I would like to perform some task after the creation of the graphic interface of the activity. I need to know the exact height and width of some views and change the layoutParams of some of those views based on the width and height. In the onResume method the views have all the parameters still equal to 0...
As for now I'm using a delayed task that runs after some time from the onCreate but this isn't a good solution at all...
What is the last method called in the activity creation? And are the views' width and height available in such method?
Call this inside of the onCreate()
final View rootView = getWindow().getDecorView().getRootView();
rootView.getViewTreeObserver().addOnGlobalLayoutListener(
new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
//by now all views will be displayed with correct values
}
});
onResume() is last, but perhaps better is onViewCreated(). Its advantage is that it is not invoked every time you regain focus. But try getting properties of your view inside of post() over layout element which you need. For example:
textView.post(new Runnable() {
#Override
public void run() {
// do something with textView
}
});
The last method that runs when activity starts is onResume().
You can find it at Activity lifecycle.
If that is not good enough for you, run delayed task from this onResume() and you'll be fine.
In the last line of the onResume() method get all the data you want. It should show you all that you need.
Use a Coroutine:
In onCreate() ...
CoroutineScope(SupervisorJob()).launch {
getImageAttributes()
}
... then use a while loop to wait until image is in View ...
private fun getImageAttributes() {
while (imageView.height == 0) { /* */ }
val h = imageView.height
val w = imageView.width
val b = imageView.clipBounds
val x = imageView.x
val y = imageView.y
val tx = imageView.translationX
val ty = imageView.translationY
}
You should add a timeout or make the Job cancellable if there is a chance that the imageView.height is going to be 0.
Related
Here is the context: I have a Activity with complex layout to which I want to transition using relatively complex Transitions. The catch is that I need to position one view (scroll_frame) below the image (I can't use XML), so I need to know it's height. It works fine the first time, however after some number of going back and forth between Activities image's height is suddenly zero (caching, race conditions?)
Here is the snippet of onCreate:
super.onCreate(savedInstanceState)
postponeEnterTransition()
setContentView(R.layout.some_id)
// ... non-essential stuff.
Glide.with(this)
.load([some resource id])
.into(object : SimpleTarget<Drawable>() {
override fun onResourceReady(d: Drawable?, t: Transition<in Drawable>?) {
// Prepare image.
image.setImageDrawable(d)
val margin = Math.max(image.measuredHeight, 0)
// ... non-essential stuff
layoutParams.setMargins(0, margin, 0, 0)
// Critical part.
scroll_frame?.layoutParams = layoutParams
// Start transition.
startPostponedEnterTransition()
}
})
The thing is that views are not given the measured height in onCreate.
Try this:
//Put this in onCreate
imageView.post(new Runnable() {
#Override
public void run() {
//This is called after view measurements are done.
//Run your glide code here.
}
});
Hope this helps.
that's because your view isn't set yet:
use this:
image.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
public void onGlobalLayout() {
//don't forget to remove the listener to prevent being called again by future layout events:
image.getViewTreeObserver().removeOnGlobalLayoutListener(this);
val margin = Math.max(image.measuredHeight, 0)
// ... non-essential stuff
layoutParams.setMargins(0, margin, 0, 0)
// Critical part.
scroll_frame?.layoutParams = layoutParams
// Start transition.
startPostponedEnterTransition()
}
}
I have a logo view, which is a full screen fragment containing single ImageView.
I have to perform some operations after the logo image is completely visible.
Following code is used to invoke the special task
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
ImageView logoImageMaster = new ImageView(getContext());
//logoImageMaster.setImageResource(resID); //even after removing this, i am getting the callback twice
try {
// get input stream
InputStream ims = getActivity().getAssets().open("product_logo.png");
// load image as Drawable
Drawable d = Drawable.createFromStream(ims, null);
// set image to ImageView
logoImageMaster.setImageDrawable(d);
}
catch(IOException ex) {
}
logoImageMaster.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() { //FIXME get called twice. Check this out, no info to distinguish first from second
// Log.e("PANEL", "onGlobalLayout of Logo IV ---------------------------------");
activityInterface.doSpecialLogic();
}
});
return logoImageMaster;
}
My exact problem is, onGlobalLayout is called twice for this view hierarchy.
I know that onGlobalLayout is invoked in performTraversal of View.java hence this is expected.
For my use case of Single parent with Single child view, I want to distinguish the view attributes such that doSpecialLogic is called once[onGlobalLayout is called twice] , after the logo image is completely made visible.
Please suggest some ideas.
OnGlobalLayoutListener gets called every time the view layout or visibility changes. Maybe you reset the views in your doSpecialLogic call??
edit
as #Guille89 pointed out, the two set calls cause onGlobalLayout to be called two times
Anyhow, if you want to call OnGlobalLayoutListener just once and don't need it for anything else, how about removing it after doSpecialLogic() call??
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.JELLY_BEAN) {
//noinspection deprecation
logoImageMaster.getViewTreeObserver().removeGlobalOnLayoutListener(this);
} else {
logoImageMaster.getViewTreeObserver().removeOnGlobalLayoutListener(this);
}
activityInterface.doSpecialLogic();
It seems to be called one time for each set done over the imageView
logoImageMaster.setImageResource(resID);
logoImageMaster.setImageDrawable(d);
You should Try using kotlin plugin in android
This layout listener is usually used to do something after a view is measured, so you typically would need to wait until width and height are greater than 0. And we probably want to do something with the view that called it,in your case
Imageview
So generified the function so that it can be used by any object that extends View and also be able to access to all its specific functions and properties from the function
[kotlin]
inline fun <T: View> T.afterMeasured(crossinline f: T.() -> Unit) {
viewTreeObserver.addOnGlobalLayoutListener(object : ViewTreeObserver.OnGlobalLayoutListener {
override fun onGlobalLayout() {
if (measuredWidth > 0 && measuredHeight > 0) {
viewTreeObserver.removeOnGlobalLayoutListener(this)
f()
}
}
})
}
[/kotlin]
Note:
make sure that ImageView is described properly in the layout. That is its layout_width and layout_height must not be wrap_content. Moreover, other views must not result in this ImageView has 0 size.
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 an HorizontalScrollView which contains a RelativeLayout. This layout is empty in the XML, and is populated from java in the onCreate.
I would like this scroll view to be initially somewhere in the middle of the RelativeLayout, which is way larger than the screen.
I tried mHorizScrollView.scrollTo(offsetX, 0); which doesn't work.
I don't know what's wrong with this.
I could post the code, but it is not really relevant. What matters is that everything is done programatically (has to :s), and that the initial position of the HorizontalScrollView has to be set programmatically.
Thanks for reading. Please tell me if you need more details or if this is not clear enough.
I found that if you extend the HorizontalScrollView and override the onLayout, you can cleanly scroll, after the super call to onLayout:
MyScrollView extends HorizontalScrollView {
protected void onLayout (boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
this.scrollTo(wherever, 0);
}
}
EDIT:
For scrolling to start or end you can use:
this.fullScroll(HorizontalScrollView.FOCUS_RIGHT/FOCUS_LEFT);
instead of
this.scrollTo(wherever, 0);
public void autoSmoothScroll() {
final HorizontalScrollView hsv = (HorizontalScrollView) view.findViewById(R.id.horiscroll);
hsv.postDelayed(new Runnable() {
#Override
public void run() {
//hsv.fullScroll(HorizontalScrollView.FOCUS_RIGHT);
hsv.smoothScrollBy(500, 0);
}
},100);
}
To test whether it's a timing issue (which I think it is), instead of calling scrollTo() in onStart, call postDelayed() with a Runnable that calls scrollTo, with a delay of 30 or so.
A better approach would be using the ViewTreeObserver to observe layouts.
View interestedInView;
onCreate(){
//Code
//Observe for a layout change
ViewTreeObserver viewTreeObserver = interestedInView.getViewTreeObserver();
if (viewTreeObserver.isAlive()) {
viewTreeObserver.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
//REMOVE THE VIEWTREE OBSERVER
//interestedInView is ready for size and position queries because it has been laid out
}
});
}
}
The problem is that the view doesn't have a size yet. The Clean way to do this is to implement the onSizeChanged of the ScrollView to send a message to a Handler in your activity to in order to notify the activity that the view has a size and that scrolling is possible.
Use view.post and write scrollTo(x,y) inside run method. This the way to invalidate view in post method as per android API document.
The scrollTo function should work. What is the layout_width of the HSV, and the view inside of it?
The onSizeChanged function should work. What you fail to understand is that the onSizeChanged should send a message to a Handler of your activity and not any callback function, because a handler will execute code in the UI thread. You cannot do UI operations outside it. Have a look at handlers.
Use Kotlin extension function.
inline fun <T : View> T.afterMeasured(crossinline f: T.() -> Unit) {
viewTreeObserver.addOnGlobalLayoutListener(object : ViewTreeObserver.OnGlobalLayoutListener {
override fun onGlobalLayout() {
if (measuredWidth > 0 && measuredHeight > 0) {
viewTreeObserver.removeOnGlobalLayoutListener(this)
f()
}
}
})
}
Usage:
mHorizontalScrollView.afterMeasured {
var scrollTo = 0
val count = (layout.svList.getChildAt(0) as LinearLayout)
.childCount
if(index < count){
val child = (layout.svList.getChildAt(0) as LinearLayout)
.getChildAt(index)
scrollTo = child.width
}
Log.d(TAG, "scrollToComment: $scrollTo")
mHorizontalScrollView.scrollTo(scrollTo, 0)
}
I have a view made up of TableLayout, TableRow and TextView. I want it to look like a grid. I need to get the height and width of this grid. The methods getHeight() and getWidth() always return 0. This happens when I format the grid dynamically and also when I use an XML version.
How to retrieve the dimensions for a view?
Here is my test program I used in Debug to check the results:
import android.app.Activity;
import android.os.Bundle;
import android.widget.TableLayout;
import android.widget.TextView;
public class appwig extends Activity {
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.maindemo); //<- includes the grid called "board"
int vh = 0;
int vw = 0;
//Test-1 used the xml layout (which is displayed on the screen):
TableLayout tl = (TableLayout) findViewById(R.id.board);
tl = (TableLayout) findViewById(R.id.board);
vh = tl.getHeight(); //<- getHeight returned 0, Why?
vw = tl.getWidth(); //<- getWidth returned 0, Why?
//Test-2 used a simple dynamically generated view:
TextView tv = new TextView(this);
tv.setHeight(20);
tv.setWidth(20);
vh = tv.getHeight(); //<- getHeight returned 0, Why?
vw = tv.getWidth(); //<- getWidth returned 0, Why?
} //eof method
} //eof class
I believe the OP is long gone, but in case this answer is able to help future searchers, I thought I'd post a solution that I have found. I have added this code into my onCreate() method:
EDITED: 07/05/11 to include code from comments:
final TextView tv = (TextView)findViewById(R.id.image_test);
ViewTreeObserver vto = tv.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
LayerDrawable ld = (LayerDrawable)tv.getBackground();
ld.setLayerInset(1, 0, tv.getHeight() / 2, 0, 0);
ViewTreeObserver obs = tv.getViewTreeObserver();
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN) {
obs.removeOnGlobalLayoutListener(this);
} else {
obs.removeGlobalOnLayoutListener(this);
}
}
});
First I get a final reference to my TextView (to access in the onGlobalLayout() method). Next, I get the ViewTreeObserver from my TextView, and add an OnGlobalLayoutListener, overriding onGLobalLayout (there does not seem to be a superclass method to invoke here...) and adding my code which requires knowing the measurements of the view into this listener. All works as expected for me, so I hope that this is able to help.
I'll just add an alternative solution, override your activity's onWindowFocusChanged method and you will be able to get the values of getHeight(), getWidth() from there.
#Override
public void onWindowFocusChanged (boolean hasFocus) {
// the height will be set at this point
int height = myEverySoTallView.getMeasuredHeight();
}
You are trying to get width and height of an elements, that weren't drawn yet.
If you use debug and stop at some point, you'll see, that your device screen is still empty, that's because your elements weren't drawn yet, so you can't get width and height of something, that doesn't yet exist.
And, I might be wrong, but setWidth() is not always respected, Layout lays out it's children and decides how to measure them (calling child.measure()), so If you set setWidth(), you are not guaranteed to get this width after element will be drawn.
What you need, is to use getMeasuredWidth() (the most recent measure of your View) somewhere after the view was actually drawn.
Look into Activity lifecycle for finding the best moment.
http://developer.android.com/reference/android/app/Activity.html#ActivityLifecycle
I believe a good practice is to use OnGlobalLayoutListener like this:
yourView.getViewTreeObserver().addOnGlobalLayoutListener(new OnGlobalLayoutListener() {
#Override
public void onGlobalLayout() {
if (!mMeasured) {
// Here your view is already layed out and measured for the first time
mMeasured = true; // Some optional flag to mark, that we already got the sizes
}
}
});
You can place this code directly in onCreate(), and it will be invoked when views will be laid out.
Use the View's post method like this
post(new Runnable() {
#Override
public void run() {
Log.d(TAG, "width " + MyView.this.getMeasuredWidth());
}
});
I tried to use onGlobalLayout() to do some custom formatting of a TextView, but as #George Bailey noticed, onGlobalLayout() is indeed called twice: once on the initial layout path, and second time after modifying the text.
View.onSizeChanged() works better for me because if I modify the text there, the method is called only once (during the layout pass). This required sub-classing of TextView, but on API Level 11+ View. addOnLayoutChangeListener() can be used to avoid sub-classing.
One more thing, in order to get correct width of the view in View.onSizeChanged(), the layout_width should be set to match_parent, not wrap_content.
Are you trying to get sizes in a constructor, or any other method that is run BEFORE you get the actual picture?
You won't be getting any dimensions before all components are actually measured (since your xml doesn't know about your display size, parents positions and whatever)
Try getting values after onSizeChanged() (though it can be called with zero), or just simply waiting when you'll get an actual image.
As F.X. mentioned, you can use an OnLayoutChangeListener to the view that you want to track itself
view.addOnLayoutChangeListener(new View.OnLayoutChangeListener() {
#Override
public void onLayoutChange(View v, int left, int top, int right, int bottom, int oldLeft, int oldTop, int oldRight, int oldBottom) {
// Make changes
}
});
You can remove the listener in the callback if you only want the initial layout.
I guess this is what you need to look at: use onSizeChanged() of your view. Here is an EXTENDED code snippet on how to use onSizeChanged() to get your layout's or view's height and width dynamically http://syedrakibalhasan.blogspot.com/2011/02/how-to-get-width-and-height-dimensions.html
ViewTreeObserver and onWindowFocusChanged() are not so necessary at all.
If you inflate the TextView as layout and/or put some content in it and set LayoutParams then you can use getMeasuredHeight() and getMeasuredWidth().
BUT you have to be careful with LinearLayouts (maybe also other ViewGroups). The issue there is, that you can get the width and height after onWindowFocusChanged() but if you try to add some views in it, then you can't get that information until everything have been drawn. I was trying to add multiple TextViews to LinearLayouts to mimic a FlowLayout (wrapping style) and so couldn't use Listeners. Once the process is started, it should continue synchronously. So in such case, you might want to keep the width in a variable to use it later, as during adding views to layout, you might need it.
Even though the proposed solution works, it might not be the best solution for every case because based on the documentation for ViewTreeObserver.OnGlobalLayoutListener
Interface definition for a callback to be invoked when the global layout state or the visibility of views within the view tree changes.
which means it gets called many times and not always the view is measured (it has its height and width determined)
An alternative is to use ViewTreeObserver.OnPreDrawListener which gets called only when the view is ready to be drawn and has all of its measurements.
final TextView tv = (TextView)findViewById(R.id.image_test);
ViewTreeObserver vto = tv.getViewTreeObserver();
vto.addOnPreDrawListener(new OnPreDrawListener() {
#Override
public void onPreDraw() {
tv.getViewTreeObserver().removeOnPreDrawListener(this);
// Your view will have valid height and width at this point
tv.getHeight();
tv.getWidth();
}
});
Height and width are zero because view has not been created by the time you are requesting it's height and width . One simplest solution is
view.post(new Runnable() {
#Override
public void run() {
view.getHeight(); //height is ready
view.getWidth(); //width is ready
}
});
This method is good as compared to other methods as it is short and crisp.
You should rather look at View lifecycle: http://developer.android.com/reference/android/view/View.html Generally you should not know width and height for sure until your activity comes to onResume state.
You can use a broadcast that is called in OnResume ()
For example:
int vh = 0;
int vw = 0;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.maindemo); //<- includes the grid called "board"
registerReceiver(new BroadcastReceiver() {
#Override
public void onReceive(Context context, Intent intent) {
TableLayout tl = (TableLayout) findViewById(R.id.board);
tl = (TableLayout) findViewById(R.id.board);
vh = tl.getHeight();
vw = tl.getWidth();
}
}, new IntentFilter("Test"));
}
protected void onResume() {
super.onResume();
Intent it = new Intent("Test");
sendBroadcast(it);
}
You can not get the height of a view in OnCreate (), onStart (), or even in onResume () for the reason that kcoppock responded
Simple Response: This worked for me with no Problem.
It seems the key is to ensure that the View has focus before you getHeight etc. Do this by using the hasFocus() method, then using getHeight() method in that order. Just 3 lines of code required.
ImageButton myImageButton1 =(ImageButton)findViewById(R.id.imageButton1);
myImageButton1.hasFocus();
int myButtonHeight = myImageButton1.getHeight();
Log.d("Button Height: ", ""+myButtonHeight );//Not required
Hope it helps.
Use getMeasuredWidth() and getMeasuredHeight() for your view.
Developer guide: View
CORRECTION:
I found out that the above solution is terrible. Especially when your phone is slow.
And here, I found another solution:
calculate out the px value of the element, including the margins and paddings:
dp to px:
https://stackoverflow.com/a/6327095/1982712
or dimens.xml to px:
https://stackoverflow.com/a/16276351/1982712
sp to px:
https://stackoverflow.com/a/9219417/1982712 (reverse the solution)
or dimens to px:
https://stackoverflow.com/a/16276351/1982712
and that's it.