTreeObserver().removeOnPreDrawListener(this); finalHeight = iv.getMeasuredHeight(); finalWidth = iv.getMeasuredWidth(); television.setText("Tallness: " + finalHeight + " Width: " + finalWidth); instrument actual; } }); 

You tin past adhd your representation scaling activity from inside the onPreDraw() technique.