I'm getting height and width of a view, inflated in the getView() method. It's a grid item.
Usually I use post() on the view to get the size, after it was attached to the layout. But it returns 0.
final View convertViewFinal = convertView;
convertView.post(new Runnable() {
#Override
public void run() {
doSomethingWithConvertView(convertViewFinal);
}
});
...
doSomethingWithConvertView(View v) {v.getWidth(); /*returns 0*/};
How do I get the size?
While using a viewTreeObserver definitely works, I have found that calling measurements requirements on inflated views can be done reliably using a runnable from the activity's view. i.e.
someActivityInstance.getWindow().getDecorView().post(new Runnable() {
#override
public void run() {
// someMeasurements
}
});
The thing is that convertview most likely is not drawn on the phone screen yet, so you have to wait until it is ready.
You need to use a ViewTreeObserver, to know exactly when the view has been drawn.
Check this answer for more info:
When Can I First Measure a View?
You probably is calling this at onCreate or onStart or onResume, methods which runs before layout measure.
But there is a lot of work arounds, this is one good option:
ViewTreeObserver vto = rootView.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
public void onGlobalLayout() {
v.getWidth();//already measured...
}
});
Where rootView may be any viewGroup in a higher level than the one you want the width.
But be aware that this listner may run more than once.
Related
I have a layout with some Views that I need to change size depending on some parameters, that depend on width of the View. The width is set to "match_parent". So when I try to get the width it returns 0. Here is what I have tried so far:
mask.getWidth();
mask.getLayoutParams().width
ViewTreeObserver vto = mask.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
mask.getViewTreeObserver().removeGlobalOnLayoutListener(this);
int width = mask.getMeasuredWidth();
}
});
So my question is how do I get the width in this situation?
Thank you.
After digging around I found a solution that answers my question but has a major problem that I am yet to resolve. We can use method post() that every View has and adds a Runnable to the message queue. So as I understand what happens is after View is fully measured in method post() we can get dimensions that we need like this:
holder.button.post(new Runnable() {
#Override
public void run() {
width = holder.button.getWidth();
}
});
However the problem here is that RecyclerView won't wait until this view is measured as and will go to next row and rows won't be updated according to measures that you expect.
If anyway has a way to go about this problem please leave a comment. Thank you.
I'm making my own custom view and having trouble accessing the layout object immediately after initializing it.
I understand the documentation says layout can be null. But is there a certain event which I can override which will tell me when it's available? I've seen answers on SO which recommend adding a ViewTreeObserver (here)
It seems weird to me that I would need a separate class to know when the layout is available. Is there another way?
From what I understood, there exist no such method which you can override to know when the layout is available. If you find ViewTreeObserver difficult, you can try posting a runnable in the UI Thread i.e.,
view.post(new Runnable() {
#Override
public void run() {
int height = view.getHeight();
int width = view.getWidth();
}
});
Basically, the initialization of the layouts occurs in onCreate() so it would be better if you try the below code in onResume() whether the custom layout is available or not.
if the custom layout is custom_layout.xml then try the below code
LayoutInflater inflater=getLayoutInflater();
View view=inflater.inflate(R.layout.custom_layout,null);
if(view!=null)
{
//Place your code over here
}
im trying to measure a ImageView, after my fragment is displayed, or if possible before.
I heared, that its not yet possible in the onActivityCreated. But somehow it works with the global Layout listener. -But how? -I have a method, wich measures and does some code, i just don't know when to call the method.
Can somebody gice an example?
the beginning of the measure method:
public void skalierung() {
InputStream dots=getResources().openRawResource(R.drawable.amountofdots);
Bitmap dotsBmp = BitmapFactory.decodeStream(dots);
View mainframe=(View)getActivity().findViewById(R.id.mainframe);
int breite=mainframe.getWidth();
Thanks!
To set a GlobalLayoutListener you have to get ViewTreeObserverof your View using the view.getViewTreeObserver() method which :
Returns the ViewTreeObserver for this view's hierarchy. The view tree observer can be used to get notifications when global events, like layout, happen.
After doing that well , you can addOnGlobalLayoutListener on your ViewTreeObserever
OnGlobalLayoutListener : Interface definition for a callback to be invoked when the global layout state or the visibility of views within the view tree changes.
and inside the onGlobalLayoutmethod you can call the getWidth on the your desired view, here's an example :
View mainframe=(View)getActivity().findViewById(R.id.mainframe);
ViewTreeObserver vto = mainframe.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
skalierung(); // here you can call the getWidth and getHeight methods
ViewTreeObserver obs = mainframe.getViewTreeObserver();
// you have to reset the ViewTreeObserver each time to ensure the reuse of the OnGlobalLayoutListener
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
obs.removeOnGlobalLayoutListener(this);
} else {
obs.removeGlobalOnLayoutListener(this);
}
}
});
Hope it helps.
I'm looking for a good way to measure the dimensions of the actual content area for an activity in Android.
Getting display always works. Simply go like this:
Display display = getWindowManager().getDefaultDisplay();
And you can get the pixel count for the entire screen. Of course this does not take into consideration the ActionBar, status bar, or any other views which will reduce the available size of the activity itself.
Once the activity is running, you can do this:
View content = getWindow().findViewById(Window.ID_ANDROID_CONTENT);
To get the activity content only. But doing this in onCreate() will result in a view with width and height of 0, 0.
Is there a way to get these dimensions during onCreate? I imagine there ought to be a way to get the measurements of any status bars and just subtract that from the total display size, but I'm unable to find a way to do that. I think this would be the only way, because the content window method will always return a view with no width/height before it is drawn.
Thanks!
You can use a layout or pre-draw listener for this, depending on your goals. For example, in onCreate():
final View content = findViewById(android.R.id.content);
content.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
//Remove it here unless you want to get this callback for EVERY
//layout pass, which can get you into infinite loops if you ever
//modify the layout from within this method.
content.getViewTreeObserver().removeGlobalOnLayoutListener(this);
//Now you can get the width and height from content
}
});
Update
as of API 16 removeGlobalOnLayoutListener is deprecated.
Change to:
content.getViewTreeObserver().removeOnGlobalLayoutListener(this)
(copied from my answer to a related question)
I use the following technique - post a runnable from onCreate() that will be executed when the view has been created:
contentView = findViewById(android.R.id.content);
contentView.post(new Runnable()
{
public void run()
{
contentHeight = contentView.getHeight();
}
});
This code will run on the main UI thread, after onCreate() has finished.
Answer with post is incorrect, because the size might not be recalculated.
Another important thing is that the view and all it ancestors must be visible. For that I use a property View.isShown.
Here is my kotlin function, that can be placed somewhere in utils:
fun View.onInitialized(onInit: () -> Unit) {
viewTreeObserver.addOnGlobalLayoutListener(object : OnGlobalLayoutListener {
override fun onGlobalLayout() {
if (isShown) {
viewTreeObserver.removeOnGlobalLayoutListener(this)
onInit()
}
}
})
}
And the usage is:
myView.onInitialized {
Log.d(TAG, "width is: " + myView.width)
}
This appears to be a duplicate question. There is an elegant answer within this SO question:
getWidth() and getHeight() of View returns 0
Which (shamelessly copied) is to override onWindowFocusChanged(), which seems to fire just after onCreate(), and where the sizes are rendered:
#Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
//Here you can get the size!
}
If you want lo load a Bitmap into a ImageView within OnCreate(), you can use this example to do it:
public static void setImageLater(#NonNull final ImageView imageView,final Bitmap bitmap){
final ViewTreeObserver observer = imageView.getViewTreeObserver();
observer.addOnGlobalLayoutListener(
new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
imageView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
imageView.setImageBitmap(bitmap);
}
});
}
You can do any work wich needs sizes in onResume(using flag like alreadyDone not to repeat it every time an Activity goes foreground). In onCreate views are not displayed, so it's normal that sizes are zeros.
I have problem with getting information about views after calling setContentView(). I'm changing layout of activity after click on button. Here is the example of my code.
public void onClickButton1(View v) {
setContentView(R.layout.activity_main);
setScreen();
}
But durring execution setScreen() method, layout still is not rendered, so I cannot call getWidth() on some view intended in layout (respectively I can but I always get 0). How I can wait until setContentView() is finished? Please notice that using of this:
#Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
setScreen();
}
is not sufficient for me. I need to change layout independently on activity cycle.
You need to attach a ViewTreeObserver to your layout:
setContentView(R.layout.yourLayoutName);
View yourLayout = findViewById(R.id.ID_OF_YOUR_LAYOUT);
ViewTreeObserver vto = yourLayout.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
//Do your work
vto.removeOnGlobalLayoutListener(this);
}
});
There's no easy way to use setContentView() to get the result you want. You either need to entirely remove all views and then inflate the new layout, use a ViewFlipper to switch between different views, or, which is IMHO the best approach, rework your app to use Fragments