What is android here?
what is Orientation here?
What is Vertical ?
I would be pleased to know if they are classes or packages or methods..?
I am confused?
Can some one explain hierarchy of it?
I am sure you have seen this inside the <LinearLayout>.
It means that whatever view you take inside the LinearLayout will be shown in screen by vertical (like Stake of views).
Every attributes started with android followed by : so here orientation is an attribute and vertical is the value to be assigned this attribute.
Update:
(Answer taken from here.)
For android:orientation="vertical", your views get stacked vertically like this:
View1
View2
View3
View4
etc...
And For android:orientation="horizontal", your views gets placed horizontally like this:
View1 View2 View3 View4 etc...
This is the XML tag for the Layout properties of any Layout Widget for Android UI.
android:orientation is the XML tag and "vertical" is value for the same. so when it will be loaded in UI framework, child of the layout will be arranged in vertical form.
These are Input parameters for XML tags . Although Java is an object oriented language ,but it does not means that you will consider every element of android as Classes . XML Layout structure is view forming technique which use native kit internally .so these #android:something are just identifier to tell the native kit what to do . nothing else .
This is the code written in android.widget.LinearLayout.java
#Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
if (mOrientation == VERTICAL) {
layoutVertical();
} else {
layoutHorizontal();
}
}
You can view the SOURCE CODE HERE, Based on the orientation and gravity attribute how the android sets Child Views into Parent.
Related
What I intend to achieve
The item view should occupy the entire height of the item
It could be that the item height is lesser than the height of the tallest item in the recyclerview, in which case it should just stick to the top like in the screenshot above.
The bug I'm running into
As in the screenshot above, views are getting truncated.
What I've tried so far
Initially I went with wrap_content on the recyclerview, now that it is supported. It didn't work when none of the views visible on the screen at the time were the tallest. This makes sense in how the view hierarchy is laid out. How can the height of something which hasn't even been bound to any data yet be calculated if the height is dependent on that data?
Workaround time :S
Instead of trying a custom layoutmanager, I first went with what I felt needed to be done - laying out all item views at the beginning to figure out their height.
There's a progressbar and an animation playing in the upper part of the screen to catch the user's attention while all this happens with recyclerview visibility set to invisible. I use two things, one didn't suffice - I've attached an observer in the adapter's onViewAttached() call and I've used a scroll change listener as well. There's a LinearSnapHelper attached to the recycler view to snap to adjacent (next or previous, depending on the scroll direction) position on scroll.
In this setup,
I'm going to each position in the recyclerview using layoutManager.smoothScrollToPosition()
Getting the child view height using
View currentChildView = binding.nextRv.getChildAt(layoutManager.findFirstCompletelyVisibleItemPosition());
if (currentChildView != null) {
currentChildHeight = currentChildView.getHeight();
}
in scroll change listener on RecyclerView.SCROLL_STATE_IDLE or by passing the height to the view attached observer mentioned above in the adapter's onViewAttachedToWindow()
#Override
public void onViewAttachedToWindow(BindingViewHolder holder) {
if (mObserver != null) {
mObserver.onViewAttached(holder.binding.getRoot().getHeight());
}
}
Storing a maxHeight that changes to the max of maxHeight and new child's height.
As is evident, this is ugly. Plus it doesn't give me the current view's height - onAttached means it's only just attached, not measured and laid out. It is the recycled view, not the view bound to current data item. Which presents problems like the truncation of view illustrated above.
I've also tried wrap_content height on the recycler view and invalidating from recycler's parent till the recycler and the child on scroll coming to SCROLL_STATE_IDLE. Doesn't work.
I'm not sure how a custom layoutmanager can help here.
Can someone guide me in the right direction?
I could not accept #Pradeep Kumar Kushwaha's answer because against one solution, I do not want different font sizes in the list. Consistency is a key element in design. Second alternative he gave couldn't work because with ellipsize I would need to give a "more" button of some sort for user to read the entire content and my text view is already taking a click action. Putting more some place else would again not be good design.
Changing the design with the simple compromise of resizing the recyclerview when the tallest, truncated item comes into focus, it turns into the simple use case of notifyItemChanged(). Even for the attempt I made using the view attached observer and scroll state listener, notifyItemChanged could be used but that approach is just too hacky. This I can live with in both code and design. Here goes the code required.
#Override
public void onScrollStateChanged(RecyclerView recyclerView, int newState) {
if (newState == RecyclerView.SCROLL_STATE_IDLE) {
int position = ((LinearLayoutManager) binding.nextRv.getLayoutManager())
.findFirstVisibleItemPosition();
if (position != nextSnippetAdapter.getItemCount() - 1) {
binding.nextRv.getAdapter().notifyItemRangeChanged(position, 2);
} else {
binding.nextRv.getAdapter().notifyItemChanged(position);
}
}
}
For my particular setup, calling for just these two elements works. It can further be optimized so as to call for single element at position + 1 in most cases, and checking and calling for the appropriate one in corner (literal) cases.
Inside your adapter where I can find two cards one on top and another on bottom
How I would have defined my layout is like this:
Cardview1
LinearLayout1 --> orientation vertical
cardview2 (Top card where text is written)
Linearlayout2 (where I can see icons such as like etc)-->orientation horizontal
Now fix the height of Linearlayout2 by setting it to wrap content.
And the height of cardview2 should be 0dp and add weight = 1
Now inside cardview2 add a TextView1 to matchparent in height and width.
Better inside textview1 add ellipsize to end and add max lines
If you want to show all lines try to find autoresizetextview library it can be founded here --> AutoResizeTextView
Hope it helps.
I think the recyclerview can be set to height wrap_content. And the items can be make like height to match_parent.
<androidx.recyclerview.widget.RecyclerView
android:layout_width="match_parent"
android:layput_height="wrap_content"/>
Item as:
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
// your coode
</androidx.constraintlayout.widget.ConstraintLayout>
I had little more requirement than the question. Even my problem solved in the way.
Remember I am using:
androidx.recyclerview:recyclerview:1.0.0-beta01
dependency for the project
I would like to know which is more profficient way of placing children in RelativeLayout. There are two approaches of doing this:
1) Place the main view with absolute position (like layout_centerInParent or set margins/paddings correspondent to parent view) After that you add other views and set them attributes like android:layout_above="#id/relative_view_id" and place them below relative view. It is not good way because your views hierarchy in xml does not match to what you see in preview.
2) You assign to children of RelativeLayout attributes with absolute id android:layout_above="#+id/relative_view_id" (+ appeared). It provides the correct views order in xml. BUT when you looking for declaration of view with relative_view_id from java code (by pressing cmd+B) Android Studio suggests all the views where you declared #+id. In our case View with attribute android:layout_above="#+id/relative_view_id" will also appear in search results.
What is your way of placing Views in RelativeLayout?
android:layout_above
Positions the bottom edge of this view above the given anchor view ID.
Accommodates bottom margin of this view and top margin of anchor view.
For your question I would prefer No 1 way .
android:layout_above="#id/relative_view_id"
Its refer the already generated id (relative_view_id) .
I have an Activity which has an EditText programmatically added to a LinearLayout inside a ScrollView.
ScrollView <- LinearLayout <- EditText(s)
Is possible to rearrange their position by seting X and Y axis or something as Swing does for Components?
This is my code:
for (Field classField : todoFields) {
CustomEditText field = new CustomEditText(this);
field.setName(classField.getName());
layoutFieldWrapper.addView(field);
}
EDIT:
Can I freely move components around the interface, for instance: Put component next to another by setting the same Y and different X or overlap any of them to other, ecc.. does it's possible?
If I get you right then you can call the method with index parameter like this:
layoutFieldWrapper.addView(field, index);
Hope this is the right suggestion or hint.
You can use RelativeLayout. Replace it with your LinearLayout inside your ScrollView. This layout gives you much accessibility. You can move your views in your user interface freely using this type of layout. You will have to play around with some attributes and try like: gravity, layout_centerVertical, padding, layout_margin, layout_width, layout_height, layout_below, layout_toRightOf, and a lot more...
Reference Link: http://developer.android.com/guide/topics/ui/layout/relative.html
I have created a custom layout manager derived from LinearLayout. (I do not really use much of LinearLayout functionality but I do not want to care about all of many ViewGroup abstract methods.) I have overwritten only
protected void onLayout(boolean changed, int l, int t, int r, int b)
method and I call child.layout(...) in MyLayout.onLayout(...) for each of its children. All other stuff is original LinearLayout. It will work fine and children will be placed correctly in their parent MyLayout if the children are simple controlls without children (grandchildren of the MyLayout).
Problems come when I use some ViewGroup (LinearLayout, ViewSwitcher, ...) with children as child of MyLayout. In this case children (of MyLayout) are placed well but grandchildren (of MyLayout) inside of each child not. It seems paramaters and values like wrap_content, fill_parent, layoutWeight are not handled correctly. For example ViewSwitcher in MyLayout does not show its content, LinearLayouts (child of MyLayout) children (grandchildren of MyLayout) with fill_parent have size of 0px, CompoundButton (child of MyLayout) sometimes does not show its text...
It seems child.layout(...) in MyLayout.onLayout sets the size and position of each child correctly but I need to call some other method to make layout in each child working well (if the child is ViewGroup with children). Is there something like that or MyLayout with just changed onLayout should work well?
Thanks for all advices.
sounds like you need to overide onMeasure and call measure() on each of the children. if you children are viewgroups and the grandchildren are views then you want to loop through the children and call measure(int,int). then the children should call measure on the grandchildren.
take a look at the linearLayout source:
http://www.grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/2.3.6_r1/android/widget/LinearLayout.java#LinearLayout.onMeasure%28int%2Cint%29
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.