Proper Way of Changing View Properties at runtime - android

So i have a view which is inflated via Xml. That view has a subView, which i need to set a marginTop with a dynamic value like this:
toolbar.getHeight() - 100
For this reason, i cannot set it to xml. I could do this:
?attr/actionBarSize
but i need specifically toolbar.getHeight() - 100
What is the proper way of accomplish this? I am doing it in the onCreate of the activity, i set a viewTreeObserver.addOnGlobalLayoutListener for that view, get the layoutParameters and add a margin.
Is this the right way to do this? The way i see it, the view is drawn, and when i run some code inside viewTreeObserver of that view, the view must be redrawn again. Is there a way of avoid this double rendering without setting a custom view?

Inside of onCreate() you can look up the value for this attribute in the current context:
int[] attrIds = new int[1]{ R.attr.actionBarSize };
TypedArray a = obtainStyledAttributes(attrIds);
// first argument is index in attrIds, second argument is
// a default value to return if not found
int actionBarSize = a.getDimensionPizelSize(0, 0);
a.recycle();
// do something with actionBarSize

Related

Get the position of a view just after an addView()

Everything is in the title. I need to add the view at some point in my relativeLayout but not necessary at the OnCreate method. What I want to do is adding a view when the user click on the RelativeLayout, no problem for that. But I need to know the position of this view as soon as possible after I used addView method. Currently I'm using postDelayed but I need to put a high value to be sure that it is displayed before taking the position of the view. I tried using post but didn't work very well so that's why i use a delayed value. I also tried something with treeObserver some time ago but maybe i used it wrong I don't know because it did not work.
Edit:
Here I create the layout param.
RelativeLayout.LayoutParams laoutparam = new RelativeLayout.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT );
laoutparam.addRule(RelativeLayout.CENTER_IN_PARENT);
Here I create my custom view and add the layoutparam to it:
Button button = (Button)findViewById(R.id.lol);
CustView view = new Bubble(getApplicationContext(), "Press this button", button);
bubble.setLayoutParams(laoutparam);
And then in the constructor of my custom RelativeLayout I do an addView(view).
Thanks for your help.
I hope this helps you with getting view location: https://www.tutorialspoint.com/how-to-get-the-absolute-coordinates-of-a-view-in-android
Example:
int loc[]=new int[2];
yourView.getLocationOnScreen(loc);
int x=loc[0];
int y=loc[1];

Android equivalent to View.setTranslationX, but to adjust width?

I have been spending hours unsuccessfully trying to adjust the width, height, and offset of a simple view in Android as the result of a button press. I have discovered that setTranslationX and setTranslationY always work; the legacy method of setLayoutParams never works once the view is laid out initially. Calls to requestLayout() and invalidate() similarly produce no results.
I have tried to setLayoutParams within the context of posting a runnable, but this does nothing.
Because setTranslationX always works, I would just use that, but unfortunately there is no equivalent method like setWidth or setHeight.
As you can see in the AOSP, setTranslationX makes a call to invalidateViewProperty, which is a private method of View.
Is there an equivalent method to setTranslationX to adjust a view width or view margin, that presumably triggers invalidateViewProperty, and, by extension, works reliably?
EDIT
While in some situations, setLayoutParams may be expected to work after the initial layout, I am in a situation where setLayoutParams has no effect after the initial layout, but setTranslationX does. My setup is as follows:
Running Android KitKat 4.4
The view in question is MATCH_PARENT for both width, height
The view in question is a child of a RelativeLayout
The view in question is a View class with a simple solid-color background drawable
Here is the view:
<View
android:id="#+id/border"
android:background="#drawable/match_background_border_transparent"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
And here is the (non-working) code meant to dynamically alter its margins, but has no effect. Again, if I call setTranslationX, that always works.
holder.toggleButton.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
imageBorder.post(new Runnable() {
#Override
public void run() {
RelativeLayout.LayoutParams p = (LayoutParams) imageBorder.getLayoutParams();
p.leftMargin = 20;
p.rightMargin = 20;
p.topMargin = 20;
p.bottomMargin = 20;
imageBorder.setLayoutParams(p);
// imageBorder.setTranslationX does have an effect if I included it here
}
});
}
});
I have determined why setTranslationX was working, but setLayoutParams was not. My views were ultimately descendents of an AdapterView. I was able to programmatically manipulate LayoutParams of the AdapterView and his siblings, but none of the AdapterView's descendents.
Additional research showed that this was a common Android question:
Margin on ListView items in android
Why LinearLayout's margin is being ignored if used as ListView row view
What was confusing was that this view was several levels deep; i.e., it went:
AdapterView -> FrameLayout -> RelativeLayout -> View
Anyhow, I was able to accomplish my programmatic layout goals by wrapping view in another view, and using setPadding.

Duplicate layout IDs returning as -1 after view replacement

Short Story:
I have a layout "layout.xml", which gets replaced by another layout "success.xml" after a successful web request. Both layouts have an ImageView that provides the backgrounds to the layouts. These 2 backgrounds both need to be the same, and both are dependent on a user preference.
Longer Story: This all happens in a Fragmnet with an AsyncTask replacing the contentView with "success.xml" in onPostExecute after the web request. This happens as follows:
View view = getView();
view = null;
view = View.inflate(context, R.layout.success, null);
What I tried to do is give both ImageViews the following android:id="#+id/background_image" and then call
ImageView background = (ImageView)view.findViewById(R.id.background_image);
background.setImageResource(R.drawable.bg1);
This background-setting works for the initial view (layout.xml), but on trying to change to "success.xml", I get a NullPointException because background is null.
I've checked and the View's id is set to -1 while the original view's background_image id is set to something sensible and valid.
I've also tried setting the second view's background id like this: android:id="#id/background_image", i.e. without the '+', but still no luck.
The added complication is that it's not just 2 layouts, but about 5 that I need to do this for, so it would be really handy to recycle view id's.
Any help would be greatly appreciated.
Your code for replacing the fragment's view will not do what you want, the original view will remain the same as you change only a reference to that view and not the actual object.
To replace the view of the fragment with the new layout you could have another ViewGroup(for example a FrameLayout) in the basic layout (layout.xml) wrapping your current content(don't forget to give it an id) of layouts.xml(as I understand this is the basic layout). Then, when it's time to replace the layout you could simply do:
// remove the current content
((ViewGroup) getView().findViewById(R.id.yourWrapperLayout)).removeAllViews();
// add the new content
View.inflate(context, R.layout.success, ((ViewGroup) getView().findViewById(R.id.yourWrapperLayout)));
You could avoid adding an extra layout if, by any chance, all your five layouts have the same type for the root view(like a LinearLayout etc). In this case you would use the same code as above but you'll modify the other layouts file to use a merge tag. Also, you'll be looking for the id of the root in the layout.xml layout into which you'll add the content of the other files.
Then you could have the same ids, but you'll have to reinitialize any reference to the views(meaning that you'll have to search for the view again if you store a reference to the view(like a Button field in the fragment class)).

Android TextView has height and width of 0

I have a small project where I want to reuse a certain UI component a few time so I created a widget by expanding a ViewGroup. In that ViewGroup I inflated a view that contained a TextView inside a LinearLayout and added that inflated view to the ViewGroup trough addView.
The outer LinearLayout expands itself perfectly but the inner TextView have getHeight() = 0 and getWith() = 0 when I view it through Hierarchy Viewer. The strange thing is that layout_height and layout_width is the values I gave them in my xml.
I don't have the code here but it looked something like this:
xml:
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView
android:text="random text.."
android:layout_with="200px"
android:layout_height="50px" />
</LinearLayout>
Java:
class MyWidget extends ViewGroup {
...
//In constructor
myView = View.inflate(context, R.layout.xml, null);
addView(myView);
//In layout
myView.layout(l, t, r, b);
I have tried to give my text view fill_parent values for size but it didn't help.
Remember:getHeight() and getWidth()return 0 if components are not drawn yet.
To find the width And height of a View before it being drawn:
First call measure
view.measure(MeasureSpec.UNSPECIFIED,MeasureSpec.UNSPECIFIED)
Now you can get width using getMeasuredWidth and height using getMeasuredHeight
int width = view.getMeasuredWidth();
int height = view.getMeasuredHeight();
I have posted some more ideas here: How to get width/height of a View
1) Here is some links to use Hierarchy Viewer on your dev phone.
http://developer.android.com/guide/developing/debugging/debugging-ui.html
and the class you'll need:
http://github.com/romainguy/ViewServer
2) You can also reuse layout like a component with the include tag:
<include android:id="#+id/your_id" layout="#layout/layout_name" />
So, I put a bounty on this one, and here is what I've found.
Inflating with a null reference is A Bad Idea(TM). Essentially, that View won't get the proper layout parameters it needs (its parent sets a whole bunch of them, with a whole bunch of magic/logic involved). So inflating into null means no parents, and no inherited layout parameters. One can manually set a number of these parameters, but due to the magic involved it might not solve your problem.
The "solution(s)" that I've come up with involve; using include (when you know how many you need) and pulling them into code, or inflating to a parent (when you need true dynamic, N things). And of course, the XML you inflate will have ID collisions, so I go about it by grabbing the last child (e.g. getChildAt(getChildCount()-1) ) of whatever I'm looking for, etc.
Did you try passing yourself as the root:
View.inflate(context, R.layout.xml, this);
Since you will be the parent of this View that complies with the javadoc spec.

Set attributes (margin, gravity, etc...) to an Android view programmatically (without XML)

I need to create a GUI (layout+views) in my .java activity class (I know it's far more flexible and easier to use .xml layout file, but I don't want to use it for now).
I can't find any setGravity() (but a "Gravity" object I can't figure how to use) or any set setMargin() method for the "View" object.
What is the easiest way to do it ?
Thanx.
For setting the margin on component. The following leaves the existing margins as previously set and sets the left margin as zero.
TextView title = ((TextView)findViewById(R.id.default_panel_title))
final ViewGroup.MarginLayoutParams lpt =(MarginLayoutParams)title.getLayoutParams();
lpt.setMargins(0,lpt.topMargin,lpt.rightMargin,lpt.bottomMargin);
title.setLayoutParams(lpt);
You can add gravity to the "layouts" not to the "controls". Try to set gravity to any of your Linear/Relative or Frame layouts using setGravity(); .
Eg:
LinearLayout lll = (LinearLayout) findViewById(R.id.layoutname);
lll.setGravity(Gravity.CENTER);

Categories

Resources